ABB - REF542+ Protection Manual 1 Mrs 755860 en 2008

REF 542plusREF 542plus

Protection Functions: Configuration and Settings

Protection manual

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Contents

Copyrights ................................................................................. 9

1. Introduction............................................................ 111.1. This manual .............................................................111.2. Use of symbols ........................................................111.3. Intended audience ....................................................111.4. Product documentation ............................................. 121.5. Document revisions.................................................. 12

2. Safety Information...................................................13

3. Analog measurement ..............................................15

4. Analog Inputs .........................................................174.1. Analog Inputs.......................................................... 17

4.1.1. Analog board selection ................................. 184.1.2. Current transformer ...................................... 194.1.3. Current Rogowski ........................................ 204.1.4. Voltage transformer ...................................... 21

4.2. General constraints .................................................. 244.3. Network characteristics ............................................. 244.4. Calculated values .................................................... 25

5. Control and monitoring ...........................................275.1. Measurement supervision NPS and PPS ..................... 27

5.1.1. Input/output description................................. 275.1.2. Configuration............................................... 285.1.3. Measurement mode ..................................... 305.1.4. Operation criteria ......................................... 305.1.5. Setting groups............................................. 305.1.6. Parameters and events................................. 31

5.2. Power factor controller .............................................. 315.2.1. Input/output description................................. 325.2.2. Configuration............................................... 335.2.3. Measurement mode ..................................... 355.2.4. Parameters and events................................. 36

6. Protection functions................................................396.1. Current protection functions ....................................... 39

6.1.1. Inrush blocking ............................................ 396.1.1.1. Input/output description .................. 396.1.1.2. Configuration ................................ 406.1.1.3. Measurement mode ....................... 426.1.1.4. Operation criteria........................... 43

Multifunction Protection and Switchgear ControlUnit


Protection manual

REF 542plusREF 542plus1MRS755860

Issued: 15.07.2003Version: C/30.04.2007

6.1.1.5. Setting groups .............................. 456.1.1.6. Parameters and events .................. 45

6.1.2. Inrush harmonic........................................... 466.1.2.1. Input/output description .................. 476.1.2.2. Configuration ................................ 476.1.2.3. Measurement mode ....................... 506.1.2.4. Operation criteria........................... 506.1.2.5. Steady-state detection.................... 516.1.2.6. Setting groups .............................. 516.1.2.7. Parameters and events .................. 51

6.1.3. Directional overcurrent protection.................... 516.1.3.1. Input/output description .................. 526.1.3.2. Configuration ................................ 536.1.3.3. Measurement mode ....................... 556.1.3.4. Operation criteria........................... 556.1.3.5. Current direction............................ 566.1.3.6. Voltage memory ............................ 576.1.3.7. Setting groups .............................. 576.1.3.8. Parameters and events .................. 58

6.1.4. Overcurrent protection .................................. 586.1.4.1. Input/output description .................. 596.1.4.2. Configuration ................................ 606.1.4.3. Measurement mode ....................... 626.1.4.4. Operation criteria........................... 626.1.4.5. Setting groups .............................. 636.1.4.6. Parameters and events .................. 63

6.1.5. Overcurrent IDMT ........................................ 646.1.5.1. Input/output description .................. 646.1.5.2. Configuration ................................ 656.1.5.3. Measurement mode ....................... 686.1.5.4. Operation criteria........................... 686.1.5.5. Setting groups .............................. 686.1.5.6. Parameters and events .................. 68

6.1.6. Earth fault protection .................................... 696.1.6.1. Input/output description .................. 706.1.6.2. Configuration ................................ 706.1.6.3. Measurement mode ....................... 726.1.6.4. Operation criteria........................... 736.1.6.5. Setting groups .............................. 736.1.6.6. Parameters and events .................. 73

6.1.7. Directional earth fault protection ..................... 736.1.7.1. Input/output description .................. 746.1.7.2. Configuration ................................ 756.1.7.3. Measurement mode ....................... 77

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REF 542plusREF 542plus Multifunction Protection and Switchgear ControlUnit


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6.1.7.4. Operation criteria........................... 786.1.7.5. Setting groups .............................. 796.1.7.6. Parameters and events .................. 80

6.1.8. Sensitive directional earth fault protection ........ 806.1.8.1. Input/output description .................. 816.1.8.2. Configuration ................................ 816.1.8.3. Measurement mode ....................... 846.1.8.4. Operation criteria........................... 846.1.8.5. Setting groups .............................. 866.1.8.6. Parameters and events .................. 86

6.1.9. Sector directional earth fault protection ............ 876.1.9.1. Input/output description .................. 886.1.9.2. Configuration ................................ 896.1.9.3. Measurement mode ....................... 946.1.9.4. Operation criteria........................... 956.1.9.5. Trip and Block areas...................... 956.1.9.6. Start drop-off delay function ............ 976.1.9.7. Setting groups .............................. 986.1.9.8. Parameters and events .................. 98

6.1.10. Earth fault IDMT .......................................... 986.1.10.1. Input/output description .................. 996.1.10.2. Configuration ...............................1006.1.10.3. Measurement mode ......................1036.1.10.4. Operation criteria..........................1036.1.10.5. Setting groups .............................1036.1.10.6. Parameters and events .................103

6.2. Voltage protection ...................................................1046.2.1. Overvoltage protection.................................104

6.2.1.1. Input/output description .................1056.2.1.2. Configuration ...............................1056.2.1.3. Measurement mode ......................1076.2.1.4. Operation criteria..........................1086.2.1.5. Setting groups .............................1086.2.1.6. Parameters and events .................109

6.2.2. Undervoltage protection ...............................1096.2.2.1. Input/output description ................. 1106.2.2.2. Configuration ............................... 1116.2.2.3. Measurement mode ...................... 1136.2.2.4. Operation criteria.......................... 1136.2.2.5. Behavior at low voltage values ....... 1146.2.2.6. Setting groups ............................. 1156.2.2.7. Parameters and events ................. 115

6.2.3. Residual overvoltage protection..................... 1166.2.3.1. Input/output description ................. 116



Protection manual


6.2.3.2. Configuration ............................... 1176.2.3.3. Measurement mode ...................... 1196.2.3.4. Operation criteria..........................1206.2.3.5. Setting groups .............................1206.2.3.6. Parameters and events .................120

6.3. Motor protection .....................................................1206.3.1. Thermal overload protection .........................120

6.3.1.1. Input/output description .................1216.3.1.2. Configuration ...............................1226.3.1.3. Measurement mode ......................1256.3.1.4. Operation criteria..........................1256.3.1.5. Thermal memory at power-down .....1266.3.1.6. Setting groups .............................1266.3.1.7. Parameters and events .................126

6.3.2. Motor start protection...................................1276.3.2.1. Input/output description .................1286.3.2.2. Configuration ...............................1286.3.2.3. Measurement mode ......................1316.3.2.4. Operation criteria..........................1316.3.2.5. Setting groups .............................1326.3.2.6. Parameters and events .................132

6.3.3. Blocking rotor .............................................1326.3.3.1. Input/output description .................1336.3.3.2. Configuration ...............................1336.3.3.3. Measurement mode ......................1366.3.3.4. Operation criteria..........................1366.3.3.5. Setting groups .............................1366.3.3.6. Parameters and events .................137

6.3.4. Number of starts.........................................1376.3.4.1. Input/output description .................1386.3.4.2. Configuration ...............................1386.3.4.3. Measurement mode ......................1406.3.4.4. Operation criteria..........................1416.3.4.5. Setting groups .............................1416.3.4.6. Parameters and events .................142

6.4. Distance protection .................................................1426.4.1. Input/output description................................1436.4.2. Configuration..............................................1446.4.3. Operation mode..........................................1506.4.4. Setting groups............................................1526.4.5. Parameters and events................................152

6.5. Differential protection...............................................1546.5.1. Transformer Differential Protection .................154

6.5.1.1. Input/output description .................154

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6.5.1.2. Configuration ...............................1556.5.1.3. Measurement mode ......................1596.5.1.4. Operation criteria..........................1596.5.1.5. Tripping characteristic ...................1616.5.1.6. Inrush stabilization ........................1626.5.1.7. Setting groups .............................1636.5.1.8. Parameters and events .................163

6.5.2. Restricted differential protection.....................1646.5.2.1. Input/output description .................1646.5.2.2. Configuration ...............................1656.5.2.3. Measurement mode ......................1686.5.2.4. Operation criteria..........................1686.5.2.5. Tripping characteristic ...................1696.5.2.6. Directional criterion for stabilization

against CT saturation ....................1706.5.2.7. Setting groups .............................1726.5.2.8. Parameters and events .................172

6.6. Other Protections....................................................1736.6.1. Unbalanced load protection ..........................173

6.6.1.1. Input/output description .................1736.6.1.2. Configuration ...............................1746.6.1.3. Measurement mode ......................1776.6.1.4. Operation criteria..........................1776.6.1.5. Setting groups .............................1786.6.1.6. Parameters and events .................179

6.6.2. Directional power protection..........................1796.6.2.1. Input/output description .................1806.6.2.2. Configuration ...............................1806.6.2.3. Measurement mode ......................1826.6.2.4. Operation criteria..........................1826.6.2.5. Setting groups .............................1836.6.2.6. Parameters and events .................183

6.6.3. Low load protection .....................................1836.6.3.1. Input/output description .................1846.6.3.2. Configuration ...............................1846.6.3.3. Measurement mode ......................1876.6.3.4. Operation criteria..........................1876.6.3.5. Setting groups .............................1876.6.3.6. Parameters and events .................187

6.6.4. Frequency supervision.................................1886.6.4.1. Input/output description .................1886.6.4.2. Configuration ...............................1896.6.4.3. Measurement mode ......................1916.6.4.4. Operation criteria..........................191



Protection manual


6.6.4.5. Setting groups .............................1926.6.4.6. Parameters and events .................192

6.6.5. Synchronism check .....................................1926.6.5.1. Input/output description .................1936.6.5.2. Configuration ...............................1936.6.5.3. Measurement mode ......................1966.6.5.4. Operation criteria..........................1966.6.5.5. Setting groups .............................1986.6.5.6. Parameters and events .................198

6.6.6. Switching resonance protection .....................1986.6.6.1. Input/output description .................1996.6.6.2. Configuration ...............................2006.6.6.3. Measurement mode ......................2026.6.6.4. Operation criteria..........................2026.6.6.5. Setting groups .............................2036.6.6.6. Parameters and events .................203

6.6.7. High harmonic protection .............................2046.6.7.1. Input/output description .................2046.6.7.2. Configuration ...............................2056.6.7.3. Measurement mode ......................2076.6.7.4. Operation criteria..........................2076.6.7.5. Setting groups .............................2086.6.7.6. Parameters and events .................208

6.6.8. Frequency protection ...................................2086.6.8.1. Input/output description .................2096.6.8.2. Configuration ...............................2106.6.8.3. Measurement mode ......................2136.6.8.4. Operation criteria..........................2136.6.8.5. Setting groups .............................2146.6.8.6. Parameters and events .................214

6.7. Autoreclose ...........................................................2156.7.1. Input/output description................................2156.7.2. Configuration..............................................2166.7.3. Operation mode..........................................2186.7.4. Setting groups............................................2206.7.5. Parameters and events................................220

6.8. Fault recorder.........................................................2226.8.1. Input/output description................................2226.8.2. Configuration..............................................2236.8.3. Operation ..................................................2246.8.4. Parameters and events................................226

7. Abbreviations ....................................................... 227

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CopyrightsThe information in this document is subject to change without notice and should notbe construed as a commitment by ABB Oy. ABB Oy assumes no responsibility forany errors that may appear in this document.

In no event shall ABB Oy be liable for direct, indirect, special, incidental orconsequential damages of any nature or kind arising from the use of this document,nor shall ABB Oy be liable for incidental or consequential damages arising fromuse of any software or hardware described in this document.

This document and parts thereof must not be reproduced or copied without writtenpermission from ABB Oy, and the contents thereof must not be imparted to a thirdparty nor used for any unauthorized purpose.

The software or hardware described in this document is furnished under a licenseand may be used, copied, or disclosed only in accordance with the terms of suchlicense.

Copyright © 2007 ABB Oy

All rights reserved.

Trademarks

ABB is a registered trademark of ABB Group. All other brand or product namesmentioned in this document may be trademarks or registered trademarks of theirrespective holders.

Guarantee

Please inquire about the terms of guarantee from your nearest ABB representative.



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1. Introduction

1.1. This manual

This manual describes how to use the protection functions available inREF 542plus.

This manual is addressed to engineering personnel and to anyone who needs toconfigure REF 542plus.

1.2. Use of symbols

This publication includes the following icons that point out safety-related conditionsor other important information:

The warning icon indicates the presence of a hazard which could resultin personal injury.

The caution icon indicates important information or warning related tothe concept discussed in the text. It might indicate the presence of ahazard which could result in corruption of software or damage toequipment or property.

The information icon alerts the reader to relevant facts and conditions.

Although warning hazards are related to personal injury, it should be understoodthat operation of damaged equipment could, under certain operational conditions,result in degraded process performance leading to personal injury or death.Therefore, comply fully with all warning and caution notices.

1.3. Intended audience

This manual is intended for operators, supervisors and administrators to supportnormal use of the product.



Protection manual


1.4. Product documentation

Name of the Manual Document ID

Real Time Clock Synchronization, IRIG-B Input Time Master 1MRS755870

CAN Manual 1VTA100189-Rev 1, en

Configuration Manual 1MRS755871

iButton Programmer User Manual 1MRS755863

Manual Part 3, Installation and Commission 1 VTA100004

Manual Part 4, Communication 1VTA100005

Motor Protection with ATEX Certification, Manual 1MRS755862

Operator’s Manual 1MRS755869

Protection Manual 1MRS755860

Technical Reference Manual 1MRS755859

Technical Reference Modbus RTU 1MRS755868

Web Manual, Installation 1MRS755865

Web Manual, Operation 1MRS755864

1.5. Document revisions

Version IED Revisionnumber

Date History

1VTA0002 15.07.2003 1st release, valid since SW V4C01

1VTA10002 Rev02 10.12.2003 2nd release, valid since SW V4D02

1VTA10002 Rev03 01.05.2004 3rd release, valid since SW V4D02e

A 28.02.2006 Document updated* language* layout

B 2.5 30.9.2006 Updated to software version V4E03x

C 2.5 SP1 30.04.2007 Updated to software version V4E04x

Applicability

This manual is applicable to REF 542plus Release 2.5. software version V4E04xand subsequent.

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2. Safety InformationThe safety warnings should always be observed. Non-observance can result indeath, personal injury or substantial damages to property. Guarantee claims mightnot be accepted when safety warnings are not respected.

Do not make any changes to the REF 542plus configuration unless youare familiar with the REF 542plus and its Operating Tool. This mightresult in disoperation and loss of warranty.



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3. Analog measurementThe 8 available Analog Input channel measures are acquired and processedaccording to the following flowchart.

A050604

Fig. 3.-1 Analog measurement

The analog signal entering the Analog Input board goes through two hardwarefilters to reduce noise. It is then sampled and converted to digital information by asigma-delta Analog/Digital converter with an acquisition rate of 19.2kHz.

The acquisition is performed in parallel on all 8 analogue channels, and therefore thedata samples of the network currents and voltages are contemporary, that is, nophase shift/time delay is introduced between the network quantities.

The digital data is then processed by a digital filter LP1 to reduce the informationbandwidth to 1,5 kHz.

This information is then provided directly to the DFT/ RMS and Math block,performing the Discrete Fourier Transformation and RMS value analysis for theprotection working on the full RMS harmonic content up to the 25th harmonic(switching resonance, high harmonic) and to the frequency protection for higherdiscrimination of zero crossing.

For all the other protection functions, the digital data is down sampled, that is, onesample each 4 is used to 4800 samples/s , maintaining the same informationbandwidth.

Furthermore, the signal is digitally filtered by LP2 and LP3 (HSTS functionanalogue quantities only) and provided to the DFT/ RMS and math block,performing the discrete fourier transformation and RMS value analysis.



Protection manual


Almost all protection functions are based on the DFT (Discrete FourierTransformation) calculation for the selected network rated frequency. Only thethermal overload protection performs the temperature calculation by applying theRMS current values, in which all harmonics are considered.

In addition the following functions use:

* Overcurrent instantaneous

To function the peak value of the measured current under transient condition for afaster response. This is when the instantaneous peak value is over three times higher.

SQRT (2) the RMS value:

I Ix peak x RMS_ _2 3> ⋅ (1)

* Inrush harmonic

The function evaluates the ratio between the current values at 2nd harmonic and atfundamental frequency.

* Differential protection

The function evaluates the measured amount of differential current at thefundamental, 2nd and 5th harmonic frequencies.

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4. Analog InputsThe Analog Inputs dialog allows the user to configure:

* Analog input channels* Network characteristics (REF 542plus can handle currents or voltages from two

different networks)* Calculated values (power, THD, mean and maximum current values over the

desired time interval)

4.1. Analog Inputs

A050606

Fig. 4.1.-1 Analog Inputs

To ease the input of analog input channels, the user can push the Get group databutton in the Inputs tab of Analog Inputs dialog and then select the used board fromthe list. This automatically configures the used analog input channels to the propersensor type and sets default values for each sensor type.



Protection manual


4.1.1. Analog board selection

A050695

Fig. 4.1.1.-1 Analog board selection

To complete the configuration of each analog input channel, that is, to set theappropriate Rated Primary and Secondary Values, the user must double-click theline in the Inputs tab of Analog Inputs dialog.

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4.1.2. Current transformer

A050607

Fig. 4.1.2.-1 Current transformer

Board Input Rated Value (IRV) at present can be 0.2, 1 or 5 A only depending on thetype of CT mounted on Analog Input board.

In case of a mismatch between Rated Secondary Value (RSV) and Board InputRated Value, REF 542plus automatically compensates the protection functionthresholds.

Default direction of the polarity for the CT is Line. If Bus is selected, the polarity ofanalog signal will be inverted to preserve directions in directional protections. Theamplitude and phase corrections can be introduced.



Protection manual


4.1.3. Current Rogowski

A050608

Fig. 4.1.3.-1 Current Rogowski

The current sensors usually cover a rated primary current range, for example thetype KEVCD 24 A covers the primary current range 80 – 1250A.

One value should be chosen as Rated Primary Value (RPV), usually the valuematching through the current sensor rated transformation ratio the Rated SecondaryValue (RSV) and Board Input Rated Value (IRV). For example, with atransformation ratio 80 A/0.150 V and RSV, IRV value of 0.150 V a RPV of 80 Acan be chosen. The RPV value introduced will be used as the rated current inprotection functions.

