DCS Thyristor Power Converters General for DC Drive … Thyristor Power Converters for DC Drive Systems Technical Guide k r e m) ... When using DC drives from ABB or any other

III A 1-1

General

3ADW000163R0201_Technical guide_e_b

M

M

DCS converter

2-Q non-regen.

Semiconductor

fuses

Semiconductor

fuses

Semiconductorfuses

4-Q resp.

2-Q regenerative

DCS converter

FUSI

NG

DCS Thyristor Power Convertersfor DC Drive Systems

Technical Guide

Medium voltage network

Power Drive

System(emitter)

Equipment

(victim)

Point of measurement

for conducted emission

Point of measurement for

radiated emission

10 m

2 nd EnvironmentPoint of measurement

1 st Environment

Propagation of conducted emissions

Public low-voltage network

Industrial low-voltage network

EMC

HIGH P

OWER

COMMUTATION

III A 1-2

General


Contents

III A TECHNICAL GUIDE

1 General

1.1 Introduction ............................................. III A 1-31.1.1 How to use this description ...................................... III A 1-31.1.2 Target group ............................................................ III A 1-3

2 Technical environment

2.1 EMC Compliant Installation and Configurationfor a Power Drive System ....................... III A 2 -1

2.1.1 Introduction ............................................................... III A 2-12.1.2 Definitions ................................................................. III A 2-22.1.3 EMC Compliant Installation Guidelines .................... III A 2-42.1.4 Summary ................................................................ III A 2-14

3 Engineering of DC drives

3.1 Fusing aspects of DC drives .................. III A 3-13.1.1 General ..................................................................... III A 3-13.1.2 Armature supply ....................................................... III A 3-23.1.3 Field supply .............................................................. III A 3-4

3.2 Commutation ........................................... III A 3-53.3 Harmonics................................................ III A 3-5

3.3.1 12-Pulse ................................................................... III A 3-13.4 Reactive power ........................................ III A 3-5

4 Modernization of old existing DC driveinstallations

4.1 1 ................................................................ III A 4-14.1.1 .................................................................................. III A 4-14.1.2 .................................................................................. III A 4-24.1.3 ...............................................................................................

4.2 System pertubation ................................. III A 4-34.2.1 .................................................................................. III A 4-44.2.2 .................................................................................. III A 4-4

4.3 Applications ............................................. III A 4-64.3.1 Master - Slave .......................................................... III A 4-74.3.2 Synchronous operation ............................................ III A 4-7

4.4 Rebuild ..................................................... III A 4-84.4.1 .................................................................................. III A 4-84.4.2 .................................................................................. III A 4-8

III A 1-3

General


1.1 IntroductionWhen using DC drives from ABB or any othersupplier there is always basic knowledge re-quired to enable you to understand:

• How your drive needs to be configured andengineered.

• How does your drive installation interact withany other installations surrounding the drive.

• What types of components need to be addedto the converter and why to guarantee thecorrect functionality.

• How need components to be matched.• What needs to be done to be inline with

existing laws and technical standards.

To have some support in to find solutions for allthese problems ABB offers this type of docu-mentation for your assistance.

All other documentation related to ABB's drivesprogram apart from this will be found in thededicated product documentation like SystemDescription, Technical Data, Operating Instruc-tion etc. and is generally available with everysingle drive delivered.

1 General

1.1.1 How to use this descriptionThe purpose of this documentation is to provideprofound general information about drives , theirengineering including additional requirementsfor special accessories, their technical environ-ment as well as basic information of how tohandle modernization of old installations.

1.1.2 Target groupAll users having basic knowledge as well asexperience in practical exercises with DC-Drives.

III A 1-4

General


III A 2-1

Technical environment


2.1 EMC Compliant Installation and Configuration for a Power DriveSystem

2 Technical environment

Practical Installations and SystemsThis manual gives a brief insight of EMC in termsof definitions and offers practical EMC solutionsand a connection example with essential re-marks and hints for the EMC compliance ofpower drive systems. The solutions can be di-rectly used or applied by OEM or Panel builder.

The Directives concerning DrivesThere are three directives that concern variablespeed drives. They are Machinery Directive,Low Voltage Directive and EMC Directive. Themain objective of the EMC Directive is to guar-antee the free movement of apparatus and tocreate an acceptable electromagnetic environ-ment in the European Economic Area (EEA).

Product-specific ManualsThe detailed information of the installation anduse of products can be found in product-specificmanuals included in the product package. Thisguide is meant to be used together with product-specific manuals.

2.1.1 Introduction

GeneralThis guide assists the design and installationpersonnel when intending to achieve compli-ance with the requirements of EMC Directive inthe user’s systems and installations, when usingDCS converters.

The purpose of this chapterThe purpose of this chapter is to guide OriginalEquipment Manufacturers (OEM), System Inte-grators and Panel builders in designing andinstalling DCS converters and their auxiliarycomponents into their own installation and sys-tems. The auxiliaries include EMC filters, linereactors, fuses, etc. If these instructions arefollowed, it is possible to fulfil EMC requirementsand give CE marking when necessary.

DefinitionsThe EMC Product Standard for Power DriveSystems, EN 61800-3 (or IEC 1800-3) is usedas normative standard for variable speed drives.The terms and definitions applied in the stand-ard are also used in this manual. The differenttypes of equipment used in this guide (refer tosection 2.1.2 Definitions) are the same as de-fined in the EMC Directive.

III A 2-2



2.1.2 Definitions

Electromagnetic Compatibility (EMC)EMC stands for Electromagnetic Compatibility.It is the ability of an electrical/electronic equip-ment to operate satisfactorily within an electro-magnetic environment without introducing intol-erable electromagnetic disturbances to any-thing in that environment (International Electro-technical Vocabulary, IEC 50 Chapter 161). Thisis a legal requirement for all equipment takeninto service within the European Economic Area(EEA).The terms used to define compatibility are shownin fig. 2.1/1.

Fig. 2.1/1 Immunity and emission compatibility.

As the variable speed drives are described as asource of interference, it is natural that all partsthat are in electrical or airborne connectionwithin the Power Drive System are part of theEMC compliance. The concept that a system isas weak as its weakest point is valid here.

ImmunityElectrical equipment should be immune to highfrequency and low frequency phenomena. High-frequency phenomena include electrostatic dis-charge (ESD), electrical fast transient (Burst),radiating electromagnetic field, conducted radiofrequency disturbance and electrical surge. Typ-ical low-frequency phenomena are mains volt-age harmonics, notches and unbalance in 3-phase networks.

EmissionThe source of high-frequency emission of thyr-istor converters is the fast switching of powercomponents such as thyristors and control elec-tronics. This high-frequency emission can prop-agate by conduction and radiation.

