IEC TR 62271-306:2012

High-voltage switchgear and controlgear - Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related to alternating current circuit-breakers

IEC/TR 62271-306:2012(E) is applicable to a.c. circuit-breakers designed for indoor or outdoor installation and for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1 000 V. This technical report addresses utility, consultant and industrial engineers who specify and apply high-voltage circuit-breakers, circuit-breaker development engineers, engineers in testing stations, and engineers who participate in standardization. It is intended to provide background information concerning the facts and figures in the standards and provide a basis for specification for high-voltage circuit-breakers. Thus, its scope will cover the explanation, interpretation and application of IEC 62271-100 and IEC 62271-1 as well as related standards and technical reports with respect to high-voltage circuit-breakers.

General Information

• Status: Published
• Publication Date: 13-Dec-2012
• ICS: 29.130.10 - High voltage switchgear and controlgear
• Technical Committee: SC 17A - Switching devices
• Drafting Committee: MT 57 - TC 17/SC 17A/MT 57
• Current Stage: PPUB - Publication issued
• Start Date: 14-Dec-2012
• Completion Date: 31-Dec-2012

Relations

• Amended By: IEC TR 62271-306:2012/AMD1:2018 - Amendment 1 - High-voltage switchgear and controlgear - Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related to alternating current circuit-breakers
• Effective Date: 05-Sep-2023

Overview - IEC TR 62271-306:2012 (Guide to AC circuit‑breaker standards)

IEC TR 62271-306:2012 is a technical report that guides the interpretation and application of IEC 62271-100, IEC 62271-1 and related IEC documents for alternating‑current (a.c.) high‑voltage circuit‑breakers. Applicable to indoor and outdoor a.c. circuit‑breakers for 50 Hz and 60 Hz systems with voltages above 1 000 V, the report provides background information, test rationale, and a basis for specification and testing of high‑voltage circuit‑breakers and switchgear.

Keywords: IEC TR 62271-306, high-voltage circuit-breakers, IEC 62271-100, IEC 62271-1, a.c. circuit-breakers, switchgear standards

Key topics and technical requirements

The report consolidates technical context and interpretation across many practical topics, including:

• Classification and duty classes

  • Electrical and mechanical endurance classes (E1/E2, M1/M2)
  • Capacitive current switching classes (C1/C2) and application guidance

• Insulation levels and dielectric testing

  • Lightning impulse and power‑frequency withstand considerations
  • Altitude and humidity correction factors, combined longitudinal insulation tests
  • Special notes on vacuum interrupter conditioning and testing

• Rated current, temperature rise and thermal testing

  • Rated normal current definitions, load‑carrying capability under ambient conditions
  • Temperature‑rise test procedures and resistance measurements

• Transient Recovery Voltage (TRV) and fault duties

  • TRV definitions, harmonization with IEEE practices, ITRV concepts
  • Short‑line fault (SLF) requirements, RRRV and surge impedance considerations

• Switching phenomena

  • Out‑of‑phase switching guidance
  • Detailed treatment of capacitive current switching, non‑sustained disruptive discharges (NSDD), and effects on restrike and overvoltages

• Testing protocols and specification guidance

  • Test circuits, operating sequences, unit and routine tests, and interpretation for specification writers

Practical applications

IEC TR 62271-306 is practical for:

• Utility and substation engineers specifying high‑voltage circuit‑breakers and switchgear
• Consultant and project engineers preparing procurement specifications
• Circuit‑breaker development and design engineers
• Testing laboratory and type‑testing personnel
• Experts contributing to standardization or performing conformity assessment

Use cases include drafting procurement specs, selecting breaker classes for capacitive switching or SLF duties, interpreting TRV test conditions, and planning dielectric and temperature‑rise tests.

Related standards

• IEC 62271-100 (a.c. circuit‑breakers)
• IEC 62271-1 (common requirements for high‑voltage switchgear and controlgear)
• Other IEC technical reports and relevant IEEE documents referenced for TRV harmonization

IEC TR 62271-306:2012 acts as a practical companion for engineers who need clear, application‑focused interpretation of high‑voltage circuit‑breaker standards.

Standards Content (Sample)

IEC/TR 62271-306 ®
Edition 1.0 2012-12
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –
Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related to
alternating current circuit-breakers

IEC/TR 62271-306:2012(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

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IEC/TR 62271-306 ®
Edition 1.0 2012-12
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –

Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related

to alternating current circuit-breakers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XM
ICS 29.130.10 ISBN 978-2-83220-558-7

– 2 – TR 62271-306 © IEC:2012(E)
CONTENTS
FOREWORD . 15
1 General . 17
1.1 Scope . 17
1.2 Normative references . 17
2 Evolution of IEC standards for high-voltage circuit-breaker . 18
3 Classification of circuit-breakers . 22
3.1 General . 22
3.2 Electrical endurance class E1 and E2 . 22
3.3 Capacitive current switching class C1 and C2 . 23
3.4 Mechanical endurance class M1 and M2 . 23
3.5 Class S1 and S2 . 24
3.5.1 General . 24
3.5.2 Cable system . 24
3.5.3 Line system . 24
3.6 Conclusion . 24
4 Insulation levels and dielectric tests . 25
4.1 General . 25
4.2 Longitudinal voltage stresses . 28
4.3 High-voltage tests . 28
4.4 Impulse voltage withstand test procedures . 29
4.4.1 General . 29
4.4.2 Application to high-voltage switching devices . 29
4.4.3 Additional criteria to pass the tests . 30
4.4.4 Review and perspective . 30
4.4.5 Theory . 33
4.4.6 Summary of 15/2 and 3/9 test methods . 36
4.4.7 Routine tests . 37
4.5 Correction factors . 37
4.5.1 Altitude correction factor . 37
4.5.2 Humidity correction factor . 40
4.6 Background information about insulation levels and tests . 41
4.6.1 Specification . 41
4.6.2 Testing . 43
4.6.3 Combined voltage tests of longitudinal insulation . 43
4.7 Lightning impulse withstand considerations of vacuum interrupters . 44
4.7.1 General . 44
4.7.2 Conditioning during vacuum interrupter manufacturing . 44
4.7.3 De-conditioning in service. 45
4.7.4 Re-conditioning in service. 45
4.7.5 Performing lightning impulse withstand voltage tests . 45
5 Rated normal current and temperature rise . 45
5.1 General . 45
5.2 Load current carrying requirements . 45
5.2.1 Rated normal current . 45
5.2.2 Load current carrying capability under various conditions of ambient
temperature and load. 46

TR 62271-306 © IEC:2012(E) – 3 –
5.3 Temperature rise testing . 49
5.3.1 Influence of power frequency on temperature rise and temperature
rise tests . 49
5.3.2 Test procedure . 49
5.3.3 Temperature rise test on vacuum circuit-breakers . 51
5.3.4 Resistance measurement . 52
5.4 Additional information . 52
5.4.1 Table with ratios I /I . 52
a r
5.4.2 Derivation of temperature rise equations . 52
6 Transient recovery voltage . 53
6.1 Harmonization of IEC and IEEE transient recovery voltages . 53
6.1.1 General . 53
6.1.2 A summary of the TRV changes . 54
6.1.3 Revision of TRVs for rated voltages of 100 kV and above . 57
6.1.4 Revision of TRVs for rated voltages less than 100 kV . 60
6.2 Initial Transient Recovery Voltage (ITRV) . 62
6.2.1 Basis for specification . 62
6.2.2 Applicability . 63
6.2.3 Test duties where ITRV is required . 63
6.2.4 ITRV waveshape . 64
6.2.5 Standard values of ITRV . 64
6.3 Testing . 65
6.3.1 ITRV measurement . 65
6.3.2 SLF with ITRV . 66
6.3.3 Unit testing . 67
7 Short-line faults . 67
7.1 Short-line fault requirements . 67
7.1.1 Basis for specification . 67
7.1.2 Technical comment . 68
7.1.3 Single-phase faults . 68
7.1.4 Surge impedance of the line . 68
7.1.5 Peak voltage factor . 69
7.1.6 Rate-of-Rise of Recovery Voltage (RRRV) factor "s" . 71
7.2 SLF testing . 72
7.2.1 Test voltage . 72
7.2.2 Operating sequence . 72
7.2.3 Test duties . 72
7.2.4 Test current asymmetry . 73
7.2.5 Line side time delay . 74
7.2.6 Supply side circuit . 74
7.3 Additional explanations on SLF . 75
7.3.1 Surge impedance evaluation . 75
7.3.2 Influence of additional capacitors on SLF interruption . 75
7.4 Comparison of surge impedances . 80
7.5 Calculation of actual percentage of SLF breaking currents . 81
7.6 TRV with parallel capacitance . 82
8 Out-of-phase switching . 85
8.1 Reference system conditions . 85
8.1.1 General . 85

