IEC 62271-110:2017

IEC 62271-110 ®
Edition 4.0 2017-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
High-voltage switchgear and controlgear –
Part 110: Inductive load switching

Appareillage à haute tension –
Partie 110: Manœuvre de charges inductives
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IEC 62271-110 ®
Edition 4.0 2017-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
High-voltage switchgear and controlgear –

Part 110: Inductive load switching

Appareillage à haute tension –

Partie 110: Manœuvre de charges inductives

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.10 ISBN 978-2-8322-4866-9

– 2 – IEC 62271-110:2017 © IEC 2017
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Type tests . 8
4.1 General . 8
4.2 Miscellaneous provisions for inductive load switching tests . 8
4.3 High-voltage motor current switching tests . 9
4.3.1 Applicability . 9
4.3.2 General . 9
4.3.3 Characteristics of the supply circuits . 10
4.3.4 Characteristics of the load circuit . 11
4.3.5 Test voltage . 11
4.3.6 Test-duties . 12
4.3.7 Test measurements . 12
4.3.8 Behaviour and condition of switching device . 12
4.3.9 Test report . 13
4.4 Shunt reactor current switching tests . 14
4.4.1 Applicability . 14
4.4.2 General . 15
4.4.3 Test circuits . 15
4.4.4 Characteristics of the supply circuit . 18
4.4.5 Characteristics of the connecting leads . 18
4.4.6 Characteristics of the load circuits . 18
4.4.7 Earthing of the test circuit . 23
4.4.8 Test voltage . 23
4.4.9 Test-duties . 23
Annex A (normative) Calculation of t values . 27
Bibliography . 29

Figure 1 – Motor switching test circuit and summary of parameters . 10
Figure 2 – Illustration of voltage transients at interruption of inductive current for first
phase clearing in a three-phase non-effectively earthed circuit . 14
Figure 3 – Reactor switching test circuit – Three-phase test circuit for in-service load

circuit configurations 1 and 2 (Table 2) . 16
Figure 4 – Reactor switching test circuit – Single-phase test circuit for in-service load
circuit configurations 1, 2 and 4 (Table 2) . 17
Figure 5 – Reactor switching test circuit − Three-phase test circuit for in-service load
circuit configuration 3 (Table 2) . 18
Figure 6 – Illustration of voltage transients at interruption of inductive current for a
single-phase test . 26

Table 1 – Test-duties at motor current switching tests . 12
Table 2 – In-service load circuit configurations . 15

– 3 – IEC 62271-110:2017 © IEC 2017
Table 3 –Values of prospective transient recovery voltages – Rated voltages 12 kV to
170 kV for effectively and non-effectively earthed systems – Switching shunt reactors
with isolated neutrals (Table 2: In-service load circuit configuration 1) . 19
Table 4 – Values of prospective transient recovery voltages – Rated voltages 100 kV to
1 200 kV for effectively earthed systems – Switching shunt reactors with earthed
neutrals (See Table 2: In-service load circuit configuration 2) . 20
Table 5 – Values of prospective transient recovery voltages – Rated voltages 12 kV to
52 kV for effectively and non-effectively earthed systems – Switching shunt reactors
with isolated neutrals (See Table 2: In-service load circuit configuration 3) . 21
Table 6 – Values of prospective transient recovery voltages – Rated voltages 12 kV to
52 kV for effectively and non-effectively earthed systems – Switching shunt reactors
with earthed neutrals (See Table 2: In-service load circuit configuration 4) . 22
Table 7 – Load circuit 1 test currents . 22
Table 8 – Load circuit 2 test currents . 23
Table 9 – Test-duties for reactor current switching tests . 24

– 4 – IEC 62271-110:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 110: Inductive load switching

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,
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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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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
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
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
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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 62271-110 has been prepared by subcommittee 17A: Switching
devices, of IEC technical committee 17: High-voltage switchgear and controlgear.
This fourth edition cancels and replaces the third edition published in 2012 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– all switching devices are now covered, not only circuit-breakers;
– a limited number of T10 tests no longer covers shunt-reactor switching tests below 52 kV;
– evaluation and reporting of a re-ignition-free arcing time window has been added.