Immunity level

Immunity limit

Emission limit

Emission level

Disturbance

Compatibilitymargin

Independent variable e.g. frequency

Equipment

level

Power Drive System (PDS)According to the EMC Product Standard EN61800-3 a variable speed drive, which controlsa driven equipment, constitutes part of an instal-lation. The standard defines a drive as a PowerDrive System (PDS).

It is recommended that design and installa-tion responsible personnel have this stand-ard available and are familiar with this stand-ard. All standards are available from thenational bodies on standardisation and fromCENELEC, rue de Stassart, 35, 1050 Brux-elles.

The machine or system made by OEM or Panelbuilder consists more or less of the PDS parts ormany PDSs in a configuration. The installationguidelines for EMC compliance described inthis manual are used within the definition ofPower Drive Systems, but the same guidelinescan, or in some cases, should be extended to allinstallation. This manual gives principles and apractical EMC connection example, which canbe applied to user's system.

Fig. 2.1 /2 Terms and abbreviations used in Drives.

Complete Drive Module CDM

Basic Drive Module BDM

Feeding section

System control and

Power Drive System PDS

Motor and Sensors

sequencing

Installation orpart of installation

Driven Equipment

Auxiliaries and others

Control, Converter andProtection

III A 2-3



Types of EquipmentEMC Directive applies to "all electrical and elec-tronic appliances together with installations con-taining electrical and/or electronic componentsliable to cause electromagnetic disturbance orthe performance of which is liable to be affectedby such disturbance".The interpretation of EMC Directive for differentconfiguration in the area of drives can be dividedinto several levels:

ComponentIn this content the interpretation of componentcan be divided into several categories. If acomponent performs a direct function, as thevariable speed drives do, they are consideredequivalent to apparatus.Direct function:Any function which meets the needs of a userand which can be directly used by such a user,without the need to make any further adjust-ments other than any connections essential forits electrical power supply or for the exchange ofanalogue or digital signals.

ApparatusA finished product containing electrical and/orelectronic components and intended to be placedon the market and/or taken into service as asingle commercial unit.

SystemSeveral items of apparatus combined to fulfil aspecific objective and intended to be placed onthe market as a single functional unit.

InstallationA combination of items of apparatus, equipmentand/or components put together at a given placeto fulfil a specific objective but not intended to beplaced on the market as a single functional unit.

CE Marking for EMCComponents with direct functions, Apparatusand Systems have to be CE marked.Components with no direct function for thefinal consumer are not CE marked.Installations are required to satisfy various bas-es of the Directives, but are not required to beCE marked.

Fig. 2.1/3 The CE mark.

Installation EnvironmentsThe PDSs can be connected to either industrialor public power distribution networks. The envi-ronment class depends on the way the PDS isconnected to the network.The environment classes are First and SecondEnvironment.

First EnvironmentThe First Environment includes domestic premis-es. It also includes establishments directly con-nected without intermediate transformer to alow-voltage power supply network which sup-plies buildings used for domestic purposes.

Second EnvironmentSecond Environment includes all establishmentsother than those directly connected to a low-voltage power supply network which suppliesbuildings used for domestic purposes.

Fig. 2.1/4 Illustration of Environment Classes andpropagation of disturbances.

PropagationFor PDSs in the second environment, the usershall ensure that excessive disturbances are notinduced into low-voltage network, even if prop-agation is through a medium voltage network.

Note! Fig. 2.1/4 shows the case when a victim isin a 1st Environment. The situation is the same ifa victim is in a 2nd Environment in anotherinstallation. The measurements are carried outin that case only in case of dispute.

Medium voltage network

Power Drive

System(emitter)

Equipment(victim)

Point of measurementfor conducted emission

Point of measurement forradiated emission

10 m

2 nd Environment

Point of measurement

1 st Environment

Propagation of conducted emissions

Public low-voltage network Industrial low-voltage network

III A 2-4



2.1.3 EMC Compliant Installation Gui-delines

NoteIn order to make the description in this chapteras short and easily readable as possible, crossreferences in the form 1 , 2 … are used.

GeneralConverters and the major part of the devices,which constitute a DC Drive, cannot fulfil theEMC requirements independently from eachother. They must be installed and connected byskilled personnel according to the guidelineslaid down in this manual. This restriction isrelated to the expression "restricted distribution"in the short description of EN 61800-3, which isthe EMC product standard for a Power DriveSystem.

Definitions

Earth, earthing for safety

Ground, grounding for EMC,connection with chassis or housing withlow inductance

Important instructions for plantswith line filters

Filter in an earthed line (TN or TT Network)The filters are suitable for earthed lines only, forexample in public European 400 V lines. Ac-cording to EN 61800-3, filters are not compati-ble in insulated industrial lines with own supplytransformers due to their safety risks in suchfloating lines (IT networks).

Earth fault detectionFilters (with internal discharging resistors), ca-bles, the converter and the motor have togethera considerable capacitance to ground, whichcan cause an increased capacitive earth cur-rent. The tripping threshold of an earth faultdetector that measures this current must beadapted to this higher value.

High voltage testBecause of the capacitors of the line filter thehigh voltage test has to be done with dc voltageto protect the components.

Warning

Line filters contain capacitors, which can keepdangerous voltages at the terminals after theswitch off of the mains voltage. The dischargeby internal resistors takes some seconds. There-fore a waiting time of at least 10 s and a voltagecheck are obligatory before you begin your workat the equipment.

Product Standard EN 61800-3EMC standard for drive systems (Power-DriveSystem), interference immunity and emis-sions in residential areas, enterprise zoneswith light industry and in industrial facilities.This standard must be complied with in the EUfor satisfying the EMC requirements for sys-tems and machines!

For emitted interference, the following apply:EN 61000-6-3 Specialised basic standard for emis-

sions in light industry can be satis-fied with special features (mains fil-ters, screened power cables) in thelower rating range *(EN 50081-1).

EN 61000-6-4 Specialised basic standard foremissions in industry*(EN 50081-2)

For interference immunity, the following apply:EN 61000-6-1 Specialised basic standard for inter-

ference immunity in residential are-as *(EN 50082-1)

EN 61000-6-2 Specialised basic standard for inter-ference immunity in industry. If thisstandard is satisfied, then the EN61000-6-1 standard is automaticallysatisfied as well *(EN 50082-2).

* The old generic standards are given in brackets

NOTE!

The conformity pro-cedure is matter ofresponsibility ofABB AutomationProducts GmbH andof the machine man-ufacturers or theplant builders corre-sponding to theirshare of the exten-sion of the electricalequipment.

III A 2-5



General safety instructions

Electrical machines or devices are items ofequipment used in industrial power installa-tions. During operation, parts of this equipmentare live and bare, or moving, rotating, etc. Theseparts may cause great material damage andserious heavy injuries, if, for instance, theircovers are removed or if they are not properlyused or operated.

