IEC 60831-2:2014

IEC 60831-2 ®
Edition 3.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Shunt power capacitors of the self-healing type for a.c. systems having a rated
voltage up to and including 1 000 V –
Part 2: Ageing test, self-healing test and destruction test

Condensateurs shunt de puissance autorégénérateurs pour réseaux à courant
alternatif de tension assignée inférieure ou égale à 1 000 V –
Partie 2: Essais de vieillissement, d'autorégénération et de destruction

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IEC 60831-2 ®
Edition 3.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Shunt power capacitors of the self-healing type for a.c. systems having a rated

voltage up to and including 1 000 V –

Part 2: Ageing test, self-healing test and destruction test

Condensateurs shunt de puissance autorégénérateurs pour réseaux à courant

alternatif de tension assignée inférieure ou égale à 1 000 V –

Partie 2: Essais de vieillissement, d'autorégénération et de destruction

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
L
CODE PRIX
ICS 29.120.99; 31.060.70 ISBN 978-2-8322-1390-2

– 2 – 60831-2 © IEC:2014
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
17 Ageing test . 6
17.1 Conditioning . 6
17.1.1 General . 6
17.1.2 Testing in air with forced circulation . 6
17.1.3 Testing in a liquid bath . 6
17.2 Test sequence . 7
17.3 Test requirements . 7
18 Self-healing test . 8
19 Destruction test . 8
19.1 Test sequence . 8
19.2 Test requirements . 10
Annex A (informative) Self-healing breakdown test equipment that may be used . 11

Figure 1 – Circuit to perform the destruction test . 9
Figure A.1 – Example of self-healing detection equipment . 11

60831-2 © IEC:2014 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SHUNT POWER CAPACITORS OF THE SELF-HEALING TYPE
FOR A.C. SYSTEMS HAVING A RATED VOLTAGE UP TO
AND INCLUDING 1 000 V –
Part 2: Ageing test, self-healing test and destruction test

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
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6) All users should ensure that they have the latest edition of this publication.
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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 60831-2 has been prepared by IEC technical committee 33: Power
capacitors and their applications.
This third edition cancels and replaces the second edition published in 1995. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Updating of the normative references;
b) Discharge cycles before ageing test carried out at ambient temperature;
c) Alternative Self-healing test at d.c. voltage;
d) Modified acceptance conditions after Self-healing test;
e) Modifications to Destruction test.

– 4 – 60831-2 © IEC:2014
The text of this standard is based on the following documents:
FDIS Report on voting
33/544/FDIS 33/551/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 60831 series, published under the general title Shunt power
capacitors of the self-healing type for a.c. systems having a rated voltage up to and including
1 000 V, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
60831-2 © IEC:2014 – 5 –
SHUNT POWER CAPACITORS OF THE SELF-HEALING TYPE
FOR A.C. SYSTEMS HAVING A RATED VOLTAGE UP TO
AND INCLUDING 1 000 V –
Part 2: Ageing test, self-healing test and destruction test

1 Scope
This part of IEC 60831 applies to capacitors according to IEC 60831-1 and gives the
requirements for the ageing test, self-healing test and destruction test for these capacitors.
NOTE The numbering of the clauses and subclauses in this standard corresponds to that of IEC 60831-1.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60831-1:2014, Shunt power capacitors of the self-healing type for a.c. systems having a
rated voltage up to and including 1 000 V – Part 1: General – Performance, testing and rating
– Safety requirements – Guide for installation and operation

