EN 62271-101:2006

SLOVENSKI STANDARD
01-december-2006
1DGRPHãþD
SIST EN 60427:2000
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High-voltage switchgear and controlgear - Part 101: Synthetic testing (IEC 62271-
101:2006)
Hochspannungs-Schaltgeräte und -Schaltanlagen - Teil 101: Synthetische Prüfung (IEC
62271-101:2006)
Appareillage a haute tension - Partie 101: Essais synthétiques (CEI 62271-101:2006)
Ta slovenski standard je istoveten z: EN 62271-101:2006
ICS:
29.130.10 Visokonapetostne stikalne in High voltage switchgear and
krmilne naprave controlgear
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 62271-101
NORME EUROPÉENNE
July 2006
EUROPÄISCHE NORM
ICS 29.130.10 Supersedes EN 60427:2000

English version
High-voltage switchgear and controlgear
Part 101: Synthetic testing
(IEC 62271-101:2006)
Appareillage à haute tension  Hochspannungs-Schaltgeräte
Partie 101: Essais synthétiques und -Schaltanlagen
(CEI 62271-101:2006) Teil 101: Synthetische Prüfung
(IEC 62271-101:2006)
This European Standard was approved by CENELEC on 2006-07-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62271-101:2006 E
Foreword
The text of document 17A/753/FDIS, future edition 1 of IEC 62271-101, prepared by SC 17A,
High-voltage switchgear and controlgear, of IEC TC 17, Switchgear and controlgear, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 62271-101 on 2006-07-01.
This European Standard supersedes EN 60427:2000.
This standard shall be read in conjunction with EN 62271-100:2001. The numbering of the subclauses of
Clause 6 is the same as in EN 62271-100. However, not all subclauses of EN 62271-100 are addressed;
merely those where synthetic testing has introduced changes.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2007-04-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2009-07-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62271-101:2006 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 62271-101:2006
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC/TS 61633 1995 High-voltage alternating current circuit-- -
breakers - Guide for short-circuit and
switching test procedures for metal-enclosed
and dead tank circuit-breakers

IEC 62271-100 2001 High-voltage switchgear and controlgear EN 62271-100 2001
Part 100: High-voltage alternating-current
circuit-breakers
IEC/TR 62271-308 2002 High-voltage switchgear and controlgear - -
Part 308: Guide for asymmetrical short-circuit
breaking test duty T100a
NORME CEI
INTERNATIONALE
IEC
62271-101
INTERNATIONAL
Première édition
STANDARD
First edition
2006-05
Appareillage à haute tension –
Partie 101:
Essais synthétiques
High-voltage switchgear and controlgear –
Part 101:
Synthetic testing
 IEC 2006 Droits de reproduction réservés  Copyright - all rights reserved
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électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
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For price, see current catalogue

62271-101  IEC:2006 – 3 –
CONTENTS
FOREWORD.11

1 Scope.15
2 Normative references .15
3 Terms and definitions .15
4 Synthetic testing techniques and methods for short-circuit breaking tests.19
4.1 Basic principles and general requirements for synthetic breaking test
methods .19
4.2 Synthetic test circuits and related specific requirements for breaking tests .25
4.3 Three-phase synthetic test methods .31
5 Synthetic testing techniques and methods for short-circuit making tests .35
5.1 Basic principles and general requirements for synthetic making test methods .35
5.2 Synthetic test circuit and related specific requirements for making tests .37
6 Specific requirements for synthetic tests for making and breaking performance
related to the requirements of 6.102 through 6.111 of IEC 62271-100 .39

Annex A (informative) Current distortion .79
Annex B (informative) Current injection methods.111
Annex C (informative) Voltage injection methods .121
Annex D (informative) Duplicate circuit (transformer or Skeats circuit) .127
Annex E (normative) Information to be given and results to be recorded for synthetic tests . 133
Annex F (informative) Special procedures for testing circuit-breakers having parallel
breaking resistors .135
Annex G (informative) Synthetic methods for capacitive-current switching .141
Annex H (informative) Re-ignition methods to prolong arcing .165
Annex I (normative) Reduction in di/dt and TRV for test duty T100a .173
Annex J (informative) Three-phase synthetic test circuits.201
Annex K (normative) Test procedure using a three-phase current circuit and one
voltage circuit .217
Annex L (normative) Splitting of test duties in test series taking into account the
associated TRV for each pole-to-clear .255
Annex M (normative) Tolerances on test quantities for type tests.275

