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EXPERIENCE AND RELIABILITY

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Short circuit loop measurementsShort circuit loop measurements

EN 61557-3

EN 60463-4-41

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EN 60364-6 EN 60364-6 Legal requirementsLegal requirements

• The HD 60364-6:2008 standard defines two types of inspections:– acceptance inspections;– periodic inspections.

• According to this standard, every system must be inspected during assembly, after assembly and before handover to the user. The acceptance inspection must include comparison of the measurements results with the relevant criteria defined, among others in the multi-sheet IEC 60364 standard, so as to check if the requirements given there have been met. In the case of enlargement or modifications of existing systems, the same full scope of tests must be performed as in the case of a new system.

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EN 60364-6 EN 60364-6 Legal requirementsLegal requirements

• During the performance of the measurements, precautions must be observed to make sure that the inspection will not cause a hazard to persons or pets and that it will not cause damage to the property and equipment even if the tested loop is defective.

• The person performing the inspection should be properly qualified and competent with regards to inspections. It must be emphasized that the person performing the inspection is responsible for preparing the system for tests, for conducting the tests, and for proper assessment of the test results (E and D license).

• An acceptance inspection consists of a visual inspection and a test. A visual inspection must be performed before the test, before the power supply of the system is switched on.

• A periodic test consists of activities necessary to determine if the system and all its components are in a condition that enables their continued operation.

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EN 60364-6 EN 60364-6 Frequency of periodicFrequency of periodic inspectionsinspections

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EN 61557 EN 61557 Selection of measuring instrumentsSelection of measuring instruments

The measuring instruments and devices must be selected in compliance with the respective parts of the EN 61557 standard:– EN 61557 - Part 1 „General requirements”– EN 61557 - Part 2 „Insulation resistance”– EN 61557 - Part 3 „Loop impedance”– EN 61557 - Part 4 „Resistance of earth connection and equipotential

bonding”– EN 61557 - Part 5 „Resistance to earth”– EN 61557 - Part 6 „Effectiveness of residual current devices (RCD) in TT,

TN and IT systems”– EN 61557 - Part 7 „Phase sequence”– EN 61557 - Part 10 „Combined measuring equipment for testing,

measuring or monitoring of protective measures”

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EN 61557 EN 61557 Permissible values of measurement errorsPermissible values of measurement errors

Permissible values of measurement errors acc. to the EN 61557 standard

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EN 61557 EN 61557 Permissible values of measurement errorsPermissible values of measurement errors

Displayed value

Error „±2%m.w”

Error„± 4 digits”

Error summary

Summary error in % for particular measurement

1,00Ω 0,02Ω 0,04Ω 0,06Ω 6%

0,50Ω 0,01Ω 0,04Ω 0,05Ω 10%

0,20Ω 0,00Ω 0,04Ω 0,04Ω 20%

0,13Ω 0,00Ω 0,04Ω 0,04Ω 30%

0,10Ω 0,00Ω 0,04Ω 0,04Ω 40%

0,05Ω 0,00Ω 0,04Ω 0,04Ω 80%

(exemplary meter with resolution 0,01Ω and basic error ± 2% m.w. ± 4 digits)

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EN 61010-1 EN 61010-1 Categories of measuring instrumentsCategories of measuring instruments

• CAT IV – measurements performed at a low-voltage system source; examples are measurements of equipment at overcurrent protection devices;

• CAT III – measurements performed in systems in buildings; examples are measurements performed at distribution boards, automatic switches, electrical system conductors, to include cables, busbars, connectors, power outlets in systems and equipment intended for industrial applications and other equipment, e.g. fixed motors permanently connected with to stationary systems;

• CAT II – measurements performed in circuits that are directly connected with low-voltage systems; examples are measurements in home appliances, portable tools, etc.;

• CAT I – measurements performed in circuits that are not connected directly to a power supply system.

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Short circuit loop measurementsShort circuit loop measurements

ZB .................. Human body impedanceRS ................. Floor and shoes resistanceRE ................ Earthing resistance of accessible conductive partsIf .................... Noise currentUc .................. Touch voltageUs .................. Voltage drop on the floor/shoes resistanceUf .................. Noise voltage (Uf=Uc+Us)

Electrical installation scheme in the case of failure

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• Basic security – insulation of active parts, covers and fencing– Constant insulation or gas insulation with casing or separation– Access difficulties in places with qualified personnel supervision

• Security in case of fault – earthings, equipotential bondings, automatic power shutdown

• Additional source of security – RCD

EN 60364-4-41EN 60364-4-41Automatic power shutdownAutomatic power shutdown

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EN 60364-4-41EN 60364-4-41Automatic power shutdown – disconnection timesAutomatic power shutdown – disconnection times

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Short-circuit loop ( TN system)

oaS UIZ

EN 60364-4-41EN 60364-4-41Automatic power shutdown – disconnection timesAutomatic power shutdown – disconnection times

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Short-circuit loop ( TT system)

VIZ aS 50

EN 60364-4-41EN 60364-4-41Automatic power shutdown – disconnection timesAutomatic power shutdown – disconnection times

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Measurement of touch voltage UST

L1

PENL3L2

Rr

Im ax280A

1

U 1

U 2

I2

PE

U (U )ST/T B

EN 60364-4-41EN 60364-4-41Automatic power shutdown – touch voltageAutomatic power shutdown – touch voltage

Voltage between energized object and the feet of the person in contact with the object

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Measurement of shock voltage UT

L1

PENL3L2

Rr

Im ax280A

1

U 1

U 2

I2

U (U )ST/T B

F

Probe

EN 60364-4-41EN 60364-4-41Automatic power shutdown – shock voltageAutomatic power shutdown – shock voltage

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Loop measurements Loop measurements L-PE, L-N and L-LL-PE, L-N and L-L

Measurement of impedance in protective circuit (L-PE) using two-pole method

L1

PENL3L2

I m ax42A1

I2

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Loop measurements Loop measurements L-PE, L-N and L-LL-PE, L-N and L-L

Measurement of impedance in L-N circuit using two-pole

method

L1

PENL3L2

I m ax42A1

I2

Measurement of impedance in L-L circuit using two-pole

method

L1

PENL3L2

I m ax42A1

I2

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180

230220 380

400

440 U [V ]

Voltage ranges for which short-circu it current is calculated

Voltage ranges for which im pedance is m easured

260

190 270 360

420340

Relationship between the network voltage and the ability to calculate the prospective short-circuit current (PSC)

Calculation of short circuit Calculation of short circuit current according to Ucurrent according to Unn and to U and to Uoo

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Zs and RsZs and RsShort circuit loop measurementsShort circuit loop measurements

Short-circuit loop impedance meters

Z-impedance

R-resistance

X-reactance

R

XZ

22 XRZ

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Loop measurement Loop measurement for network diagnosisfor network diagnosis

• Loop measurements to determine aging of the network – comparing results of measurements after each period

• Big test current – diagnosis of diameter of cable

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Big test current and Big test current and 4-wire method – big accuracy4-wire method – big accuracy

Four-pole method - theory

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Big test current and Big test current and 4-wire method – big accuracy4-wire method – big accuracy

Measurement of impedance in TN- system

L1

PENL3L2

Rr

Im ax280A

1

U 1

U 2

I2

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Measurement rules and meter connection scheme

VIZ aS 50oaS UIZ

Short circuit loop measurements Short circuit loop measurements in networks secured with RCDin networks secured with RCD

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The Art of Electical Measurement

Thank you for your attention

MEASUREMENT INSTRUMENTS