The rated transformation ratio of current sensors, typically 80 A/0.150V, shall always be correctly introduced to avoid incorrectmeasurements. Such ratio shall equal the ratio of RPV over RSV.

IRV at present can be only 0.150 V depending on the Rogowski sensor input onAnalog Input board. In case of a mismatch between RSV and IRV, REF 542plusautomatically compensates the protection function thresholds.

Default direction for the polarity of the Rogowski current sensors is Line. If Bus isselected, the polarity of analog signal will be inverted to preserve directions indirectional protections. The amplitude and phase corrections can be introduced.

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4.1.4. Voltage transformer

Voltage transformers can be phase, line or residual (open delta) voltagetransformers.

Phase-voltage transformer

A050609

Fig. 4.1.4.-1 Phase-voltage transformer

Phase-voltage transformers normally refer the rated phase-voltage at primary sidewith rated phase voltage on the secondary side, for example:

203

1003

kV V: (2)

This is shown below RSV line in the Transformer ratio dialog. Whenentering the VT rated voltage data, it is not necessary to perform division by:

3 (3)

IRV at present can be 100 V only depending on the input transformer mounted onAnalog Input Board.



Protection manual


In case of a mismatch between RSV and IRV, REF 542plus automaticallycompensates protection function thresholds. If Invert phase is selected, the polarityof analog signal will be inverted. The amplitude and phase corrections can beintroduced.

Line voltage transformer

A050612

Fig. 4.1.4.-2 Line voltage transformer

Line voltage transformers normally refer rated line voltage at primary side withrated voltage on secondary side, for example 20 kV:100 V. This is shown below theRSV line in Transformer ratio dialog.


In case of a mismatch between RSV and IRV, REF 542plus automaticallycompensates protection function thresholds. If Invert phase is selected, the polarityof analog signal will be inverted. The amplitude and phase corrections can beintroduced.

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Residual voltage transformer (open delta)

A050683

Fig. 4.1.4.-3 Residual voltage transformer (open delta)

Residual voltage transformers normally refer rated phase-voltage at the primary sidewith secondary side rated voltage of each winding in the open delta, for example:

203

1003

kV : (4)

This is shown below RSV line in Transform ratio dialog.

When entering VT rated voltage data, it is not necessary for the user to perform anydivision. The user must simply select in the VT type dialog the correspondingsecondary winding denominator.


In case of a mismatch between RSV and IRV, REF 542plus automaticallycompensates the protection function thresholds. If Invert phase is selected, thepolarity of analog signal will be inverted. The amplitude and phase corrections canbe introduced.



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4.2. General constraints

* Channels 1... 6 can be used only for phase currents, phase voltages or linevoltages

* Channels 7 and 8 can be used also either for neutral current, residual voltage orline voltage for synchronism check function.

* Current and voltage sensors inside the triples 1 ... 3 and 4 ... 6 must have thesame characteristics (RPV, RSV and IRV)

4.3. Network characteristics

A050687

Fig. 4.3.-1 Networks tab

REF 542plus can handle two different networks or network parts having the samefrequency. By default only one network is used.

If the second network is needed, it must be enabled in the Networks tab of AnalogInputs dialog.

For each network the rated nominal voltage and current can be configured. Thesevalues are used by HMI led bars to scale the displayed quantities.

All the protection functions refer to Analog Input RPV as In, Un toscale Start values.

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4.4. Calculated values

A050688

Fig. 4.4.-1 Calculated values

The preferred reference system, that is load or generator, and some calculations canbe enabled in REF 542plus:

* Power (either three-phase or Aaron)* Mean and maximum current values* Total harmonic distortion (on voltage sensors only)

An example of the calculation of the power and the power factor is described in thefollowing. The power calculation is based on the fundamental component at ratednetwork frequency, which is 50 or 60 Hz, of the current and voltage measurementquantities. The fundamental component is calculated by DFT (Discrete FourierTransformation). The DFT always calculates the real and the imaginary componentof the phasors:

A070172

Fig. 4.4.-2 Discrete Fourier Transformation

In REF 542plus, which is connected to a voltage and current transformer, thefollowing phasors are available:

Voltage: ImV V j V= +Re (5)

Current: ImI I j I= +Re (6)



Protection manual


As shown in the equation above, the voltage and current phasors are complexquantities. The power is calculated by multiplying the voltage and currentquantities. Consequently, the power can also be expressed as a complex quantity.

Power: S P j Q= + (7)

In the equation above, S is the apparent power, P the active power and Q the reactivepower. However, according to the theory of power calculation, the powercalculation is performed by using the conjugated complex quantity of the currentphasor.

Conjugatedcurrent: - ImI I j I* Re= (8)

Consequently, the equation for the power calculation is as follows:

S V I P j Q V I V I j V I V I= = + = + +* ( . . ) ( . - . Re Re Im Im Im Re Re Im ))(9)

The active power P can be calculated as follows:

P V I V I= +Re Re Im Im . . (10)

For the reactive power, the following equation can be applied:

Q V I V I= Im Re Re Im . - . (11)

The apparent power is then:

S V I V I V I V I= +( ) + ( )Re Re Im Im Im Re Re Im . . . - . 2 2 (12)

The power factor is:

cosϕ = PS

(13)

In the equation above, φ is the angle between the apparent power S and the activepower P, which ranges from -1 to +1. For a three-phase system, the calculation mustbe carried out in each phase or in two phases using the Aaron scheme and the resultmust be added together.

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5. Control and monitoring

5.1. Measurement supervision NPS and PPS

REF 542plus provides two types of measurement supervision functions. Each ofthem can be independently activated:

* Positive Phase Sequence (PPS)* Negative Phase Sequence (NPS)

A050689

Fig. 5.1.-1 Measurement supervision

5.1.1. Input/output description

Table 5.1.1.-1 Input

Name Type Description

BS Digital signal (active high) Blocking signal

When the BS signal becomes active, the measurement supervision function is resetno matter its state. This means that all the output pins go low generating the requiredevents (if any), and all the internal registers and timers are cleared. The protectionfunction will then remain in idle state until the BS signal goes low.

Table 5.1.1.-2 Output


Warning Digital signal (active high) Warning signal

Failing Digital signal (active high) Failing signal

Warning is the start signal. Warning signal will be activated when the startconditions are true. The negative phase sequence value exceeds the setting thresholdvalue for NPS , and the positive phase sequence value falls below the settingthreshold value for PPS.

Failing signal will be activated when the start conditions are true and the operatingtime has elapsed.



Protection manual


5.1.2. Configuration

A050690

Fig. 5.1.2.-1 General

A050691

Fig. 5.1.2.-2 Sensors

The measurement supervision functions operate on all sensors in a triple. The analogchannels 1-3 or 4-6 can be used to supervize the phase currents, phase voltages orline voltages.

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A050692

Fig. 5.1.2.-3 Parameters

Start Value: Positive/Negative phase sequence threshold for Start condition detection.

Time: Time delay for Trip condition detection.

A050693

Fig. 5.1.2.-4 Events



Protection manual


A050694

Fig. 5.1.2.-5 Pins

5.1.3. Measurement mode

Measurement supervision functions evaluate the measured amount of positive andnegative phase sequence values at the fundamental frequency.

5.1.4. Operation criteria

If the negative phase sequence value exceeds the setting threshold value (Startvalue) in the NPS based functions, or if the positive phase sequence value fallsbelow the setting threshold (Start value) the function enters the START status andraises the warning. After the preset operating time (Time delay) has elapsed, thefailing signal is generated.

The measurement function will come back in passive status and the warning signalwill be cleared, if the negative phase sequence value falls below 0.95 the settingthreshold value for NPS , or if the positive phase sequence value exceed 1.05 thesetting threshold value for PPS.

The measurement function will exit the failing status and the failing signal will becleared when the negative phase sequence value falls below 0.4 the setting thresholdvalue for NPS, or if the positive phase sequence value exceed 1.05 the settingthreshold value for PPS.

5.1.5. Setting groups

Two parameter sets can be configured for each of the measurement supervisionfunctions.

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5.1.6. Parameters and events

Table 5.1.6.-1 Setting values

Parameter Values Unit Default Explanation

Start value(PPS)

0.30 ... 0.90 In or Un 0.85 PPS threshold to undergo.

Time delay 30 ... 30000 ms 1000 Time delay from start condition(warning signal) to failingsignal.

Start value(NPS)

0.05 ... 0.40 In or Un 0.10 NPS threshold to be exceeded.

Time delay 30 ... 30000 ms 1000 Time delay from start conditionto failing signal.

Table 5.1.6.-2 Events

Code Event reason

E0 Warning signal is active

E1 Warning signal cancelled

E6 Failing signal is active

E7 Failing signal is back to inactive state

E18 Function block signal is active

E19 Function block signal is back to inactive state

By default all events are disabled.

5.2. Power factor controller

The power factor controller is designed to control reactive power compensation inpower systems. The magnitude of the reactive power in the network is derived fromthe measured power factor. Consequently, the power factor controller permanentlymonitors the power factor, which is defined as the ratio of the effective power to theactive power. The PFC then controls the switching ON/OFF the available capacitorsbanks to reach the set power factor target.

A050697

Fig. 5.2.-1 Power factor controller



Protection manual





BL Digital signal (active high) Blocking signal

DISCONNECT Digital signal (active high) Disconnect all capacitorbanks

RESET Digital signal (active high) Reset the function

OVERTEMP. Digital signal (active high) Overtemperature

VMIN / VMAX Digital signal (active high) Voltage out of range

VA MAX Digital signal (active high) Overload due to overvoltage

MODE: MAN. Digital signal (active high) Mode manual

SET NIGHT Digital signal (active high) Set night parameter

MANUAL CONTROL BANK 0 Digital signal (active high) Switch bank 0 manually




CHECKED BACK BANK 0 Digital signal (active high) Status on indication bank 0




When the BS signal becomes active, the protection function is reset no matter itsstate. This means that all the output pins go low generating the required events (ifany), and all the internal registers and timers are cleared. The protection functionwill then remain in idle state until BS signal goes low.



Q ALARM Digital signal (active high) Alarm indication Q

COS ФALARM Digital signal (active high) Alarm indication cos Ф

OPERAT. ALARM Digital signal (active high) Operation Alarm (reset onlyby power off)

GENERAL ALARM Digital signal (active high) General alarm

SWITCH ON/OFF BANK 0 Digital signal (active high) Bank 0 on (high), off (low)




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A050698


A050699

Fig. 5.2.2.-2 Capacitor banks



Protection manual


A050700

Fig. 5.2.2.-3 Control data

A050701

Fig. 5.2.2.-4 Time

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A050702



A050750

Fig. 5.2.2.-6 Pins

5.2.3. Measurement mode

When a reactive power consumer is switched into the network, the current variableincreases. Simultaneously, the phase displacement increases in relation to the relatedvoltage quantity. As a result, the reactive power increases and the power factor isreduced correspondingly. Because of the increase in the current measured quantity



Protection manual


and the angle of the phase displacement, an increased voltage drop in the powersystem must be taken into account. For more detailed information please refer to thecorresponding application notes.




Neutral zone 105 … 200 % QCO 115

Pickup zone 0 … 100 % QCO 0

Reactive power ofsmallest QCO

1 … 20000 kVA 100

Number of banks 1 … 4 1

Maximum switchingcycles

1 … 10000 2500

Set point cos phi 0.7 ... 1.0 Ind/cap 0.9 ind

Limiting value cos phi 0 … 1 Ind/cap 0

Discharge blockingtime

1 … 7200 s 900

Dead Time 1 … 120 s 10

Power on delay 1 … 7200 s 900

Duration ofintegration

1 … 7200 s 900


Code Event reason

E0 Bank 0 on

E1 Bank 1 on

E2 Bank 2 on

E3 Bank 3 on

E4 Bank 0 off

E5 Bank 1 off

E6 Bank 2 off

E7 Bank 3 off

E8 Overtemperature started

E9 Overtemperature back

E10 Va max started

E11 Va max back

E12 Vmin/Vmax started

E13 Vmin/Vmax back

E14 Command DISCONNECT started

E15 Command DISCONNECT back

E16 Cos phi warning started

E17 Cos phi warning back

E18 Alarm Q started

E19 Alarm Q back

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Table 5.2.4.-2 Events (Continued)

Code Event reason

E20 Warning switching cycle

E21 Alarm reset

E22 Block signal started

E23 Block signal back

E24 Manual operating mode

E25 Automatic operating mode

E26 Night mode

E27 Day mode



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39

6. Protection functions

6.1. Current protection functions

6.1.1. Inrush blocking

REF 542plus has one inrush blocking protection function. This function is replacedfrom the inrush harmonic function and it has to be preferred when a very fastresponse time is required only.

The following current protection functions are blocked by the inrush blockingprotection function without the need of additional wiring in the FUPLA (that is, theblock to the protection functions is implicit).

* Overcurrent instantaneous* Overcurrent high* Overcurrent low* Directional overcurrent high* Directional overcurrent low* IDMT* Earthfault IDMT

A050769

Fig. 6.1.1.-1 Inrush blocking

6.1.1.1. Input/output description

Table 6.1.1.1.-1 Input



When the BS signal becomes active, the protection function is reset (no matter itsstate). This means that all the output pins go low generating the required events (ifany) and all the internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low.



Protection manual


Table 6.1.1.1.-2 Output


S L1 Digital signal (active high) Start signal of IL1



TRIP Digital signal (active high) Trip signal

S L1-3 are the start signals phase selective. The phase starting signal will beactivated when the respective phase current start conditions are true and theovercurrent protection will be implicitly blocked until the operating time (Time)has elapsed.

The TRIP signal will be activated when the start conditions are true (inrushdetection), the maximum measured current exceeds the threshold (limit N•I>>) andthe relevant overcurrent protection operating time has elapsed.

6.1.1.2. Configuration

A050770

Fig. 6.1.1.2.-1 General

Output Channel different from 0 means direct execution of the trip command, thatis, skipping FUPLA cyclic evaluation.

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A050811

Fig. 6.1.1.2.-2 Sensors

The protection function operates on any combination of current phases in a triple,for example, it can operate as single phase, double phase or three-phase protectionon phase currents belonging to the same system.

A050812

Fig. 6.1.1.2.-3 Parameters



Protection manual


N: Threshold I>> multiplier for fault detection and inrush protection trip

M: Threshold I> multiplier for inrush detection

Time: Overcurrent protection blocking Time at inrush detection

A050813

Fig. 6.1.1.2.-4 Events

A050814

Fig. 6.1.1.2.-5 Pins

6.1.1.3. Measurement mode

Inrush blocking function evaluates the current at the fundamental frequency.

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6.1.1.4. Operation criteria

An inrush is detected if the maximum measured current exceeds the threshold M•I>within 60 ms after it exceeded 10% of current threshold I>.

Here I> is the threshold (Start value I>) of the overcurrent low protectionfunction. If this protection function is not installed, the threshold of IDMTprotection function (Base current Ieb:, if installed) is used or a standard valueof 0.05•IN (if IDMT also is not installed).

If an inrush is detected, the above-listed protection functions are blocked until theend of inrush has been detected or the maximum preset inrush duration (that is,Time) has elapsed.

The end of inrush condition is detected when the maximum measured current fallsbelow M•0.65•I>. A counter is then started and 100 ms later the end of inrush isassumed. The current protection functions are then released from the block.

At feeder start-up, with current zero, the implicit block of theovercurrent protection function is already active. Only as the currentincreases, the inrush condition is evaluated and the block can bereleased if an inrush is not present.

The inrush blocking itself becomes a protection function, if the maximum measuredcurrent exceeds the limit N•I>> after the inrush detection. The operating time is thatof the overcurrent instantaneous (if installed) or 80 ms.

Here I>> is the threshold (Start value I>>) of the overcurrent high protectionfunction. If this protection function is not installed, the threshold of overcurrentinstantaneous protection function (if installed) is used or a standard value of 0.10•IN(if overcurrent instantaneous also is not installed).

The following three diagrams are not scaled, but they are provided solely for a betterunderstanding of the explanations of how the inrush blocking works.

Tesb is the operation counter that is compared to the set overcurrent protectionblocking time (that is, Time).

In Fig. 6.1.1.4.-1 inrush is detected within the 60 ms window. Then the end ofinrush condition is detected and the block released before protection-blocking timeexpires.



Protection manual


A050815

Fig. 6.1.1.4.-1 Current-time characteristic of the detected inrush process

In Fig. 6.1.1.4.-2 inrush is detected within the 60 ms window. Then the end ofinrush condition is detected and the block released before protection-blocking timeexpires. The current value is over the I> threshold and that protection function willstart timing and trip in due time.

A050816

Fig. 6.1.1.4.-2 Current-time characteristic of the detected overload

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In Fig. 6.1.1.4.-3 inrush is detected within the 60 ms window, no end of inrushcondition is detected and the protection-blocking time expires. The current value isover the I>> threshold and that protection function will start timing and trip in duetime.

A050817

Fig. 6.1.1.4.-3 Current-time characteristic when no inrush condition is detected

6.1.1.5. Setting groups

Two parameter sets can be configured for the inrush blocking protection function.

6.1.1.6. Parameters and events

Table 6.1.1.6.-1 Setting values


N 2.0 ... 8.0 2.0 Threshold I>> multiplier for faultdetection and trip

M 3.0 ... 4.0 3.0 Threshold I> multiplier for inrushdetection

Time 200 ... 100000 ms 250 overcurrent protection blockingTime after inrush detection



Protection manual


Table 6.1.1.6.-2 Events

Code Event reason

E0 Start L1 started

E1 Start L1 back

E2 Start L2 started

E3 Start L2 back

E4 Start L3 started

E5 Start L3 back

E6 Trip started

E7 Trip back

E18 Protection block started

E19 Protection block back


6.1.2. Inrush harmonic

REF 542plus has an inrush harmonic function, which can be used to temporarilyblock other protection functions.

The following current protection functions are blocked by the inrush harmonicprotection function without the need of additional wiring in the FUPLA, that is, theblock to the protection functions is implicit.

* Overcurrent instantaneous* Overcurrent high* Overcurrent low* Directional overcurrent high* Directional overcurrent low* IDMT* Earthfault IDMT

A050818

Fig. 6.1.2.-1 Inrush harmonic

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When the BS signal becomes active, the protection function is reset (no matter itsstate). This means that all the output pins go low generating the required events (ifany) and all internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low.



Start Digital signal (active high) Start signal

Start signal can be wired in FUPLA to signal inrush condition status or to theprotection functions BS input pins (different from those listed above and implicitlyblocked) to temporarily block during an inrush transient. This means that the blockto the protection functions is explicit.


