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

IEC 60831-1:2014 is applicable to both capacitor units and capacitor banks intended to be used, particularly, for power-factor correction of a.c. power systems having a rated voltage up to and including 1 000 V and frequencies of 15 Hz to 60 Hz. This part of IEC 60831 also applies to capacitors intended for use in power filter circuits. Additional definitions, requirements, and tests for power filter capacitors are given in Annex A. The object of this part of IEC 60831 is to:
- formulate uniform rules regarding performances, testing and rating;
- formulate specific safety rules;
- provide a guide for installation and operation. This third edition cancels and replaces the second edition published in 1996 and Amendment 1:2002. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- Updating of the normative references;
- Test conditions have been clarified;
- Thermal stability test has been clarified;
- Maximum permissible voltage and current have been clarified;
- The protection of the environment has been amended with safety concerns and plastic quality requirements.
The contents of the corrigendum of May 2014 have been included in this copy.

Condensateurs shunt de puissance autoregénérateurs pour réseaux à courant alternatif de tension assignée inférieure ou égale à 1 000 V - Partie 1: Généralités - Caractéristiques fonctionnelles, essais et valeurs assignées - Règles de sécurité - Guide d'installation et d'exploitation

IEC 60831-1:2014 s'applique aux condensateurs unitaires et aux batteries de condensateurs autorégénérateurs destinés plus particulièrement à la correction du facteur de puissance des réseaux à courant alternatif de tension assignée inférieure ou égale à 1 000 V et de fréquence comprise entre 15 Hz et 60 Hz. Cette partie de la CEI 60831 s'applique également aux condensateurs destinés à être utilisés dans des circuits de filtrage. Les définitions, les exigences et les essais complémentaires pour les condensateurs de filtrage en courants forts sont indiqués dans l'Annexe A. La présente partie de la CEI 60831 a pour objet:
- de formuler des règles uniformes pour les performances, les essais et les caractéristiques assignées;
- de formuler des règles spécifiques de sécurité;
- de fournir un guide pour l'installation et l'utilisation. Cette troisième édition annule et remplace la seconde édition parue en 1996 et l'Amendement 1:2002. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- mise à jour des références normatives;
- clarification des conditions d'essai;
- clarification de l'essai de stabilité thermique;
- clarification de la tension maximale et du courant maximal autorisés;
- modification des mesures de sécurité et des exigences en matière de qualité du plastique pour la protection de l'environnement. Mots clés: condensateurs unitaires et aux batteries de condensateurs autorégénérateurs, règles uniformes pour les performances, essais et les caractéristiques assignées règles spécifiques de sécurité; guide pour l'installation et l'utilisation. Le contenu du corrigendum de mai 2014 a été pris en considération dans cet exemple.

General Information

• Status: Published
• Publication Date: 10-Feb-2014
• ICS: 11.040.50 - Radiographic equipment
• ICS: 29.120.30 - Plugs, socket-outlets, couplers
• ICS: 29.120.99 - Other electrical accessories
• ICS: 31.060.70 - Power capacitors
• Technical Committee: TC 33 - Power capacitors and their applications
• Drafting Committee: MT 21 - TC 33/MT 21
• Current Stage: PPUB - Publication issued
• Start Date: 11-Feb-2014
• Completion Date: 28-Feb-2014

Relations

• Corrected By: IEC 60831-1:2014/COR1:2014 - Corrigendum 1 - 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
• Effective Date: 05-Sep-2023
• Revises: IEC 60831-1:1996/AMD1:2002 - Amendment 1 - Shunt power capacitors of the self-healing type for a.c. systems having a rated voltage up to and including 1000 V - Part 1: General - Performance, testing and rating - Safety requirements - Guide for installation and operation
• Effective Date: 05-Sep-2023
• Revises: IEC 60831-1:1996 - Shunt power capacitors of the self-healing type for a.c. systems having a rated voltage up to and including 1000 V - Part 1: General - Performance, testing and rating - Safety requirements - Guide for installation and operation
• Effective Date: 05-Sep-2023

Overview

IEC 60831-1:2014 specifies requirements for shunt power capacitors of the self-healing type for a.c. systems with a rated voltage up to and including 1 000 V and frequencies 15 Hz to 60 Hz. Covering both single capacitor units and capacitor banks, this third edition (2014) updates performance, testing and rating rules, safety requirements, and provides a practical guide for installation and operation. It also includes Annex A with additional definitions and tests for power filter capacitors and incorporates the May 2014 corrigendum.