It must therefore be ensured that- only qualified experts perform work at

these machines and devices,- these persons always have available -

among other things - the operatinginstructions and other product-specificdocumentation supplied along whenperforming work, and are obliged to meetthe requirements laid down in thesedocuments,

- non-qualified persons are not authorised toperform any work at or near thesemachines and devices.

The operating instructions cannot take into con-sideration every possible case of configuration,operation or maintenance. Thus, they mainlygive such advice only, which is required byqualified personnel for normal operation of themachines and devices in industrial installations.

If in special cases the electrical machines anddevices are intended for use in non-industrialinstallations - which may require stricter safetyregulations (e.g. protection against contact bychildren or similar) -, these additional safetymeasures must be carried out by the customerduring assembly.

Earth connections must be made according toIEC 364!

III A 2-6



1 Classification

Fig. 2.1/5: Classification

Not applicable

First environment (residential area with light industry) with restricted distribution

Not applied, since general distribution sales channel excluded

satisfied

satisfied

MM

19

4

21

22 23

13

25

18

21

2

21 21

13

25

249 / 249 /

5

Mains filter

Converter

Line reactor

Supply transformer for a residential area (rating normally ≤ 1,2 MVA)

Earthed public 400-V network with neutral conductor

Medium-voltage network

Earthed neutral

To

oth

er

load

s, e

.g. d

rive

sys

tem

s

An isolating transformer with an earthed screen and earthed iron core renders mains filter and line reactor superfluous.

Operation at public low-voltage network

together with other loads of all kinds.

Residential area

To

oth

er

load

s w

hich

hav

e to

be

pro

tect

ed

from

the

syst

em d

istu

rban

ces

caus

ed

by

pow

er c

onv

ert

ers

(HF

inte

rfer

enc

e an

d co

mm

utat

ion

no

tche

s)

Converter

MMMM MM

19

21

22 23

13

25

18

21 21

13

25

4

22 23

14

26

14

26

13

25

13

25

21

18

21 21 21

2 2

4

22 23 22

249 / 249 / 249 / 249 /

5

alte

rnat

ive

alte

rnat

ive

Line reactor + Y-capacitor


Supply transformer for a residential area (rating normally ≤ 1.2 MVA)

Earthed neutral


To

othe

r lo

ads,

e.g

. dr

ive

sys

tem

s

Mains filter

Line reactor

Converter Converter

Mains filter

Line reactor

Converter Converter

An isolating transformer with an earthed screen and earthed iron core renders mains filter and line reactor superfluous.

Operation at public low-voltage network

together with other loads of all kinds.

To

othe

r lo

ads,

e.g

. dr

ive

sys

tem

s

To

othe

r lo

ads

whi

ch h

ave

to b

e pr

otec

ted

from

the

syst

em d

istu

rban

ces

caus

ed b

y po

we

r co

nver

ters

(H

F in

terf

eren

ce a

nd c

omm

utat

ion

notc

hes)


Operation at public low-voltage network together with other loads of all kinds.

Light industry Residential area

III A 2-7



The field supply is not depicted inthis overview diagram. For thefield current cables, the samerules apply as for the armature-circuit cables.

MMMM

19

21 21 21

2

4

13

25

13

25

14

26

14

26

18

22 23 22 23

249 / 249 /

Supply transformer for a residential area (rating normally ≤ 1.2 MVA)

Earthed 400-V network with neutral conductor; 3~ ≤ 400 A

Operation at low-voltage network together with other loads of all kinds, apart from some kinds of sensitive communication equipment.

To

othe

r lo

ads,

e.g

. dr

ive

sys

tem

s

Line reactor + Y-capacitor Line reactor

Converter Converter

Mains filter

Earthed neutral


Industrial zone

alte

rnat

ive

alte

rnat

ive

MMMM

13

25

13

25

14

26

14

26

6

20

4

22 23

249 /

20

21 21

Convertertransformer

Cas

e-re

fere

nced

EM

C a

naly

sis

alte

rnat

ive

Converter transformer with earthed

iron core (and earthed screen where appropriate)

alte

rnat

ive

I > 400 A and/or U > 500 V

Operation with separate power converter transformer. If there are other loads at the same secondary winding, these must be able to cope with the commutation gaps caused by the power converter. In some cases, commutating reactors will be required.

To

othe

r lo

ads,

e.g

. dr

ive

sys

tem

s

Converter Converter

Line reactor


Industrial zone

Legend

Unscreened cable with restriction

Screened cable

EN 61800-3

EN 61000-6-3

EN 61000-6-4

EN 61000-6-2

EN 61000-6-1

satisfied

satisfied

Second environment (industry) with restricted distribution

on customer's request satisfied

Not applicable

Standards

III A 2-8



2 Three-phase filtersEMC filters are necessary to fulfil the standardfor emitted interference if a converter shall berun at a public low voltage line, in Europe forexample with 400 V between the phases. Suchlines have an earthed neutral conductor. ABBoffers suitable three - phase filters for 400 V and25 A...600 A and 500 V filters for 440 V linesoutside Europe (see System description / Tech-nical data).

Lines with 500 V to 1000 V are not public. Theyare local lines inside factories, and they do notsupply sensitive electronics. Therefore convert-ers do not need EMC filters if they shall run with500 V and more (see also 6).

3 Single-phase filters for field supply

Many field supply units are single - phase con-verters for up to 50 A excitation current. Theycan be supplied by two of the three input phasesof the armature supply converter. Then a fieldsupply unit does not need an own filter as shownat the connection example (24).

If the phase voltage to the neutral conductorshall be taken (230 V in a 400 V line) then aseparate filter is necessary as shown below.ABB offers such filters for 250 V and 6...55 A(see System description / Technical data).

3-PH FILTER

1-PH FILTER

ML1L2L3

N

Fig. 2.1/6 Connection of single and three phase filters

4 Line reactors (Commutation reactors)

Converters cause short-duration short circuitsat their AC inputs, so - called commutationnotches. Such notches down to 0 V (100%depth) can be accepted at the secondary wind-ings of converter (dedicated) transformers (op-eration without line reactors). However, theirdepth must be reduced if the same transformershall supply more than one converter. In suchcase line reactors are necessary. They mustcause about 1% relative voltage drop at ratedcurrent. So - called 1% reactors are also neces-sary if the power of the converter is very lowcompared with the available power of the trans-former or supply line. ABB offers suitable 1%

reactors.According to the European product standard EN61800-3, the commutation notches must bekept below 20% of the line voltage in the firstenvironment, whereas an upper limit of 40 % isspecified for the second environment. This tar-get can be achieved with the aid of line reactors.The inductance of these reactors to be appliedin the first environment must have 4 times thevalue of the network inductance at the convert-er's connection point (point of common cou-pling, PCC) as shown in fig. 2.1/7. Therefore inmany cases so-called 4% reactors are neces-sary, and therefore ABB offers also suitable 4%line reactors besides the 1% reactors (see Sys-tem description / Technical data).