A050819





Protection manual


A050820


The protection function operates on any set of phase currents in a triple.

A050821


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Minimum current threshold: Current threshold for inrush detection.

Fault current threshold: Current threshold for fault detection.

Harmonic ratio threshold: 2nd/fundamental current ratio threshold for inrushdetection.

A050822


A050823

Fig. 6.1.2.2.-5 Pins



Protection manual



Inrush harmonic protection function evaluates the ratio between current values at2nd harmonic and at fundamental frequency.


If for at least one phase current:

the current is not in steady-state condition,

AND the current value at fundamental frequency is above the preset minimumcurrent threshold (that is, Min current threshold),

AND the current value is below the preset maximum current threshold (that is,Fault current threshold),

AND the harmonic ratio between the current values at 2nd harmonic and atfundamental frequency exceeds the preset threshold (that is, Harmonic ratiothreshold)

then the protection function is started and the start signal will be activated.

The start criteria is illustrated in the following flowchart:

A050824

The protection function will remain in START status until at least for one phase theabove conditions (steady state excluded) are true. It will come back in passive statuswith a 10ms delay when:

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for all the phases at least one condition falls below 0.95 the setting threshold value(that is, Min Current threshold or Harmonic ratio thresholdrespectively),

OR at least for one phase the current value exceeds the preset maximum currentthreshold (that is, Fault current threshold).

6.1.2.5. Steady-state detection

Steady-state condition is detected if:

the current value at fundamental frequency falls below the preset minimum currentthreshold (that is, Min current threshold) for at least 10 ms,

OR the current value at fundamental frequency is between 95% and 105% of theprevious period for at least one period.


Two parameter sets can be configured for the harmonic inrush protection function.




Minimum currentthreshold

0.05 ... 40.00 ln 0.5 Current threshold for inrushdetection, if exceeded the inrushconditions are evaluated.

Fault currentthreshold

0.05 ... 40.00 ln 2 Current threshold for faultdetection, if exceeded the inrushstart is set to low.

Harmonic ratiothreshold

5 ... 50 % 10 2nd/fundamental current ratiothreshold for in-rush detection.


Code Event reason

E0 Protection has started

E1 Start is cancelled

E18 Protection block signal is active started

E19 Protection block signal is back to inactive state


6.1.3. Directional overcurrent protection

REF 542plus has two directional definite time functions, each of which can beindependently activated:



Protection manual


A050825

Fig. 6.1.3.-1 Overcurrent directional high set (I>> ->)

A050826

Fig. 6.1.3.-2 Overcurrent directional low set (I> ->)






Table 6.1.3.1.-2 Outputs






BO Digital signal (active high) Block output signal

S L1-3 are the start signals phase selective. The phase starting signal will beactivated when respective phase current start conditions are true (current exceeds thesetting threshold value and the fault is in the specified direction).

The TRIP signal will be activated when at least for a phase current the startconditions are true and the operating time has elapsed.

The Block Output (BO) signal becomes active when the protection function detectsa current exceeding the preset value and the fault direction opposite to the specifieddirection.

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A050827



A050828


The protection function operates on any combination of current phases in a triple,for example, it can operate as single phase, double phase or three-phase protectionon the phase currents belonging to the same system.



Protection manual


The faulty phase current is combined with the voltage of the corresponding soundphases. The required voltage measure is automatically selected and displayed in theGeneral dialog.

A050829


Direction: Directional criteria to be assessed together to overcurrentcondition for the START detection.

Start Value: Current threshold for overcurrent condition detection.

Time: Time delay for overcurrent trip condition detection.

A050830


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A050871

Fig. 6.1.3.2.-5 Pins


The directional overcurrent protection function evaluates the current and voltage atthe fundamental frequency.


If the measured current exceeds the setting threshold value (Start Value), andthe fault is in the specified direction (backward/forward), the protectionfunction is started. The start signal is phase selective. It means that when at least forone phase current the above conditions are true, the relevant start signal will beactivated.

If the preset threshold value (Start Value) is exceeded and the fault is in theopposite direction to the specified one, the Block Output signal becomes active. Theprotection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared if forall the phases the current falls below 0.95 the setting threshold value (or the faultcurrent changes direction).

When the protection has entered the start status and the preset operating time(Time) has elapsed, the function goes in TRIP status and the trip signal isgenerated.

The protection function will exit the TRIP status and the trip signal will be clearedwhen the measured current value falls below 0.4 the setting threshold value.



Protection manual


To determine the fault direction REF 542plus must be connected to the three-phasevoltages. The protection function has a voltage memory, which allows a directionaldecision to be produced even if a fault occurs in the close up area of the voltagetransformer/sensor (when the voltage falls below 0.1 x Un).

6.1.3.5. Current direction

Detection of the current direction is obtained by calculating the reactive power,which is computed combining the faulty phase current with the voltage of thecorresponding sound phases. The reactive power calculation uses voltage andcurrent measurements at the fundamental frequency. Before the calculations, thevoltages are shifted to a lagging angle of 45°.

The reactive power is calculated like the following:

Q

L1 23

L2 31 L3 12

= × × +× × + × ×

( sin )( sin ) ( sin )I UI U I U

ϕϕ ϕ

1

2 3

(14)

Where is:

Q Reactive power

IL1,2,3 Current of phase 1, 2 and 3

U12,23,31 Line voltages between phases 1-2, 2-3 and 3-1 after shifting -45°

φ1,2,3 Angles between the currents and the corresponding voltages

Only the phases whose current exceeds preset threshold are used in the calculation.

If the result of the calculation leads to a negative reactive power, which is greaterthan 5% of the nominal apparent power, the fault is in forward direction. Otherwise,the fault is in backward direction.

A directional signal can be sent to the opposite station using the output (trip) and/orthe Block Output (BO) signal. The content of a directional signal from the oppositestation (BO output) can be used to release tripping of its own directional protectivefunction. This enables a directional comparison protection to be established.

Fig. 6.1.3.5.-1 shows the forward and backward direction in the impedance plane incase of a balanced three-phase fault.

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A052091

Fig. 6.1.3.5.-1 Diagram of the directional overcurrent protection in case of balancedthree-phase faults

Because the application of the fault-current is in combination with the soundvoltages, the directional decision area can change. This change depends on thepower system parameters in case of nonsymmetrical fault condition. The criteria forforward and backward direction is derived from the calculated reactive power.

6.1.3.6. Voltage memory

The directional overcurrent protection function includes a voltage memory feature.This allows a directional decision to be produced even if a fault occurs in the closeup area of the voltage transformer/sensor.

At a sudden loss of voltage, a fictive voltage is used for direction detection. Thefictive voltage is the voltage measured before the fault has occurred, assuming thatthe voltage is not affected by the fault. The memory function enables the functionblock to operate up to 300 seconds after a total loss of voltage.

When the voltage falls below 0.1 x Un, the fictive voltage is used. The actualvoltage is applied again as soon as the voltage rises above 0.1 x Un for at least 100ms. The fictive voltage is also discarded if the measured voltage stays below 0.1 xUn for more than 300 seconds.


Two parameter sets can be configured for each of the overcurrent directional definitetime protection functions.



Protection manual





Start Value 0.05 ... 40 In 0.2 Current threshold for faultdetection.

Time 40 ... 30000 ms 80 Operating Time between startand trip.

Direction forward/backward

- backward Direction criteria.


Code Event reason

E0 Protection start on phase L1

E1 Start on phase L1 cancelled





E6 Trip signal is active

E7 Trip signal is back to inactive state

E16 Block signal is active

E17 Block signal is back




6.1.4. Overcurrent protection

REF 542plus provides three overcurrent definite time protection functions, see thefollowing figures. Each of them can be independently activated.

A050873

Fig. 6.1.4.-1 Overcurrent definite time instantaneous (I>>>)

A050874

Fig. 6.1.4.-2 Overcurrent definite time high set (I>>)

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A050875

Fig. 6.1.4.-3 Overcurrent definite time low set (I>)





When the BS signal becomes active, the protection function is reset (no matter itsstate). This means that all the output pins go low generating the required events (ifany) and all the internal registers and timers are cleared. The protection function willthen remain in idle state until BS signal goes low.







S L1-3 are the start signals phase selective. The phase starting signal will beactivated when the respective phase current start conditions are true.




Protection manual



A050876



A050877


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The protection functions operate on any combination of phase currents in a triple,for example, it can operate as single phase, double phase or three-phase protectionon the phase currents belonging to the same system.

A050878


Start Value: Current threshold for overcurrent condition detection.

Time: Time delay for overcurrent Trip condition detection.

A050879




Protection manual


A050880

Fig. 6.1.4.2.-5 Pins


All overcurrent definite time functions evaluate the current RMS value at thefundamental frequency. In case of the overcurrent definite time instantaneous, thepeak value of the measured current is also used under transient condition for a fasterresponse. When the instantaneous peak value is higher than three times SQRT (2)the RMS value:

I Ix peak x RMS_ _2 3> ⋅ (15)


If the measured current exceeds the setting threshold value (Start Value), theovercurrent protection function is started. The start signal is phase selective, that is,when at least the value of one phase current is above the setting threshold value therelevant start signal will be activated.

The protection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared, if forall the phases the current falls below 0.95 the setting threshold value. After theprotection has entered the start status and the preset operating time (Time) haselapsed, function goes in TRIP status and the trip signal is generated.


All overcurrent definite time functions can be used in parallel to generate a currenttime-step characteristic, as shown in the following figure.

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A050882

Fig. 6.1.4.4.-1 Current time-step characteristic


Two parameter sets can be configured for each of the overcurrent definite timeprotection functions.




Start Value I>,I>>

0.05 ... 40.00 In 0.50 Current threshold forovercurrent conditiondetection.

Time 20 ... 300000 ms 80 Time delay for overcurrentTrip condition.

Start Value I>>> 0.1 ... 40.00 In 0.50 Current threshold forovercurrent conditiondetection.

Time 15 ... 30000 ms 80 Time delay for overcurrentTrip condition.


Code Event reason










Protection manual


Table 6.1.4.6.-2 Events (Continued)

Code Event reason


E18 Protection block signal is active



6.1.5. Overcurrent IDMT

REF 542plus makes available an IDMT function in which one at the time of the fourcurrent-time characteristics can be activated:

* Normal inverse* Very inverse* Extremely inverse* Long-term inverse

A050883

Fig. 6.1.5.-1 Overcurrent IDMT












S L1-3 are the start signals phase selective. The phase starting signal will beactivated when the respective phase current start conditions are true (the phasecurrent value is above 1.2 times the setting threshold value).

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The TRIP signal will be activated when at least for a phase current the startconditions are true and the calculated operating time has elapsed.


A050884



A050885

Fig. 6.1.5.2.-2 IDMT type



Protection manual


A050886


The protection functions operate on any combination of phase currents in a triple,for example, it can operate as single phase, double phase or three-phase protectionon phase currents belonging to the same system.

A050887


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Base current (Ieb): Current threshold for overcurrent condition detection.

Time multiplier (k): Parameter to vary time delay for Trip condition

The trip time is calculated according to the British Standard (BS 142) when the timemultiplier k is used; when the time multiplier k is set to one (k=1) the IDMT curve isin accordance to the IEC 60255-3.

A050888


A050889

Fig. 6.1.5.2.-6 Pins



Protection manual



IDMT protection function evaluates the RMS value of phase currents at thefundamental frequency.


If the measured current exceeds the setting threshold value (Base current Ieb)by a factor 1.2 the protection function is started. The start signal is phase selective,that is, when at least one phase current is above 1.2 times the setting threshold value,the relevant start signal will be activated.

The protection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared, if forall the phases the current falls below 1.15 the setting threshold value. When theprotection enters the start status the operating time is continuously recalculatedaccording to the set parameters and measured current value. If the calculatedoperating time is exceeded, the function goes in TRIP status and the trip signalbecomes active.

The operating time depends on the measured current and the selected current-timecharacteristic. The protection function will exit the TRIP status and the trip signalwill be cleared when the measured current value falls below 0.4 the setting thresholdvalue.


Two parameter sets can be configured for the IDMT protection function.




Type NI/VI/EI/LTI - NI Tripping characteristic accordingto the IEC 60255-3 curvedefinition.

Base current(Ieb)

0.05 ... 40 In 0.5 Fault current factor threshold forstart condition detection.

Time multiplier (k) 0.05 ... 1.50 - 0.50 Time multiplier to vary time delayfor Trip condition according toBS 142.

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Code Event reason

E0 Protection start on phase L1.

E1 Start on phase L1 cancelled.





E6 Trip signal is active.

E7 Trip signal is back to inactive state.

E18 Protection block signal is active.

E19 Protection block signal is back to inactive state.


6.1.6. Earth fault protection

REF 542plus has two earth fault definite time protection functions, which can beactivated and the parameters set independently of each other, see the followingfigures.

A050890

Fig. 6.1.6.-1 Earth fault high

A050891

Fig. 6.1.6.-2 Earth fault low



Protection manual











The Start signal will be activated when the measured or calculated neutral currentexceeds the setting threshold value (Start Value).

The TRIP signal will be activated when the start conditions are true and theoperating time (Time) has elapsed.


A050892



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A050893


The protection functions can operate on measured or calculated (on any set of phasecurrents in a triple) neutral current.

A050894




Protection manual


Start Value: Current threshold for earth fault condition detection.

Time: Time delay for earth fault Trip condition detection.

A050895


A050896

Fig. 6.1.6.2.-5 Pins


All earth fault definite time protection functions evaluate the measured residualcurrent or the calculated neutral current at the fundamental frequency.

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If the measured or calculated neutral current exceeds the setting threshold value(Start Value), the earth fault protection function is started.

The protection function will come back in passive status and the start signal will becleared if the neutral current falls below 0.95 the setting threshold value.

After the protection has entered the start status and the preset operating time (Time)has elapsed, function goes in TRIP status and the trip signal is generated.

The protection function will exit the TRIP status and the trip signal will be clearedwhen the neutral current value falls below 0.4 the setting threshold value.


Two parameter sets can be configured for each earth fault protection function.




Start value 0.05 ... 40.00 In 0.10 Current threshold for earth faultcondition detection.

Time 40 ... 30000 ms 200 Time delay for earth fault Tripcondition detection.


Code Event reason

E0 Start started

E1 Start back

E6 Trip started

E7 Trip back




6.1.7. Directional earth fault protection

REF 542plus has two directional earth fault protection functions, each of which canbe independently activated and configured, see the following figures.



Protection manual


A050897

Fig. 6.1.7.-1 Earth fault directional low

A050898

Fig. 6.1.7.-2 Earth fault directional high





When the BS signal becomes active, the protection function is reset (no matter itsstate), this means that all the output pins go low generating the required events (ifany) and all the internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low.






The Start signal will be activated when the measured or calculated neutral currentexceeds the setting threshold value (Start Value) and the fault is in the specifieddirection.


The Block Output (BO) signal becomes active when the protection function detectsa current exceeds the preset value and the fault direction opposite to the speccifieddirection.

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A050899



A050900


The protection functions can operate on neutral current and residual voltagequantities measured through dedicated sensor(s) or calculated from the current andvoltage phase components in a triple.



Protection manual


A050971


Net Type: Parameter defining the connection to ground network typology.

Direction: Directional criteria to be assessed together to earth fault conditionfor START detection.

Start Value: Current threshold for earth fault condition detection.

Time: Time delay for earth fault Trip condition detection.

Voltage U0: Residual or neutral voltage threshold.

(The convention used to define Trip or Block area with respect to residual voltageU0 vector is described in the following, based on the typical connection diagram ofcurrent and voltage transformers for a generic feeder provided in the Section ).

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A050972


A050973

Fig. 6.1.7.2.-5 Pins


All directional earth fault definite time protection functions evaluate the measured orcalculated amount of neutral current I0 and voltage U0 at the fundamentalfrequency.



Protection manual



The direction is determined (hence the protection function is active) only if theneutral voltage is above the preset threshold (that is, Voltage U0).

The way the direction is determined depends on the selected network type(isolated/earthed).

If parameter Net type is set to isolated, then the neutral current is of capacitive type.Then its main component is on an orthogonal projection with respect to the neutralvoltage.

A050974

Fig. 6.1.7.4.-1 Operating characteristic of the earth fault directional protection(isolated network sin φ)

If parameter Net type is set to earthed, then the neutral current is of resistive type.Then its main component is on a projection parallel to the neutral voltage.

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A050975

Fig. 6.1.7.4.-2 Operating characteristic of the earth fault directional protection(earthed network cos φ)

If the following conditions are true:

* Neutral voltage value is above the preset threshold (that is, Voltage U0)* AND “significant” component of neutral current value exceeds the setting

threshold value (Start Value)* AND the direction is as selected (that is, backward/forward),

then the protection function is started.

When the preset threshold values (Start Value and Uo) are exceeded and thefirst two conditions are true but the fault is in the opposite direction to the specifiedone, the Block Output signal becomes active.

The protection function will come back in passive status and the start signal will becleared if the neutral current “significant” component value falls below 0.95 thesetting threshold value OR if the conditions on Neutral voltage value OR directionare not true.


The protection function will exit the TRIP status and the trip signal will be clearedwhen the neutral current “significant” component value falls below 0.4 the settingthreshold value.


Two parameter sets can be configured for each directional earthfault protectionfunction.



Protection manual





Net type Isolated/earthed

- Isolated Network grounding typology.

Direction Forward/backward

- Backward Directional criteria.

Start value 0.05 ... 40.00 In 0.10 “Significant” componentthreshold


Voltage U0 0.02 ... 0.70 Un 0.10 Neutral or residual voltagethreshold.


Code Event reason

E0 Protection start



E7 Trip signal is back to inactive

E16 Block output signal is active

E17 Block output signal is back to inactive




6.1.8. Sensitive directional earth fault protection

REF 542plus has one sensitive directional earth fault protection function (67NSensitive).

With respect to the two directional earth fault protection functions (67N), the 67Nsensitive protection can be configured to set the maximum sensitivity direction at auser defined angle (Angle delta). The only additional requirement is to acquirethe neutral current I0 through a dedicated earth transformer in order to have theproper precision.

A050976

Fig. 6.1.8.-1 Sensitive directional earth fault protection

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When the BS signal becomes active, the protection function is reset (no matter itsstate), this means that all the output pins go low generating the required events (ifany) and all internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low.






The Start signal will be activated when the measured residual voltage exceeds thesetting threshold value (Voltage Uo) and the neutral current is in the specifiedTrip area.


The Block Output (BO) signal becomes active when the protection function detectsresidual voltage and neutral current exceeds the preset values, but the fault (neutralcurrent) is in the block area (opposite to the specified direction, Angle delta).


A050977




Protection manual



A050978


The protection functions can operate on neutral current and residual voltagequantities.