– 4 – TR 62271-306 © IEC:2012(E)
8.1.2 Case A . 85
8.1.3 Case B . 86
8.2 TRV parameters introduced into Tables 1b and 1c of the first edition of
IEC 62271-100 . 87
8.2.1 General . 87
8.2.2 Case A . 87
8.2.3 Case B . 88
8.2.4 TRV parameters for out-of-phase testing . 88
9 Switching of capacitive currents . 90
9.1 General . 90
9.2 General theory of capacitive current switching . 90
9.2.1 De-energisation of capacitive loads . 90
9.2.2 Energisation of capacitive loads . 103
9.3 Non-sustained disruptive discharge (NSDD) . 121
9.4 General application considerations . 124
9.4.1 General . 124
9.4.2 Maximum voltage for application . 124
9.4.3 Rated frequency . 124
9.4.4 Rated capacitive current . 124
9.4.5 Voltage and earthing conditions of the network . 125
9.4.6 Restrike performance . 126
9.4.7 Class of circuit-breaker . 126
9.4.8 Transient overvoltages and overvoltage limitation . 126
9.4.9 No-load overhead lines . 128
9.4.10 Capacitor banks . 130
9.4.11 Switching through transformers . 137
9.4.12 Effect of transient currents . 138
9.4.13 Exposure to capacitive switching duties during fault switching . 140
9.4.14 Effect of load . 140
9.4.15 Effect of reclosing . 141
9.4.16 Resistor thermal limitations . 141
9.4.17 Application considerations for different circuit-breaker types. 141
9.5 Considerations of capacitive currents and recovery voltages under fault
conditions . 143
9.5.1 Voltage and current factors . 143
9.5.2 Reasons for these specific tests being non-mandatory in the
standard . 144
9.5.3 Contribution of a capacitor bank to a fault . 144
9.5.4 Switching overhead lines under faulted conditions . 145
9.5.5 Switching capacitor banks under faulted conditions . 146
9.5.6 Switching cables under faulted conditions. 148
9.5.7 Examples of application alternatives . 148
9.6 Explanatory notes regarding capacitive current switching tests . 149
9.6.1 General . 149
9.6.2 Restrike performance . 149
9.6.3 Test programme . 149
9.6.4 Subclause 6.111.3 of IEC 62271-100:2008 – Characteristics of
supply circuit . 149
9.6.5 Subclause 6.111.5 of IEC 62271-100:2008 – Characteristics of the
capacitive circuit to be switched . 149

TR 62271-306 © IEC:2012(E) – 5 –
9.6.6 Subclause 6.111.9.1.1 of IEC 62271-100:2008 – Class C2 test duties . 149
9.6.7 Subclauses 6.111.9.1.1 and 6.111.9.2.1 of IEC 62271-100:2008 –
Class C1 and C2 test duties . 150
9.6.8 Subclauses 6.111.9.1.2 and 6.111.9.1.3 of IEC 62271-100:2008 –
Single-phase and three-phase line- and cable-charging current
switching tests . 150
9.6.9 Subclauses 6.111.9.1.2. to 6.111.9.1.5 of IEC 62271-100:2008 –
Three-phase and single-phase line, cable and capacitor bank
switching tests . 150
9.6.10 Subclauses 6.111.9.1.4 and 6.111.9.1.5 of IEC 62271-100:2008 –
Three-phase and single-phase capacitor bank switching tests . 150
10 Gas tightness . 151
10.1 Specification. 151
10.2 Testing . 151
10.3 Cumulative test method and calibration procedure for type tests on closed
pressure systems . 152
10.3.1 Description of the cumulative test method. 152
10.3.2 Sensitivity, accuracy and calibration . 153
10.3.3 Test set-up and test procedure . 153
10.3.4 Example: leakage rate measurement of a circuit-breaker during low
temperature test . 154
11 Miscellaneous provisions for breaking tests . 155
11.1 Energy for operation to be used during demonstration of the rated operating
sequence during short-circuit making and breaking tests . 155
11.2 Alternative operating mechanisms . 156
11.2.1 General . 156
11.2.2 Comparison of the mechanical characteristics . 157
11.2.3 Comparison of T100s test results . 159
11.2.4 Additional test T100a . 161
11.2.5 Conclusions . 162
12 Rated and test frequency . 162
12.1 General . 162
12.2 Basic considerations . 163
12.2.1 Temperature rise tests . 163
12.2.2 Short-time withstand current and peak withstand current tests . 163
12.2.3 Short-circuit making current . 163
12.2.4 Terminal faults . 163
12.2.5 Short-line fault . 164
12.2.6 Capacitive current switching . 164
12.3 Applicability of type tests at different frequencies . 164
12.3.1 Temperature rise tests . 164
12.3.2 Short-time withstand current and peak withstand current tests . 165
12.3.3 Short-circuit making current test . 165
12.3.4 Terminal faults (direct and synthetic tests) . 165
12.3.5 Short-line fault (direct and synthetic tests) . 166
12.3.6 Capacitive current switching . 166
13 Terminal faults. 167
13.1 General . 167
13.2 Demonstration of arcing time . 167
13.3 Demonstration of the arcing time for three-phase tests . 168

– 6 – TR 62271-306 © IEC:2012(E)
13.4 Power frequency recovery voltage and the selection of the first-pole-to-clear
factors 1,0; 1,2; 1,3 and 1,5 . 168
13.4.1 General . 168
13.4.2 Equations for the first, second and third-pole-to-clear factors . 169
13.4.3 Standardised values for the second- and third- pole-to-clear factors . 171
13.5 Characteristics of recovery voltage . 171
13.5.1 Values of rate-of-rise of recovery voltage and time delays . 171
13.5.2 Amplitude factors . 172
13.6 Arcing window and k requirements for testing . 172
p
13.7 Single-phase testing to cover three-phase testing requirements . 176
13.8 Combination tests for k = 1,3 and 1,5. 176
pp
13.9 Suitability of a particular short-circuit current rated circuit-breaker for use at
an application with a lower short-circuit requirement. 176
13.10 Basis for the current and TRV values of the basic short-circuit test-duty T10 . 177
14 Double earth fault . 178
14.1 Basis for specification . 178
14.2 Short-circuit current . 179
14.3 TRV . 179
14.4 Determination of the short-circuit current in the case of a double-earth fault . 180
15 Transport, storage, installation, operation and maintenance . 182
15.1 General . 182
15.2 Transport and storage . 183
15.3 Installation. 184
15.4 Commissioning . 184
15.5 Operation . 186
15.6 Maintenance . 186
16 Inductive load switching . 186
16.1 General . 186
16.2 Shunt reactor switching . 187
16.2.1 General . 187
16.2.2 Chopping overvoltages . 187
16.2.3 Re-ignition overvoltages . 194
16.2.4 Oscillation circuits . 195
16.2.5 Overvoltage limitation . 197
16.2.6 Circuit-breaker specification and selection . 198
16.2.7 Testing . 200
16.3 Motor switching . 200
16.3.1 General . 200
16.3.2 Chopping and re-ignition overvoltages . 201
16.3.3 Voltage escalation . 202
16.3.4 Virtual current chopping . 202
16.3.5 Overvoltage limitation . 203
16.3.6 Circuit-breaker specification and selection . 204
16.3.7 Testing . 204
16.4 Unloaded transformer switching . 205
16.4.1 General . 205
16.4.2 Oil-filled transformers . 205
16.4.3 Dry type transformers . 206
16.5 Shunt reactor characteristics . 207