Key topics and technical requirements

• Scope and application: Power-factor correction and power filter circuits in a.c. systems ≤ 1 000 V.
• Performance and rating: Uniform rules for capacitance measurement, output calculation and tolerances (see Clauses 7–8).
• Testing framework: Classification into routine, type and acceptance tests (Clause 6) with specific tests such as:
  • Capacitance and loss angle (tan δ) measurements (Clauses 7–8, 14)
  • Voltage tests between terminals and between terminals and container (Clauses 9–10)
  • Sealing, thermal stability, ageing, self‑healing and destruction tests (Clauses 12–19)
  • Lightning impulse and discharge tests (Clauses 15–16)
• Overload limits: Maximum permissible voltage and current clarified (Clauses 20–21).
• Safety and environment: Specific safety rules, discharge-device requirements, container connections and amended environmental protection and plastic quality provisions (Clauses 22–25).
• Marking and documentation: Rating plates, warning plates and instruction sheets for units and banks (Clauses 26–27).
• Installation and operation guidance: Practical guidance on rated voltage selection, operating temperature, overvoltages, overload currents, switching/protection devices, EMC and special service conditions (Clauses 28–37).

Applications and practical value

IEC 60831-1:2014 is essential for:

• Manufacturers designing and certifying self-healing shunt capacitors and capacitor banks.
• Test laboratories performing type, routine and acceptance testing to international criteria.
• Power utilities and industrial electrical engineers specifying components for power-factor correction and harmonic filter applications in low-voltage networks (≤ 1 kV).
• Installers and commissioning teams using the guide to ensure safe installation, proper connection, discharge precautions and compliance with EMC and environmental requirements.

Practical benefits include improved product safety, consistent test procedures, clear rating limits for voltage/current, and installation guidance that reduces field failures and compliance risks.

Related standards

This edition updates normative references used across IEC documentation for capacitors and should be used in conjunction with other IEC electrotechnical standards referenced in the normative section. Annex A specifically addresses additional requirements for power filter capacitors. For procurement, design and conformity activities, consult the latest IEC catalog and national adoptions.

Standards Content (Sample)

IEC 60831-1 ®
Edition 3.0 2014-02
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
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
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IEC 60831-1 ®
Edition 3.0 2014-02
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
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

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
RM
ICS 29.120.99, 31.060.70 ISBN 978-2-8322-1429-9

– 2 – IEC 60831-1:2014 RLV © IEC 2014
CONTENTS
FOREWORD . 5

SECTION 1: GENERAL
1 Scope and object . 7
2 Normative references . 8
3 Terms and definitions . 8
4 Service conditions . 12
4.1 Normal service conditions . 12
4.2 Unusual service conditions . 13
SECTION 2: QUALITY REQUIREMENTS AND TESTS
5 Test requirements. 13
5.1 General . 13
5.2 Test conditions . 13
6 Classification of tests . 13
6.1 Routine tests. 13
6.2 Type tests . 14
6.3 Acceptance tests . 14
7 Capacitance measurement and output calculation . 15
7.1 Measuring procedure . 15
7.2 Capacitance tolerances . 15
8 Measurement of the tangent of the loss angle (tan δ) of the capacitor . 15
8.1 Measuring procedure . 15
8.2 Loss requirements . 16
9 Voltage tests between terminals . 16
9.1 Routine test . 16
9.2 Type test . 16
10 Voltage tests between terminals and container . 16
10.1 Routine test . 16
10.2 Type test . 17
11 Test of internal discharge device . 17
12 Sealing test . 18
13 Thermal stability test . 18
14 Measurement of the tangent of the loss angle (tan δ) of the capacitor at elevated
temperature . 19
14.1 Measuring procedure . 19
14.2 Requirements . 19
15 Lightning impulse voltage test between terminals and container . 20
16 Discharge test . 20
17 Ageing test . 21
18 Self-healing test . 21
19 Destruction test . 21