Due to the maximum power of public 400 Vtransformers(PMAX = 1.2 MVA IMAX = 1732 A) and dueto their relative short circuit voltage VSC of 6%or 4% the maximum AC current which is availa-ble for a converter is 346 A or 520 A (IDC ≤ 422 Aor 633 A).

XPCC

Converter

Supply transformer of a residental region with light industry (rated power normally ≤ 1.2 MVA). With reference to EN 61800-3 the rated power of transformer must be at least 4 times the rated power of the PDS.

Earthed public 400 V line with neutral conductor

Earthedstar point

Medium-voltage line

Line choke

PCCNotches ≤ 20 %

vSC = 4 % or 6 %

Imax = 1.7 kA

For vSC = 4 %: XPCC ≥ 5.40 mΩ (LPCC ≥ 17.2 µH)

For vSC = 6 %: XPCC ≥ 8.12 mΩ (LPCC ≥ 25.8 µH)

For vSC = 4 %: XCHOKE ≥ 4 x XPCC = 21.6 mΩ (LCHOKE ≥ 68.8 µH)

For vSC = 6 %: XCHOKE ≥ 4 x XPCC = 32.48 mΩ (LCHOKE ≥ 103.2 µH)

Example:

2

*nom

nomPCCSCPCC PVvX ≥

%20≤+ CHOKEPCC

PCC

XXX

PCCCHOKE XX *4≥⇒

For vSC = 4 %: IDC ≤ 633 A

For vSC = 6 %: IDC ≤ 422 A

Fig. 2.1/7 Required minimum line reactorimpedance for installation of converter in first environment

Often the maximum current is not limited by thetransformer but by the power cable to the indus-try region. Therefore it is necessary to ask theenergy supply company concerning the lineimpedance and the current which is available atthe desired point of common coupling (PCC).

III A 2-9



5 Separation transformers

A separation transformer makes line reactorsunnecessary because of its leakage induct-ance, and a grounded screen between its wind-ings saves an EMC filter, see 1 and 4. Thescreen and the iron core must be well connectedwith the mounting plate of the converter. If thetransformer is located outside the convertercubicle the screen of a screened 3-phase cablemust make this connection.

6 Converter (dedicated) transformers

A converter (dedicated) transformer transfershigh power directly from a medium voltage lineto a single large converter or to a local lowvoltage line for several converters (see 20).Furthermore it acts as separation transformer.

If such a converter transformer has no screenthe EMC demands are nevertheless fulfilled inmost cases because the RF interference energycan hardly get via the medium-voltage line andthe transformer of the public line to the loadswhich must be protected against pertubances.In the case of a dispute a measurement must bedone at the point of common coupling (publiclow - voltage line) according to EN 61 800-3.

7 Installation hints

8 Cabinets

All metal cubicles available on the market can beused; however, their mounting plates must havewell conducting surfaces according to 9. If adrive system is placed in more than one cubicletheir mounting plates must be connected bybroad pieces of well conducting sheet metal.

9 Mounting plate

The mounting plate must be made from steelwith zinc surfaces and without any painting. ThePE copper bar must be mounted directly on themounting plate without any insulating meansbetween, and it must be connected with theplate by several bolts distributed in equal dis-tances along its length.

10 Placement of devicesThe converter, the line reactor, fuses, contac-tors and the EMC filter are to be placed on themounting plate so that the connections can be

made as short as possible, especially thosefrom the converter via the line reactor to the filter,and that the requirements in 15 can be fulfilled.The surface of the components to be mountedon the mounting plate has to be free of coatingmaterial (see 28).

11 Screening

12 Signal cables

The cables for digital signals, which are longerthan 3 m and all cables for analogue signals,must be screened. Each screen must be con-nected at both ends by metal clamps (see fig.2.1/8) or comparable means directly on cleanmetal surfaces, if both earthing points belong tothe same earth line. Otherwise a capacitor mustbe connected to earth on one end. In the con-verter cubicle this kind of connection must bemade directly on the sheet metal as close aspossible to the terminals (see 27 ) and if thecable comes from outside also on the PE bar(see 25 and 26 ). At the other end of the cable thescreen must be well connected with the housingof the signal emitter or receiver.

Fig. 2.1/8 Connection of a cable screen with the aidof metal clamp to the metal surface of the PCB carrier at aDCS converter

13 Power cables with screens

Power cables with screens are necessary, ifthey run over long distances (>20 m) where theyare susceptible to EMC environmental condi-tions. The cable may have e.g. either a braidedor spiral screen made preferably of copper oraluminium. The transfer impedance Z

T of the

III A 2-10



power cable must be less than 0.1 Ω/m in thefrequency range up to 100 MHz, in order toensure an effective reduction of emission and asignificant increase of immunity. The screenmust be pressed by a well conducting metalclamp directly against the mounting plate or thePE bar of the converter cubicle (see 24). Anotherconnection option is via EMC sleeve.

There the contact surface shall be clean and aslarge as possible. The PE wire can be connect-ed with a normal cable socket at the PE bar.Screened cables to the armature and to theexcitation winding cause the lowest noise level.

14 Power cables without screens

If a screen is not necessary (see 13) the arma-ture current cable must be a four-wire cablebecause two wires are needed as conductorsfor the parasitic RF currents from the motor tothe RF filter in the cubicle. The unscreened fieldcurrent cable F must be installed directly alongthe armature cable A as shown in fig. 2.1/9. A 2-wire cable is sufficient.

PE

PE

AF

Fig. 2.1/9 Cross-sectional view of arrangement offield current cable F and armature cable A.

The arrangement according to 26 has beentested with a 20 m long motor cable with theresult that the conducted emission requirementsare fulfilled. If the connections to the armatureare made from single-wire cables, especially if nparallel wires are necessary for higher currents,then n+1 PE cables must be arranged together

with them on a cable rail as shown in principle bythe fig. 2.1/10 with n=4.

PE + PE- + PE- + PE- + PE-

Fieldcurrentcables

Armaturecurrentcables

PEprotective

conductors

Cable rail is effectiveas shield against

RF radiation(to be grounded at both ends

according to 24 )

Fig. 2.1/10 Cross-sectional view of arrangement offield current cable F and armature cable A for highercurrents

15 Placement of cables within the cabinet

All power cables which are directly connectedwith the converter (U1, V1, W1, C1, D1) musteither be screened or be kept close together andclose to the mounting plate and separate from allother cables (L1, L2, L3 included) and especiallyfrom unscreened signal cables. A recommend-ed separation possibility is to place these powercables at the rear side of the mounting plate. Ifdirect crossings of "polluted" cables and others,especially signal cables, are inevitable thenthey must be made rectangular.

16 Placement of cables outside the cabi-net

The power cables must be arranged parallel andclose together, see drawings in 14. The speedfeedback must be screened and placed directlyalong the power cables to the motor if thehousing of the tacho machine is electricallyconnected with the housing of the motor. If thehousing of the tachometer or the encoder isinsulated from the motor then a distance be-tween the power and signal cables is advanta-geous.