– 6 – 60831-2 © IEC:2014
17 Ageing test
17.1 Conditioning
17.1.1 General
The temperature of the case during the first part (17.2a)) and the third part (17.2c)) of the
ageing test shall be the highest mean temperature in 24 h (see Table 1, IEC 60831-1:2014)
plus the difference between the measured temperature of the case and the cooling air
temperature recorded at the end of the thermal stability test carried out on an identical unit.
The second part (17.2b)) of the ageing test should be performed at room temperature.
The two test methods indicated below are intended to ensure that the capacitor case
temperature is maintained constant during the test.
The two methods are considered as being equivalent.
The units that are not sealed shall be tested in air, with forced circulation.
17.1.2 Testing in air with forced circulation
The capacitor unit is mounted in an enclosure in which heated air is circulated with an air
velocity such that temperature variations at any point of the enclosure do not exceed ± 2 °C.
The sensitive element of the thermostat regulating the temperature in the capacitor enclosure
shall be located on the surface of the capacitor container, three-quarters of the way up.
The capacitor shall be placed in a vertical position with the terminals upright.
When many capacitors are tested together, they shall be placed with sufficient clearance
between them in order to have sufficient temperature uniformity.
After placing the capacitor in the unheated enclosure, the thermostat shall be set at a tempe-
rature equal to that indicated in 17.1.1.
Then, without energizing the capacitor, the enclosure shall be brought to thermal stability,
which shall be deemed to have been reached when the container temperature of the capacitor
has reached the stated temperature with a tolerance of ± 2 °C.
The capacitor shall then be energized at the voltage stated in 17.2a).
17.1.3 Testing in a liquid bath
The capacitor unit is immersed in a container filled with a liquid which, by appropriate heating,
is kept at the temperature indicated in 17.1.1 during the whole test.
This temperature is maintained with a permissible change of ± 2 °C.
Care shall be taken to ensure that the temperature in the neighbourhood of the capacitor is
within these limits.
The capacitor is not energized until it has reached the temperature of the liquid bath.
The capacitor shall then be energized at the voltage stated in 17.2a).
Where the terminal insulation, or the insulation of cables permanently attached to the
capacitor, is of material that might be damaged by the heating liquid, it is permissible for the

60831-2 © IEC:2014 – 7 –
capacitors to be positioned in such a manner that these terminals or cables are just above the
surface of the liquid.
17.2 Test sequence
Before the test, the capacitance shall be measured as prescribed in 7.1 of IEC 60831-1:2014.
The test sequence is in three parts as follows:
a) The capacitor shall be energized at a voltage equal to 1,25 U for 750 h. Taking the
N
tolerances of the supply voltage into account, this test voltage shall be the average
voltage for the whole test duration.
b) The capacitor shall then be subjected to 1 000 discharge cycles consisting of:
– charging the capacitor to a d.c. voltage of 2 U ;
N
– discharging the capacitor through an inductance of:
1 000
L = ± 20 % in microhenry (µH)
C
in which C is the measured capacitance in microfarads (µF).
The cables used for the external circuit and the inductance shall have a cross-section
appropriate to the maximum permissible current (see Clause 21 of IEC 60831-1:2014).
The duration of each cycle shall be 30 s minimum.
The connection for this part of the test shall be as described in Clause 16 of IEC 60831-
1:2014.
c) Repetition of item a).
During the whole test sequence the temperature of the case shall be maintained equal to that
indicated in 17.1.1.
In the case of three-phase capacitors, the first and the third parts of the test sequence
(items a) and c)) shall be carried out with all the phases energized at 1,25 U . This can be
N
obtained either by using a three-phase source, or by using a monophase source and
modifying the internal capacitor connections.
Due to long duration of this test, voltage interruptions may occur unexpectedly. During these
interruptions, the capacitor units shall remain in the same test setup and the test time is also
interrupted. If power is interrupted to the heating enclosure, the ageing test shall resume with
the same starting conditions as described in 17.1.2 or 17.1.3.
17.3 Test requirements
During the test no permanent breakdown, open circuit or flashover shall occur.
At the end of the test the capacitor shall cool down freely to the ambient temperature and the
capacitance shall then be measured under the same conditions as before the test.
The maximum permitted variation of capacitance compared to the values measured before
the test shall be 3 % averaged over all the phases and 5 % on one phase.
The voltage test between terminals and container shall be carried out with the same pro-
cedures as prescribed in 10.1 of IEC 60831-1:2014.
The sealing test shall be repeated as prescribed in Clause 12 of IEC 60831-1:2014.

– 8 – 60831-2 © IEC:2014
18 Self-healing test
This test may be carried out on a complete unit, or on a separate element or on a group of
elements that are a part of the unit, provided the element or the elements under test are
identical to those used in the unit and their conditions are similar to those they have in the
unit. The choice is left to the manufacturer.
The capacitor or element shall be subjected for 10 s to an a.c. voltage of 2,15 U or to a d.c.
N
voltage of 3,04 U (2,15 U a.c. peak value).
N N
If fewer than five breakdowns occur during this time, the voltage shall be increased slowly
until five breakdowns have occurred since the beginning of the test or until the voltage has
reached 3,5 U in a.c or 4,95 U in d.c.
N N
If fewer than five breakdowns have occurred when the voltage has reached the above stated
voltage limit for a time of 10 s, the test shall be finished, if at least one clearing has occurred.
If no breakdown has occurred, the test may be continued until at least one breakdown is
obtained or may be interrupted and repeated on another identical unit or element, at the
choice of the manufacturer.
Before and after the test, the capacitance and tan δ shall be measured.
No change of the capacitance equal/higher than 0,5 % shall be permitted.
–4
The following formula shall be checked: tan δ ≤ 1,1 tan δ + 1 × 10 , (at 50 or 60 Hz)
Where tan δ is the value after the test and tan δ is the value before the test.