Bibliography.281

Figure 1 – Interrupting process – Basic time intervals .63
Figure 2 – Example of recovery voltage .65
Figure 3 – Equivalent surge impedance of the voltage circuit for the current injection
method .67
Figure 4 – Making process – Basic time intervals.69

62271-101  IEC:2006 – 5 –
Figure 5 – Typical synthetic make circuit for single-phase tests .71
Figure 6 – Typical synthetic make circuit for three-phase tests (k = 1,5).73
pp
Figure 7 – Comparison of arcing time settings during three-phase direct tests (left)
and three-phase synthetic (right) for T100s with k = 1,5 .75
pp
Figure 8 – Comparison of arcing time settings during three-phase direct tests (left)
and three-phase synthetic (right) for T100a with k = 1,5.77
pp
Figure A.1 – Direct circuit, simplified diagram .93
Figure A.2 – Prospective short-circuit current .93
Figure A.3 – Distortion current .93
Figure A.4 – Distortion current .95
Figure A.5 – Simplified circuit diagram.97
Figure A.6 – Current and arc voltage characteristics for symmetrical current .99
Figure A.7 – Current and arc voltage characteristics for asymmetrical current .101
Figure A.8 – Reduction of amplitude and duration of final current loop of arcing .103
Figure A.9 – Reduction of amplitude and duration of final current loop of arcing .105
Figure A.10 – Reduction of amplitude and duration of final current loop of arcing .107
Figure A.11 – Reduction of amplitude and duration of final current loop of arcing .109
Figure B.1 – Typical current injection circuit with voltage circuit in parallel with the test
circuit-breaker.115
Figure B.2 – Injection timing for current injection scheme with circuit B.1.115
Figure B.3 – Typical current injection circuit with voltage circuit in parallel with the
auxiliary circuit-breaker.117
Figure B.4 – Injection timing for current injection scheme with circuit B.3.117
Figure B.5 – Examples of the determination of the interval of significant change of arc
voltage from the oscillograms .119
Figure C.1 – Typical voltage injection circuit diagram with voltage circuit in parallel
with the auxiliary circuit-breaker (simplified diagram) .123
Figure C.2 – TRV waveshapes in a voltage injection circuit with the voltage circuit in
parallel with the auxiliary circuit-breaker .125
Figure D.1 – Transformer or Skeats circuit.129
Figure D.2 – Triggered transformer or Skeats circuit .131
Figure G.1 – Capacitive current circuits (parallel mode) .147
Figure G.2 – Current injection circuit.149
Figure G.3 – LC oscillating circuit .151
Figure G.4 – Inductive current circuit in parallel with LC oscillating circuit.153
Figure G.5 – Current injection circuit, normal recovery voltage applied to both
terminals of the circuit-breaker.155
Figure G.6 – Synthetic test circuit (series circuit), normal recovery voltage applied to
both sides of the test circuit breaker .157
Figure G.7 – Current injection circuit, recovery voltage applied to both sides of the
circuit-breaker.159
Figure G.8 – Making test circuit .161
Figure G.9 – Inrush making current test circuit.163

62271-101  IEC:2006 – 7 –
Figure H.1 – Typical re-ignition circuit diagram for prolonging arc-duration .167
Figure H.2 – Combined Skeats and current injection circuits.169
Figure H.3 – Typical waveforms obtained during an asymmetrical test using the circuit
in Figure H.2.171
Figure J.1a – Three-phase synthetic combined circuit.205
Figure J.1b – Waveshapes of currents, phase-to-ground and phase-to phase voltages
during a three-phase synthetic test (T100s; k = 1,5 ) performed according to the
pp
three-phase synthetic combined circuit .207
Figure J.2a – Three-phase synthetic circuit with injection in all phases for k = 1,5 .209
pp
Figure J.2b – Waveshapes of currents and phase-to-ground voltages during a three-
phase synthetic test (T100s; k =1,5) performed according to the three-phase
pp
synthetic circuit with injection in all phases .211
Figure J.3a – Three-phase synthetic circuit for terminal fault tests with k = 1,3
pp
(current injection method) .213
Figure J.3b – Waveshapes of currents, phase-to-ground and phase-to-phase voltages
during a three-phase synthetic test (T100s; k =1,3 ) performed according to the
pp
three-phase synthetic circuit shown in Figure J.3a .213
Figure J.3c – TRV voltages waveshapes of the test circuit described in Figure J.3a.215
Figure K.1 – Example of a three-phase current circuit with single-phase synthetic injection . 237
Figure K.2 – Representation of the testing conditions of Table K.1a.239
Figure K.3 – Representation of the testing conditions of Table K.1b.241
Figure K.4 – Representation of the testing conditions of Table K.2a.243
Figure K.5 – Representation of the testing conditions of Table K.2b.245
Figure K.6 – Representation of the testing conditions of Table K.3a.247
Figure K.7 – Representation of the testing conditions of Table K.3b.249
Figure K.8 – Representation of the testing conditions of Table K.4a.251
Figure K.9 – Representation of the testing conditions of Table K.4b.253
Figure L.1 – Graphical representation of the test shown in Table L.1 .267
Figure L.2 – Graphical representation of the test shown in Table L.2 .269