17 Others

18 Earthed public low voltage linesThe rated voltages of a public European lowvoltage line are 400 V between the 3 phases and230 V between a phase and the neutral conduc-tor. These voltages are provided by a transform-er with its 3-phase secondary winding in starconnection. The star point is connected with theneutral conductor and it is earthed at the trans-former station. The electrical power is distribut-ed by 4-wire cables to the electricity consumers.At a cable stub to a consumer, the neutral

EMC sleeve

Lead-through plate

Strip this part of the cable covering

Base plate

Strain relief

Cover

Cable shield

Insulation

sleeve.dsf

III A 2-11



conductor must be earthed (local earth of thehouse or plant), and then it is split into a neutraland a PE conductor. Therefore a 3-phase loadwith neutral conductor must be supplied by a 5-wire cable. Converters, however, are 3-phaseloads which do not need the neutral conductor inmost cases. They can be supplied by 4-wirecables as shown in fig. 2.1/5. The change fromthe earthed neutral conductor outside the house,plant or factory to the internal PE conductor withthe local earthing point between is not shown inthis figure. Power limitation: see end of section4!

19 Public low voltage lines in industrial

regionsIn an industrial region the noise level which iscaused by converters is allowed to be 10 dBhigher than in a residential region with includedlight industry. Therefore the protection targetsconcerning EMC can be met without screenedmotor cables if these cables are configuredaccording to 14.

A public low voltage line of an industrial regionmay have an own supply transformer as shownin fig. 2.1/5, but often the lines of an industrialregion and of a residential one are supplied bya common transformer. This depends on thepower consumption of both regions and on theirdistance. Power limitation: see end of 4!

The dashed line between the lines of both re-gions indicates the version with only one trans-former. This dashed line represents a powercable from the transformer at the right to theindustrial region at the left. The power cable isimportant also for the EMC. Due to its length itreduces the noise level by at least 10 dB from theindustrial to the residential region.

20 Industrial low voltage lines

Industrial low voltage lines are local lines inplants or factories. They have own supply trans-formers (see 6). In most cases they are insulat-ed (IT network / no earthed star point) and theirvoltages are often higher than 400 V. The loadstolerate higher noise levels. Therefore and be-cause industrial lines are decoupled from publiclines by their transformers and distances, con-verters do not need EMC filters at industrial low-voltage lines (see 6). Problems for other loads

on the same line caused by commutation notch-es can be solved with the aid of line reactors (see4).

Insulated lines must have also an earth conduc-tor. The earth conductor is important for thefeedback of parasitic RF noise currents from theDC motor via the converter to the earth point ofthe supply transformer of the line. Without sucha conducted feedback the loop of the parasiticRF noise current is closed via the earth with theresult that roving parts of this current can inter-fere with electronic equipment far away from thedrive.

21 Fuses at the stubs from the low volt-age line

At the stubs the cross-sections of the conduc-tors become lower than in the main cable. There-fore fuses are prescribed which are adapted tothe reduced cross section, and they must belocated close to the stubs. This principle must berepeated at each reduction of the cross sectionfrom the stub at the main cable via the distribu-tion net in a house or factory down to theconnection point of a converter. The resultingfuse hierarchy is not shown in fig. 2.1/5. Only thefuses of the lowest rank are mentioned.

22 Fast FusesThe converters are protected against overloadby their control systems. Therefore dangerousovercurrents can be caused only by faults in theconverters themselves or in the loads. In suchcases the thyristors can be protected only withthe aid of special fast fuses. Such fast fuses areshown directly at the AC connection points of theconverters in fig. 2.1/5 as well as in the connec-tion example, with more details, at the beginningof 24. But fast fuses outside the converters arenecessary only for units of the lower powerrange. Larger converters comprise the fast sem-iconductor fuses.

23 Stub for auxiliary devicesExamples for auxiliary devices: field supply con-verters, transformers, fan motors.

24 Connection example in accordancewith EMCSee fig. 2.1/11.

III A 2-12



25 Armature and field cables with screensfor "first environment"See fig. 2.1/11.

26 Armature and field cables withoutscreens for "second environment"See fig. 2.1/11.

27 Encoder inputs and analogue I/OSee fig. 2.1/11.

Remarks

28 Internal ground connections

Additionally to the PE connections good HFconnections to ground must be realised with theaid of a mounting plate which has a well con-ducting surface (sheet metal from zinc-platedsteel for example). This means, the housings ofall components like the line filter and the con-verter must be pressed directly to the mountingplate by at least four fixing bolts. The seatingsurfaces of the housings must be free from nonconducting coating. These ground connectionsare indicated in the drawing at the top by thefollowing symbol (symbol often used to indicatemass or chassis):

The PE bar must be connected with the mount-ing plate by many bolts, which are distributedalong its whole length with equal distances.That's the reason the above symbol is usedseveral times in the drawing.

29 Earth connectionsAll devices are connected with the PE bar by themounting plate and also by PE conductors. ThePE bar is earthed via the PE conductor of the 3-phase power cable.

Protective earth (PE) connectionsThe drive shall be earthed only by the earthconductor of the line cable. This serves forprotection reasons and is indicated by the fol-lowing symbol:

An additional local earthing, especially at themotor, raises the level of the RF noise on the linecable.

Earth connections between motor and driv-en machineThe earth of a grounded machine must beconnected to the earth of the driving motor, inorder to avoid floating potential.

Thermal motor protectionIt is recommended that the cable of thermalmotor protection device is fed through an appro-priate filter at the point of entry into cubicle, inorder to suppress EMC disturbances.

III A 2-13



Fig. 2.1/11 Connection example in compliance with EMC

Important hintThe example shows the principle structure of a DC drive and its connections. It is not a bindingrecommendation, and it cannot respect all conditions of a plant. Therefore each drive must beconsidered separately and with respect to the special application. Additionally the generalinstallation and safety rules must be taken into account.

A F

C1/D1 F+/F-

M

A1 A2

F1

F2

A1 A2

F1

F2

L1

L2

L3

U1

V1

W1C1

D1

U1

V1 F-F+

PE

PE

PE

PE

A

F

A F

T

AF

AF

C1/D1 F+/F-

PE

PE

I/O

Mounting plate

DC motor

Tac

ho

ScreensContact to the motorhousing at the whole

screen perimeter

Filter

Mounting plate with PE busbar and terminals

DC motor

Tac

hoS

cree

n

Fieldsupplyunit

Armature and field cables with screens for

"first environment"

Armature and field cables without

screens suitable for "second

environment"

Hint: The armature current cable must contain a third wire for a PE connection if the copper cross section of the screen cannot fulfil the PE safety demands.

terminals on the CON-x board

Mounting plate with PE busbar and terminals

terminals on the CON-x board

inte

rmed

iate

term

inal

s

pre

fere

d s

olu

tio

n

PE bar

to filter, choke...

directly to

lower edgeof the PCB

carrier

TachoEncoder, analogue I/O,and digital I/O (>3 m)

TachoEncoder, analogue I/O,and digital I/O (>3 m)

directly to

lower edgeof the PCB

carrier

to filter, choke...

inte

rmed

iate

term

inal

s

pre

fere

d s

olu

tio

n

PE bar

III A 2-14



2.1.4 Summary

EC Declaration of Conformity for DCSConvertersAn EMC declaration of conformity covering DCSconverters verifies that they comply with theprovisions of the European Low Voltage andEMC Directives (Directive 73/23/EEC, as amend-ed by Directive 89/336/EEC and 93/68/EEC).