The neutral current I0 is acquired through the dedicated transformer in order to havethe proper precision. The residual voltage U0 can be either measured through adedicated sensor or calculated from the voltage phase components in a triple.

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A050979


Current I0: Current threshold for dir. earth fault condition detection

Time: Time delay for dir. earth fault Trip condition detection

Angle alpha: Parameter to improve the discrimination of the directional decision

Angle delta: Angle between U0 vector and the direction of maximum sensitivity

Voltage U0: Residual or neutral voltage threshold

The convention used to define Trip or Block area with respect to residual voltage U0vector is described in the following, based on the typical connection diagram ofcurrent and voltage transformers for a generic feeder.

A050980




Protection manual


A050981

Fig. 6.1.8.2.-5 Pins


Sensitive earth fault direction protection function evaluates the amount of residualcurrent I0 and voltage U0 at the fundamental frequency. All sub harmonic disturbingsignals down to 1/3 of the fundamental frequency is completely filtered out.



* Residual voltage value is above the preset threshold (voltage U0)* AND Neutral current value is in the trip area of the protection function, then the

protection function is started.

If the condition of the voltage U0 is true, but the neutral current value is in the blockarea, the protection function remains idle and the Block Output signal becomesactive. When the neutral current value is in the passive area both the Start and Blocksignals are inactive.

The protection function will come back in passive status and the start signal will becleared if the neutral current OR residual voltage value fall below 0.95 the settingthreshold value.


The protection function will exit the TRIP status and the trip signal will be clearedwhen the neutral current OR residual voltage value fall below 0.4 the settingthreshold value. To ensure the required sensitivity and discrimination for the earth

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fault detection, in its implementation in REF 542plus the operating characteristic isformed with additional adjustability. The following diagram shows the shape of theoperating characteristic.

A050982

Fig. 6.1.8.4.-1 Operating characteristic of the earth fault directional sensitiveprotection for isolated network (φ = 90°)

A060411

Fig. 6.1.8.4.-2 Operating characteristic of the earth fault directional sensitiveprotection for earthed network (φ = 180°)



Protection manual


The value of δ (that is Angle delta between U0 vector and the direction of maximumsensitivity) can be configured in the range from –180° to 180°. This provides theoption of using the earth fault directional sensitive protection for every type ofnetwork grounding situation. Assuming that the connection is done according to therecommended connection diagram, the setting can be selected as follows:

* δ = 90° for isolated network* δ = 180° for earth fault compensated or resistance earthed network.

The “significant” component of neutral current is its projection on the direction ofmaximum sensitivity. Neutral current value is in the trip or block area when the“significant” component exceeds the setting threshold value (Current I0).

The other parameter α (that is, Angle alpha) is used to improve the discrimination ofthe directional decision.


Two parameter sets can be configured for the sensitive directional earth-faultprotection function.




Current I0 0.05 ... 2.00 In 1.00 Earth fault current threshold.


Angle alpha 0.0 ... 20.0 ° 20.0 Discrimination of thedirectional decision.

Angle delta -180.0 ... 180.0 ° 0.0 Angle between U0 andmaximum sensitivity direction.

Voltage U0 0.05 ... 0.70 Un 0.50 Neutral or residual voltagethreshold.


Code Event reason

E0 Protection is start




E16 Block output is active

E17 Block output is back to inactive

E18 Protection block is active

E19 Protection block is back to inactive


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6.1.9. Sector directional earth fault protection

REF 542plus can install up to 10 sector directional earth fault protection functions(67N Sector). The value of Sector Angular Width (that is Angle Δφ betweenU0 vector and the direction of maximum sensitivity) can be configured in the rangefrom –180° to 180°. This provides the option of using the sector directional earthfault protection for every type of network grounding situation (isolated, earthed orcompensated).

With respect to the sensitive directional earth fault protection function (67NSensitive), the 67N Sector protection enables:

* Multiple instances (1 … 10 different stages)* Fully configurable sensor interface, enabling I0 and U0 quantities to be directly

acquired through dedicated transformers or calculated from the current/voltagephase components

* Direction enable/disable configuration, it can be used as earth fault (non-directional) protection

* Start criteria based on neutral current Magnitude or Basic Angle to set themaximum sensitivity direction at a user defined angle Sector Basic Angle.

* Angular sector Trip area configurable by a user defined angle. SectorAngular Width.

* Neutral current and residual voltage configurable Start Drop-off delaysto enable stable protection operation during transients, as in the presence ofintermittent arcing phenomena.

A050983

Fig. 6.1.9.-1 Sector directional earth fault protection



Protection manual






When theBS signal becomes active, the protection function is reset (no matter itsstate), This means that all the output pins go low generating the required events (ifany) and all internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low.






The Start signal will be activated when the measured residual voltage exceeds thesetting threshold value (Voltage Uo) and the neutral current is in the specifiedTrip sector.


The Block Output (BO) signal becomes active when the protection function detectsresidual voltage and neutral current exceeding the preset values, but the fault(neutral current) is in the block area (opposite to the specified direction, SectorBasic Angle).

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A050984


Output channel different from 0 means direct execution of the trip command, that is,skipping FUPLA cyclic evaluation.

Stage order can be reassigned by the selection Stage window in the General dialog.

A050985




Protection manual


The protection functions can operate on neutral current and residual voltagequantities.

The neutral current I0 and the residual voltage U0 can be either measured through adedicated sensor or calculated from the current and voltage phase components in atriple.

In order to assure the proper precision the Start values settings areevaluated in the in the Parameters dialog taking into account the wholeanalog input acquisition chain. A warning is issued if the presetthreshold does not satisfy this check.

A050986

Fig. 6.1.9.2.-3 Settings

The Settings configuration dialog window provides the main options for theoperation of the protection:

The Direction Enable checkbox provides the option of deactivating the directionalcriteria. When it is not checked, the protection behaves as earth fault (non-directional) protection and all the parameters relevant to the sector are disabled.Only the Current Start Drop-off option is still available.

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A050987


The Start Criteria options enable to select between two different criterion onhow to monitor the neutral current I0. The diagrams below show how this featureworks:

* Neutral Current magnitude, when selected, the measured magnitude ofthe neutral current phasor is compared to the preset threshold I0s (NeutralCurrent Start Value).

* Neutral Current Basic Angle, when selected, the component I0b of themeasured neutral current phasor in the direction of the Basic Angle φb (directionof maximum sensitivity ) is compared to the preset threshold I0s (NeutralCurrent Start Value).



Protection manual


A050988

Fig. 6.1.9.2.-5 Neutral Current Magnitude

A050989

Fig. 6.1.9.2.-6 Neutral Current Basic Angle behavior

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The “significant” component of neutral current is its projection I0b on the directionof maximum sensitivity φb. Neutral current value may enter the trip or block areawhen the “significant” component exceeds the setting threshold value (NeutralCurrent Start Value).

A050990


Neutral Current Start Value (I0): Current threshold for directional earth-faultcondition detection.

Residual Voltage Start Value (U0): Voltage threshold for directional earth-faultcondition detection.

Operating Time (t): Time delay for dir. earth-fault Trip conditiondetection.

Sector Basic Angle: Angle φb between U0 vector and thebisector (direction of maximum sensitivity)

Sector Angular Width: Angle defining the angular Trip area(sector)

Current Start Drop-off delay: Delay to the reset of Start condition withintermittent earth-fault current.

Voltage Start Drop-off delay: Delay to the reset of Start condition withintermittent residual voltage.

Angles are referenced to the voltage phasor U0 in a clockwise convention.

The convention used to define Trip or Block area with respect to residual voltage U0vector is described in the following, based on the typical connection diagram ofcurrent and voltage transformers for a generic feeder.



Protection manual


A050991


A050992

Fig. 6.1.9.2.-9 Pins


Sector directional earth fault protection function evaluates the amount of residualcurrent I0 and voltage U0 at the fundamental frequency.

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When the directional criteria is not active (Direction Enable; checkbox NOTchecked) in the following description only the condition on neutral current valuemagnitude is evaluated (that is, compared with setting threshold value NeutralCurrent Start Value).


* Residual voltage value is above the preset threshold (that is, Residual VoltageStart Value U0)

* AND Neutral current phasor is in the trip area (sector) of the protection function,then the protection function is started.

If the condition of the voltage U0 is true but the neutral current phasor is in theblock area, the protection function remains idle and the Block Output signalbecomes active. When the neutral current phasor is in the passive area both the Startand Block signals are inactive.

The protection function will come back in passive status and the start signal will becleared (when both Current Start Drop-off time and Voltage Start Drop-off time arezero and therefore inactive) if the neutral current or residual voltage value fall below0.95 the setting threshold value or the neutral current phasor exits the activation area(Trip or Block area).


The protection function will exit the TRIP status and the trip signal will be clearedwhen the neutral current or residual voltage value fall below 0.4 the settingthreshold value or the Neutral current phasor exits the activation area.

6.1.9.5. Trip and Block areas

To ensure the required sensitivity and discrimination for the earth fault detection, inits implementation in REF 542plus the operating characteristic is formed withadditional adjustability.

The following diagrams show the shape of the operating characteristic. Theprotection behaves differently depending on the Neutral Current Start Criteriaselected.

If Neutral Current magnitude Start Criteria is selected, the trip areaand the block area are 360° complementary, the passive area is the circle of presetthreshold radius (that is, Neutral Current Start Value).



Protection manual


A050993

Fig. 6.1.9.5.-1 Operating characteristic of the sector directional earth fault protectionfunction, Neutral Current Magnitude

If Neutral Current Basic Angle Start Criteria is selected, thebehavior is dependent on the angle Δφ defining the angular Trip area (SectorAngular Width).

* Δφ < 180°, the block area corresponds to the semiplane opposite to the trip area.* Δφ < 180°, the trip area is limited to 180°, the block area is 360° complementary

to the preset Sector Angular Width Δφ, the passive area around includes parts ofthe Sector Angular Width in the plane opposite to the trip area.

Due to directionality of the criterion, no Neutral current phasor even if exceedingpreset threshold value with component I0b , “significant” component of neutralcurrent projected on the direction of maximum sensitivity φb, opposite to φb canstart the protection function.

A050995

Fig. 6.1.9.5.-2 Operating characteristic of the sector directional earth fault protectionfunction, Neutral Current Basic Angle.

The start criteria (Magnitude Vs. Basic Angle) changes significantlythe shape of passive, block and trip areas.

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6.1.9.6. Start drop-off delay function

To ensure the required sensitivity and discrimination for the earth fault in order toavoid flickering of the Start signal in case of intermittent currents and voltages twodrop-off delay timers have been provided to delay the reset of the start status.

If the drop-off delay timer is active (t>0), the protection function will not come backin passive status and the start signal will not be cleared when the relevant Startcondition falls below 0.95 the setting threshold.

Thus, after the protection has entered the start status the start status is sustained.After the preset operating time (Time) has elapsed, the function goes in TRIP statusand the trip signal is generated if the start status is still sustained and the startconditions are again verified.

If the voltage Start drop-off time is set to a value different from zero when theresidual voltage drops-off (Uo falls below 0.95 the setting threshold value) the startstatus will be reset after the voltage start drop-off time is elapsed. If voltage islacking for a time interval shorter than voltage start drop-off time the start outputwill not be affected by the voltage shortage.

A050997

Fig. 6.1.9.6.-1 Voltage Delayed Start Drop-Off

Similarly, if the current start drop-off time is set to a value different from zero whenthe neutral current phasor drops-off (exit the trip area) the start status will be resetafter the current start drop-off time is elapsed. If the neutral current phasor stays outof the activation area for a time shorter than current start drop-off time the Startoutput won’t be affected.

A050998

Fig. 6.1.9.6.-2 Current delayed start drop-off



Protection manual



Two parameter sets can be configured for the sector directional earth fault protectionfunction.




Neutral currentstart value I0

0.002 ... 8.00 In 1.000 Earth fault current threshold.

Residual voltagestart value U0

0.004 ... 0.700 Un 0.500 Residual voltage threshold.

Operating time t 30 ... 60000 ms 500 Operating time between startand trip.

Sector basicangle

-180.0 ... 180.0 ° 0.0 Angle between U0 andmaximum sensitivitydirection.

Sector angularwidth

0.0 ... 360.0 ° 360.0 Angle defining the angularTrip area.

Current startdrop/off delay

0 … 1000 ms 0 Start reset delay forintermittent current I0.

Voltage startdrop/off delay

0 … 1000 ms 0 Start reset delay forintermittent voltage U0.


Code Event reason





E16 Block output is active

E17 Block output is back to inactive




6.1.10. Earth fault IDMT

The dependent earth fault current timer protection, like IDMT, is a time-delayfunction with a set of hyperbolic current-time characteristics. An earth-fault IDMTfunction, in which four current-time characteristics may be selected, can be activatedin REF542:

* Normal inverse* Very inverse* Extremely inverse and* Long-term inverse

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A050999

Fig. 6.1.10.-1 Earth fault IDMT










The Start signal will be activated when the measured or calculated neutral currentexceeds the setting threshold value (Base current Ieb) by a factor 1.2. TheTRIP signal will be activated when the start conditions are true and the calculatedoperating time has elapsed.



Protection manual



A051000


From 0 means direct execution of the trip command, that is, skipping FUPLA cyclicevaluation.

A051003

Fig. 6.1.10.2.-2 IDMT Type

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A051004


The protection function can operate on measured or calculated (on any set of phasecurrents in a triple) neutral currents.

A051005




Protection manual


Base current (Ieb): Current threshold for overcurrent condition detection

Time multiplier (k): Parameter to vary time delay for Trip condition

The trip time is calculated according to British Standard (BS 142) when the timemultiplier k is used. When the time multiplier k is set to one (k=1) the IDMT curveis in accordance to IEC 60255-3.

A051006

Fig. 6.1.10.2.-5 Events

A051007

Fig. 6.1.10.2.-6 Pins

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Earth fault IDMT function evaluates the measured amount of residual current at thefundamental frequency.


If the measured or calculated neutral current exceeds the setting threshold value(Base current Ieb) by a factor 1.2, the protection function is started.

The protection function will come back in passive status and the start signal will becleared if the neutral current falls below 1.15 the setting threshold value.

When the protection enters the start status, the operating time is continuouslyrecalculated according to the set parameters and measured current value. If thecalculated operating time is exceeded, the function goes in TRIP status and the tripsignal becomes active.

The operating time depends on the measured current and the selected current-timecharacteristic.

The protection function will exit the TRIP status and the trip signal will be clearedwhen the measured or calculated neutral current value falls below 0.4 the settingthreshold value.


Two parameter sets can be configured for the earth-fault IDMT protection function.




Type NI/VI/EI/LTI - NI Tripping characteristic accordingto the IEC 60255-3 curvedefinition.

Base current(Ieb)

0.05 ... 40 - 0.5 Fault current factor threshold forstart condition detection.

Time multiplier(k)

0.05 ... 1.50 - 0.50 Time multiplier to vary time delayfor Trip condition according toBS 142.



Protection manual



Code Event reason








6.2. Voltage protection

6.2.1. Overvoltage protection

There are three overvoltage definite time protection functions in REF 542plus,which can be independently activated and parameterized. See the following figures.

A051008

Fig. 6.2.1.-1 Overvoltage instantaneous

A051009

Fig. 6.2.1.-2 Overvoltage high

A051010

Fig. 6.2.1.-3 Overvoltage low

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S L1-3 are the start signals phase selective. The phase starting signal will beactivated when the respective phase (line) voltage start conditions are true (voltageexceeds the setting threshold value).

The TRIP signal will be activated when at least for a phase voltage the startconditions are true and the operating time has elapsed.


A051011




Protection manual



A051012


The protection functions can operate on any combination of phase (or line) voltagesin a triple, for example, it can operate as single phase or double phase, three-phaseprotection on voltages belonging to the same system.

A051013


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Start Value: Voltage threshold for overvoltage condition detection

Time: Time delay for overvoltage Trip condition detection

A051014


A051015

Fig. 6.2.1.2.-5 Pins


Overvoltage protection functions evaluate the phase or line voltage RMS value atthe fundamental frequency.



Protection manual



If the measured voltage exceeds the setting threshold value (Start Value), theovervoltage protection function is started. The start signal is phase selective. Itmeans that when at least the value of one phase voltage is above the settingthreshold value the relevant start signal will be activated.

The protection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared if forall the phases the voltage falls below 0.95 the setting threshold value. After theprotection has entered the start status and the preset operating time (Time) haselapsed, the function goes in TRIP status and the trip signal is generated.

The protection function will exit the TRIP status and the trip signal will be clearedwhen the measured voltage value falls below 0.4 the setting threshold value.

The overvoltage protective functions, like the overcurrent protective functions, areused in a time graded coordination. An example of grading is shown in thefollowing diagram.

A051016

Fig. 6.2.1.4.-1 Overvoltage response grading.


Two parameter sets can be configured for each of the overvoltage protectionfunctions.

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Start Value U>,U>>

0.1 ... 3.00 Un 0.50 Voltage threshold for Startcondition detection.

Time 40 ... 30000 ms 80 Time delay for Trip condition.

Start Value U>>> 0.1 ... 3.00 Un 0.50 Voltage threshold for Startcondition detection.



Code Event reason



E2 Protection starton phase L2







E19 Block signal is back to inactive state


6.2.2. Undervoltage protection

There are three undervoltage protection functions in REF 542plus, which can beactivated and parameters set independently of one another. See the followingfigures.

A051017

Fig. 6.2.2.-1 Undervoltage instantaneous

A051018

Fig. 6.2.2.-2 Undervoltage high



Protection manual


A051019

Fig. 6.2.2.-3 Undervoltage low





When the BS signal becomes active, the protection function is reset (no matter itsstate). It means that all the output pins go low generating the required events (if any)and all the internal registers and timers are cleared. The protection function will thenremain in idle state until the BS signal goes low.







S L1-3 are the start signals phase selective. The phase starting signal will beactivated when respective phase (line) voltage start conditions are true (voltage fallsbelow the setting threshold value).

The TRIP signal will be activated when at least for a phase voltage the startconditions are true and the operating time has elapsed.

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A051020



A051021


The protection functions can operate on any combination of phase (or line) voltagesin a triple, for example, it can operate as single phase, double phase or three-phaseprotection on voltages belonging to the same system.



Protection manual


Min Ser

Highlight

A051022


Start Value: Voltage threshold for undervoltage condition detection.

Time: Time delay for undervoltage Trip condition detection.

A051023


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A051024

Fig. 6.2.2.2.-5 Pins


Undervoltage protection functions evaluate the phase or line voltage RMS value atthe fundamental frequency.