Table 1 – Test circuits for test duties T100s and T100a .31
Table 2 – Test duties T10, T30, T60 and T100s .33
Table 2a – First-pole-to-clear factor: 1,5 – Test parameters during three-phase
interruption .33
Table 2b – First-pole-to-clear factor: 1,3 – Test parameters during three-phase
interruption .33
Table 3 – Synthetic test methods for test duties T10, T30, T60, T100s, T100a, SP,
DEF, OP and SLF .59
Table I.1a – Last current loop parameters for 50 Hz operation in relation to short-circuit
test duty T100a τ = 45 ms.175
Table I.1b – Last current loop parameters for 50 Hz operation in relation to short-circuit
test duty T100a τ = 60 ms.177
Table I.1c – Last current loop parameters for 50 Hz operation in relation to short-circuit
test duty T100a τ = 75 ms.179
Table I.1d – Last current loop parameters for 50 Hz operation in relation to short-circuit
test duty T100a τ = 120 ms.181

62271-101  IEC:2006 – 9 –
Table I.2a – Last current loop parameters for 60 Hz operation in relation to short-circuit
test duty T100a τ = 45 ms.183
Table I.2b – Last current loop parameters for 60 Hz operation in relation to short-circuit
test duty T100a τ = 60 ms.185
Table I.2c – Last current loop parameters for 60 Hz operation in relation to short-circuit
test duty T100a τ = 75 ms.187
Table I.2d – Last current loop parameters for 60 Hz operation in relation to short-circuit
test duty T100a τ = 120 ms.189
Table I.3a – Last loop di/dt reduction for 50 Hz under three-phase conditions with the
first pole to clear in phase A and the required asymmetry in phase C.191
Table I.3b – Last loop di/dt reduction for 60 Hz under three- phase conditions with the
first pole to clear in phase A and the required asymmetry in phase C.193
Table I.4a – Corrected TRV values for k = 1,3 and f = 50 Hz.195
pp r
Table I.4b – Corrected TRV values for k = 1,3 and f = 60 Hz.197
pp r
Table I.4c – Corrected TRV values for k = 1,5 and f = 50 Hz.199
pp r
Table I.4d – Corrected TRV values for k = 1,5 and f = 60 Hz.199
pp r
Table K.1a – Demonstration of arcing times for a first-pole-to-clear factor of 1,5.219
Table K.1b – Alternative demonstration of arcing times for a first-pole-to-clear factor
of 1,5 .221
Table K.2a – Demonstration of arcing times for a first-pole-to-clear factor of 1,3.223
Table K.2b – Alternative demonstration of arcing times for a first-pole-to-clear factor
of 1,3 .225
Table K.3a – Demonstration of arcing times for a first-pole-to-clear factor of 1,5.229
Table K.3b – Alternative demonstration of arcing times for a first-pole-to-clear factor
of 1,5 .231
Table K.4a – Demonstration of arcing times for a first-pole-to-clear factor of 1,3.233
Table K.4b – Alternative demonstration of arcing times for a first-pole-to-clear factor
of 1,3 .235
Table L.1 – Test procedure for a first-pole-to-clear factor of 1,5.257
Table L.2a – Alternative demonstration of arcing times for a first-pole-to-clear factor
of 1,3 .259
Table L.2b – Simplified test procedure for a first-pole-to-clear factor of 1,3.261
Table L.3 – Test procedure for asymmetrical currents in the case of a first-pole-to-
clear factor of 1,5.263
Table L.4 – Test procedure for asymmetrical currents in the case of a first-pole-to-
clear factor of 1,3.265
Table L.5 – Required arcing windows in ° for different asymmetrical conditions, f =
r
50 Hz.271
Table L.6 – Required arcing windows in ° for different asymmetrical conditions, f =
r
60 Hz.273
Table M.1 – Tolerances on test quantities for type tests.277