– 5 – IEC 62271-110:2017 © IEC 2017
The text of this International Standard is based on the following documents:
FDIS Report on voting
17A/1151/FDIS 17A/1155/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62271 series can be found, under the general title High-voltage
switchgear and controlgear, on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
The contents of the corrigenda of December 2017 and February 2018 have been included in
this copy.
– 6 – IEC 62271-110:2017 © IEC 2017
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 110: Inductive load switching

1 Scope
This part of IEC 62271 is applicable to AC switching devices designed for indoor or outdoor
installation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltages
above 1 000 V and applied for inductive current switching. It is applicable to switching devices
(including circuit-breakers in accordance with IEC 62271-100) that are used to switch
high-voltage motor currents and shunt reactor currents and also to high-voltage contactors
used to switch high-voltage motor currents as covered by IEC 62271-106.
Switching unloaded transformers, i.e. breaking transformer magnetizing current, is not
considered in this document. The reasons for this are as follows:
a) Owing to the non-linearity of the transformer core, it is not possible to correctly model the
switching of transformer magnetizing current using linear components in a test laboratory.
Tests conducted using an available transformer, such as a test transformer, will only be
valid for the transformer tested and cannot be representative for other transformers.
b) As detailed in IEC TR 62271-306, the characteristics of this duty are usually less severe
than any other inductive current switching duty. Such a duty may produce severe
overvoltages within the transformer winding(s) depending on the re-ignition behaviour of
the switching device and transformer winding resonance frequencies.
NOTE 1 The switching of tertiary reactors from the high-voltage side of the transformer is not covered by this
document.
NOTE 2 The switching of shunt reactors earthed through neutral reactors is not covered by this document.
However, the application of test results according to this document, on the switching of neutral reactor earthed
reactors (4-leg reactor scheme), is discussed in IEC TR 62271-306.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60050-441, International Electrotechnical Vocabulary – Chapter 441: Switchgear,
controlgear and fuses (available at www.electropedia.org)
IEC 62271-1:2017, High-voltage switchgear and controlgear – Part 1: Common specifications
for alternating current switchgear and controlgear
IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: Alternating current
circuit-breakers
IEC 62271-100:2008/AMD1:2012
IEC 62271-106:2011, High-voltage switchgear and controlgear – Part 106: Alternating current
contactors, contactor-based controllers and motor-starters

– 7 – IEC 62271-110:2017 © IEC 2017
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-441,
IEC 62271-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
inductive current
power-frequency current drawn by an inductive circuit having a power factor 0,5 or less
3.2
current chopping
abrupt current interruption in a switching device at a point-on-wave other than the natural
power-frequency current zero
3.3
virtual current chopping
current chopping in one of the three phases in a three-phase circuit originated by transients in
another phase of the circuit
3.4
suppression peak
first peak of the transient voltage to earth on the load side of the switching device following
current interruption
Note 1 to entry: Suppression peak is not necessarily the absolute maximum of the transient recovery voltage.
Previous breakdowns may have appeared at higher voltage values.
3.5
recovery peak
maximum value of the voltage across the switching device occurring when the polarity of the
recovery voltage is equal to the polarity of the power-frequency voltage
Note 1 to entry: Recovery peak is not necessarily the absolute maximum of the transient recovery voltage.
Previous breakdowns may have appeared at higher voltage values.
3.6
re-ignition
resumption of current between the contacts of a mechanical switching device during a
breaking operation with an interval of zero current of less than a quarter cycle of power
frequency
Note 1 to entry: In the case of inductive load switching the initiation of the re-ignition is a high-frequency event,
which can be of a single or multiple nature and may in some cases be interrupted without power-frequency follow
current.
3.7
re-ignition-free arcing time window
period of arc duration during a breaking operation during which the contacts of a mechanical
switching device reach sufficient distance to exclude re-ignition