If the measured voltage falls below the setting threshold value (Start Value), theundervoltage protection function is started. The start signal is phase selective. Itmeans that when at least the value of one phase voltage is below the settingthreshold value the relevant start signal will be activated.

The protection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared, if forall the phases the voltage raises above 1.05 the setting threshold value. After theprotection has entered the start status and the preset operating time (Time) haselapsed, function goes in TRIP status and the trip signal is generated.


The undervoltage protection functions are used in a graded coordination. Anexample of staging is shown in the following diagram.



Protection manual


A051025

Fig. 6.2.2.4.-1 Undervoltage protection response stages

6.2.2.5. Behavior at low voltage values

A051026

Fig. 6.2.2.5.-1 Under Voltage

Because a de-energized feeder has no voltage, an undervoltage protection functionremains activated. It is not be possible then to switch the feeder on again.

Therefore, the Under Voltage configuration dialog provides the option ofdeactivating the undervoltage protection functions when the voltage is in the range 0to 40% of the setting voltage threshold (Start Value).

The diagrams below shows how this feature works when the “lowest voltage = 0”flag is checked:

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A051027

Fig. 6.2.2.5.-2 Configuration of the undervoltage limit = 0

If 40% is considered too high, the undervoltage function can also be blocked, forexample, through the circuit-breaker auxiliary contact by connecting a signal (highat CB open) to the BS input pin inside FUPLA.


Two parameter sets can be configured for each of the undervoltage protectionfunctions.




lowest voltage =0 used

used/notused

- not used When “used” the U< functionsare active below the 0.4 StartValue

Start Value U<,U<<

0.1 ... 1.20 Un 0.50 Voltage threshold for Startcondition detection.


Start Value U<<< 0.1 ... 1.20 Un 0.50 Voltage threshold for Startcondition detection.



Code Event reason










Protection manual


Table 6.2.2.7.-2 Events (Continued)

Code Event reason


E18 Protection block signal is active state



6.2.3. Residual overvoltage protection

There are two residual overvoltage protection functions in REF 542plus, which canbe independently activated and parameterized. See the following figures.

A051029

Fig. 6.2.3.-1 Residual overvoltage high

A051030

Fig. 6.2.3.-2 Residual overvoltage low





When theBS signal becomes active, the protection function is reset (no matter itsstate). This means that, all the output pins go low generating the required events (ifany) and all the internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low.

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The Start signal will be activated when the measured or calculated residual voltageexceeds the setting threshold value (Start Value).

The TRIP signal will be activated when the start condition is true and the operatingtime (Time) has elapsed.


A051031





Protection manual


A051032


The protection functions can operate on residual voltage measured through adedicated sensor (for example, open delta connected voltage transformers) orcalculated from the voltage phase (line) components in a triple.

A051033


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UNe Voltage threshold for residual overvoltage condition detection

Time: Time delay for residual overvoltage Trip condition detection

A051034


A051035

Fig. 6.2.3.2.-5 Pins


Residual overvoltage protection functions evaluate the residual voltage at thefundamental frequency.



Protection manual



If the measured voltage exceeds the setting threshold value (UNe), the residualovervoltage protection function is started.

The protection function will come back in passive status and the start signal will becleared if the voltage falls below 0.95 the setting threshold value.

After the protection has entered the start status and the preset operating time (Time)has elapsed, the function goes in TRIP status and the trip signal is generated.



Two parameter sets can be configured for each of the residual overvoltage protectionfunctions.




UNe 0.10 ... 3.00 Un 0.50 Voltage threshold for Startcondition detection.



Code Event reason

E0 Start started

E1 Start back

E6 Trip started

E7 Trip back




6.3. Motor protection

The protection functions described in the following subsections are provided forprotection of the motor from overloads and faults.

6.3.1. Thermal overload protection

REF 542plus has one thermal overload protection function.

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A050780

Fig. 6.3.1.-1 Thermal overload protection


Table 6.3.1.1.-1 Inputs



RST Trigger signal (active low-to-high) Reset signal


When the reset input pin (RST) is triggered, the estimated motor temperature is setto the parameter value Trst (Reset Temperature Trst).



Warn Digital signal (active high) Warning signal


Overheat Digital signal (active high) Overheat signal

Sensor Error Digital signal (active high) Error on RTD (used with 0 ... 20mainput)

The Warn signal will be activated when the calculated temperature exceeds thesetting threshold value (Twarn).

The Trip signal will be activated when the calculated temperature exceeds thesetting threshold value (Ttrip).

The Overheat signal will be activated when the calculated temperature exceeds thesetting threshold value Nominal Motor Temperature (TMn).

The Sensor Error signal will be activated when the external environmenttemperature (Tenv) sensor use is set and its failure is detected.



Protection manual



A050781



A050782


The protection function operates on any combination of phase currents in a triple,for example, it can operate as single phase, double phase or three-phase protectionon phase currents belonging to the same system.

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An external sensor connected to the 4-20 mA Analog Input can directly measure theenvironment temperature. When it is used, it is automatically selected and displayedin the General dialog.

A050783


Nominal Motor Temperature (TMn): Nominal Motor Temperature,asymptotically reached at IMn withenvironment temperature Tenv

Nominal Motor Current (IMn): Nominal Motor current for operationalcondition detection

Initial Temperature (Tini): Initial motor temperature at protectioninitialasing

Time Constant Off: Time constant for cooling down

Time Constant Normal: Time constant for motor operationalcondition

Time Constant Overheat: Time constant for overload condition



Protection manual


A050784


Trip Temperature (Ttrip): Temperature threshold for trip condition

Warning Temperature (Twarn): Temperature threshold for warningcondition

Environment Temperature (Tenv): Ambient temperature

Reset Temperature (Trst): Initial (i.e. after reset by RST input PIN)motor temperature

A050785


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A050786

Fig. 6.3.1.2.-6 Pins


Thermal overload protection function evaluates the square average of phase currentsat the fundamental frequency. The instantaneous temperature estimation is based onthe average of the phase currents monitored.

The environment temperature can either be set in the Parameter dialog (Tenv) ormeasured through as external sensor and a 4-20 mA Analog Input. In case of anexternal measure failure the set parameter Tenv is used as backup.


The thermal overload protection function estimates the instantaneous value of motortemperature.

If the estimated instantaneous temperature exceeds the first setting threshold value(Twarn), the protection function enters the START status and generates aWARNING signal.

If the estimated instantaneous temperature exceeds the second setting thresholdvalue, the protection function generates a TRIP signal.

If the estimated instantaneous temperature exceeds the setting threshold value(Nominal Motor Temperature TMn), the protection function generates anoverheat signal.

The protection function will exit the START status and come back in passive status.The start signal will be cleared if the estimated temperature falls below the settingthreshold value Twarn.



Protection manual


The protection function will exit the TRIP status and the trip signal will be clearedwhen the estimated temperature falls below the setting threshold value Ttrip.

The protection function avoids also reconnection after a trip of overheated machinesuntil the estimated motor temperature falls below the warning temperature Twarn(according to calculated motor cooling process, based on Time Constant OFF).

When the thermal overload protection is instantiated the motor temperature can beestimated. Therefore, after a trip for maximum number of starts, an overheatedmotor cannot be reconnected until its temperature has fallen below the warningtemperature (Twarn). Therefore, the time to decrement the number of start counterswill be the maximum between the setting time interval (Reset Time, t rst) andthe motor cooling-down time estimation.

If the protection function is reset by means of the reset input pin (RST), theestimated motor temperature will be set to value Trst (Reset Temperature).

6.3.1.5. Thermal memory at power-down

At power-down, REF 542plus saves the estimated motor temperature (T) and atsubsequent power-up is able to estimate the new motor temperature, under thehypothesis that the motor was cooling in the meantime (that is the timeconstant OFFis used).


Two parameter sets can be configured for the thermal overload protection function.




Nominal MotorTemperature (TMn)

50 ... 400 °C 100 Motor temperature at ratedcondition

Nominal Motor Current(IMn)

0.1 ... 5.0 In 1.0 Current for operational mode (τ)detection

Initial Temperature(Tini)

10 ... 400 °C 50 Initial temperature after ResetSignal at BS

Constant Off(I < 0.1 x IMn)

10 ... 100000 s 500 Cooling time constant

Time Constant Normal 10 ... 20000 s 500 Time constant under normal loadcondition

Time ConstantOverheat (I > 2 x IMn)

10 ... 20000 s 500 Time constant under overloadcondition

Trip Temperature(Ttrip)

50 ... 400 °C 100 Temperature threshold for Tripcondition

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Table 6.3.1.7.-1 Setting values (Continued)


Warning Temperature(Twarn)

50 ... 400 °C 100 Temperature threshold for warncondition

EnvironmentTemperature (Tenv)

10 ... 50 °C 20 Ambient Temperature

Reset Temperature(Trst)

10 ... 400 °C 100 Initial (after reset by RST PIN)motor temperature


Code Event reason


E1 Warning signal is back to inactive state



E16 Overheat signal is active

E17 Overheat signal is back to inactive state

E18 Protection block signal is active


E20 Reset input signal is active

E21 Reset input signal is back to inactive state

E22 Sensor error is active

E23 Sensor error is back to inactive state


6.3.2. Motor start protection

REF 542plus has one motor start protection function.

A050787

Fig. 6.3.2.-1 Motor start protection



Protection manual












The Start signal will be activated when the current exceeds 10% motor nominalcurrent value IMn and within 100 ms the setting threshold value (Motor StartIMs).

The TRIP signal will be activated when the start conditions are true and thecalculated current-time integration (Is2 x Time) is exceed.

The Block Output (BO) signal becomes active at protection initialization until whenthe current exceeds 10% motor nominal current value IMn.


A050788


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Output Channel different from 0 means direct execution of the trip command, that isskipping FUPLA cyclic evaluation.

A050789



A050790




Protection manual


Nominal Motor Current (IMn): Nominal Motor current for operational conditiondetection

Start Value (Is): Motor start current for Trip condition detection (startenergy integral I2t)

Time: Time for Trip condition detection

Motor Start (IMs): Current threshold for motor start condition detection

A050791


A050792

Fig. 6.3.2.2.-5 Pins

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Motor start protection function evaluates the current at the fundamental frequency.

The maximum measured motor current IRMS_max is used to detect Start and Tripconditions.

The motor start behavior depends on the switching torque of the specific machineload. The manufacturer assigns an allowable current-time start integral I2t for motorsor, as an alternative, information on the maximum allowable start current and themaximum allowable start time is provided.


A motor start is detected if:

* The maximum measured motor current exceeds 0.10 the setting threshold valuenominal motor current (Nominal Motor Current IMn)

* Within 100 ms later the measured motor current exceeds the setting motor startdetection (Motor Start IMs).When a motor start is detected the protection isstarted, the start signal is activated and the current-time integral

i t dt( )2∫ (16)

is calculated.

The protection function will come back in passive status and the start signal will becleared if the maximum motor current falls below 0.95 the setting motor startdetection threshold value (IMs). At that time, calculation of current-time integral isstopped.

After the protection has entered the start status and the calculated current-timeintegration exceeds the default

I Ts2 ⋅ (17)

value, where:

* Is is Start current parameter (Start Value Is)* T is Time parameter (Time)

the function goes in TRIP status and the trip signal is generated.

The protection function will exit the TRIP status and the trip signal will be clearedwhen the measured current value falls below 0.95 the setting motor start detectionthreshold value (IMs).



Protection manual



Two parameter sets can be configured for the motor start protection function.




Nominal MotorCurrent (IMn)

0.20 ... 2.00 In 1.00 Motor nominal current for Startcondition

Start Value (Is) 1.00 ... 20.00 IMn 1.00 Trip condition detection (integral I2t)

Time 40 ... 300000 ms 10000 Time for integral Trip condition

Motor Start (IMs) 0.20 ... 0.80 Is 0.70 Current threshold for Start condition


Code Event reason

E0 Protection start

E1 Start cancelled








6.3.3. Blocking rotor

A050793

Fig. 6.3.3.-1 Blocking rotor

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When theBS signal becomes active, the protection function is reset (no matter itsstate). This means that all the output pins go low generating the required events (ifany) and all internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low. This input can be assigned tothe speed indicator signal (tachometer generator or a speed switch).







S L1-3 are the start signals phase selective. The phase starting signal will beactivated when respective phase current start conditions are true (one phase currentexceeds Start Value Is).



A050794




Protection manual



A050795


The protection function operates on any combination of phase currents in a triple,for example, it can operate as single phase, double phase or three-phase protectionon phase currents belonging to the same system.

A050796


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Nominal Motor Current (IMn): Nominal Motor current

Start Value (Is): Current threshold for motor start conditiondetection

Time: Time delay for Trip condition detection

A050797


A050798

Fig. 6.3.3.2.-5 Pins



Protection manual



Blocking rotor protection function evaluates the current at the fundamentalfrequency. It operates like an overcurrent protection function.

The blocking rotor protective function is used to detect a locked rotor condition bysensing the current increase arising from the loss of synchronism between the rotorrevolving and phase voltages.

It can be used to monitor the starting characteristics of three-phase asynchronousmotors to check whether the rotor braking is on and other conditions preventing themotor to speed up. If this malfunction occurs, the starting current would flowpermanently and the motor would be thermally overloaded.


The blocking rotor protection function can be blocked on the BS input. Theblocking input can be provided by a speed switch or by the start signal output fromthe motor start protection function.

A tachometer generator or a speed switch is used to send a defined signal at aspecified speed. If the rotor of the monitored motor is locked, the missing speedsignal will ensure that the overcurrent function in the protective function willcontinue to remain active.

The protection function can also be used without a speed signal by using the startsignal output from the motor start protection function to block it during the motorstarting phase. When the motor start condition is detected the blocking rotorfunction is blocked by the BS input.

If the measured current exceeds the setting motor starting threshold value (StartValue, Is), the protection function is started. The start signal is phase selective Itmeans that when at least the value of one phase current is above the setting thresholdvalue the relevant start signal will be activated (SL 1-3).

The protection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared if forall the phases the current falls below 0.95 the setting threshold value. After theprotection has entered the start status and the preset operating time (Time) haselapsed, function goes in TRIP status and the trip signal is generated.



Two parameter sets can be configured for the blocking rotor protection functions.

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Nominal MotorCurrent IMn

0.20 ... 2.00 In 1.00 Nominal Motor current

Start Value Is 1.00 ... 20.00 Imn 1.00 Current threshold for motor startcondition detection

Time 40 ... 30000 ms 10000 Time delay for Trip condition detection


Code Event reason










6.3.4. Number of starts

REF 542plus has an additional motor protection function that supervizes the numberof motor starts. It distinguishes between the cold and warm starts, the allowablenumber which is generally provided by the motor manufacturer. The starting signal(Start output) of the motor start protection function is used to count the starts.

A050799

Fig. 6.3.4.-1 Number of starts



Protection manual






SI Trigger signal (active high) Motor start signal


The SI signal is used to provide to the number of start function the start signaloutput from the motor start protection function by wiring the connection in FUPLA.It is used to count the motor number of starts.



Warn Digital signal (active high) Warning signal


The Warn signal will be activated when the cold (or warm) starts counter reaches thesetting threshold value maximum number of starts (Ncs and Nws respectively).

The TRIP signal will be activated when the cold (or warm) starts counter exceedsthe setting threshold value maximum number of starts (Ncs and Nws respectively).


A050800


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A050801


Max Num. of Warm Starts (Nws): Motor manufacturer declared N° of starts abovetemperature threshold Tws

Max Num. of Cold Starts (Ncs): Motor manufacturer declared N° of starts belowtemperature threshold Tws

Reset Time (t rst): Cooling down motor time; time to dissipate theheat of a motor start

Warm Start Temp. Threshold (Tws): Above Tws temperature thereshold a start isassumed to be warm



Protection manual


A050802


A050803

Fig. 6.3.4.2.-4 Pins


Number of starts protection function supervizes the motor number of starts. Thestarting signal of motor start protection function is used to count starts.

It is also important to distinguish between the cold and warm starts, the allowablenumber of which is generally provided by the motor manufacturer.

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Motor temperature estimated by the thermal overload function is used to determinewhether a start is cold or a warm. When the thermal overload function is notinstantiated, a cold start is assumed.


If thermal overload protection is not enabled, the estimated machine temperature isnot available and the warm counter is not increased (the warm counter is frozen tozero). In this case, all the counted starts are classified as cold.

When the thermal overload protection is enabled the estimated motor temperature iscompared with the setting temperature threshold (Warm Start Temp.Threshold Tws). Above Tws temperature thereshold a start is assumed to bewarm, below it is assumed to be a cold start.

At every motor start (detected by the motor start protection function), depending onthe type of start (warm or cold start) the related counter is incremented by one unit.At every warm start, both the warm counter and the cold counter are incremented.Cold starts to increment only the cold counter.

If no start has occurred after the setting time interval (Reset Time, t rst) it isassumed that the motor had time to cool down and both the cold and warm startcounters are decremented by one unit.

If the preset number of warm (Max Num. of Warm Starts, Nws) or respectivelyof cold starts (Max Num. of Cold Starts, Ncs) is reached, the protectionfunction is started and the relevant warning signal will be activated. If there isanother start, the protection function will enter the TRIP status and the trip signalwill be activated.

If the protection function is in TRIP status and the above condition is satisfied, theprotection function will exit the trip status and the trip signal will be cleared. Theprotection function is in TRIP status and the trip signal remains active until the resetperiod t rst has expired. Then both cold and warm start counters are decrementedand the trip signal will be cleared.

The protection function will exit START status, come back in passive status and thestart signal will be cleared, if the cold and warm counters fall below the respectivemaximum setting values Ncs and Nws, that is after the reset period t rst has expired.


Two parameter sets can be configured for the number of starts protection functions.



Protection manual





Max num. of warmstarts (Nws)

1 ... 10 - 1 Number of starts above Tws

Max num. of coldstarts (Ncs)

1 ... 10 - 1 Number of starts below Tws

Reset time (t rst) 1.00 ...7200.00

s 30.00 Time to cool down after a start

Warm start temp.threshold (Tws)

20 ... 200 °C 80 Temperature threshold to define awarm start


Code Event reason

E0 Protection start

E1 Start cancelled




E15 Warning signal is back to inactive state




6.4. Distance protection

The distance protection is dedicated to protect a meshed medium-voltage system ora simple high-voltage system.

A050804

Fig. 6.4.-1 Distance protection

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Table 6.4.1.-1 Inputs



SIGNAL COMP Digital signal (active high) Signal comparison scheme

When the BL signal becomes active, the protection function is reset (no matter itsstate). This means that all the output pins go low generating the required events (ifany) and all internal registers and timers are cleared. The protection function willthen remain in idle state until the BL signal goes low.