62271-101  IEC:2006 – 11 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 101: Synthetic testing
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62271-101 has been prepared by subcommittee 17A: High-voltage
switchgear and controlgear, of IEC technical committee 17: Switchgear and controlgear.
This first edition cancels and replaces the third edition of IEC 60427 published in 2000. This
first edition constitutes a technical revision.
The text of this standard is based on the third edition of IEC 60427 and the following
documents:
FDIS Report on voting
17A/753/FDIS 17A/755/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

62271-101  IEC:2006 – 13 –
This publication shall be read in conjunction with IEC 62271-100. The numbering of the
subclauses of Clause 6 is the same as in IEC 62271-100. However, not all subclauses of IEC
62271-100 are addressed; merely those where synthetic testing has introduced changes.
The IEC 62271-100 series consists of the following parts, under the general title High-voltage
switchgear and controlgear:
Part 100: High-voltage alternating-current circuit-breakers
Part 101: Synthetic testing
Part 102: Alternating current disconnectors and earthing switches
Part 104: Alternating current switches for rated voltages of 52 kV and above
Part 105: Alternating current switch-fuse combinations
Part 107: Alternating current fused circuit-switchers for rated voltages above 1 kV up to and
including 52 kV
Part 108: High voltage alternating current disconnecting circuit-breakers for rated voltages
of 72,5 kV and above
Part 109: Alternating-current series capacitor by-pass switches
Part 110: Inductive load switching
A list of the other parts belonging to the IEC 62271 series can be found on the IEC website
http://www.iec.ch. Further information is available on http://tc17.iec.ch.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
___________
Some of these parts are still in the process of being developed.

62271-101  IEC:2006 – 15 –
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 101: Synthetic testing
1 Scope
This part of IEC 62271 mainly applies to a.c. circuit-breakers within the scope of IEC 62271-
100. It provides the general rules for testing a.c. circuit-breakers, for making and breaking
capacities over the range of test duties described in 6.102 to 6.111 of IEC 62271-100, by
synthetic methods.
NOTE Circuits for the test duties described in 6.111 have not yet been standardized. However, present methods
are given in Annex G.
It has been proven that synthetic testing is an economical and technically correct way to test
high-voltage a.c. circuit-breakers according to the requirements of IEC 62271-100 and that it
is equivalent to direct testing.
The methods and techniques described are those in general use. The purpose of this
standard is to establish criteria for synthetic testing and for the proper evaluation of results.
Such criteria will establish the validity of the test method without imposing restraints on
innovation of test circuitry.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 61633:1995, High-voltage alternating current circuit-breakers – Guide for short-circuit and
switching test procedures for metal-enclosed and dead tank circuit-breakers
IEC 62271-100:2001, High-voltage switchgear and controlgear – Part 100: High-voltage
alternating current circuit-breakers
IEC 62271-308:2002, High-voltage switchgear and controlgear – Part 308: Guide for asym-
metrical short-circuit test duty T100a
3 Terms and definitions
For the purposes of this document, the terms and definitions of IEC 62271-100, as well as the
following terms and definitions, apply.
3.1
direct test
test in which the applied voltage, the current and the transient and power-frequency recovery
voltages are all obtained from a circuit having a single-power source, which may be a power
system or special alternators as used in short-circuit testing stations or a combination of both