Compliance with the EMC DirectiveThe EMC Directive defines the requirements forimmunity and emissions of electrical equipmentused in the European Economic Area (EEA).The EMC product standard EN 61800-3 coversthe requirements stated for thyristor power con-verters. DCS thyristor power converters complywith the EMC Directive in industrial low voltagenetwork (up to 1000 V; also IT network), publiclow-voltage network in industrial regions and inearthed public low voltage network (restricteddistribution) with the provisions summarised inthe following three subsections.

Industrial Low-Voltage Network1. Industrial low voltage lines are local lines

in plants or factories with their own supplytransformers (with earthed iron core),which decouple the industrial lines fromthe public lines. EMC filters are thereforenot needed in industrial low voltage lines.

2. If static screening between primary andsecondary windings of the supplytransformer is present, it must be earthedin order utilise the filtering effect.

3. Problems caused by commutation notchescan be solved by insertion of appropriateline reactors.

4. The motor and control cables of the DCSconverter must be installed in accordancewith the specifications outlined in section2.1.3 - Installation hints 7 of this chapter.

Note: The DCS converter must not be equippedwith EMC filter (refer to section 2.1.3 - Generalof this chapter) if installed in floating networks(IT-Network). The mains become connected toearth potential through the EMC Y filter capac-itors. This may cause danger or cause damageto the unit. Furthermore a floating network is notpublic. Therefore higher noise levels are al-lowed.Note: If screened motor cables are not availabledue to very high rated armature current, strictadherence to section 2.1.3 - Power cables with-out screens in this chapter is required.

Public Low-VoltageNetwork in Industrial Regions1. The DCS converters must be equipped

with EMC filters (refer to publicationTechnical data for appropriate filter ratings)and line reactors.

2. The motor and control cables of the DCSconverter must be installed in accordancewith the specifications outlined in section2.1.3 - Installation hints of this chapter.

Note: If screened motor cables are not availabledue to very high rated armature current, strictadherence is required to section 2.1.3 - Powercables without screens of this chapter.

Earthed Public Low-Voltage Network (Re-stricted Distribution)1. The DCS converters must be equipped

with EMC filters and line reactors.2. The motor and control cables of the DCS

converter are basically screened.3. In case a separation transformer is

applied, its screen and iron core must begrounded. If no static screen is present, anappropriate filter must be used.

C-Tick Marking for DCS ConvertersA "C-Tick" mark is attached o each variablespeed drive in order to verify compliance withthe relevant standard ("IEC 61800-3 (1996) -Adjustable speed electrical power drive sys-tems - Part 3: EMC product standard includingspecific test methods"), mandated by the Trans-Tasman Electromagnetic Compatibility Scheme.

Definitions

EMC stands for Electromagnetic Compatibili-ty. It is the ability of electrical/electronic equip-ment to operate without problems within anelectromagnetic environment. Likewise, theequipment must not disturb or interfere withany other product or system within its locality.

The Trans-Tasman Electromagnetic Compati-bility Scheme (EMCS) was introduced by theAustralian Communication Authority (ACA)and the Radio Spectrum Management Group(RSM) of the New Zealand Ministry of Eco-nomic Development (NZMED) in November2001. The aim of the scheme is to protect theradiofrequency spectrum by introducing tech-nical limits for emission from electrical/elec-tronic products.

III A 2-15



First environment includes establishmentsconnected to a low-voltage network, whichsupplies buildings used for domestic purpos-es.

Second environment includes establishmentsconnected to a network not supplying domes-tic premises.

Restricted distribution: mode of sales distribu-tion in which the manufacturer restricts thesupply of equipment to suppliers, customersor users who separately or jointly have techni-cal competence in the EMC requirements ofthe application of drives.

Unrestricted distribution: mode of sales distri-bution in which the supply of equipment is notdependent on the EMC competence of thecustomer or user for the application of drives.

Compliance with IEC 61800-3

First environment (restricted distribution)The drive complies with the limits of IEC61800-3 with the following provisions:

1. The drive is equipped with an EMC filter.2. The drive is installed according to the instruc-

tions given in figure 2.1/5.3. The motor and control cables used are select-

ed as specified in figure 2.1/5.4. Maximum cable length is 100 meters.

Notes:The drive must not be equipped with the EMCwhen installed to IT (unearthed) networks. Themains become connected to earth potentialthrough the EMC filter capacitors. In IT systemsthis may cause danger or damage the unit.

Second environmentThe drive complies with the limits of IEC61800-3 with the following provisions:

1. It is ensured that no excessive emission ispropagated to a neighbouring low-voltagenetwork (refer to figure 2.1/4 and 2.1/5). Insome cases, the natural suppression in trans-formers and cables is sufficient. If in doubt theuse of EMC filters and/or supply transformerswith static screening between primary andsecondary windings is strongly recommend-ed.

2. The drive is installed according to the instruc-tions given in figure 2.1/4 and 2.1/5.

3. The motor and control cables used are select-ed as specified in figure 2.1/4 and 2.1/5.

III A 2-16



III A 3-1

Engineering of DC drives


3.1 Fusing aspects of DC drives

3.1.1 GeneralProtection elements such as fuses or overcur-rent relays are used whenever overcurrentscannot entirely be ruled out. In some configura-tions, this will entail the following questions:firstly, at what point should which protectiveelement be well suited incorporated? And sec-ondly, in the event of what faults will the elementin question provide protection against damage?

Fig. 3.1.1/1 Arrangement of the switch-off elements for thearmature supply

3 Engineering of DC drives

A thyristor can be switched on in a controlledmanner by a firing pulse, but it cannot switchedoff by any command. It will switch-off automato-cally when the current drops below the holdingcurrent and no firing pulse is generated; it can beswitched off by forcing the current below theholding current. The earliest switch-off momentis prepared by the next zero crossing of the linevoltage half-wave when firing pulses are movedto the safe position. Until then, full short-circuitcurrent is flowing over the thyristor. The durationconcerned will depend on the firing momentwithin the half-wave, and can already result indestruction, or at least preliminary damage.