Table 6.4.1.-2 Outputs


< Z1 Digital signal (active high) Z1 signal used for signalcomparison

START L1 Digital signal (active high) Start signal in L1



EARTH START Digital signal (active high) Start Earth signal

GENERAL START Digital signal (active high) General start signal




Protection manual



A050805


Output Channel different from 0 means direct execution of the trip command, that isskipping FUPLA cycle evaluation.

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A050806

Fig. 6.4.2.-2 Start values

A050807

Fig. 6.4.2.-3 Zones



Protection manual


A050808

Fig. 6.4.2.-4 Zone 1

A050809

Fig. 6.4.2.-5 Zone 2

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A050831

Fig. 6.4.2.-6 Zone 3

A050832

Fig. 6.4.2.-7 Zone overreach



Protection manual


A050833

Fig. 6.4.2.-8 Zone autoreclose (control)

A050834

Fig. 6.4.2.-9 Directional backup

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A050835

Fig. 6.4.2.-10 Non-directional backup

A050836

Fig. 6.4.2.-11 Phase selection



Protection manual


A050837

Fig. 6.4.2.-12 Parameters earth factors

A050838


6.4.3. Operation mode

The distance protection comprises the following subordinate functions:

* Start* Impedance determination* Directional memory* Tripping logic

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To run the protection function, the phase currents and the phase voltagesmeasurement quantities are required. The phase currents and the phase voltages arearranged in consecutive groups of three. The following combinations can beconfigured:

* Measuring input 1,2,3: current signals; measuring input 4,5,6: voltage signals inphase L1, L2, L3

* Measuring input 1,2,3: voltage signals; measuring input 4,5,6: current signals inphase L1, L2, L3

The start function is intended to check for the presence of a system failure and todetect the type of the fault. The appropriate measured quantities for determining theimpedance and the directional decision are selected depending on the type of systemfault. Once the direction and the zone of the system fault have been determined, thetripping logic is used to determine the trip time in accordance with the setimpedance time characteristic.

A signal comparison protection scheme, which enables to protect a very short lineselectively, is also integrated. This requires pilot wires for signal exchange.

For the network operation, it is important to localize the fault as soon as possibleafter the system fault has been switched off in order to repair the damage. Becausethe medium-voltage networks are usually spread over wide areas, fault-trackinginformation in km or in reactive ohm is desirable for network operation after thesystem fault has been tripped. For this reason, the fault locator, which can derive thefault distance from the measured fault impedance, is also implemented in thedistance protection. It calculates the distance in km to the fault from the nominalvalue of the cable reactance.

The requirement of current transformers for distance protection mustbe fulfilled. Otherwise the proper function behavior can not be assure.Besides, the fault locator would not be in position to display the correctvalue.

Once the system fault has been switched off, it may also be of interest for the systemoperator to carry out a fault analysis from a disturbance recorder and the sequencesof the appearance of the signaling events. The fault recorder function can be startedeither by an external signal (via a binary input) or by a signal from the distanceprotection. The general start or the trip signal can be used for this purpose.

If the fault recorder is started by the general start signal, the system quantities will berecorded. However, a correct fault reactance can only be detected if the fault is in thefirst protection zone. Therefore, it is recommended to start the fault recorder by atrip signal.

The option of switching the distance protection over to the overcurrent protectionshall normally be provided. This procedure is generally referred to the so-calledemergency overcurrent protection and is required if the voltage measurement



Protection manual


quantities do not exist anymore, for example due to an MCB failure. Detailedinformation regarding to the operation principle and the calculation of the settingparameter can be found in the related application note.




Table 6.4.5.-1 General parameter

Net type: high ohmic, low ohmic

Used sensors: I: 1-3; U: 4-6 or I: 4-6; U: 1-3

Earth start: IE> used or IE> unused (residual current)

Switching ontofaults:

normal behavior, overreach zone used or trip after occurrence ofgeneral start signal

Signal Comp.Time:

30 … 30,000 ms (set 1/set 2), default 30 ms

Table 6.4.5.-2 Start values


I> 0.05 ... 4.00 In 1.00 Phase current high set

IN> 0.05 ... 4.00 In 0.20 Residual current

UF 0.05 ... 0.90 Un 0.50 Phase or line voltage (nettype)

IF> 0.05 ... 4 In 0.50 Phase current low set

Table 6.4.5.-3 Choose zone


Cable reactance 0.05 ... 120 Ohm/km

1

OH line reactance 0.05 ... 120 Ohm/km

1

Border OH/cable 0.05 ... 120 Ohm 1

Type of transmission line only cable, only OH line, OH line before cable or cablebefore OH line

Table 6.4.5.-4 Zone 1, 2, 3, Zone Overreach, Autoreclose (border)


Resistance R 0.05 ... 120 Ohm 1

Reactance X 0.05 ... 120 Ohm 1

Angle delta 1 -45 ... 0 ° 0

Angle delta 2 90 ... 135 ° 90

Time 20 ... 10000 ms 20

Direction forward,backward or zone

unused

- zone un-used

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Table 6.4.5.-5 Directional backup


Angle delta 1 -45 ... 0 ° 0

Angle delta 2 90 ... 135 ° 90

Time 20 ... 10000 ms 20

Direction forward,backward or zone

unused

- zone un-used

Table 6.4.5.-6 Non-directional backup


Time 20 ... 10000 ms 20

Table 6.4.5.-7 Phase selection

Parameter Trip Selection

Normal acycle L3 - L1 - L2

Normal cycle L3 - L1 - L2 - L3

Inverse acycle L1 - L3 - L2

Inverse cycle L3 - L2 - L1 - L3

Table 6.4.5.-8 Earth factor


Factor k 0 ... 10

Angle k -60 ... 60 °


Code Event reason

E0 Start L1 started

E1 Start L1 back

E2 Start L2 started

E3 Start L2 back

E4 Start L3 started

E5 Start L3 back

E6 Trip started

E7 Trip back

E16 Z1< started

E17 Z1< back



E22 General start started

E23 General start back

E24 Earth start started

E25 Earth start back

E28 Signal comparison started

E29 Signal comparison back




Protection manual


6.5. Differential protection

6.5.1. Transformer Differential Protection

Differential protection can be used to protect power transformers, motors andgenerators. The protection function has the following properties:

* Differential protection of two windings power transformer* Amplitude and vector group adaptation* Zero sequence current compensation* Three-fold tripping characteristic* Inrush stabilization by 2nd and 5th harmonics* Stabilization during through-faults also in case of current transformers (CT)

saturation

A050849

Fig. 6.5.1.-1 Transformer Differential Protection





When BS signal becomes active, the protection function is reset (no matter its state),i.e. all output pins go low generating the required events (if any) and all internalregisters and timers are cleared. The protection function will then remain in idlestate until BS signal goes low.




BH2 Digital signal (active high) Block by 2nd harmonic signal

BH5 Digital signal (active high) Block by 5th harmonic signal

GB Digital signal (active high) General Block output signal

The TRIP signal will be activated when at least one of the calculated differentialcurrents Id exceeds the bias-dependent setting threshold value AND if the harmonicstabilization is enabled, the harmonic content of differential current is below the setthresholds (2nd ,5thThreshold).

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When the harmonic stabilization is enabled, the Block Output (BH2, BH5) signalsbecome active if the protection function detects a differential current exceeding thepreset threshold and the harmonic content of differential current is above the setthresholds (2nd ,5thThreshold).


A050850


Output Channel different from 0 means direct execution of the trip command (that isskipping FUPLA cyclic evaluation).



Protection manual


A050851


Transformer differential protection requires 6 current sensors; it operates on two setsof phase currents in a triple on primary and secondary side of the transformer.

A050852

Fig. 6.5.1.2.-3 Transformer

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A050853

Fig. 6.5.1.2.-4 Current

Primary nominal current: Nominal transformer current on primaryside.

Secondary nominal current: Nominal transformer current on secondaryside, to be used for power transformer ratiocompensation.

All the Differential protection thresholds are referred the Rated powertransformer current Ir (p.u) in per unit; i.e. normalized on the primaryor secondary nominal power transformer current (Primary,Secondary nominal current). In this way all differences due toCT ratios and board transformer analog input are automaticallynormalized.

Threshold current: First region Id threshold.

Unbiased region limit: First region Ib threshold.

Slightly biased region threshold: Second region Id threshold.

Slightly biased region limit: Second region Ib threshold.

Heavily biased slope: Third region slope.

Trip by Id>: Upper Id threshold for Trip conditiondetection.



Protection manual


A050854

Fig. 6.5.1.2.-5 Harmonics

2nd, 5th Harmonic

Threshold: Threshold value for 2nd, 5th harmonic content detection.

Block: Flag enabling the harmonic content detection. When thresholdvalue is exceeded it blocks the protection function andgenerates a blocking signal.

A050855


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A050856

Fig. 6.5.1.2.-7 Pins


Differential protection function evaluates the measured amount of differentialcurrent at the fundamental, 2nd and 5th harmonic frequencies.


Transformer differential protection is a current comparison scheme for theprotection of a component with two sides, like for example two windings powertransformer, therefore the incoming and outgoing currents through the component tobe protected are compared with each other.

If no fault exists in the protection zone, the incoming current and the outgoingcurrent are identical.

Therefore the difference between those currents, the differential current Id, is usedas criteria for fault detection. The protection zone of transformer differentialprotection is limited by the place where the current transformers or current sensorsare installed.

The signals path and the measurement processing to obtain the differential current Idsed as criteria for fault detection are described in the following flowchart:



Protection manual


A050857

Fig. 6.5.1.4.-1 The signals path and the measurement processing

After transformer ratio compensation and vector group adaptation the bias anddifferential currents are calculated on the three phases.

If harmonic stabilization is enabled (in “Harmonic” dialog window), 2nd and/or 5th

harmonic contents of differential currents are calculated.

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If at least one of the calculated differential currents Id is above the bias (of theconsidered phase) dependent setting threshold (given by the tripping characteristic,Threshold current, Slightly biased region threshold,Heavily biased slope or Trip by Id>), then (if required) the check forharmonic stabilization is performed.

If harmonic content of differential current Id is above the set threshold (2nd

,5thThreshold), then the protection function will be blocked and the relevantBlock signal will be activated, else it goes in TRIP status and the trip signal isgenerated. The Block of the protection function with the corresponding signalgeneration will appear, if the Id harmonic content exceeds the setting thresholdvalue for the 2nd and the 5th. harmonics.

The protection function will remain in TRIP status if there is at least one differentialcurrent above the threshold. It will come back in passive status and the Trip signalwill be cleared if for all the phases the differential current falls below 0.4 the settingthreshold value. To perform the current comparison, it is necessary to correct theamplitude of the currents to compensate the transformer ratio. The amplitudecorrection is done by software. In the case of power transformer protection forexample, the current measurement quantities on the primary and the secondary sideare corrected by taking into account the different nominal values of the sensors andprimary/secondary nominal current parameters.

6.5.1.5. Tripping characteristic

The tripping characteristic of the transformer differential protection function is athree-fold characteristic. In the following figure the characteristic is shown.

A050858

Fig. 6.5.1.5.-1 Tripping characteristic of the transformer differential protectionfunction



Protection manual


The tripping characteristic is drawn on p.u. basis after normalization of I1 and I2currents on on the primary or secondary nominal power transformer current(Primary, Secondary nominal current). Therefore Id and Ib currents areexpressed in p.u. as multiples of the Rated power transformer current Ir (p.u).

The bias currents are defined as the average values (in p.u.) between primary andsecondary currents obtained after transformation ratio compensation and vectorgroup adaptation.

Due to the measurement error of the current quantities on both sides of the object tobe protected, a small differential current Id will occur during normal operationcondition.

The first fold of the characteristic curve is given by the settable threshold value ofthe differential current (Threshold current) and the bias current limit(Unbiased region limit).

The second fold of the characteristic curve is defined by the threshold value of thedifferential current (Slightly biased region threshold) and the biascurrent limit (Slightly biased region limit).

Afterwards a line with a selectable slope (Heavily biased slope) continuesthe characteristic.

In case of the occurrence of a high differential current, a direct tripping can also begenerated by the threshold value (Trip by Id>) as the third fold of the trippingcharacteristic. The setting value should be selected in such a way, that no trippingcould happen during the energizing of the power transformer.

6.5.1.6. Inrush stabilization

When switching on a power transformer without the connected loads, a high inrushcurrent might occur. As consequence, there could be some unwanted tripping

To stabilize this condition of the power transformer the presence of the 2nd harmonicin the differential current can be used as criteria. Therefore the ratio of the 2nd

harmonic current to the current at fundamental frequency is important. As soon asthe threshold value (threshold) is exceeded, the protection function is blockedand a blocking signal is activated.

In case of switching on a power transformer in parallel without the connected loads,the inrush current can also be generated in the transformer which is already inoperation. In this case, it is necessary to detect the 5th harmonic in the differentialcurrent to avoid the undesired tripping.

For that reason, the differential protection in REF 542plus is foreseen with the 2nd

and the 5th harmonic blocking possibilities, which can be set separately from eachother.

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Two parameter sets can be configured for the transformer differential protectionfunction.




Transformer group 0 ... 11 - 0 Parameters for vector groupadaptation and transformationratio compensation betweenprimary - secondary currents.

Transformerearthing:

Primary side Yes/No - No

Secondary side Yes/No - No

Primary nominalcurrent

10 ... 100000 A 100

Secondary nominalcurrent

10 ... 100000 A 100

Threshold current 0.10 ... 0.50 Ir (p.u.) 0.20 First region Id threshold.

Unbiased regionlimit

0.50 ... 5.00 Ir (p.u.) 0.50 First region Ib threshold.

Slightly biasedregion threshold

0.20 ... 2.00 Ir (p.u.) 0.20 Second region Id threshold.

Slightly biasedregion limit

1.00 ... 10.00 Ir (p.u.) 3.00 Second region Ib threshold.

Heavily biasedregion slope

0.40 ... 1.00 - 0.40 Third region slope.

Trip by Id> 5.00 ... 40.00 Ir (p.u.) 6.00 Upper Id threshold for Trip.

Second harmonic:Thresholdblock

0.10 ... 0.30Enabled/Disabled

Id-

0.30Enabled

Stabilization against no loadtransformer inrush current

Fifth harmonic:Thresholdblock

0.10 ... 0.30Enabled/Disabled

Id-

0.30Enabled

Stabilization againsttransformer overexitationcurrent


Code Event reason



E18 Protection block signal is in active state

E19 Protection block signal is back to inactive

E20 Block signal due to the 2nd harmonic is active

E21 Block signal due to the 2nd harmonic back to inactive

E24 Block signal due to the 5th harmonic is active

E25 Block signal due to the 5th harmonic is back to inactive

E26 General block harmonic start

E27 General block harmonic back



Protection manual



6.5.2. Restricted differential protection

Restricted differential protection can be used as restricted earth fault protection todetect and disconnect a fault in the grounding system of the transformer.

A050859

Fig. 6.5.2.-1 Restricted differential protection





When the BS signal becomes active, the protection function is reset (no matter itsstate), this means that all the output pins go low generating the required events (ifany) and all the internal registers and timers are cleared. The protection function willthen remain in idle state until the BS signal goes low.





The Start signal will be activated when the differential current Id exceeds the settingthreshold value.

The TRIP signal will be activated when the start and trip conditions are true and theoperating time (Time) has elapsed.

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A050860



A050861




Protection manual


The protection function operates on the comparison of two neutral currents; thezero-sequence current calculated by means of current measures acquired from thelines (on any set of phase currents in a triple), and the measured earth-fault currentflowing through the neutral conductor towards the ground. The protection is used incase of star windings with earthed neutral transformers.

A050862


A050864


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Rated current: Rated current for CT ratio compensationand currents normalization

Unbiased region threshold: First region Id threshold

Unbiased region limit: First region Ib threshold

Slightly biased region threshold: Second region Id threshold

Slightly biased region limit: Second region Ib threshold

Heavily biased slope: Third region slope

Relay Operate Angle: Directional criteria

Time: Time delay for trip condition detection

A050865




Protection manual


A050866

Fig. 6.5.2.2.-6 Pins


The restricted differential protection function evaluates the differential currentbetween two neutral currents at the fundamental frequency.

The two currents can be the calculated or measured residual current I0 from thephase currents compared with the neutral current IG in the transformer restrictedearth-fault application, in case of line differential protection, the neutral currents ofeach end of the line (I1.and I2).


The restricted differential protection is a current comparison scheme. Therefore, theincoming and outgoing currents, through the object to be protected, are comparedwith each other. If no fault exists in the protection zone, the incoming current andthe outgoing current are identical. That is why the difference between those currents,the differential current Id = I0 - IG = I2 - I1, is used as criteria for fault detection.

The protection zone of the restricted differential protection is limited by the placewhere the current transformers or current sensors are installed.

If the calculated differential current Id is above the bias-dependent setting threshold(given by the tripping characteristic, Unbiased region threshold,Slightly biased region threshold or Heavily biased slope),protection function is started and the Start signal will be activated.

The protection function will come back in passive status and the start signal will becleared, if the differential current Id falls below 0.95 the setting threshold value.

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If the start conditions are true then the following conditions are checked:

Direction. The directional check is made only if I0 is more than 3% of the ratedcurrent (Rated current Ir). If the result of the check means “external fault”, thetrip is not issued. If the directional check cannot be executed, then direction is nolonger a condition for a trip.

External fault. For as long as the external fault persists (flag enabled in passivecondition only, for Id< 0.5 the lower setting threshold and IG> 0.5 the Ratedcurrent Ir), an additional temporary condition is introduced, which requires thatIG has to be higher than 0.5 Ir for protection temporarily desensitization.

Bias. The bias current Ib is above 0.5 the maximum bias current calculated duringthe start condition period. Ibtrip > 0.5 Ibmax (start period).

When the protection has entered the start status and the preset operating time(Time) has elapsed, the function goes in TRIP status and the trip signal is generatedif all the above conditions are true.

The protection function will exit TRIP status to come back in passive status and theTrip signal will be cleared, if the differential current Id falls below 0.4 the settingthreshold value.

6.5.2.5. Tripping characteristic

The tripping characteristic of the restricted differential protection function is a three-fold characteristic. In Fig. 6.5.2.5.-1 the characteristic is shown.

A050867

Fig. 6.5.2.5.-1 Tripping characteristic

The tripping characteristic is drawn on p.u. basis after normalization of I1 and I2currents on power transformer rated current (Rated current Ir).



Protection manual


The bias current is per definition always the one with the higher magnitude, Ib =max (IG, I0) or Ib = max (I1, I2).