TR 62271-306 © IEC:2012(E) – 7 –
16.5.1 General . 207
16.5.2 Shunt reactors rated 72,5 kV and above . 207
16.5.3 Shunt reactors rated below 72,5 kV . 208
16.6 System and station characteristics . 209
16.6.1 General . 209
16.6.2 System characteristics . 209
16.6.3 Station characteristics . 209
16.7 Current chopping level calculation . 210
16.8 Application of laboratory test results to actual shunt reactor installations . 215
16.8.1 General . 215
16.8.2 Overvoltage estimation procedures . 215
16.8.3 Case studies . 217
16.9 Statistical equations for derivation of chopping and re-ignition overvoltages . 222
16.9.1 General . 222
16.9.2 Chopping number independent of arcing time . 222
16.9.3 Chopping number dependent on arcing time . 222
Annex A (informative) Consideration of d.c. time constant of the rated short-circuit
current in the application of high-voltage circuit-breakers . 224
Annex B (informative) Interruption of currents with delayed zero crossings . 248
Annex C (informative) Parallel switching . 263
Annex D (informative) Application of current limiting reactors. 270
Annex E (informative) Explanatory notes on the revision of TRVs for circuit-breakers
of rated voltages higher than 1 kV and less than 100 kV . 274
Annex F (informative) Current and test-duty combination for capacitive current
switching tests . 278
Annex G (informative) Grading capacitors . 291
Annex H (informative) Circuit-breakers with opening resistors . 295
Annex I (informative) Circuit-breaker history . 318
Bibliography . 320

Figure 1 – Probability of acceptance (passing the test) for the 15/2 and 3/9 test series . 31
Figure 2 – Probability of acceptance at 5 % probability of flashover for 15/2 and 3/9
test series . 32
Figure 3 – User risk at 10 % probability of flashover for 15/2 and 3/9 test series . 32
Figure 4 – Operating characteristic curves for 15/2 and 3/9 test series . 35
Figure 5 – α risks for 15/2 and 3/9 test methods . 36
Figure 6 – β risks for 15/2 and 3/9 test methods. 37
Figure 7 – Ideal sampling plan for AQL of 10 % . 37
Figure 8 – Disruptive discharge mode of external insulation of switchgear and
controlgear having a rated voltage above 1 kV up to and including 52 kV . 41
Figure 9 – Temperature curve and definitions . 51
Figure 10 – Evaluation of the steady state condition for the last quarter of the test
duration shown in Figure 9 . 51
Figure 11 – Comparison of IEEE, IEC and harmonized TRVs, example for 145 kV at
100 % I with k = 1,3 . 56
sc pp
Figure 12 – Comparison of IEEE, IEC and harmonized TRVs with compromise values
of u and t , example for 145 kV at 100 % I with k = 1,3 . 59
1 1 sc pp
– 8 – TR 62271-306 © IEC:2012(E)
Figure 13 – Comparison of TRV’s for cable-systems and line-systems . 61
Figure 14 – Harmonization of TRVs for circuit-breakers < 100 kV . 62
Figure 15 – Representation of ITRV and terminal fault TRV . 64
Figure 16 – Typical graph of line side TRV with time delay and source side with ITRV . 66
Figure 17 – Effects of capacitor size on the short-line fault component of recovery
voltage with a fault 915 m from circuit-breaker . 77
Figure 18 – Effect of capacitor location on short-line fault component of transient
recovery voltage with a fault 760 m from circuit-breaker . 78
Figure 19 – TRV obtained during a L test duty on a 145 kV, 50 kA, 60 Hz circuit-
breaker . 80
Figure 20 – TRV vs. ωIZ as function of t/t when t /t = 4,0 . 85
dL L dL
Figure 21 – Typical system configuration for out-of-phase breaking for case A . 86
Figure 22 – Typical system configuration for out-of-phase breaking for Case B . 86
Figure 23 – Voltage on both sides during CO under out-of-phase conditions . 89
Figure 24 – Fault currents during CO under out-of-phase . 89
Figure 25 – TRVs for out-of-phase clearing (enlarged) . 89
Figure 26 – Single-phase equivalent circuit for capacitive current interruption . 91
Figure 27 – Voltage and current shapes at capacitive current interruption . 92
Figure 28 – Voltage and current wave shapes in the case of a restrike . 93
Figure 29 – Voltage build-up by successive restrikes . 94
Figure 30 – Recovery voltage of the first-pole-to-clear at interruption of a three-phase
non-effectively earthed capacitive load . 95
Figure 31 – Cross-section of a high-voltage cable . 96
Figure 32 – Screened cable with equivalent circuit . 96
Figure 33 – Belted cable with equivalent circuit . 96
Figure 34 – Recovery voltage peak in the first-pole-to-clear as a function of C /C
,
1 0
delayed interruption of the second phase . 99
Figure 35 – Typical current and voltage relations for a compensated line . 100
Figure 36 – Half cycle of recovery voltage . 101
Figure 37 – Recovery voltage on first-pole-to-clear for three-phase interruption:
capacitor bank with isolated neutral . 102
Figure 38 – Parallel capacitor banks . 105
Figure 39 – Equivalent circuit of a compensated cable . 109
Figure 40 – Currents when making at voltage maximum and full compensation . 110
Figure 41 – Currents when making at voltage zero and full compensation . 110
Figure 42 – Currents when making at voltage maximum and partial compensation . 111
Figure 43 – Currents when making at voltage zero and partial compensation . 112
Figure 44 – Typical circuit for back-to-back cable switching . 114
Figure 45 – Equivalent circuit for back-to-back cable switching . 116
Figure 46 – Bank-to-cable switching circuit . 118
Figure 47 – Equivalent bank-to-cable switching circuit . 118
Figure 48 – Energisation of no-load lines: basic phenomena . 120
Figure 49 – Pre-insertion resistors and their function . 120
Figure 50 – NSDD in a single-phase test circuit . 121
Figure 51 – NSDD (indicated by the arrow) in a three-phase test . 122

TR 62271-306 © IEC:2012(E) – 9 –
Figure 52 – A first example of a three-phase test with an NSDD causing a voltage shift
in all three phases of the same polarity and magnitude . 122
Figure 53 – A second example of three-phase test with an NSDD (indicated by the
arrow) causing a voltage shift in all three phases of the same polarity and magnitude . 123
Figure 54 – A typical oscillogram of an NSDD where a high resolution measurement
was used to observe the voltage pulses produced by the NSDD . 123
Figure 55 – Example of the recovery voltage across a filter bank circuit-breaker . 126
Figure 56 – RMS charging current versus system voltage for different line
configurations at 60 Hz . 129
Figure 57 – Typical circuit for back-to-back switching . 132
Figure 58 – Example of 123 kV system . 135
Figure 59 – Voltage and current relations for capacitor switching through interposed
transformer . 138
Figure 60 – Station illustrating large transient inrush currents through circuit-breakers
from parallel capacitor banks . 139
Figure 61 – Fault in the vicinity of a capacitor bank . 144
Figure 62 – Recovery voltages and currents for different interrupting sequences . 146
Figure 63 – Reference condition . 147
Figure 64 – Comparison of reference and alternative mechanical characteristics . 158
Figure 65 – Closing operation outside the envelope . 159
Figure 66 – Mechanical characteristics during a T100s test . 160
Figure 67 – Arcing windows and k value for three-phase fault in a non-effectively
p
earthed system . 172
Figure 68 – Three-phase unearthed fault current interruption . 173
Figure 69 – Arcing windows and k values for three-phase fault to earth in an
p
effectively earthed system at 800 kV and below . 174
Figure 70 – Arcing windows and k values for three-phase fault to earth in an
p
effectively earthed system above 800 kV . 175
Figure 71 – Simulation of three-phase to earth fault current interruption at 50 Hz . 176
Figure 72 – Representation of a system with a double earth fault . 179
Figure 73 – Representation of circuit with double-earth fault . 180
Figure 74 – Fault currents relative to the three-phase short-circuit current . 182
Figure 75 – General case for shunt reactor switching . 188
Figure 76 – Current chopping phenomena . 189
Figure 77 – General case first-pole-to-clear representation . 189
Figure 78 – Single phase equivalent circuit for the first-pole-to-clear . 190
Figure 79 – Voltage conditions
...

IEC/TR 62271-306 ®
Edition 1.0 2012-12
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –
Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related to
alternating current circuit-breakers

IEC/TR 62271-306:2012(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

Useful links:
IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org
The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and
by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and
committee,…). definitions in English and French, with equivalent terms in
It also gives information on projects, replaced and additional languages. Also known as the International
withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.