Fig. 3.1.1/2 Thyristor behavior with EMF = 0 V

Even ultra-fast monitoring programs in the drivesoftware can no longer switch-off fired thyris-tors, so that only a semiconductor fuse can

ensure adequate protection. It is, however, def-initely possible that the fuse will not yet tripduring one half-wave. Fuse and thyristor, how-ever, are already suffering preliminary damage,which may not become apparent until later.

Basic principles1. Only semiconductor fuses of matched size

can in the event of a fault protect the powersemiconductors. Unprotected power semi-conductors may explode and cause the de-vice to catch fire.

2. In earthed networks, only semiconductorfuses in the supply can protect the device inthe event of an earth fault.

3. Well suited semiconductor fuses constitutean optimum protection for the semiconduc-tors only in "hard" networks. In "soft" net-works, and in the motor circuit, the protectionis questionable. In "soft" networks, duringregenerative operation, an increased risk ofconduction-through must be anticipated. Inthe motor circuit, high-speed DC circuit-breaker constitute optimum protection.

4. Semiconductor fuses in the armature circuitmust be dimensioned for DC voltages, so asto assure an adequate spark-quenching gapin the event of a fault. A compromise is provid-ed by two series-connected fuses, as usedin the AC power supply of small modules orthe power section of big ones.

5. In 2-Q devices, no circulating current occurs.If a thyristor failure due to overload or aqualitative defect results in a phase-to-phaseshort-circuit, only semiconductor fuses canprotect the device.

6. In the case of 2-Q devices, in regenerativemode, conduction-through is possible as in 4-Q operation, with the consequence of over-current.

7. Conventional fuses in the tapered feeder tothe power converter can be replaced by semi-conductor fuses, if the feeder's cross-sec-tional areas are matched at least to the de-vice's rated line current (local regulations nottaken into account). A thermal overload in theevent of a fault will first destroy the semicon-ductor fuses before upstream componentscan suffer damage. The power converterdevice is, however, protected electronicallyor by the matched semiconductor fuses. Theseries connection of fuses can thus be dis-pensed with.

M...

.

.

.

3

2

2

Fa_asp_c.dsf

For field supplysee Fig. 3.1.4/1

AC supply: public mains / plant's mains

Cabinet

Thy

risto

r di

sabl

e

Thyristor conductingduring short circuit

I >> I nominal

U

t

rectified line voltage

line voltage

Fusing_thyristors_a.dsf

III A 3-2



SF6Insulation faults may occur withinthe cabling of the mains supply, thepower converter and the motor.These can be subdivided into faultsfinally resulting in a short-circuit andthose leading to an earth fault.• In the event of a short-circuit, the

following generally appliesI >> Inom

• In the event of an earth fault, de-pending on where the fault hasoccurred, the current may rangebetween I = Inom and I >> Inom

Basic Principles 1 + 2 + 3 + 4

Faults within the unit electronics

SF1The power converter's working modewill usually be current-limiting. Themaximum current corresponds to thecurrent limitation set. If this limitationfeature or one of the requisite com-ponents fails, then the current willfrequently rise sharply.

SF2If one or more than one false firingpulses are produced, e.g. due tocomponent faults or other influenc-ing factors, then the current will like-wise rise sharply.

Basic Principles 1 + 3 + 4

SF3If -with four-quadrant units- thyris-tors of both bridges become con-ductive, circulating current is theconsequence. The causes involvedmay be component defects or otherinfluencing factors. The current onthe three-phase side will rise sub-stantially.

Basic Principles 1 + 5

SF4In the case of regeneration, the ratioof motor voltage and line voltagerises above 1.05, which is followedby a situation called "shoot-through".The current rises substantially.Possible causes include:• network malfunctions (line und-

ervoltage)• overspeed due to the load in-

volved (load accel-erates motor)or due to a control error

• field supply generates a field cur-rent larger than Ie nom or controlerror in the field weakening range Basic Principles 1 + 3 + 4 + 6

SF5Semiconductor faults can be mani-fested in that a thyristor no longerfires or in that it is permanently con-ductive.

Basic Principles 1 + 3 + 4 + 5+ 6

3.1.2 Armature supplyPossible sources of faults (SF) are explained based on thearmature supply. They can be applied to the field supply as well.

Faults caused by power components

Defective system conditions leading to commutationfailure

M

protect the converter

protect the motor

Ia >> Ianom

M


Ia >> Ianom

protect the motor

M


I >> InomAC

M


protect the motor

Ia >> Ianom

IAC >> Inom

M


IAC >> Inom

Ia >> Ianom


protect the motor /the converter

III A 3-3



Due to cost saving in some of customer applica-tions standard fuses are used instead of "moreexpensive" semiconductor fuses. Under normaland stable operating conditions, this is evenunderstandable and comprehensible, as longas fault scenarios can be ruled out.

In the event of a fault , however, the saving may

Protection level of other solutions

Complies with Basic Principles on:1 – Explosion hazard yes2 – Earth fault yes3 – “Hard“ networks yes4 – Spark-quenching gap yes5 – Short-circuit yes6 – 2Q regenerative yes

Complies with Basic Principles on:1 - Explosion hazard no2 - Earth fault partly, only

with 4-Q, betweenfuse and motor

3 - "Hard" networks no4 - Spark-quenching gap no5 - Short-circuit no6 - 2Q regenerative no

LV HRC = Low Voltage High Rupturing Capacity.LV HRC refers to DIN 43 620, mechanical dimensions ofthe fuses. The different characteristics between semicon-ductor and standard fuses are only recognized by the typenumber.Note: NH (in german) = LV HRC (in english)

M M

DC unit

2-Q

DC unit

4-Q

only onesemiconductor

fuse

LV HRCstandard

fuses

LV HRCstandard

fuses

Recommendations

cause very high consequential costs. Explodingpower semiconductors may not only destroy thepower converter, but also cause fires.

Adequate protection against short-circuit andearth fault, as laid down in the EN50178 stand-ard, is possible only with appropriate semicon-ductor fuses.

M M

DCS converter

2-Q non-regen.

Semiconductorfuses

Semiconductorfuses

Semiconductorfuses

4-Q resp.2-Q regenerative

DCS converter


Conclusion

III A 3-4



3.1.3 Field supply

Basically, similar conditions apply for both fieldsupply and armature-circuit supply. Dependingon the power converter used (diode bridge, half-controlled bridge, fully controlled 4-quadrantbridge), some of the fault sources may notalways be applicable. Due to special systemconditions, such as supply via an autotrans-former or an isolating transformer, new protec-tion conditions may additionally apply.

The F3.2 and F3.3 fuse types serve as lineprotectors and cannot protect the field supplyunit. Only pure HRC fuses or miniature circuit-breakers may be used. Semiconductor fuseswould be destroyed, for example, by the trans-former’s starting current inrush.