After the compensation of different sensor nominal values, the differential current Idand the bias current Ib are calculated.

The first fold of the characteristic curve is given by the settable threshold value ofthe differential current (Unbiased region threshold) and the bias currentlimit (Unbiased region limit).

The second fold of the characteristic curve is defined by the threshold value of thedifferential current (Slightly biased region threshold) and the biascurrent limit (Slightly biased region limit).

Afterwards a line with a selectable slope (Heavily biased slope) continues thecharacteristic.

In case of an external fault characterized from a high fault current, it could happenthat the different CTs do not transform the primary current the same way (even ifthey have the same characteristics), allowing the circulation of a differential currentthrough the protection.

The tripping characteristic allows facing CT introduced error (for example due tophase and ratio error, different CT load or magnetic properties), without decreasingthe sensitivity of the differential protection. In fact, in case of high line currents andhigh ground current, the higher differential current threshold compensates such anerror even if there are differences about the I0 and IG transformation.

6.5.2.6. Directional criterion for stabilization against CT saturation

Earth faults on lines connecting the power transformer occur much more often thanearth faults on a power transformer winding. It is important therefore that therestricted earth fault protection should remain secure during an external fault andimmediately after the fault has been cleared by some other protection.

The directional criterion is applied in order to distinguish between internal andexternal earth faults in case of CT saturation, to prevent misoperations at heavyexternal earth faults. This criterion is applicable is the residual current I0 is at least3% Ir.

For an external earth fault with no CT saturation, the residual current in the lines I0and the neutral current IG are equal in magnitude and phase. The current in theneutral IG is used as directional reference because it flows for all earth faults in thesame direction.

To stabilize the behavior against CT saturation, a phase comparison scheme isintroduced. In case of a heavy current fault with saturation of one or more CT, themeasured currents IG and I0 may no more be equal, nor will their positions in thecomplex plane be the same, and a certain value of false differential current Id canappear.

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If the fault is inside of the protection zone, the currents to be compared must have aphase shift to each other. That is why a so-called relay operate angle ROA (RelayOperating Angle) is introduced, like shown in Fig. 6.5.2.6.-1. The direction ofneutral current is inside the ROA, if it is an internal fault. The direction of bothcurrent is outside the ROA for external faults.

A050868

Fig. 6.5.2.6.-1 Currents at an external earth fault with CTs saturation

In case of an internal fault, the I0 lies into the operate area for internal fault and theprotection is allowed to operate, see Fig. 6.5.2.6.-2.

A050869

Fig. 6.5.2.6.-2 Currents at an internal earth fault



Protection manual


ROA can be taken out of operation by setting it to 180°, if no CT saturation has tobe considered.

In case the restricted differential is used for the line application, the sameconsiderations apply by using I1 and I2 neutral currents.


Two parameter sets can be configured for the restricted differential protectionfunction.




Referencenominal current

1 ... 100000 A 100 Reference current for CT ratiocompensation/ currents normalization.

Unbiased regionthreshold

0.05 ... 0.50 Ir 0.30 First region Id threshold.

Unbiased regionlimit

0.01 ... 1.00 Ir 0.50 First region Ib threshold.

Slightly biasedregion slope

0.01 ... 2.00 - 0.70 Second region Id threshold.

Slightly biasedregion limit

0.01 ... 2.00 Ir 1.25 Second region Ib threshold.

Heavily biasedregion slope

0.10 ... 1.00 - 1.00 Third region slope.

Relay operateangle

60 ... 180 ° 75 Directional criteria.

Time 0.04 ...100.00

s 0.05 Time delay for trip condition detection.


Code Event reason

E0 Protection start

E1 Start cancelled



E16 Block signal is active state





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6.6. Other Protections

6.6.1. Unbalanced load protection

REF 542plus has one unbalanced load protection function.

A050870

Fig. 6.6.1.-1 Unbalanced load protection





RST Trigger signal (active low-to-high) Reset signal


When the reset input pin (RST) is triggered, the protection function is reset.






The Start signal will be activated when the calculated negative phase sequencecurrent exceeds the setting threshold value (Is).

The TRIP signal will be activated when the start conditions are true and theoperating time has elapsed.

The Block Output (BO) signal becomes active when the protection function exitTRIP status and remains active for the setting delay time (Reset Time).



Protection manual



A050901


Output Channel different from 0 means direct execution of the trip command(skipping FUPLA cyclic evaluation).

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A050902



A050903




Protection manual


Is: Current threshold for negative sequencecondition detection

K: Heating parameter to vary time delay fortrip condition

Reset Time: Time BO output is high (for example toblock the re-closing possibility of a motor)

Timer decreasing rate: Parameter to vary thermal memory effect

A050904


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A050905

Fig. 6.6.1.2.-5 Pins


Unbalanced load protection function evaluates the measured amount of negativephase sequence current at the fundamental frequency.

The negative-sequence three phase system L1 - L3 - L2 is superimposed on thethree-phase system that corresponds to the standard phase sequence. This results indifferent field intensities in the magnetic laminated cores. The points withparticularly high field intensities, the so-called hot spots, lead to the localoverheating.


If the calculated negative phase sequence current exceeds the setting threshold value(Is), then the protection function is started and the start signal will be activated.

When the protection enters the START status, the operating time is continuouslyrecalculated according to the set parameters (K, Is) and the negative phasesequence current value.

If the calculated operating time is exceeded, the function goes in TRIP status and thetrip signal becomes active.



Protection manual


The protection function will exit the TRIP status and the trip signal will be clearedwhen the measured current value falls below 0.4 the setting threshold value. Theoperating time depends on the calculated negative phase sequence as follows:

t KI I

=−2

2 2S

(18)

where:

t Time until the protective function trips under sustained overcurrent

K Heating parameter of the component

I2 Calculated negative phase sequence current expressed in In

IS Start threshold expressed in In

According to the standard the characteristic is only defined for I2/Is in the range upto 20. If the values of the mentioned ratio are higher than 20, the operation timeremains constant as the operation time calculated for Is/I2= 20.

If a trip is generated, for example in case of a motor protection, the motor should beblocked for reclosing. The BO signal is dedicated to block the reclosing possibilityof the motorin this case. The BO signal remains active for the reset time after thefunctions exit TRIP status.

Thermal memory

To avoid machine overheating in case of an intermittent negative phase sequencecurrent, the internal time counter is not cleared when the negative phase sequencecurrent falls below the start threshold. Instead, it is linearly decremented with time,using a user-configurable slope (that is timer decreasing rate related to the setting ofthe Reset Time). 100% means full memory and 0% means no memory.


Two parameter sets can be configured for the unbalanced load protection function.

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Is 0.05 ... 0.30 In 0.10 Current threshold for negativesequence detection

K 0.5 ... 30.0 - 10.0 Heating parameter

Reset time 0 ... 2000 s 60 Time to reset BO after a trip

Timer decreasingrate

0 ... 100 % 10 Parameter to vary thermal memoryeffect


Code Event reason







E18 Protection block is back to inactive state

E19 Protection block is back to inactive state

E20 Reset input is active

E21 Reset input is back to inactive state


6.6.2. Directional power protection

Directional power protection function can be added as a supervision function withgenerators, transformers and three-phase asynchronous motors.

A050906

Fig. 6.6.2.-1 Directional power protection



Protection manual





BI Digital signal (active high) Blocking signal

When the BI signal becomes active, the protection function is reset (no matter itsstate). This means that all the output pins go low generating the required events (ifany) and all the internal registers and timers are cleared. The protection function willthen remain in idle state until the BI signal goes low.




TRIP Digital signal (active high) TRIP signal

The Start signal will be activated when the calculated active power exceeds thesetting threshold value (Max Reverse Load) and the power flow is in the oppositedirection to the specified one.

The TRIP signal will be activated when the start conditions are true and theoperating time has elapsed.


A050907



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A050908


Direction: Directional criteria to be assessed with Power flow for STARTdetection

Nominal Real Power: Power reference Pn for quantities normalization

Max Reverse Load: Power threshold in opposition to set direction for start detection

Operating Time: Time delay for trip condition detection

A050909




Protection manual


A050910

Fig. 6.6.2.2.-4 Pins


The directional power protection function evaluates the active power at thefundamental frequency.


The directional power supervision compares the calculated active power with apreset nominal value (Pn, Nominal Real Power) and a set power flow direction(Direction).

If the calculated active power exceeds the setting threshold value (Max ReverseLoad), and the power flow is in the opposite direction to the specified one(backward/forward), the protection function is started and the start signal isgenerated.

The protection function will come back in passive status and the start signal will becleared if the calculated active power falls below 0.95 the setting threshold value, orthe power flow changes direction.

When the protection has entered the start status and the preset operating time(Operating Time) has elapsed, the function goes in TRIP status and the tripsignal is generated.


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Two parameter sets can be configured for the directional power protection function.




Direction Forward /Backward

Backward Directional criteria forSTART detection

Nom. active power 1 ... 1000000 kW 1000 Power reference fornormalization

Max reverse load 1 ... 50 % Pn 5 Power threshold forSTART detection

Operating time 1.0 ... 1000 s 10 Time delay for tripcondition


Code Event reason

E0 Protection start

E1 Start cancelled






6.6.3. Low load protection

REF 542plus has one low load protection function.

Three-phase asynchronous motors are subject to load variations. The low loadmonitoring function is provided to supervize the motor operational conditions foroperation below the required load.

A050911

Fig. 6.6.3.-1 Low load protection



Protection manual











The Start signal will be activated when the function is enabled (maximum phasecurrent above Min. Current) and the calculated active power falls below 0.95 thesetting threshold value (Min. Load).

The TRIP signal will be activated when the start conditions are true and theoperating time (Operating Time) has elapsed.


A050912



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A050913


The protection functions operate on any combination of phase currents in a triple,for example, it can operate as single-phase, double-phase or three-phase protectionon phase currents belonging to the same system.

A050914




Protection manual


Nominal Real Power: Power reference Pn for quantities normalization

Min. Load: Power threshold for start detection

Min. Current: Current threshold for start detection

Operating Time: Time delay for Trip condition detection

A050915


A050916

Fig. 6.6.3.2.-5 Pins

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The low load protection function evaluates the measured amount of current and ofactive power at the fundamental frequency.


Low load protection function is enabled only if the maximum phase current of theconfigured sensors is above the preset threshold value (Min Current). It thennormalizes the active power on a preset nominal value (Pn, Nominal RealPower).

When enabled, if the calculated active power falls below 0.95 the preset thresholdvalue (Min. Load) the protection function is started and the Start signal isgenerated.

The protection function will come back in passive status and the start signal will becleared if the calculated active power exceeds the setting threshold value.

After the protection has entered the start status and the preset operating time(Operating Time) has elapsed, function goes in TRIP status and the trip signal isgenerated.

The protection function will exit the TRIP status and the trip signal will be clearedwhen the calculated active power exceeds 1.05 the setting threshold value.


Two parameter sets can be configured for low load protection function.




Nom. real power 1 ... 1000000 kW 1000 Power reference fornormalization

Min load 5 ... 100 % Pn 10 Power threshold for startdetection

Min current 2 ... 20 % In 5 Current threshold for startdetection

Operating time 1.0 ... 1000 s 10 Time delay for trip conditiondetection



Protection manual



Code Event reason

E0 Start started

E1 Start back

E6 Trip started

E7 Trip back




6.6.4. Frequency supervision

REF 542plus has one frequency supervision function.

It is worth checking the network frequency for it to remain within the set limitswhen time and frequency-dependent processes are involved. Frequency changesinfluence, for example, the power dissipation, the speed (motors) and the firingcharacteristics (converters) of equipment. The frequency supervision function isused to report frequency variations in a configurable frequency range.

A050917

Fig. 6.6.4.-1 Frequency supervision






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The Start signal will be activated when the frequency exceeds the setting thresholdvalue (Start Value).



A050918



Sensors:

The supervision function selects automatically the best sensor. It operates preferablyon a voltage sensor, but it can work also on a current sensor.



Protection manual


A050919


Start Value: Frequency threshold for start condition detection


A050920


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A050921

Fig. 6.6.4.2.-4 Pins


The frequency supervision function evaluates network frequency on the measuredvalue of the first available (voltage or current) sensor.


If the measured network frequency is outside the allowed range, the supervisionfunction is started.

If the measured network frequency remains outside the allowed range for at leastoperating time setting, a trip signal becomes active.

If the measured network frequency falls outside the allowed range, that is thenetwork nominal frequency plus/minus the setting threshold value (StartValue), the frequency supervision function is started and the Start signal isgenerated.

The frequency supervision function will come back in passive status and the startsignal will be cleared, if the frequency difference to the nominal network frequencyfalls below 0.95 the setting threshold value.

When the protection has entered the start status and the preset operating time(Time) has elapsed, the function goes in TRIP status and the Trip signal isgenerated.

The protection function will exit the TRIP status and the trip signal will be clearedwhen the measured frequency value falls back within the allowed range, that is thenetwork nominal frequency plus/minus 0.95 the setting threshold value.



Protection manual



Two parameter sets can be configured for frequency supervision function.




Start value 0.04 ... 5.0 Hz 0.20 Frequency threshold for startcondition detection

Time 1.0 ... 300.00 s 10.00 Time delay for Trip conditiondetection


Code Event reason

E0 Start started

E1 Start back

E6 Trip started

E7 Trip back




6.6.5. Synchronism check

REF 542plus has one synchronism check protection function.

Paralleling monitoring is required if two networks are interconnected whosevoltages may differ in quantity, phase angle and frequency as a result of differentpower supplies (SYN). The switching operation for coupling the separate systemscan be enabled by the Synchronism Check SYN signal.

A050922

Fig. 6.6.5.-1 Synchronism check

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BI Digital signal (active high) Blocking signal

When the BI signal becomes active, the protection function is reset (no matter itsstate). This means that all the output pins go low generating the required events (ifany) and all the internal registers and timers are cleared. The protection function willthen remain in idle state until the BI signal goes low.




SYN Digital signal (active high) Sync signal

The Start signal will be activated when both the differential voltage ΔU and phasedifference ΔΦ between corresponding line voltages of two networks fall below thesetting threshold values (Delta Voltage AND Delta Phase respectively).

The SYN signal to parallel networks will be activated when the start conditions aretrue and the operating time (Time) has elapsed.


A050923




Protection manual


A050924


The protection function operates on the combinations of phase (or line) voltagesreported in the following table. The two phase voltages belonging to the twonetworks or a line voltage belonging to the second network are needed.

A050925


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Delta Voltage: Maximum allowed amplitude difference between two synchronousnetworks

Delta Phase: Maximum allowed phase difference between two synchronousnetworks

Time: Time delay for synchro condition detection

A050926


A050927

Fig. 6.6.5.2.-5 Pins



Protection manual



Synchronism check protection function evaluates the measured amplitude and therate of change of differential voltage between two networks corresponding the linevoltages.


The synchronism check protection function monitors the differential voltage ΔUbetween corresponding line and phase voltages of two networks and their phasedifference ΔΦ.

If the measured differential voltage and phase difference fall below the settingthreshold values (Delta Voltage AND Delta Phase respectively), thesynchro check protection function is started.

The protection function will come back in passive status and the start signal will becleared if differential voltage and phase difference exceed 1.05 the setting thresholdvalue. After the protection has entered the start status and the preset operating time(Time) has elapsed, the signal for parallel switching of networks (SYN) isgenerated.

The protection function will exit the synchro status and the SYN signal will becleared when the start conditions on differential voltage and phase difference valuesbecome false. Delta Voltage:Maximum allowed amplitude difference betweenthe two synchronous networks.

The determination of the setting of the synchronism check function is shown in anexample below. If two networks must be switched in parallel, the voltage amplitudesin both networks must first be almost the same and should have approximately thevalue of the rated voltage.

As long as the frequencies in the networks are different, the two networks cannaturally not be synchronized. A phase displacement will therefore occur betweenthe two voltages that are compared.

As a result, a voltage difference occurs as a function of time. This voltage differenceis the criteria for whether the two systems can be switched in parallel. The voltagecondition are shown in an example in the following diagram.

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A060106

Fig. 6.6.5.4.-1 diagram of the voltage quantities with unequal frequencies.

As shown in the diagram, the phase difference that needs to be set depends on thesetting of the differential voltage as follows:

ΔΔ

δ = ⎛⎝⎜

⎞⎠⎟

arctanU

U(19)

Δδ Setting the phase difference

ΔU Setting the differential voltage as start value

U Rated voltage as reference quantity

The equation for the required voltage difference can be calculated as follows:

Δ ΔU U= tan δ (20)

A time window t, which is equal to the time setting, can be used to check thefrequency variation

tT f

fn n=

2

360

Δ

Δ

δo

(21)

t Time window to check frequency deviation

Tn Period duration at rated frequency

fn Rated frequency

Δf Frequency difference

As long as the frequency deviation remains within the allowable limit, the set timeexpires and generates the signal "SYN" to be formed for parallel switching of bothnetworks.

An example of the calculation of the setting is as follows:



Protection manual


In a system with 50 Hz rated frequency the voltage deviation may be 20%.Consequently, the setting of the phase shift according to the above calculation is, atthe maximum 11°. The minimum time setting can then be calculated according tothe above equation to be 0.6 seconds.


Two parameter sets can be configured for the synchronism check protectionfunction.




Delta voltage 0.02 ... 0.40 Un 0.05 Max amplitude difference

Delta phase 5 ... 50 ° 10 Max phase difference

Time 0.2 ... 1000 s° 100.00 Time delay for synchro detection


Code Event reason

E0 Protection start

E1 Start cancelled

E6 Synch is present

E7 Synch is not present




6.6.6. Switching resonance protection

REF 542plus has one switching resonance protection function, to be used togetherwith the power factor controller and the high harmonic protection.

A050930

Fig. 6.6.6.-1 Switching resonance protection

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PFC OP Trigger signal (active low-to-high) PFC operation trigger


The PFC OP trigger is provided by the PFC function block to temporarily enable theresonance protection function at switching-in or switching-out of PFC controlledcapacitor banks.



Start L1 Digital signal (active high) Start signal of IL1




S L1-3 are the start signals phase selective. The phase starting signal will beactivated when respective phase current start conditions are true.

The TRIP signal will be activated when at least for one phase current the startconditions are true and the operating time has elapsed.



Protection manual



A050931



A050932


The protection function operates on any combination of line or phase voltages in atriple, for example, it can operate as single-phase, double-phase or three-phaseprotection on voltages belonging to the same system.