IEC Just Published - webstore.iec.ch/justpublished Customer Service Centre - webstore.iec.ch/csc
Stay up to date on all new IEC publications. Just Published If you wish to give us your feedback on this publication
details all new publications released. Available on-line and or need further assistance, please contact the
also once a month by email. Customer Service Centre: [e-mail].

IEC/TR 62271-306 ®
Edition 1.0 2012-12
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –

Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related

to alternating current circuit-breakers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
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ICS 29.130.10 ISBN 978-2-83220-558-7

– 2 – TR 62271-306 © IEC:2012(E)
CONTENTS
FOREWORD . 15
1 General . 17
1.1 Scope . 17
1.2 Normative references . 17
2 Evolution of IEC standards for high-voltage circuit-breaker . 18
3 Classification of circuit-breakers . 22
3.1 General . 22
3.2 Electrical endurance class E1 and E2 . 22
3.3 Capacitive current switching class C1 and C2 . 23
3.4 Mechanical endurance class M1 and M2 . 23
3.5 Class S1 and S2 . 24
3.5.1 General . 24
3.5.2 Cable system . 24
3.5.3 Line system . 24
3.6 Conclusion . 24
4 Insulation levels and dielectric tests . 25
4.1 General . 25
4.2 Longitudinal voltage stresses . 28
4.3 High-voltage tests . 28
4.4 Impulse voltage withstand test procedures . 29
4.4.1 General . 29
4.4.2 Application to high-voltage switching devices . 29
4.4.3 Additional criteria to pass the tests . 30
4.4.4 Review and perspective . 30
4.4.5 Theory . 33
4.4.6 Summary of 15/2 and 3/9 test methods . 36
4.4.7 Routine tests . 37
4.5 Correction factors . 37
4.5.1 Altitude correction factor . 37
4.5.2 Humidity correction factor . 40
4.6 Background information about insulation levels and tests . 41
4.6.1 Specification . 41
4.6.2 Testing . 43
4.6.3 Combined voltage tests of longitudinal insulation . 43
4.7 Lightning impulse withstand considerations of vacuum interrupters . 44
4.7.1 General . 44
4.7.2 Conditioning during vacuum interrupter manufacturing . 44
4.7.3 De-conditioning in service. 45
4.7.4 Re-conditioning in service. 45
4.7.5 Performing lightning impulse withstand voltage tests . 45
5 Rated normal current and temperature rise . 45
5.1 General . 45
5.2 Load current carrying requirements . 45
5.2.1 Rated normal current . 45
5.2.2 Load current carrying capability under various conditions of ambient
temperature and load. 46

TR 62271-306 © IEC:2012(E) – 3 –
5.3 Temperature rise testing . 49
5.3.1 Influence of power frequency on temperature rise and temperature
rise tests . 49
5.3.2 Test procedure . 49
5.3.3 Temperature rise test on vacuum circuit-breakers . 51
5.3.4 Resistance measurement . 52
5.4 Additional information . 52
5.4.1 Table with ratios I /I . 52
a r
5.4.2 Derivation of temperature rise equations . 52
6 Transient recovery voltage . 53
6.1 Harmonization of IEC and IEEE transient recovery voltages . 53
6.1.1 General . 53
6.1.2 A summary of the TRV changes . 54
6.1.3 Revision of TRVs for rated voltages of 100 kV and above . 57
6.1.4 Revision of TRVs for rated voltages less than 100 kV . 60
6.2 Initial Transient Recovery Voltage (ITRV) . 62
6.2.1 Basis for specification . 62
6.2.2 Applicability . 63
6.2.3 Test duties where ITRV is required . 63
6.2.4 ITRV waveshape . 64
6.2.5 Standard values of ITRV . 64
6.3 Testing . 65
6.3.1 ITRV measurement . 65
6.3.2 SLF with ITRV . 66
6.3.3 Unit testing . 67
7 Short-line faults . 67
7.1 Short-line fault requirements . 67
7.1.1 Basis for specification . 67
7.1.2 Technical comment . 68
7.1.3 Single-phase faults . 68
7.1.4 Surge impedance of the line . 68
7.1.5 Peak voltage factor . 69
7.1.6 Rate-of-Rise of Recovery Voltage (RRRV) factor "s" . 71
7.2 SLF testing . 72
7.2.1 Test voltage . 72
7.2.2 Operating sequence . 72
7.2.3 Test duties . 72
7.2.4 Test current asymmetry . 73
7.2.5 Line side time delay . 74
7.2.6 Supply side circuit . 74
7.3 Additional explanations on SLF . 75
7.3.1 Surge impedance evaluation . 75
7.3.2 Influence of additional capacitors on SLF interruption . 75
7.4 Comparison of surge impedances . 80
7.5 Calculation of actual percentage of SLF breaking currents . 81
7.6 TRV with parallel capacitance . 82
8 Out-of-phase switching . 85
8.1 Reference system conditions . 85
8.1.1 General . 85

– 4 – TR 62271-306 © IEC:2012(E)
8.1.2 Case A . 85
8.1.3 Case B . 86
8.2 TRV parameters introduced into Tables 1b and 1c of the first edition of
IEC 62271-100 . 87
8.2.1 General . 87
8.2.2 Case A . 87
8.2.3 Case B . 88
8.2.4 TRV parameters for out-of-phase testing . 88
9 Switching of capacitive currents . 90
9.1 General . 90
9.2 General theory of capacitive current switching . 90
9.2.1 De-energisation of capacitive loads . 90
9.2.2 Energisation of capacitive loads . 103
9.3 Non-sustained disruptive discharge (NSDD) . 121
9.4 General application considerations . 124
9.4.1 General . 124
9.4.2 Maximum voltage for application . 124
9.4.3 Rated frequency . 124
9.4.4 Rated capacitive current . 124
9.4.5 Voltage and earthing conditions of the network . 125
9.4.6 Restrike performance . 126
9.4.7 Class of circuit-breaker . 126
9.4.8 Transient overvoltages and overvoltage limitation . 126
9.4.9 No-load overhead lines . 128
9.4.10 Capacitor banks . 130
9.4.11 Switching through transformers . 137
9.4.12 Effect of transient currents . 138
9.4.13 Exposure to capacitive switching duties during fault switching . 140
9.4.14 Effect of load . 140
9.4.15 Effect of reclosing . 141
9.4.16 Resistor thermal limitations . 141
9.4.17 Application considerations for different circuit-breaker types. 141
9.5 Considerations of capacitive currents and recovery voltages under fault
conditions . 143
9.5.1 Voltage and current factors . 143
9.5.2 Reasons for these specific tests being non-mandatory in the
standard . 144
9.5.3 Contribution of a capacitor bank to a fault . 144
9.5.4 Switching overhead lines under faulted conditions . 145
9.5.5 Switching capacitor banks under faulted conditions . 146
9.5.6 Switching cables under faulted conditions. 148
9.5.7 Examples of application alternatives . 148
9.6 Explanatory notes regarding capacitive current switching tests . 149
9.6.1 General . 149
9.6.2 Restrike performance . 149
9.6.3 Test programme . 149
9.6.4 Subclause 6.111.3 of IEC 62271-100:2008 – Characteristics of
supply circuit . 149
9.6.5 Subclause 6.111.5 of IEC 62271-100:2008 – Characteristics of the
capacitive circuit to be switched . 149