– 8 – IEC 62271-110:2017 © IEC 2017
4 Type tests
4.1 General
Circuit-breakers according to IEC 62271-100 and contactors according to IEC 62271-106 do
not have dedicated inductive switching ratings. However, switching devices applied for this
purpose shall meet the requirements of this document.
For shunt reactor switching test of circuit-breakers, the rated insulation level values stated in
Tables 1a, 1b, 3 and 4 of IEC 62271-1:2017 are applicable with the exception of combined
voltage tests across the isolating distance (columns (6) and (8) in Table 3 and column (7) in
Table 4).
The type tests are in addition to those specified in the relevant product standard, with the
exception of short-line faults, out-of-phase switching and capacitive current switching.
NOTE 1 The reason for this exception is the source-less nature of the shunt reactor load circuit.
NOTE 2 In some cases (high chopping overvoltage levels, or where a neutral reactor is present or in cases of
shunt reactors with isolated neutral), it can be necessary to specify an appropriate insulation level which is higher
than the rated values stated above.
Inductive current switching tests performed for a given current level and type of application
may be considered valid for another current rating and same type of application as detailed
below:
a) for shunt reactor switching at rated voltages of 52 kV and above, tests at a particular
current level are to be considered valid for applications with a higher current level up to
150 % of the tested current value;
b) for shunt reactor switching at rated voltages below 52 kV, type testing is required;
c) for high-voltage motor switching, type testing for stalled motor currents at 100 A and 300 A
is considered to cover stalled motor currents in the range 100 A to 300 A and up to the
current associated with the short-circuit current of test-duty T10 according to 6.106.1 of
IEC 62271-100:2008 for circuit-breakers and up to the rated operational current for
contactors.
With respect to a) the purpose of type testing is also to determine a re-ignition-free arcing
time window for controlled switching purposes (refer to IEC TR 62271-302) and caution
should be exercised when considering applications at higher currents than the tested values
since the re-ignition-free arcing window can increase at higher current.
Annex B of IEC 62271-100:2008 can be used with respect to tolerances on test quantities.
4.2 Miscellaneous provisions for inductive load switching tests
Subclause 6.102 of IEC 62271-100:2008+IEC 62271-100:2008/AMD1:2012 is applicable with
the following addition:
High-voltage motor current and shunt reactor switching tests shall be performed at rated
auxiliary and control voltage or, where necessary, at maximum auxiliary and control voltage to
facilitate consistent control of the opening and closing operation according to 6.102.3.1 of
IEC 62271-100:2008.
For gas filled switching devices (including vacuum switching devices using gaseous media for
insulation), tests shall be performed at the rated functional pressure for interruption and
insulation, except for test-duty 4, where the pressure shall be the minimum functional
pressure for interruption and insulation.

– 9 – IEC 62271-110:2017 © IEC 2017
4.3 High-voltage motor current switching tests
4.3.1 Applicability
Subclause 4.3 is applicable to three-phase alternating current switching devices having rated
voltages above 1 kV and up to 17,5 kV, which are used for switching high-voltage motors.
Tests may be carried out at 50 Hz with a relative tolerance of ±10 % or 60 Hz with a relative
tolerance of ±10 %, both frequencies being considered equivalent.
Motor switching tests are applicable to all three-pole switching devices having rated voltages
equal to or less than 17,5 kV, which may be used for the switching of three-phase
asynchronous squirrel-cage or slip-ring motors. The switching device may be of a higher rated
voltage than the motor when connected to the motor through a stepdown transformer.
However, the usual application is a direct cable connection between switching device and
motor. When tests are required, they shall be made in accordance with 4.3.2 to 4.3.9.
When overvoltage limitation devices are mandatory for the tested equipment, the voltage
limiting devices may be included in the test circuit provided that the devices are an intrinsic
part of the equipment under test.
No limits to the overvoltages are given as the overvoltages are only relevant to the specific
application. Overvoltages between phases may be as significant as phase-to-earth
overvoltages.
4.3.2 General
The switching tests can be either field tests or laboratory tests. As regards overvoltages, the
switching of the current of a starting or stalled motor is usually the more severe operation.
Due to the non-linear behaviour of the motor iron core, it is not possible to exactly model the
switching of motor current using linear components in a test station. Tests using linear
components to simulate the motors can be considered to be more conservative than switching
actual motors.
For laboratory tests a standardized circuit simulating the stalled condition of a motor is
specified (refer to Figure 1). The parameters of this test circuit have been chosen to represent
a relatively severe case with respect to overvoltages and will cover the majority of service
applications.
The laboratory tests are performed to prove the ability of a switching device to switch motors
and to establish its behaviour with respect to switching overvoltages, re-ignitions and current
chopping. These characteristics may serve as a basis for estimates of the switching device’s
performance in other motor circuits. Tests performed with the test currents defined in 4.3.3
and 4.3.4 demonstrate the capability of the switching device to switch high-voltage motors up
to its rated interrupting current.
For field tests, actual circuits are used with a supply system on the source side and a cable
and motor on the load side. There may be a transformer between the switching device and
motor. However, the results of such field tests are only valid for switching devices working in
circuits similar to those during the tests.
The apparatus under test includes the switching device with overvoltage protection devices if
they are normally fitted.
NOTE 1 Overvoltages can be produced when switching running motors. This condition is not represented by the
substitute circuit and is generally considered to be less severe than the stalled motor case.
NOTE 2 The starting period switching of a slip-ring motor is generally less severe due to the effect of the starting
resistor.
– 10 – IEC 62271-110:2017 © IEC 2017