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A050933


Voltage THD Start value: THD amplitude threshold

Delta Voltage THD Start value: THD amplitude difference threshold

Voltage THD Time Delay: Time delay for THD detection


PFC OP Time: Enabling time at PFC trigger

Rms Voltage Start value: Function enabling voltage threshold condition

A050934




Protection manual


A050935

Fig. 6.6.6.2.-5 Pins


Switching resonance protection function evaluates the amount of voltage RMS withharmonic content up to the 25th harmonic and THD (Total Harmonic Distortion).


Operation of switching resonance protection function is triggered by an externalsignal connected to input pin ‘PFC OP’ (provided by the PFC function switch ON/OFF output pins) and remains enabled for the preset time (PFC OP Time).

At PFC OP trigger instant, the voltage THD values are saved.

While enabled, if there is for at least one phase voltage (respectively line voltage,depending on the configuration):

* The RMS value is above the preset threshold (Rms Voltage Start value)* The THD value is above the preset threshold (Voltage THD Start value)

for at least the preset detection time (Voltage THD Time Delay)* The variation of THD value with respect to the saved value (that is THD value at

trigger time) is above the preset threshold (that is Delta Voltage THD Startvalue) for at least the preset detection time (that is Voltage THD TimeDelay)

Then the protection function is started. The start signal is phase selective. When theabove conditions are true at least the for one phase voltage, then the relevant startsignal (S L1-3) will be activated.

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The protection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared if forall the phases the voltage falls below 0.95 one of the setting threshold values (RmsOR Voltage THD OR Delta Voltage THD).



Two parameter sets can be configured for the switching resonance protectionfunction.




Voltage THD startvalue

5 ... 50 % 5 THD amplitude threshold

Delta Voltage THDstart value

1 ... 50 % 2 THD amplitude difference threshold

Voltage THD timedelay

0.01 ... 60.00 s 0.03 Stabilizing delay for THD detection

Time 0.05 ... 60.00 s 0.10 Time delay for Trip conditiondetection

PFC OP time 0.01 ... 120.00 s 0.06 Function enabling time at PFCtrigger

Rms voltage startvalue

0.10 ... 1.00 Un 0.50 Function enabling Voltagethreshold condition


Code Event reason



E2 Protection started timing on phase L2






E16 Block output signal is active

E17 Block output signal is back to inactive



E20 PFC operation started

E21 PFC operation back



Protection manual



6.6.7. High harmonic protection

REF 542plus has one high harmonic protection function, to be used together withthe power factor controller and the switching resonance protection.

A050936

Fig. 6.6.7.-1 High harmonic protection












S L1-3 are the start signals phase selective. The phase starting signal will beactivated when respective phase current start conditions are true.


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A050937



A050938


The protection function operates on phase or line voltages in a triple.



Protection manual


A050939


Voltage THD Startvalue: THD amplitude threshold

Voltage THD Time Delay: Time delay for THD detection


Rms Voltage Startvalue: Function enabling Voltage thresholdcondition

A050940


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A050941

Fig. 6.6.7.2.-5 Pins


High harmonic protection function evaluates the measured amount of voltage RMSand THD (Total Harmonic Distortion).


If there is at least one phase voltage (respectively line voltage, depending on theconfiguration):

* The RMS value is above the preset threshold (Rms Voltage Start value)* The THD value is above the preset threshold (Voltage THD Start value)

for at least the preset detection time (Voltage THD Time Delay).

Then the protection function is started. The start signal is phase selective. It meansthat when the above conditions are true at least the for one phase voltage, then therelevant start signal (S L1-3) will be activated.

The protection function will remain in START status until there is at least one phasestarted. It will come back in passive status and the start signal will be cleared if forall the phases the voltage falls below 0.95 one of the setting threshold values (RmsOR Voltage THD OR Delta Voltage THD).




Protection manual



Two parameter sets can be configured for the high harmonic protection function.




Voltage THDstart value

1 ... 50 % 10 THD amplitude threshold

Voltage THDtime delay

0.01 ... 360 s 0.50 Stabilizing delay for THD detection

Time 0.05 ... 360 s 0.50 Time delay for Trip conditiondetection

Rms voltagestart value

0.10 ... 1.00 Un 0.50 Function enabling Voltage thresholdcondition


Code Event reason

E0 Start L1 started

E1 Start L1 back

E2 Start L2 started

E3 Start L2 back

E4 Start L3 started

E5 Start L3 back

E6 Trip started

E7 Trip back

E16 Block signal started

E17 Block signal back




6.6.8. Frequency protection

REF 542plus can install up to 6 frequency protection functions per protected net.

The frequency protection function is used to detect frequency variations in aconfigurable amplitude and rate of change frequency range.

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A050942

Fig. 6.6.8.-1 Frequency protection










BLOCK Digital signal (active high) Block output signal

The start signal is activated if the start condition is fulfilled. If the setting value ofthe start signal is selected below the nominal frequency, the protection functionoperates as underfrequency protection. If the setting value is selected above thenominal frequency, the protection function operates as overfrequency protection.Also the rate rise of the frequency decrease or increase can be detected. The tripsignal is generated according to the selected setting of the trip logic. The blockoutput signal appears if the line voltage or the phase voltage depending on thesetting parameter is below the setting value of the undervoltage threshold value.



Protection manual



A050943



A050944

Fig. 6.6.8.2.-2 Trip Logic

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A050945


The protection functions can operate on any combination of phase or line voltagesin a triple, for example, it can operate as single phase or double phase, three-phaseprotection on voltages belonging to the same system. The default setting is to usethe line voltage.

A050946




Protection manual


Start value: Delta frequency amplitude threshold, withrespect to the rated network frequency fr. If setbelow fr, it behaves as underfrequency,otherwise as overfrequency.

Frequency gradient: Rate of frequency change threshold


Undervoltage threshold: Minimum voltage threshold to be exceed forprotection enabling, otherwise it is blocked

A050947


A050948

Fig. 6.6.8.2.-6 Pins

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Frequency protection functions evaluate the frequency and/or the frequency gradientof voltage signals through the zero-crossing detection of the voltage measurementquantity. The measure is performed on the first voltage measure available above theminimum voltage amplitude (Undervoltage threshold).


The start condition and trip logic is selected by the user and it can be:

* Frequency only (only frequency value is considered)* Frequency and frequency gradient (both the values must exceed thresholds to

have a start and trip)* Frequency or frequency gradient (at least one of the values must exceed the

threshold to have a start and trip)

Depending on the set frequency threshold (Start Value) with respect to thenetwork rated frequency, the protection function behaves either as underfrequencyor overfrequency protection. For example, if the set frequency threshold is belowrated frequency value, the protection function behaves as underfrequency).

The condition on frequency gradient, when used, is in the same direction as thecondition on frequency. For example, if the protection function is set asunderfrequency, the frequency gradient is significant only if it is negative and if theactual frequency is below the rated value.

If the frequency cannot be measured or one of the three phases or line voltages(according to the selected setting parameter) falls below 0.95 the Undervoltagethreshold value, then the protection function is blocked and a block signal isgenerated. The protection function will exit the block status and clear the blocksignal if the minimum voltage amplitude rises above the setting threshold value.

Do not set the Undervoltage Threshold value too close to 1. Thecalculated value of the voltage itself is also dependent on the frequencydue to the impacts of the applied sampling rate. If the frequency goesdown, the calculated value of the voltage might be lower than theactual voltage value, which again will lead to an unwanted blocking ofthe protection.

In case the minimum voltage amplitude is above the undervoltage threshold valueand the frequency can be measured, the start condition is fulfilled if the value of themeasured frequency is below or exceeds the Start value setting parameter. Forsetting the value above the rated frequency the overfrequency condition will bedetected. On the contrary an underfrequency condition will generate the start signal.For selecting a Trip Logic with Frequency gradient, the start signal will begenerated similarly. The Frequency gradient is positive for overfrequencycondition and negative for underfrequency condition.



Protection manual


The protection function will exit the Trip status and the trip signal will be clearedwhen all the start conditions fall below 0.95 of the calculated threshold value setting(Start Value and/or Frequency gradient). For example, if the setting forthe frequency protection with 50 Hz rated frequency is selected as following:

Start Value 49 Hz

Undervoltage threshold 0.7 Ur

The resetting value for the Start Value is:

50 Hz – 0.95 (50 Hz – 49 Hz) = 49.05 Hz

and for the Undervoltage threshold is:

0.7 Ur / 0.95 = 0.74 Ur

When the protection has entered the start status, if the above conditions remain trueand the preset operating time (Time) has elapsed, the function goes in TRIP statusand the trip signal is generated.

The protection function will exit the TRIP status and the trip signal will be clearedwhen all the start conditions fall below 0.95 the setting threshold value (StartValue and/or Frequency gradient).


Two parameter sets can be configured for each of the frequency protectionfunctions.




Trip criteria f / f_AND_df/dt /f_OR_df/dt

- f Definition of start/trip criteria

Start value 40.00 ... 75.00 Hz 49.9559.95

Delta frequency amplitudethreshold

Frequencygradient

0.10 ... 1.00 Hz/s 0.50 Rate of frequency changethreshold

Time 0.10 ... 30.00 s 0.50 Time delay for trip conditiondetection

Undervoltagethreshold

0.10 ... 1.00 Un 0.20 Minimum voltage thresholdfunction block/enabling

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Code Event reason

E0 Protection start

E1 Start cancelled



E16 Block output signal is active state

E17 Block output signal is back to inactive state




6.7. Autoreclose

The autoreclose function can be used to reclose the circuit breaker automaticallywhen a protection function has tripped. This function block can be applied to all theprotection functions available in REF 542plus.

A050949

Fig. 6.7.-1 Autoreclose





1 SHOT Digital signal (active high) AR only performing single shot

CB OK Digital signal (active high) CB drive ready for the following AR

EX. TRIG Digital signal (active high) Triggering of AR by an external signal

INCR. Digital signal (active high) Increment the number of shots

STOP AR Digital signal (active high) Immediate stopping of the AR cycles

TEST Digital signal (active high) Test of AR cycle (O-CO-CO…)




Protection manual




CLOSE CB Digital signal (active high) CB close signal

OPEN CB Digital signal (active high) CB open signal

AR ACTIVE Digital signal (active high) High as long as AR is active

AR FAILED Digital signal (active high) High in case of an unsuccessful AR

SHOT 1 Digital signal (active high) 1st Shot signal ofAR

SHOT 2 Digital signal (active high) 2nd Shot signal of AR

SHOT 3 Digital signal (active high) 3rd Shot signal ofAR

SHOT 4 Digital signal (active high) 4th Shot signal of AR

SHOT 5 Digital signal (active high) 5th Shot signal ofAR


A050950


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A050951


A050952




Protection manual


A050953


A050954

Fig. 6.7.2.-5 Pins

6.7.3. Operation mode

The autoreclose function block can be operated in two different modes.

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Start and trip controlled

In this operation mode, the difference of the time duration between the start and thetrip signal of the related protection function is evaluated. Therefore, the differentsettings of the specified time are provided. If the time difference between theprotection start and trip signal is within the specified time, the AR-cycle is releasedand respectively continued. The corresponding CB shall be reclosed after therelating dead time is elapsed. If the condition is not fulfilled, the AR function blockwill be blocked. To continue the operation of the feeder, the AR function blockneeds to be released locally or remotely via the station control system.

Start controlled

This operation mode initiates the AR-Cycle only by a start signal of the relatedprotection function. The tripping time for each shot can be delayed separately. Thisdelayed tripping is need in some application, for example to burn out a falling treeon the overhead line. Therefore, the operation time of the protection function willnow be controlled by AR. Normally, the first shot shall have a relatively shortoperation time in the range of 30 to 100 ms. The second and the following shot shallhave longer operation time in the range of 1 to 10 s. If this mode is selected, thesettings of the specified time are to be used to control the operation time of thefollowing shots.

Both AR function can carry out a maximum of 5 shots.

The configuration can be done by a selection table. All the protection functionswhich can be connected are shown in the table. The columns are foreseen to define,which of the protection functions will activate specific AR shots. By selecting therelated protection functions in each shot,AR will be initiated according to theoperation mode defined previously. The protection function can be redefined aftereach shot. In the example, AR will operate as follows:

Due to the operation time dependency on the fault current, the IDMTand earth-fault IDMT are not listed. If this protection shall be used toinitiate the AR-cycle, the relating trip signal shall be connected by aFUPLA wire to the input EX.TRIG of the AR function block.

The distance protection can only be used in start and trip control mode.If the AR status is ready, the overreach zone of the distance protectionwill be activated. After the first shot, the overreach zone will not beactivated anymore. The trip will be done according to the setting of therelated impedance zone.



Protection manual


To ensure the proper function of AR, the trip of the protection shall besend directly to the so-called 2-2 switch object, which controls andoperatesCB. There is no need to make a FUPLA wiring between theAR function block, 2-2 switch object and the related protectionfunctions.

The external trigger is to be selected, if AR will be triggered by an externalprotection function. The trip must be connected to a binary input of REF 542plus.Afterwards, the external trip signal needs to be wired to the external trigger inputEX. TRIG of the AR function block.

If the AR-cycle is initiated by the input EX. TRIG, the same wire ofthis input signal must also be used to open CB via the 2-2 switchobject. Otherwise, in case of blocking AR by a blocking signal, noopening of CB by the external protection will be possible.






Number of reclosurecycles

0 ... 5 1

Reclaim time 10 ... 30 s 30

Specific time first shot 0.04 ... 30 s 0.5

Dead time first shot 0.1... 100 s 0.3

Specific time secondshot

0.04 ... 30 s 0.5

Dead time secondshot

0.1 ... 100 s 0.3

Specific time thirdshot

0.04 ... 30 s 0.5

Dead time third shot 0.1 ... 100 s 0.3

Specific time fourthshot

0.04 ... 30 s 0.5

Dead time fourth shot 0.1 ... 100 s 0.3

Specific time fourthshot

0.04 ... 30 0.5

Dead time fourth shot 0.1 ... 100 0.3

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Code Event reason

E8 AR active started

E9 AR active back

E10 General enable started

E11 General enable back

E12 Test enable started

E13 Test enable back

E14 AR failed started

E15 AR failed back

E18 Block AR started

E19 Block AR back

E20 AR 1. shot started

E21 AR 1. shot back

E22 CB OK started

E23 CB OK back

E24 CB OK internal drop delayed started

E25 CB OK internal drop delayed back

E26 External trigger started

E27 External trigger back

E28 Shot increment started

E29 Shot increment back

E30 Stop AR started

E31 Stop AR back

E32 Test started

E33 Test back

E40 Close CB started

E41 Close CB back

E42 Open CB started

E43 Open CB back

E48 Shot 1 started

E49 Shot 1 back

E50 Shot 2 started

E51 Shot 2 back

E52 Shot 3 started

E53 Shot 3 back

E54 Shot 4 started

E55 Shot 4 back

E56 Shot 5 started

E57 Shot 5 back




Protection manual


6.8. Fault recorder

This function block allows the eight REF 542plus analog input signals to berecorded for a period of at least 1 second and for a maximum of 5 seconds. It is alsopossible to record up to 32 digital signals simultaneously from the FUPLA.

A050958

Fig. 6.8.-1 Fault recorder


Inputs

Table 6.8.1.-1 Inputs



1 ... 32 Digital signal (active high) 32 Input for recording binarysignal

START Digital signal (active high) Start of the fault recording

OVERFLOW Digital signal (active high) Overflow signal indication

When the BL signal becomes active, the fault recorder function is reset (no matterits state). This means that all the output pins go low generating the required events(if any) and all the internal registers and timers are cleared. The fault recorderfunction will then remain in idle state until the BL signal goes low.

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A050959

Fig. 6.8.2.-1 General and setting parameters

Name: User defined Analog Input meaning

Factor: Analog input scaling factor used for display

Time before fault: Recording duration before recorder start inputtrigger

Recording time: Total allocated duration, it limits the number ofrecords (from 5 to 1) in the ring buffer

Time after fault: Recording duration after recorder start inputtrigger



Protection manual


A050960

Fig. 6.8.2.-2 Pins

6.8.3. Operation

The fault recorder is started within the application. The recording time of the faultrecorder is a combination of the time before the fault and the time after the fault. Thetime before the fault refers to the period recorded before the fault recorder is actuallystarted from a protection start signal. The time after the fault is the period after thefault recorder has started. Dynamic recording of the fault record, for example, fromstart signal to signal CB OFF is not possible.

The ring buffer process saves the specific fault record, that is, the oldest fault recordis always overwritten with a new one. The number of saved fault records depends onthe record time. The total duration of all saved fault records is 5 seconds themaximum, if it is set to a lower value it limits the number of records in the buffer.

n = int((recording time/(time before + time after)

For example, 5 fault records can be saved with a record time of 1 s, that is, theminimum record time (time before the fault + time after the fault) that can be set.

The fault records are exported with the configuration software and then converted tothe COMTRADE format. The fault records can also be exported via the bus of thestation control system. The conversion to the COMTRADE format has to be carriedout in the station control system.

The following limitations must be taken into account on the use of thefault recorder:

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* At least one protective function must be configured.* The start signal for the fault recorder must be implemented inFUPLA.

The analog signals are digitized and processed with a 1.2 kHz sampling rate,because they are decisive for the protection trips. They are therefore within a timegrid of 0.833 ms. The start and trip signals from the protection functions arerecorded and sent to the binary outputs immediately.

On the contrary, the digital signals are processed in accordance with the FUPLAcycle time. The cycle time depends on the application in this case. The digitalsignals are therefore in a grid that is significantly larger than the analog signal grid.

The fault recorder is dedicated for recording the fault data during a short circuit inthe network. The data can be exported from the REF 542plus later and displayedwith a suitable program.

A050961

Fig. 6.8.3.-1 Graphic display of fault record data of a two-pole short circuit with theWINEVE® program



Protection manual





Time before fault 100 ... 2000 ms 100 Recording duration before therecorder start

Recording time 1000 ... 5000 ms 2500 User defined limit to the totalduration of the buffer, that is torecords number

Time after fault 100 ... 4900 ms 1000 Recording duration after therecorder start

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7. Abbreviations

Abbreviation Description

AR Auto reclosure

BI Binary input

CB Circuit-breaker

CT Current transformer

DFT Discrete Fourier Transformation

FUPLA Function block programming language; Function plan;Function chart

HMI Human-machine interface

IDMT Inverse definite minimum time characteristic

NPS Negative-phase-sequence

PFC Power factor controller

RMS Root mean square

ROA Relay operating angle

RTD Resistance temperature device

SI Sensor input

VT Voltage transformer



Protection manual


ABB OyDistribution AutomationP.O.box 699FI-65101 VaasaFINLAND+358 10 22 11+358 10 22 224 1094http://www.abb.com/substationautomation

1MRS755860

EN

4/2007

Documents

ABB - REF542+ Protection Manual 1 Mrs 755860 en 2008