TR 62271-306 © IEC:2012(E) – 5 –
9.6.6 Subclause 6.111.9.1.1 of IEC 62271-100:2008 – Class C2 test duties . 149
9.6.7 Subclauses 6.111.9.1.1 and 6.111.9.2.1 of IEC 62271-100:2008 –
Class C1 and C2 test duties . 150
9.6.8 Subclauses 6.111.9.1.2 and 6.111.9.1.3 of IEC 62271-100:2008 –
Single-phase and three-phase line- and cable-charging current
switching tests . 150
9.6.9 Subclauses 6.111.9.1.2. to 6.111.9.1.5 of IEC 62271-100:2008 –
Three-phase and single-phase line, cable and capacitor bank
switching tests . 150
9.6.10 Subclauses 6.111.9.1.4 and 6.111.9.1.5 of IEC 62271-100:2008 –
Three-phase and single-phase capacitor bank switching tests . 150
10 Gas tightness . 151
10.1 Specification. 151
10.2 Testing . 151
10.3 Cumulative test method and calibration procedure for type tests on closed
pressure systems . 152
10.3.1 Description of the cumulative test method. 152
10.3.2 Sensitivity, accuracy and calibration . 153
10.3.3 Test set-up and test procedure . 153
10.3.4 Example: leakage rate measurement of a circuit-breaker during low
temperature test . 154
11 Miscellaneous provisions for breaking tests . 155
11.1 Energy for operation to be used during demonstration of the rated operating
sequence during short-circuit making and breaking tests . 155
11.2 Alternative operating mechanisms . 156
11.2.1 General . 156
11.2.2 Comparison of the mechanical characteristics . 157
11.2.3 Comparison of T100s test results . 159
11.2.4 Additional test T100a . 161
11.2.5 Conclusions . 162
12 Rated and test frequency . 162
12.1 General . 162
12.2 Basic considerations . 163
12.2.1 Temperature rise tests . 163
12.2.2 Short-time withstand current and peak withstand current tests . 163
12.2.3 Short-circuit making current . 163
12.2.4 Terminal faults . 163
12.2.5 Short-line fault . 164
12.2.6 Capacitive current switching . 164
12.3 Applicability of type tests at different frequencies . 164
12.3.1 Temperature rise tests . 164
12.3.2 Short-time withstand current and peak withstand current tests . 165
12.3.3 Short-circuit making current test . 165
12.3.4 Terminal faults (direct and synthetic tests) . 165
12.3.5 Short-line fault (direct and synthetic tests) . 166
12.3.6 Capacitive current switching . 166
13 Terminal faults. 167
13.1 General . 167
13.2 Demonstration of arcing time . 167
13.3 Demonstration of the arcing time for three-phase tests . 168

– 6 – TR 62271-306 © IEC:2012(E)
13.4 Power frequency recovery voltage and the selection of the first-pole-to-clear
factors 1,0; 1,2; 1,3 and 1,5 . 168
13.4.1 General . 168
13.4.2 Equations for the first, second and third-pole-to-clear factors . 169
13.4.3 Standardised values for the second- and third- pole-to-clear factors . 171
13.5 Characteristics of recovery voltage . 171
13.5.1 Values of rate-of-rise of recovery voltage and time delays . 171
13.5.2 Amplitude factors . 172
13.6 Arcing window and k requirements for testing . 172
p
13.7 Single-phase testing to cover three-phase testing requirements . 176
13.8 Combination tests for k = 1,3 and 1,5. 176
pp
13.9 Suitability of a particular short-circuit current rated circuit-breaker for use at
an application with a lower short-circuit requirement. 176
13.10 Basis for the current and TRV values of the basic short-circuit test-duty T10 . 177
14 Double earth fault . 178
14.1 Basis for specification . 178
14.2 Short-circuit current . 179
14.3 TRV . 179
14.4 Determination of the short-circuit current in the case of a double-earth fault . 180
15 Transport, storage, installation, operation and maintenance . 182
15.1 General . 182
15.2 Transport and storage . 183
15.3 Installation. 184
15.4 Commissioning . 184
15.5 Operation . 186
15.6 Maintenance . 186
16 Inductive load switching . 186
16.1 General . 186
16.2 Shunt reactor switching . 187
16.2.1 General . 187
16.2.2 Chopping overvoltages . 187
16.2.3 Re-ignition overvoltages . 194
16.2.4 Oscillation circuits . 195
16.2.5 Overvoltage limitation . 197
16.2.6 Circuit-breaker specification and selection . 198
16.2.7 Testing . 200
16.3 Motor switching . 200
16.3.1 General . 200
16.3.2 Chopping and re-ignition overvoltages . 201
16.3.3 Voltage escalation . 202
16.3.4 Virtual current chopping . 202
16.3.5 Overvoltage limitation . 203
16.3.6 Circuit-breaker specification and selection . 204
16.3.7 Testing . 204
16.4 Unloaded transformer switching . 205
16.4.1 General . 205
16.4.2 Oil-filled transformers . 205
16.4.3 Dry type transformers . 206
16.5 Shunt reactor characteristics . 207

TR 62271-306 © IEC:2012(E) – 7 –
16.5.1 General . 207
16.5.2 Shunt reactors rated 72,5 kV and above . 207
16.5.3 Shunt reactors rated below 72,5 kV . 208
16.6 System and station characteristics . 209
16.6.1 General . 209
16.6.2 System characteristics . 209
16.6.3 Station characteristics . 209
16.7 Current chopping level calculation . 210
16.8 Application of laboratory test results to actual shunt reactor installations . 215
16.8.1 General . 215
16.8.2 Overvoltage estimation procedures . 215
16.8.3 Case studies . 217
16.9 Statistical equations for derivation of chopping and re-ignition overvoltages . 222
16.9.1 General . 222
16.9.2 Chopping number independent of arcing time . 222
16.9.3 Chopping number dependent on arcing time . 222
Annex A (informative) Consideration of d.c. time constant of the rated short-circuit
current in the application of high-voltage circuit-breakers . 224
Annex B (informative) Interruption of currents with delayed zero crossings . 248
Annex C (informative) Parallel switching . 263
Annex D (informative) Application of current limiting reactors. 270
Annex E (informative) Explanatory notes on the revision of TRVs for circuit-breakers
of rated voltages higher than 1 kV and less than 100 kV . 274
Annex F (informative) Current and test-duty combination for capacitive current
switching tests . 278
Annex G (informative) Grading capacitors . 291
Annex H (informative) Circuit-breakers with opening resistors . 295
Annex I (informative) Circuit-breaker history . 318
Bibliography . 320

Figure 1 – Probability of acceptance (passing the test) for the 15/2 and 3/9 test series . 31
Figure 2 – Probability of acceptance at 5 % probability of flashover for 15/2 and 3/9
test series . 32
Figure 3 – User risk at 10 % probability of flashover for 15/2 and 3/9 test series . 32
Figure 4 – Operating characteristic curves for 15/2 and 3/9 test series . 35
Figure 5 – α risks for 15/2 and 3/9 test methods . 36
Figure 6 – β risks for 15/2 and 3/9 test methods. 37
Figure 7 – Ideal sampling plan for AQL of 10 % . 37
Figure 8 – Disruptive discharge mode of external insulation of switchgear and
controlgear having a rated voltage above 1 kV up to and including 52 kV . 41
Figure 9 – Temperature curve and definitions . 51
Figure 10 – Evaluation of the steady state condition for the last quarter of the test
duration shown in Figure 9 . 51
Figure 11 – Comparison of IEEE, IEC and harmonized TRVs, example for 145 kV at
100 % I with k = 1,3 . 56
sc pp
Figure 12 – Comparison of IEEE, IEC and harmonized TRVs with compromise values
of u and t , example for 145 kV at 100 % I with k = 1,3 . 59
1 1 sc pp
– 8 – TR 62271-306 © IEC:2012(E)
Figure 13 – Comparison of TRV’s for cable-systems and line-systems . 61
Figure 14 – Harmonization of TRVs for circuit-breakers < 100 kV . 62
Figure 15 – Representation of ITRV and terminal fault TRV . 64
Figure 16 – Typical graph of line side TRV with time delay and source side with ITRV . 66
Figure 17 – Effects of capacitor size on the short-line fault component of recovery
voltage with a fault 915 m from circuit-breaker . 77
Figure 18 – Effect of capacitor location on short-line fault component of transient
recovery voltage with a fault 760 m from circuit-breaker . 78
Figure 19 – TRV obtained during a L test duty on a 145 kV, 50 kA, 60 Hz circuit-
breaker . 80
Figure 20 – TRV vs. ωIZ as function of t/t when t /t = 4,0 . 85
dL L dL
Figure 21 – Typical system configuration for out-of-phase breaking for case A . 86
Figure 22 – Typical system configuration for out-of-phase breaking for Case B . 86
Figure 23 – Voltage on both sides during CO under out-of-phase conditions . 89
Figure 24 – Fault currents during CO under out-of-phase . 89
Figure 25 – TRVs for out-of-phase clearing (enlarged) . 89
Figure 26 – Single-phase equivalent circuit for capacitive current interruption . 91
Figure 27 – Voltage and current shapes at capacitive current interruption . 92
Figure 28 – Voltage and current wave shapes in the case of a restrike . 93
Figure 29 – Voltage build-up by successive restrikes . 94
Figure 30 – Recovery voltage of the first-pole-to-clear at interruption of a three-phase
non-effectively earthed capacitive load . 95
Figure 31 – Cross-section of a high-voltage cable . 96
Figure 32 – Screened cable with equivalent circuit . 96
Figure 33 – Belted cable with equivalent circuit . 96
Figure 34 – Recovery voltage peak in the first-pole-to-clear as a function of C /C
,
1 0
delayed interruption of the second phase . 99
Figure 35 – Typical current and voltage relations for a compensated line . 100
Figure 36 – Half cycle of recovery voltage . 101
Figure 37 – Recovery voltage on first-pole-to-clear for three-phase interruption:
capacitor bank with isolated neutral . 102
Figure 38 – Parallel capacitor banks . 105
Figure 39 – Equivalent circuit of a compensated cable . 109
Figure 40 – Currents when making at voltage maximum and full compensation . 110
Figure 41 – Currents when making at voltage zero and full compensation . 110
Figure 42 – Currents when making at voltage maximum and partial compensation . 111
Figure 43 – Currents when making at voltage zero and partial compensation . 112
Figure 44 – Typical circuit for back-to-back cable switching . 114
Figure 45 – Equivalent circuit for back-to-back cable switching . 116
Figure 46 – Bank-to-cable switching circuit . 118
Figure 47 – Equivalent bank-to-cable switching circuit . 118
Figure 48 – Energisation of no-load lines: basic phenomena . 120
Figure 49 – Pre-insertion resistors and their function . 120
Figure 50 – NSDD in a single-phase test circuit . 121
Figure 51 – NSDD (indicated by the arrow) in a three-phase test . 122