62271-101  IEC:2006 – 17 –
3.2
synthetic test
test in which all of the current, or a major portion of it, is obtained from one source (current
circuit), and in which the applied voltage and/or the recovery voltages (transient and power
frequency) are obtained wholly or in part from one or more separate sources (voltage circuits)
3.3
test circuit-breaker
circuit-breaker under test (see 6.102.2 of IEC 62271-100:2001)
3.4
auxiliary circuit-breaker(s)
circuit-breaker(s) forming part of a synthetic test circuit used to put the test circuit-breaker
into the required relation with various circuits
3.5
current circuit
that part of the synthetic test circuit from which all or the major part of the power-frequency
current is obtained
3.6
voltage circuit
that part of the synthetic test circuit from which all or the major part of the applied voltage
and/or recovery voltage is obtained
3.7
prospective current (of a circuit and with respect to a circuit-breaker)
current that would flow in the circuit if each pole of the test and auxiliary circuit-breakers were
replaced by a conductor of negligible impedance
[IEV 441-17-01, modified]
3.8
actual current
current through the test circuit-breaker (prospective current modified by the arc voltage of the
test and auxiliary circuit-breakers)
3.9
distortion current
calculated current equal to the difference between the prospective current and the actual
current
3.10
post-arc current
current which flows through the arc gap of a circuit-breaker when the current and arc voltage
have fallen to zero and the transient recovery voltage has begun to rise
3.11
current-injection method
synthetic test method in which the voltage circuit is applied to the test circuit-breaker before
power-frequency current zero
3.12
initial transient making current
ITMC
transient current which flows through the circuit-breaker at the moment of voltage breakdown
prior to the initiation of current from the current circuit during making

62271-101  IEC:2006 – 19 –
3.13
injected current
current supplied by the voltage circuit of a current injection circuit when it is connected to the
circuit-breaker under test
3.14
voltage-injection method
synthetic test method in which the voltage circuit is applied to the test circuit-breaker after
power frequency current zero
3.15
reference system conditions
conditions of an electrical system having the parameters from which the rated and test values
of IEC 62271-100 are derived
3.16
time delay of making device
t
m
time interval, during synthetic making test, between the instant of breakdown of the applied
voltage and the initiation of current from the current circuit
3.17
minimum clearing time
sum of the minimum opening time, minimum relay time (½ cycle), and the minimum arcing
time for the minor loop of the first-pole-to-clear, during test duty T100a only, as declared by
the manufacturer. This definition should be used only for the determination of the test
parameters for test duty T100a.
NOTE 1 The minimum clearing time obtained during the tests should not be lower than the value declared by the
manufacturer. Prior to the tests, the minimum opening time should be measured at maximum trip coil voltage
maximum pressure for operation and minimum pressure for interruption. If the minimum opening time measured
prior to the tests is lower than the one declared by the manufacturer, this lower value should be used for the
determination of the required test parameters.
NOTE 2 This definition assumes that the minimum clearing time obtained with the minimum pressure for
interruption is similar to the one that would be obtained with the maximum pressure for interruption. Normally, the
minimum clearing time is obtained with the maximum pressure for interruption. If such pressure condition is giving
a minimum clearing time such that the minimum clearing time range applicable (as given in Tables 1a to 2d of
IEC 62271-308:2002) for tests is different than the one obtained at minimum pressure for interruption, then it is
permissible to verify the minimum clearing time by using the maximum pressure for interruption.
3.18
pre-strike
voltage breakdown between the contacts during a making operation which initiates current
flow
4 Synthetic testing techniques and methods for short-circuit breaking tests
4.1 Basic principles and general requirements for synthetic breaking test methods
Any particular synthetic method chosen for testing shall adequately stress the test circuit-
breaker. Generally, the adequacy is established when the test method meets the requirements
set forth in the following subclauses.