Switchgear
Motor substitute
Source U under test
Bus representation Cable
r
L L R
s
L
b2
L
b1 R
p
Z
e
C
C
s p
IEC
Key
U rated voltage
r
Z earthing impedance impedance high enough to limit the phase-to-earth
e
fault current to less than the test current (can be
infinite)
L
source side inductance ωL ≤ 0,1 ωL, but prospective short-circuit current ≤
s
s
the rated short-circuit current of the tested switching
device
C supply side capacitance 0,03 µF to 0,05 µF for supply circuit A
s
1,5 µF to 2 µF for supply circuit B
L inductance of capacitors and
≤ 2 µH
b1
connections
Bus representation 5 m to 7 m in length spaced appropriate to the rated
voltage
L inductance of connections
≤ 5 µH
b2
Cable 100 m ± 10 m, screened, surge impedance 30 Ω to
50 Ω
L motor substitute inductance
load circuit 1: 100 A ± 10 A
load circuit 2: 300 A ± 30 A
R motor substitute resistance cos φ ≤ 0,2
C motor substitute parallel frequency 10 kHz to 15 kHz
p
capacitance
R motor substitute parallel resistance amplitude factor 1,6 to 1,8
p
Figure 1 – Motor switching test circuit and summary of parameters
4.3.3 Characteristics of the supply circuits
4.3.3.1 General
A three-phase supply circuit shall be used. The tests shall be performed using two different
supply circuits A and B as specified in 4.3.3.2 and 4.3.3.3, respectively. Supply circuit A
represents the case of a motor connected directly to a transformer. Supply circuit B
represents the case where parallel cables are applied on the supply side.
4.3.3.2 Supply circuit A
The three-phase supply may be earthed through a high ohmic impedance so that the supply
voltage is defined with respect to earth. The impedance value shall be high enough to limit a
prospective line-to-earth fault current to a value below the test current.

– 11 – IEC 62271-110:2017 © IEC 2017
The source inductance L shall not be lower than that corresponding to the rated short-circuit
s
breaking current of the tested switching device. Its impedance shall also be not higher than
0,1 times the impedance of the inductance in the load circuit (see 4.3.4).
The supply side capacitance C is represented by three capacitors connected in earthed star.
s
Their value, including the natural capacitance of the circuit shall be 0,04 µF ± 0,01 µF. The
inductance L of the capacitors and connections shall not exceed 2 µH.
b1
The busbar inductance is represented by three bars forming a busbar each 6 m ± 1 m in
length and spaced at a distance appropriate to the rated voltage.
4.3.3.3 Supply circuit B
As supply circuit A with the value of the supply side capacitance increased to
1,75 µF ± 0,25 µF.
4.3.4 Characteristics of the load circuit
4.3.4.1 General
A three-phase load circuit shall be used. The motor substitute circuit is connected to the
switching device under test by 100 m ± 10 m of screened cable. It is recommended that the
cable be connected directly to the terminals of the motor or substitute circuit.
The inductance of any intermediate connection should not exceed 3 µH. The shield of the
cable shall be earthed at both ends as shown in Figure 1. The tests shall be performed using
two different motor substitute circuits as specified in 4.3.4.2 and 4.3.4.3. The inductance L
b2
of the connections between the switching device and cable shall not exceed 5 µH.
NOTE The use of a three-phase test circuit is necessary in order to allow the possibility of virtual current
chopping.
4.3.4.2 Motor substitute circuit 1
Series-connected resistance and inductance shall be arranged to obtain a current of
100 A ± 10 A at a power factor less than 0,2 lagging. The star point shall not be connected to
shall be connected in parallel with each phase impedance and
earth. Resistance R
p
capacitance C between each phase and earth so that the motor substitute circuit has a
p
natural frequency of 12,5 kHz ± 2,5 kHz and an amplitude factor of 1,7 ± 0,1 measured in
each phase with the other two phases connected to earth. The prospective transient recovery
voltages values shall be determined in accordance with Annex F of IEC 62271-100:2008.
A transformer may be introduced at the load end of the cable. This shall be considered as part
of the motor substitute circuit.
4.3.4.3 Motor substitute circuit 2
As motor substitute circuit 1, but with the series resistance and inductance reduced to obtain
a current of 300 A ± 30 A at a power factor less than 0,2 lagging. The prospective transient
recovery voltage shall be as specified for motor substitute circuit 1.
4.3.5 Test voltage
a) The average value of the applied voltages shall be not less than the rated voltage U
r
divided by √3 and shall not exceed this value by more than 10 % without the consent of
the manufacturer.
The differences between the average value and the applied voltages of each pole shall not
exceed 5 %.
The rated voltage U is that of the switching device when using the substitute circuit, but is
r
that of the motor when an actual motor is used.