TR 62271-306 © IEC:2012(E) – 9 –
Figure 52 – A first example of a three-phase test with an NSDD causing a voltage shift
in all three phases of the same polarity and magnitude . 122
Figure 53 – A second example of three-phase test with an NSDD (indicated by the
arrow) causing a voltage shift in all three phases of the same polarity and magnitude . 123
Figure 54 – A typical oscillogram of an NSDD where a high resolution measurement
was used to observe the voltage pulses produced by the NSDD . 123
Figure 55 – Example of the recovery voltage across a filter bank circuit-breaker . 126
Figure 56 – RMS charging current versus system voltage for different line
configurations at 60 Hz . 129
Figure 57 – Typical circuit for back-to-back switching . 132
Figure 58 – Example of 123 kV system . 135
Figure 59 – Voltage and current relations for capacitor switching through interposed
transformer . 138
Figure 60 – Station illustrating large transient inrush currents through circuit-breakers
from parallel capacitor banks . 139
Figure 61 – Fault in the vicinity of a capacitor bank . 144
Figure 62 – Recovery voltages and currents for different interrupting sequences . 146
Figure 63 – Reference condition . 147
Figure 64 – Comparison of reference and alternative mechanical characteristics . 158
Figure 65 – Closing operation outside the envelope . 159
Figure 66 – Mechanical characteristics during a T100s test . 160
Figure 67 – Arcing windows and k value for three-phase fault in a non-effectively
p
earthed system . 172
Figure 68 – Three-phase unearthed fault current interruption . 173
Figure 69 – Arcing windows and k values for three-phase fault to earth in an
p
effectively earthed system at 800 kV and below . 174
Figure 70 – Arcing windows and k values for three-phase fault to earth in an
p
effectively earthed system above 800 kV . 175
Figure 71 – Simulation of three-phase to earth fault current interruption at 50 Hz . 176
Figure 72 – Representation of a system with a double earth fault . 179
Figure 73 – Representation of circuit with double-earth fault . 180
Figure 74 – Fault currents relative to the three-phase short-circuit current . 182
Figure 75 – General case for shunt reactor switching . 188
Figure 76 – Current chopping phenomena . 189
Figure 77 – General case first-pole-to-clear representation . 189
Figure 78 – Single phase equivalent circuit for the first-pole-to-clear . 190
Figure 79 – Voltage conditions
...

IEC TR 62271-306 ®
Edition 1.1 2018-08
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –
Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related to
alternating current circuit-breakers

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IEC TR 62271-306 ®
Edition 1.1 2018-08
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –

Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related

to alternating current circuit-breakers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.10 ISBN 978-2-8322-6010-4

IEC TR 62271-306 ®
Edition 1.1 2018-08
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
High-voltage switchgear and controlgear –
Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related to
alternating current circuit-breakers

– 2 – IEC TR 62271-306:2012+AMD1:2018 CSV
© IEC 2018
CONTENTS
FOREWORD . 14
INTRODUCTION to the Amendment . 16
1 General . 17
1.1 Scope . 17
1.2 Normative references . 17
2 Evolution of IEC standards for high-voltage circuit-breaker . 18
3 Classification of circuit-breakers . 22
3.1 General . 22
3.2 Electrical endurance class E1 and E2 . 22
3.3 Capacitive current switching class C1 and C2 . 23
3.4 Mechanical endurance class M1 and M2 . 24
3.5 Class S1 and S2 . 24
3.6 Conclusion . 25
4 Insulation levels and dielectric tests . 25
4.1 General . 25
4.2 Longitudinal voltage stresses . 29
4.3 High-voltage tests . 29
4.4 Impulse voltage withstand test procedures . 30
4.5 Correction factors . 38
4.6 Background information about insulation levels and tests . 42
4.7 Lightning impulse withstand considerations of vacuum interrupters. 45
5 Rated normal current and temperature rise. 46
5.1 General . 46
5.2 Load current carrying requirements . 46
5.3 Temperature rise testing . 50
5.4 Additional information . 53
6 Transient recovery voltage . 54
6.1 Harmonization of IEC and IEEE transient recovery voltages . 54
6.2 Initial Transient Recovery Voltage (ITRV) . 64
6.3 Testing . 67
6.4 General considerations regarding TRV . 69
6.5 Calculation of TRVs . 80
7 Short-line faults . 82
7.1 Short-line fault requirements . 82
7.2 SLF testing . 87
7.3 Additional explanations on SLF. 90
7.4 Comparison of surge impedances . 95
7.5 Calculation of actual percentage of SLF breaking currents Test current and
line length tolerances for short-line fault testing . 95
7.6 TRV with parallel capacitance . 98
8 Out-of-phase switching . 100
8.1 Reference system conditions . 100
8.2 TRV parameters introduced into Tables 1b and 1c of the first edition of
IEC 62271-100 . 102
9 Switching of capacitive currents . 105
9.1 General . 165

© IEC 2018
9.2 General theory of capacitive current switching . 166
9.3 Capacitor bank switching . 172
9.4 No-load cable switching. 175
9.5 No-load transmission line switching . 189
9.6 Voltage factors for capacitive current switching tests . 195
9.7 General application considerations . 197
9.8 Considerations of capacitive currents and recovery voltages under fault
conditions . 215
9.9 Explanatory notes regarding capacitive current switching tests . 219
10 Gas tightness . 221
10.1 Specification . 221
10.2 Testing . 222
10.3 Cumulative test method and calibration procedure for type tests on closed
pressure systems . 230
11 Miscellaneous provisions for breaking tests . 234
11.1 Energy for operation to be used during demonstration of the rated operating
sequence during short-circuit making and breaking tests . 234
11.2 Alternative operating mechanisms . 235
12 Rated and test frequency . 240
12.1 General . 240
12.2 Basic considerations . 241
12.3 Applicability of type tests at different frequencies . 242
13 Terminal faults Symmetrical and asymmetrical currents . 245
13.1 General . 255
13.2 Arcing time. 256
13.3 Symmetrical currents . 256
13.4 Asymmetrical currents . 263
13.5 Double earth fault . 270
13.6 Break time . 274
14 Double earth fault Synthetic making and breaking tests . 275
14.1 General . 279
14.2 Current injection methods . 280
14.3 Duplicate transformer circuit . 284
14.4 Voltage injection methods . 286
14.5 Current distortion . 289
14.6 Step-by-step method to prolong arcing . 304
14.7 Examples of the application of the tolerances on the last current loop based

on 4.1.2 and 6.109 of IEC 62271-101:2012 . 305
15 Transport, storage, installation, operation and maintenance. 306
15.1 General . 306
15.2 Transport and storage . 306
15.3 Installation . 307
15.4 Commissioning. 307
15.5 Operation . 309
15.6 Maintenance . 309
15.7 Corrosion: Information regarding service conditions and recommended test
requirements . 309
15.8 Electromagnetic compatibility on site . 310
16 Inductive load switching . 311