62271-101  IEC:2006 – 21 –
A circuit-breaker has two basic positions: closed and open. In the closed position a circuit-
breaker conducts full current with negligible voltage drop across its contacts. In the open
position it conducts negligible current but with full voltage across the contacts. This defines
the two main stresses, the current stress and the voltage stress, which are separated in time.
If closer attention is paid to the voltage and current stresses during the interrupting process
(Figure 1), three main intervals can be recognized:
– High-current interval
The high-current interval is the time from contact separation to the start of the significant
change in arc voltage. The high-current interval precedes the interaction and high-voltage
intervals.
– Interaction interval
The interaction interval is the time from the start of the significant change in arc voltage
prior to current zero to the time when the current including the post-arc current, if any,
ceases to flow through the test circuit-breaker (see also Clause B.2).
– High-voltage interval
The high-voltage interval is the time from the moment when the current including the post-
arc current, if any, ceases to flow through the test circuit-breaker to the end of the test.
4.1.1 High-current interval
During the high-current interval the test circuit-breaker shall be stressed by the test circuit in
such a way that the starting conditions for the interaction interval, within tolerances to be
specified, are the same as under reference system conditions.
In synthetic test circuits the ratio of the power-frequency voltage of the current circuit to the
arc voltage is low in comparison with tests at reference system conditions due to:
– the voltage of the current circuit being a fraction of the system voltage;
– the fact that the arc voltages of the test circuit-breaker and of the auxiliary circuit-breaker
are added.
As a result the duration of the current loop and the peak value of the current will be reduced.
This distortion of the current is outlined in Annex A.
Considerations with respect to the arc energy released in the test circuit-breaker lead to a
maximum permissible influence in terms of tolerances on two characteristic values of the
shape of the current, i.e. current-peak value and current-loop duration (see Annex A).
The tolerance on the amplitude and the power frequency of the prospective breaking current
is given in 6.103.2 and 6.104.3 of IEC 62271-100. Therefore, the following conditions
concerning the actual current through the test circuit-breaker shall be met:
– for symmetrical testing the current amplitude and final loop duration shall not be less than
90 % of the required values based on rated current;
– for asymmetrical testing, the current amplitude and final loop duration shall be between
90 % and 110 % of the required values, based on rated current and time constant (see
Tables I.1a to I.2d).
62271-101  IEC:2006 – 23 –
Adjustment measures:
The amplitude and duration of the last current loop may be adjusted by several means,
such as
– increasing or decreasing of the r.m.s. value of the short-circuit test current,
– changing of the frequency of the test current,
– using pre-tripping or delayed tripping,
– changing the instant of current initiation (initial d.c. component).
For reference see 5.3 of IEC 62271-308.
4.1.2 Interaction interval
During the interaction interval, the short-circuit current stress changes into high-voltage stress
and the circuit-breaker performance can significantly influence the current and voltages in the
circuit. As the current decreases to zero, the arc voltage may rise to charge parallel
capacitance and distort current passing through the arc. After the current zero the post-arc
conductivity may result in additional damping of the transient recovery voltage and thus
influence the voltage across the circuit-breaker and the energy supplied to the ionized contact
gap. The interaction between the circuit and the circuit-breaker immediately before and after
current zero (i.e. during the interaction interval) is of extreme importance to the interrupting
process.
During the interaction interval, the current and voltage waveforms shall be the same for a
synthetic test as under reference system conditions (see 3.15), taking into account the
possible deviations of the current and voltage from the prospective values due to the
interaction between the circuit-breaker and the circuit.
The interaction interval presents the critical time for the thermal failure mode of the circuit-
breaker. Therefore, it is of extreme importance that the shape and magnitude of the
prospective transient recovery voltage (TRV) corresponds to that associated with the
prospective current of the relevant test duty.
The above implies strict requirements for the test circuit. The requirements are given for the
current injection method in 4.2.1 and for the voltage injection method in 4.2.2.
NOTE Depending on the test circuit used, the interaction between circuit and test circuit-breaker may be
disturbed by the behaviour of the auxiliary circuit-breaker during the critical interval around current zero.
The arc voltage of the auxiliary circuit-breaker should be less than or equal to the arc voltage of the test circuit-
breaker.
If an auxiliary circuit-breaker with a higher arc voltage is used, a higher power-frequency voltage of the current
circuit may be necessary.
4.1.3 High-voltage interval
During the high-voltage interval, the gap of the test circuit-breaker is stressed by the recovery
voltage.
The prospective TRV shall comply with the requirements of 4.102, 4.105, 4.106 and 6.104.5
of IEC 62271-100.
Suitable methods for determining the prospective TRV in synthetic test circuits can be
selected from Annex F of IEC 62271-100.

62271-101  IEC:2006 – 25 –
The impedance of the voltage circuit shall be low enough to give clear evidence of breakdown,
if any.
NOTE 1 If the test circuit-breaker is fitted with parallel breaking resistors, a special procedure may be necessary
(see Annex F).
NOTE 2 If the TRV is obtained from more than one source the overall waveshape should not show any
appreciable discontinuity.
In principle, the power-frequency recovery voltage for the basic short-circuit test duties should
preferably be a.c. and shall equate with the requirements of 6.104.7 of IEC 62271-100. In
synthetic testing, the recovery voltage is supplied from a voltage circuit, either
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