NOTE 1 Breakdown during the test may be detected by an oscilloscope or by an acoustic or a high-frequency test
method.
In particular, self-healing breakdown test equipment as shown in Annex A could be used.
NOTE 2 The test carried out on a part of a unit can facilitate the detection of self-healing breakdown.
For polyphase capacitors, the test voltages should be adjusted accordingly.
When comparing the results of capacitance and tan δ measurement obtained before and after
the test, two factors should be taken into account:
a) the reproducibility of the measurement;
b) the fact that an internal change in the dielectric may cause a small change in the
capacitance without detriment to the capacitor.
19 Destruction test
19.1 Test sequence
The test shall be carried out on a capacitor unit. If necessary the discharge resistors shall be
disconnected in order to avoid burning.
A capacitor which has passed the ageing test may be used.
For polyphase units the test shall be carried out between two terminals only. In the case of
three-phase delta connection two terminals shall be short-circuited. For star connection no
terminals shall be short-circuited.

60831-2 © IEC:2014 – 9 –
The principle of the test is to promote failures in the elements by d.c. voltage and sub-
sequently to check the behaviour of the capacitor when an a.c. voltage is applied.
The capacitor shall be mounted in a circulating air oven having a temperature equal to the
maximum ambient air temperature of the temperature category of the capacitor.
When all the parts of the capacitor have reached the temperature of the oven the following
test sequence shall be performed with the circuit given in Figure 1.
a) With the selector switches H and K in positions 1 and a respectively, the a.c. voltage
source is set to 1,3 U and the capacitor current is recorded.
N
b) The d.c. source is set to 10 U . The switch H is then set to position 2 and the variable
N
resistor is adjusted to give a d.c. short-circuit current of 300 mA.
c) Switch H is set to position 3 and switch K to position b in order to apply the d.c. test
voltage to the capacitor which is maintained until the voltmeter indicates approximately
zero for at least 3 s.
Alternatively, it is also possible to gradually increase the d.c. voltage (to maximum 10 U )
N
until a 300 mA short circuit-current is created in the capacitor, and maintained for at least
3 s.
The capacitor that becomes open circuit after the d.c. conditioning shall be replaced by
another sample and not counted.
d) Switch K is then set to position a again in order to apply the a.c. test voltage to the
capacitor for a period of 3 min when the current is again noted.
The following conditions may be obtained:
– the ammeter I and the voltmeter U both indicate zero. In this case the fuse-link shall be
checked. If it has blown it shall be replaced. Then the a.c. voltage is applied to the capa-
citor and if the fuse-link blows again the procedure is interrupted. If the fuse-link does not
blow the procedure consisting in the application to the capacitor of d.c. and a.c. voltage as
prescribed in items c) and d) continues using only the switch K;
– the current indicated by the ammeter I is lower than 66 % of the initial value and the
voltmeter U indicates 1,3 U . In this case the procedure is interrupted;
N
– the current indicated by the ammeter I is higher than 66 % of the initial value. In this case
the procedure (d.c. – a.c.) continues.
When the procedure is interrupted the capacitor is cooled to the ambient temperature and the
voltage test between terminals and container is carried out according to 10.1 of IEC 60831-
1:2014 applying an a.c. voltage of 1 500 V.
R
A I
H
U
b
K
AC
D.C.
a
V
b
IEC  0311/14
a
Figure 1 – Circuit to perform the destruction test

– 10 – 60831-2 © IEC:2014
The minimum short-circuit current of the a.c. generator shall be 2 000 A at the capacitor
terminals.
A time-lag fuse-link for protecting the setup shall be used.
The rated current I of the fuse-link shall be obtained by the formula:
F
I = KI ± 10 % in amperes (A)
F
where:
K =
Q
Q = Q in kilovars (kvar), in the case of a single-phase capacitor;
N
Q = 2/3 Q , in kilovars (kvar), in the case of a three-phase delta-connected capacitor
N
with two terminals connected together or three-phase star-connected capacitor with
two terminals connected only. (This is because the testing voltage has to be adjusted
when performing the test, see following note.);
I = I , in amperes (A), in the case of a single phase of star-connected three-phase
N
capacitor;
I = 2/√3(=1,155) I , in amperes (A), in the case of a three-phase delta-connected
N
capacitor with two term
...