– 4 – IEC TR 62271-306:2012+AMD1:2018 CSV
© IEC 2018
16.1 General . 311
16.2 Shunt reactor switching . 312
16.3 Motor switching . 325
16.4 Unloaded transformer switching . 330
16.5 Shunt reactor characteristics . 336
16.6 System and station characteristics . 338
16.7 Current chopping level calculation . 339
16.8 Application of laboratory test results to actual shunt reactor installations . 344
16.9 Statistical equations for derivation of chopping and re-ignition overvoltages . 351
17 Information and technical requirements relevant for enquiries, tenders and orders . 352
17.1 General . 352
17.2 Normal and special service conditions (refer to Clause 2 of IEC 62271-
1:2007) . 352
17.3 Ratings and other system parameters (refer to Clause 4 IEC 62271-1:2007) . 352
17.4 Design and construction (refer to Clause 5 of IEC 62271-1:2007) . 353
17.5 Documentation for enquiries and tenders . 354
Annex A (informative) Consideration of DC time constant of the rated short-circuit
current in the application of high-voltage circuit-breakers . 355
A.1 General . 378
A.2 Basic theory . 379
A.3 Network reduction . 382
A.4 Special case time constants . 382
A.5 Guidance for selecting a circuit-breaker . 383
A.6 Discussion regarding equivalency . 393
A.7 Current and TRV waveshape adjustments during tests . 395
A.8 Conclusions . 401
Annex B (informative) Interruption of currents with delayed zero crossings . 402
B.1 General . 417
B.2 Faults close to major generation . 417
B.3 Conditions for delayed current zeros on transmission networks . 433
Annex C (informative) Parallel switching . 437
C.1 General .
C.2 Circuit-breaker characteristics .
C.3 Analysis and rules .
C.4 Parallel switching in practice .
C.5 Conclusions .
Annex D (informative) Application of current limiting reactors . 444
D.1 General . 447
D.2 Pole factor considerations . 448
D.3 Oscillatory component calculation . 449
D.4 Series reactors on shunt capacitor banks . 455
Annex E (informative)  Explanatory notes on the revision of TRVs for circuit-breakers
of rated voltages higher than 1 kV and less than 100 kV Guidance for short-circuit and
switching test procedures for metal-enclosed and dead tank circuit-breakers . 456
E.1 General . 459
E.2 General description of special features and possible interactions . 459
Annex F (informative) Current and test-duty combination for capacitive current
switching tests . 463
F.1 General . 463

© IEC 2018
F.2 Combination rules . 463
F.3 Examples . 464
Annex G (informative) Grading capacitors . 476
G.1 Grading capacitors . 476
Annex H (informative) Circuit-breakers with opening resistors . 480
H.1 General . 480
H.2 Background of necessity of overvoltage limitation . 480
H.3 Basic theory on the effect of opening resistors . 481
H.4 Review of TRV for circuit-breakers with opening resistors for various
interrupting duties . 489
H.5 Performance to be verified . 497
H.6 Time sequence of main and resistor interrupters . 500
H.7 Current carrying performance . 501
H.8 Dielectric performance during breaking tests . 501
H.9 Characteristics of opening resistors . 501
Annex I (informative) Circuit-breaker history . 503
Bibliography . 505

Figure 1 – Probability of acceptance (passing the test) for the 15/2 and 3/9 test series . 32
Figure 2 – Probability of acceptance at 5 % probability of flashover for 15/2 and 3/9
test series. 33
Figure 3 – User risk at 10 % probability of flashover for 15/2 and 3/9 test series . 33
Figure 4 – Operating characteristic curves for 15/2 and 3/9 test series . 36
Figure 5 – α risks for 15/2 and 3/9 test methods . 37
Figure 6 – β risks for 15/2 and 3/9 test methods . 38
Figure 7 – Ideal sampling plan for AQL of 10 % . 38
Figure 8 – Disruptive discharge mode of external insulation of switchgear and
controlgear having a rated voltage above 1 kV up to and including 52 kV . 42
Figure 9 – Temperature curve and definitions . 52
Figure 10 – Evaluation of the steady state condition for the last quarter of the test
duration shown in Figure 9 . 52
Figure 11 – Comparison of IEEE, IEC and harmonized TRVs, example for 145 kV at
100 % I with k = 1,3 . 57
sc pp
Figure 12 – Comparison of IEEE, IEC and harmonized TRVs with compromise values
of u and t , example for 145 kV at 100 % I with k = 1,3 . 60
1 1 sc pp
Figure 13 – Comparison of TRV’s for cable-systems and line-systems . 63
Figure 14 – Harmonization of TRVs for circuit-breakers < 100 kV . 64
Figure 15 – Representation of ITRV and terminal fault TRV . 66
Figure 16 – Typical graph of line side TRV with time delay and source side with ITRV . 68
Figure 17 – Effects of capacitor size on the short-line fault component of recovery
voltage with a fault 915 m from circuit-breaker . 92
Figure 18 – Effect of capacitor location on short-line fault component of transient
recovery voltage with a fault 760 m from circuit-breaker . 93
Figure 19 – TRV obtained during a L test duty on a 145 kV, 50 kA, 60 Hz circuit-
breaker . 94
Figure 20 – TRV vs. ωIZ as function of t/t when t /t = 4,0 . 100
dL L dL
Figure 21 – Typical system configuration for out-of-phase breaking for case A . 101

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Figure 22 – Typical system configuration for out-of-phase breaking for Case B . 101
Figure 23 – Voltage on both sides during CO under out-of-phase conditions . 104
Figure 24 – Fault currents during CO under out-of-phase . 104
Figure 25 – TRVs for out-of-phase clearing (enlarged) . 105
Figure 64 – Comparison of reference and alternative mechanical characteristics . 236
Figure 65 – Closing operation outside the envelope . 237
Figure 66 – Mechanical characteristics during a T100s test . 238
Figure 75 – General case for shunt reactor switching . 312
Figure 76 – Current chopping phenomena . 313
Figure 77 – General case first-pole-to-clear representation . 314
Figure 78 – Single phase equivalent circuit for the first-pole-to-clear . 315
Figure 79 – Voltage conditions at and after current interruption . 316
Figure 80 – Shunt reactor voltage at current interruption . 317
Figure 81 – Re-ignition at recovery voltage peak for a circuit with low supply side
capacitance . 319
Figure 82 – Field oscillogram of switching out a 500 kV 135 Mvar solidly earthed shunt
reactor . 320
Figure 83 – Single-phase equivalent circuit . 321
Figure 84 – Motor switching equivalent circuit . 327
Figure 87 – Arc characteristic . 340
Figure 88 – Rizk’s equivalent circuit for small current deviations from steady state . 340
Figure 89 – Single phase equivalent circuit . 341
Figure 90 – Circuit for calculation of arc instability . 342
Figure 91 – Initial voltage versus arcing time . 347
Figure 92 – Suppression peak overvoltage versus arcing time . 347
Figure 93 – Calculated chopped current levels versus arcing time . 347
Figure 94 – Calculated chopping numbers versus arcing time . 347
Figure 95 – Linear regression for all test points . 348
Figure 96 – Representation of a four-parameter TRV and a delay line . 70
Figure 97 – Representation of a specified TRV by a two-parameter reference line and
a delay line . 71
Figure 98 – Single-phase equivalent circuit for capacitive current interruption . 166
Figure 99 – Voltage and current shapes at capacitive current interruption . 167
Figure 100 – Voltage and current wave shapes in the case of a restrike . 168
Figure 101 – Voltage build-up by successive restrikes . 169
Figure 102 – Example of an NSDD during capacitive current interruption . 170
Figure 103 – Recovery voltage of the first-pole-to-clear at interruption of a three-
phase non-effectively earthed capacitive load . 171
Figure 104 – General circuit for capacitor bank switching . 172
Figure 105 – Typical circuit for no-load cable switching . 176
Figure 106 – Individually screened cable with equivalent circuit . 177
Figure 107 – Belted cable with equivalent circuit . 177
Figure 108 – Cross-section of a high-voltage cable . 178
Figure 109 – Equivalent circuit for back-to-back cable switching . 182