– 12 – IEC 62271-110:2017 © IEC 2017
b) The power-frequency recovery voltage of the test circuit may be stated as a percentage of
the power-frequency recovery voltage specified below. It shall not be less than 95 % of the
specified value and shall be maintained in accordance with 6.104.7 of
IEC 62271-100:2008+IEC 62271-100:2008/AMD1:2012.
The average value of the power-frequency recovery voltages shall not be less than the
rated voltage U of the switching device divided by √3.
r
The power-frequency recovery voltage of any pole should not deviate by more than 20 %
from the average value at the end of the time for which it is maintained.
The power-frequency recovery voltage shall be measured between terminals of a pole in
each phase of the test circuit. Its r.m.s. value shall be determined on the oscillogram
within the time interval of one half cycle and one cycle of test frequency after final arc
extinction, as indicated in Figure 44 of IEC 62271-100:2008. The vertical distance (V , V
1 2
and V respectively) between the peak of the second half-wave and the straight line drawn
between the respective peaks of the preceding and succeeding half-waves shall be
measured, and this, when divided by 2√2 and multiplied by the appropriate calibration
factor, gives the r.m.s. value of the recorded power-frequency recovery voltage.
4.3.6 Test-duties
The motor current switching tests shall consist of four test-duties as specified in Table 1.
Table 1 – Test-duties at motor current switching tests
Motor substitute
Test-duty Supply circuit
circuit
1 A 1
2 A 2
3 B 1
4 B 2
The number of tests for each test-duty shall be 20 tests with the initiation of the closing and
tripping impulses distributed at intervals of approximately 9 electrical degrees.
The above tests shall be make–break tests or separate making and breaking tests except that
when using an actual motor they shall only be make–break tests. When tests are made using
the motor substitute circuit, the contacts of the switching device shall not be separated until
any DC component has become less than 20 %. When switching an actual motor, a
make-break time of 200 ms is recommended.
4.3.7 Test measurements
At least the following quantities shall be recorded by oscillograph or other suitable recording
techniques with bandwidth and time resolution high enough to measure the following:
– power-frequency voltage;
– power-frequency current;
– phase-to-earth voltage, at the motor or motor substitute circuit terminals, in all three
phases.
4.3.8 Behaviour and condition of switching device
The criteria for successful testing of a circuit-breaker are as follows:
a) the behaviour of the circuit-breaker during the motor switching tests fulfils the conditions
given in 6.102.8 of IEC 62271-100:2008 as applicable;

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b) voltage tests shall be performed in accordance with 6.2.11 of
IEC 62271-100:2008+IEC 62271-100:2008/AMD1:2012;
c) all re-ignitions shall take place between the arcing contacts.
The criteria for successful testing of contactors are listed in 6.102.9 of IEC 62271-106:2011.
4.3.9 Test report
In addition to the requirements of Annex C of IEC 62271-100:2008, the test report shall
include a thorough description of the circuit, including the following details:
a) main dimensions and characteristics of the bus and connections to the switching device;
b) the characteristics of the cable:
1) length;
2) rated values;
3) type;
4) main insulation dielectric – cross-linked polyethylene (XLPE), paper/oil, etc.;
5) earthing;
6) capacitances;
7) surge impedance.
c) the parameters of the substitute motor circuit:
1) natural frequency;
2) amplitude factor;
3) current;
4) power factor.
d) or details of the actual motor:
1) type and rating;
2) rated voltage;
3) winding connection;
4) rated motor current;
5) starting current and power factor.
e) overvoltage characteristics.
The following characteristics of the voltages at the motor or motor substitute circuit terminals
at each test (Figure 2) shall be evaluated:
: maximum overvoltage;
– u
p
– u : suppression peak overvoltage;
ma
– u : load side voltage peak to earth;
mr
– u : maximum peak-to-peak voltage excursion at re-ignition and/or restrike.
s
When overvoltages occur which may be hazardous for a specific application, or where
switching device characteristics are required, a more comprehensive test programme will be
required which is beyond the scope of this document.