Possible field supply units (R):- SDCS-FEX-1: uncontrolled diode bridge;

commutating reactor K notnecessary

Fault Source: SF5, 6- SDCS-FEX-2: half-controlled bridge, 1Q;

due to EMC reasons com-mutating reactor K is highlyrecommended

Fault Source: SF1, 5, 6- DCF 503: half-controlled bridge, 1Q;

commuataing rector K is al-ready built-in Fault Source:SF1, 5, 6

- DCF 504: fully controlled bridge, 4Q;commuataing rector K is al-ready built-in

Fault Source: SF1, 3, 4, 6- DCF x01/2: fully controlled 3-phase

bridge, 2Q/4Q;Fault Source: SF1, 3, 4, 6

SF1 and 6, the current is limited to relativelysmall overcurrents due to the ohmic content ofthe field winding, so that the fuses may perhapsnot be tripped.

SF 4 can also occur in the case of field supplyunits, but will not cause such a rapid and sub-stantial current rise as encountered with anarmature-circuit supply; this is due to the signif-icantly higher inductance of the field winding.

In contrast to the armature-circuit supply, fusesare never used on the DC side for the fieldsupply, since a fuse trip might under certain

circumstances lead to greater damage thanwould the cause tripping the fuse in the firstplace (small, but long-lasting overcurrent; fuseageing; contact problems; etc.).

ConclusionIf conditions similar to those for armature-circuitsupply are to apply, like for example protectionof the field supply unit and the field winding, thena semiconductor fuse (super-quick-acting F3.1)must be used.

Recommendation

Fig 3.1.3/1 Configurations for field supplies

2F3.1

ND30 /built-in

F3.3

2

2

F3.2

F3.1

F3.1

FF_ASP_b.dsf

ND30 /built-in

III A 3-5



3.2 Commutation

GeneralWhen power converters are operated with thy-ristors, the line voltage is short-circuited duringcommutation from one thyristor to the next. Thisoperation causes voltage dips in the mains.

The information based on the different configu-rations can be applied for the armature supply(DCS converters) and for the field supply (3-phase DCF converters).

For the connection of a power converter systemto the mains the following configurations can bemade:

Configuration AWhen using the power converter,a minimum of 1% impedance isrequired to ensure proper perform-ance of the snubber circuit. A linereactor can be used to meet thisminimum impedance requirement.The value must therefore not dropbelow 1% u

k (relative impedance

voltage). It should not exceed 10%u

k, due to considerable voltage drops which

would then occur.

Configuration BIf special requirements have to bemet at the connecting point, differ-ent criteria must be applied forselecting a line reactor. These re-quirements are most often definedas a voltage dip in percent of thenominal supply voltage.The combined impedance of Z

Line

and ZLR

constitute the total seriesimpedance of the installation. Theratio between the line impedance

and the line reactor impedance determines thevoltage dip at the connecting point.

VoltagedipZ

Z ZLine

Line LR=

+*100%

Example:Maximum allowable voltage dip is 20% at thepower converter's connecting point. Above equa-tion used and simplified to:

Z ZLR Line= 4 * (1)

Since the line impedance is seldom known (it

can be determined by means of a measuringroutine), and the short-circuit power at the samepoint is more frequently available, the line reac-tor can be calculated by means of this value.Assumption: The system short-circuit power atthe power converter’s connecting point is 180times the power converter’s rated power.• The system’s relative impedance voltage u

k

can thus be determined:

uk Line = =1180

100% 055%* .

• In accordance with equation (1), the followingapplies for the line reactor:

u Uk LR K Line= =4 2 2%* .

• Since the line reactor has to be sized specificto a power converter , the relative variable u

k

must be converted into an absolute value. Forthis purpose, the following equation applies:

uI f L

Uk

dN N LR

N=

* * * * *23

3 2π

IdN: rated direct currentfN: rated frequency of the systemUN: rated line voltageLLR: line reactor inductance

Connectingpoint

LineLLine

LLR

Connectingpoint

Line

uk LR ca. 1%

With reference to the power converter:

- The line reactors- have been allocated to the units nominal

current- are independent of converter's voltage clas-

sification; at some converter types the sameline choke is used up to 690 V line voltage

- are based on a duty cycle- can be used for DCS as well as for DCF

converters- The duty cycle taken into account varies from

line choke to line choke and is between 80%and 100%. If the converter is sized on a dutycycle or is used for a drive running with highload all time like extruders do next steps tocheck the overall selection:- Calculate the I

DCrms based on the duty cycle

and the motor current- Multiply the I

rms of the line choke by 1.2

- In case Irms

is higher than IDCrms

the combina-tion is okay

III A 3-6



An examination of volume and costs results inthe following configuration:

Configuration CIf an isolation transformer is used,it is often possible to comply withcertain connecting conditions perConfiguration B without using anadditional line reactor. The condi-tion described in Configuration Awill then likewise be satisfied, sincethe u

k is >1 %.

Connectingpoint

Line

- In case Irms

is lower than IDCrms

take the linechoke used for the next bigger converterwith the same voltage classification

- If the line choke should be used for aDCF converter make sure the nominal fieldcurrent doesn't exceed the thermal current ofthe choke. In case the field current is higherthan I

rms of the line choke take the one used for

the next bigger converter with the same volt-age classification

- For units >2000 A or >690 V, we recommendusing one isolation transformer per powerconverter as configuration C.

Configuration C1If 2 or more converters should besupplied by one transformer thefinal configuration depends on thenumber of drives in use and theirpower capability. Configuration Aor B has to be used which arebased on commutation chokes, ifthe drive system consists of C1,C2 or A5 converters. In case onlytwo converters type A6 / A7 (A6 +

A6, A6 + A7, A7 + A7) are involved no commu-tation chokes are necessary because the de-sign of these converters is adapted to that wir-ing.

Line

Connectingpoint

LLR LLR

Configuration DIn the case of high power convert-er outputs or high currents, a pow-er converter transformer must fre-quently be used for voltage match-ing. If an autotransformer is usedfor this purpose, a commutatingreactor must additionally be used ifspecial conditions must be com-plied with as per Configuration B,the reason for this being that the u

k

of commonly used autotransformers is general-ly too small. If you do not have to allow for specialconditions of this kind, you must neverthelesscheck whether the u

k of the autotransformer

concerned is sufficient for satisfying Configura-tion A.

Connectingpoint

Line

LLR

III A 3-7



III A 3-8



3AD

W 0

00 1

63 R

0201

RE

V B

10_2

003

ABB Automation Products GmbHPostfach 118068619 Lampertheim • GERMANYTelefon +49(0) 62 06 5 03-0Telefax +49(0) 62 06 5 03-6 09www.abb.com/dc

*163R0201A3440000**163R0201A3440000*

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Documents

DCS Thyristor Power Converters General for DC Drive … Thyristor Power Converters for DC Drive Systems Technical Guide k r e m) ... When using DC drives from ABB or any other