© IEC 2018
Figure 110 – Equivalent circuit of a compensated cable . 183
Figure 111 – Currents when making at voltage maximum and full compensation . 185
Figure 112 – Currents when making at voltage zero and full compensation . 186
Figure 113 – Currents when making at voltage maximum and partial compensation . 187
Figure 114 – Currents when making at voltage zero and partial compensation . 187
Figure 115 – RMS charging current versus system voltage for different line
configurations at 60 Hz . 189
Figure 116 – General circuit for no-load transmission line switching . 190
Figure 117 – Recovery voltage peak in the first-pole-to-clear as a function of C /C ,
1 0
delayed interruption of the second phase . 191
Figure 118 – Typical current and voltage relations for a compensated line . 193
Figure 119 – Half cycle of recovery voltage . 193
Figure 120 – Energisation of no-load lines: basic phenomena . 194
Figure 121 – Recovery voltage on first-pole-to-clear for three-phase interruption:
capacitor bank with isolated neutral . 196
Figure 122 – Example of the recovery voltage across a filter bank circuit-breaker . 198
Figure 123 – Typical circuit for back-to-back switching. 204
Figure 124 – Example of 123 kV system . 205
Figure 125 – Voltage and current relations for capacitor switching through interposed
transformer . 209
Figure 126 – Station illustrating large transient inrush currents through circuit-breakers
from parallel capacitor banks . 211
Figure 127 – Fault in the vicinity of a capacitor bank . 216
Figure 128 – Recovery voltage and current for first-phase-to-clear when the faulted
phase is the second phase-to-clear . 217
Figure 129 – Recovery voltage and current for last-phase-to-clear when the faulted
phase is the first-phase-to-clear . 217
Figure 130 – Basic circuit for shunt capacitor bank switching . 218
Figure 131 – Example of a tightness coordination chart, TC, for closed pressure
systems . 223
Figure 132 – Interrupting windows and k value for three-phase fault in a
p
non-effectively earthed system . 258
Figure 133 – Three-phase unearthed fault current interruption . 259
Figure 134 – Interrupting windows and k values for three-phase fault to earth in an
p
effectively earthed system at 800 kV and below . 260
Figure 135 – Interrupting windows and k values for three-phase fault to earth in an
p
effectively earthed system above 800 kV . 260
Figure 136 – Simulation of three-phase to earth fault current interruption at 50 Hz . 261
Figure 137 – Case 1 with interruption by a first pole (blue phase) after minor loop of
current with intermediate asymmetry . 265
Figure 138 – Case 2 with interruption of a last pole-to-clear after a major extended
loop of current with required asymmetry and longest arcing time . 266
Figure 139 – Case 3 with interruption of a last pole-to-clear after a major extended
loop of current with required asymmetry but not the longest arcing time . 267
Figure 140 – Case 4 with interruption by the first pole in the red phase after a major
loop of current with required asymmetry and the longest arcing time (for a first-pole-to-
clear) . 268
Figure 141 – Representation of a system with a double earth fault . 270

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Figure 142 – Representation of circuit with double-earth fault . 271
Figure 143 – Fault currents relative to the three-phase short-circuit current . 274
Figure 144 – Principle of synthetic testing . 280
Figure 145 – Typical current injection circuit with voltage circuit in parallel with the test
circuit-breaker . 281
Figure 146 – Injection timing for current injection scheme with the circuit given in
Figure 145 . 282
Figure 147 – Examples of the determination of the interval of significant change of arc
voltage from the oscillograms . 283
Figure 148 – Transformer or Skeats circuit . 284
Figure 149 – Triggered transformer or Skeats circuit. 285
Figure 150 – Typical voltage injection circuit diagram with voltage circuit in parallel
with the auxiliary circuit-breaker (simplified diagram) . 287
Figure 151 – TRV waveshapes in a voltage injection circuit with the voltage circuit in
parallel with the auxiliary circuit-breaker . 288
Figure 152 – Direct test circuit, simplified diagram . 290
Figure 153 – Prospective short-circuit current flow . 290
Figure 154 – Distortion current flow . 290
Figure 155 – Distortion current . 291
Figure 156 – Simplified circuit diagram for high-current interval . 292
Figure 157 – Current and arc voltage characteristics for symmetrical current and
constant arc voltage . 294
Figure 158 – Current and arc voltage characteristics for asymmetrical current and
constant arc voltage . 295
Figure 159 – Reduction of amplitude and duration of final current loop of arcing for

symmetrical current and constant arc voltage . 296
Figure 160 – Reduction of amplitude and duration of final current loop of arcing for
symmetrical current and linearly rising arc voltage . 297
Figure 161 – Reduction of amplitude and duration of final current loop of arcing for
asymmetrical current and constant arc voltage . 298
Figure 162 – Reduction of amplitude and duration of final current loop of arcing for

asymmetrical current and linearly rising arc voltage . 299
Figure 163 – Typical re-ignition circuit diagram for prolonging arc-duration . 304
Figure 164 – Typical waveshapes obtained during a symmetrical test using the circuit
in Figure 163 . 305
Figure 165 – Unloaded transformer switching circuit representation . 333
Figure 166 – Transformer side oscillation (left) and circuit-breaker transient recovery
voltage (right) . 333
Figure 167 – Re-ignition loop circuit . 335
Figure A.1 – Simplified single-phase circuit . 379
Figure A.2 – Percentage DC component in relation to the time interval from the
initiation of the short-circuit for the standard time constants and for the alternative
special case time constants (from IEC 62271-100) . 380
Figure A.3 – First valid operation in case of three-phase test (τ = 45 ms) on a circuit-
breaker exhibiting a very short minimum arcing time . 390
Figure A.4 – Second valid operation in case of three-phase test on a circuit-breaker
exhibiting a very short minimum arcing time . 390
Figure A.5 – Third valid operation in case of three-phase test on a circuit-breaker
exhibiting a very short minimum arcing time . 391

© IEC 2018
Figure A.6 – Plot of 60 Hz currents with indicated DC time constants . 394
Figure A.7 – Plot of 50 Hz currents with indicated DC time constants . 394
Figure A.8 – Three-phase testing of a circuit-breaker with a DC time constant of the
rated short-circuit breaking current longer than the test circuit time constant . 397
Figure A.9 – Single phase testing of a circuit-breaker with a DC time constant of the
rated short-circuit breaking current shorter than the test circuit time constant . 399
Figure A.10 – Single-phase testing of a circuit-breaker with a DC time constant of the
rated short-circuit breaking current longer than the test circuit time constant . 401
Figure B.1 – Single-line diagram of a power plant substation . 418
Figure B.2 – Performance chart (power characteristic) of a large generator . 419
Figure B.3 – Circuit-breaker currents i and arc voltages u in case of a three-phase
arc
fault following underexcited operation: non-simultaneous fault inception . 419
Figure B.4 – Circuit-breaker currents i and arc voltages u in case of a three-phase
arc
fault following underexcited operation: Simultaneous fault inception at third phase
voltage zero . 420
Figure B.5 – Circuit-breaker currents i and arc voltages u in case of a three-phase
arc
fault following underexcited operation: Simultaneous fault inception at third phase
voltage crest . 420
Figure B.6 – Circuit-breaker currents i and arc voltages u under conditions of a non-
arc
simultaneous three-phase fault, underexcited operation and failure of a generator
transformer . 421
Figure B.7 – Circuit-breaker currents i and arc voltages u under conditions of a non-
arc
simultaneous three-phase fault following full load operation . 422
Figure B.8 – Circuit-breaker currents i and arc voltages u under conditions of a
arc
non-simultaneous three-phase fault following no-load operation . 423
Figure B.9 – Circuit-breaker currents i and arc voltages u under conditions of
arc
unsynchronized closing with 90° differential angle . 424
Figure B.10 – Comparison of TRV test curve for out-of-phase (red) and system-source
short-circuit (green) .
...