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u
u
a
Supply side voltage
u
p
u
ma
u
u
u
in
s
Load side voltage
t
u u
k w
u
Neutral point
mr
average voltage
IEC
Key
u power-frequency voltage crest value to earth
u neutral voltage shift at first-pole interruption
k
u switching device arc voltage
a
u = u + u initial voltage at the moment of current chopping
in 0 a
u suppression peak voltage to earth
ma
u
load side voltage peak to earth
mr
u voltage across the switching device at re-ignition
w
u maximum overvoltage to earth (could be equal to u or u if no re-ignitions occur)
p ma mr
u maximum peak-to-peak overvoltage excursion at re-ignition
s
Figure 2 – Illustration of voltage transients at interruption of inductive current
for first phase clearing in a three-phase non-effectively earthed circuit
4.4 Shunt reactor current switching tests
4.4.1 Applicability
These tests are applicable to three-phase alternating current switching devices (mainly
circuit-breakers) which are used for steady-state switching of shunt reactors that are directly
connected to the switching device without interposing transformer. Tests may be carried out
at 50 Hz or 60 Hz with a relative tolerance of ±10 %. Tests performed at 60 Hz shall be
considered as valid for 50 Hz. Tests at 50 Hz are valid for 60 Hz provided that the minimum
arcing time without re-ignition is shorter than 8,3 ms.

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NOTE If the re-ignition-free arcing window is shorter than 8,3 ms, there is no possibility of re-ignition at a second
current zero at 60 Hz test even if only 50 Hz tests have been carried out. Most switching devices have a
re-ignition-free arcing window shorter than 8,3 ms.
4.4.2 General
Reactor switching is an operation where small differences in circuit parameters can produce
large differences in the severity of the duty. The results from any one series of tests cannot
simply be applied to a different set of conditions.
NOTE Further guidance is given in IEC TR 62271-306.
The switching tests can be either field tests or laboratory tests. Results from field tests are
only valid for switching devices applied in circuits similar to those in the tests.
Standard circuits are specified in order to demonstrate the ability of the switching device to
interrupt reactor currents and to determine chopping characteristics (suppression peak
overvoltages) and re-ignition behaviour. The parameters of these test circuits represent
typical cases of application with relatively severe transient recovery voltage (TRV) and are
regarded as covering the majority of service applications.
If the switching device is used to switch reactor currents smaller than the standardized values,
the test current should be adjusted to give the lower limit of the actual current range. The
lower the current the more severe the switching duty is for the switching device.
Laboratory tests may be made using an actual reactor but the re-ignitions and overvoltage
magnitudes during switching will not necessarily be valid for other cases of installation.
4.4.3 Test circuits
Four in-service load circuit configurations are possible as shown in Table 2.
Table 2 – In-service load circuit configurations
In-service Switching device Reactor neutral TRV values Test circuit
configuration location earthing
1 Source side of Isolated Table 3 Figure 3 or Figure 4
reactor
2 Earthed Table 4 Figure 3 or Figure 4
3 Neutral side of Isolated Table 5 Figure 5
reactor
4 Earthed Table 6 Figure 4 or Figure 5

The in-service load circuit configurations are covered by three test circuits detailed in
Tables 3, 4, 5 and 6 and Figures 3, 4 and 5, respectively.
NOTE 1 Applying a switching device on the neutral side of the reactor is only a consideration at rated voltages of
52 kV and below and the TRV values shown in Tables 5 and 6 are limited to this range.
NOTE 2 The test circuit shown in Figure 4 is applicable for in-service configuration 4 even though the switching
device location is on the source side of the reactor.
For circuit-breakers the requirements of 6.102.1 and 6.102.2 of
IEC 62271-100:2008+IEC 62271-100:2008/AMD1:2012 shall be fulfilled.
For three-pole in one enclosure type switching devices, single pole testing is permissible
provided that the correct transient recovery voltages to earth (enclosure) are achieved.
For non-earthed reactors on solidly earthed systems, three-pole testing is impractical at
higher rated voltages. Single-pole testing is permissible on the basis that the neutral point is
earthed prior to
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