SECTION 3: OVERLOADS
20 Maximum permissible voltage . 21
20.1 Long-duration voltages . 21
20.2 Switching voltages . 21
21 Maximum permissible current . 22
SECTION 4: SAFETY REQUIREMENTS
22 Discharge device . 22
23 Container connections . 22
24 Protection of the environment . 22
25 Other safety requirements . 23
SECTION 5: MARKINGS
26 Marking of the unit . 23
26.1 Rating plate . 23
26.2 Standardized connection symbols . 24
26.3 Warning plate . 24
27 Marking of the bank . 24
27.1 Instruction sheet or rating plate . 24
27.2 Warning plate . 24
SECTION 6: GUIDE FOR INSTALLATION AND OPERATION
28 General . 24
29 Choice of the rated voltage . 25
30 Operating temperature . 26
30.1 General . 26
30.2 Installation . 26
30.3 High ambient air temperature . 26
30.4 Evaluation of losses . 26
31 Special service conditions . 26
32 Overvoltages . 27
33 Overload currents . 28
34 Switching and protective devices and connections . 28
35 Choice of creepage distance . 29
36 Capacitors connected to systems with audio-frequency remote control . 29
37 Electromagnetic compatibility (EMC) . 30
37.1 Emission . 30
37.2 Immunity . 30
37.2.1 General . 30
37.2.2 Low-frequency disturbances . 30
37.2.3 Conducted transients and high-frequency disturbances . 30
37.2.4 Electrostatic discharges . 30
37.2.5 Magnetic disturbances . 30
37.2.6 Electromagnetic disturbances . 31

– 4 – IEC 60831-1:2014 RLV © IEC 2014
Annex A (normative) Additional definitions, requirements and tests for power filter
capacitors . 32
A.1 Terms and definitions . 32
A.2 Quality requirements and tests . 32
A.2.1 Capacitance tolerance . 32
A.2.2 Voltage test between terminals (see Clause 9) . 33
A.2.3 Thermal stability test (see Clause 13) . 33
A.3 Overloads – Maximum permissible current (see Clause 21) . 33
A.4 Markings – Instruction sheet or rating plate (see 27.1) . 33
A.5 Guide for installation and operation – Choice of the rated voltage (see
Clause 29) . 33
Annex B (informative) Formulae for capacitors and installations . 34
B.1 Computation of the output of three-phase capacitors from three single-
phase capacitance measurements . 34
B.2 Resonance frequency . 34
B.3 Voltage rise . 34
B.4 Inrush transient current . 35
B.4.1 Switching in of single capacitor . 35
B.4.2 Switching of capacitors in parallel with energized capacitor(s) . 35
B.4.3 Discharge resistance in single-phase units or in one-phase or
polyphase units . 35
Bibliography . 37

Figure B.1 – k values depending on the method of connection of the resistors with the
capacitor units . 36

Table 1 – Letter symbols for upper limit of temperature range . 12
Table 2 – Ambient air temperature for the thermal stability test . 18
Table 3 – Admissible voltage levels in service . 21

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 1: General – Performance, testing and rating –
Safety requirements – Guide for installation and operation

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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This redline version of the official IEC Standard allows the user to identify the changes
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– 6 – IEC 60831-1:2014 RLV © IEC 2014
International Standard IEC 60831-1 has been prepared by IEC technical committee 33: Power
capacitors and their applications.
This third edition cancels and replaces the second edition published in 1996 and Amendment
1:2002. 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) Test conditions have been clarified;
c) Thermal stability test has been clarified;
d) Maximum permissible voltage and current have been clarified;
e) The protection of the environment has been amended with safety concerns and plastic
quality requirements.
The text of this standard is based on the following documents:
FDIS Report on voting
33/543/FDIS 33/550/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 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.
The contents of the corrigendum of May 2014 have been included in this copy.

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

Section 1: General
1 Scope and object
This part of the IEC 60831 series is applicable to both capacitor units and capacitor banks
intended to be used, particularly, for power-factor correction of a.c. power systems having a
rated voltage up to and including 1 000 V and frequencies of 15 Hz to 60 Hz.
This part of IEC 60831 also applies to capacitors intended for use in power filter circuits.
Additional definitions, requirements, and tests for power filter capacitors are given in Annex A.
The following capacitors are excluded from this part of IEC 60831:
– Shunt power capacitors of the non-self-healing type for a.c. systems having a rated
voltage up to and including 1 000 V (IEC 60931-1, -2 and -3).
– Shunt capacitors for a.c. power systems having a rated voltage above 1 000 V
(IEC 60871-1, -2, -3 and -4).
– Capacitors for inductive heat-generating plants operating at frequencies between 40 Hz
and 24 000 Hz (IEC 60110-1 and -2).
– Series capacitors (IEC60143-1, -2, -3 and -4).
– Capacitors for motor applications and the like AC motor capacitors (IEC 60252-1 and -2).
– Coupling capacitors and capacitor dividers (IEC 60358-1).
– Capacitors to be used in for power electronic circuits (IEC 61071).
– Small a.c. capacitors to be used for fluorescent and discharge lamps (IEC 61048 and
IEC 61049).
– Capacitors for suppression of radio interference (under consideration).
– Capacitors intended to be used in various types of electrical equipment, and thus
considered as components.
– Capacitors intended for use with d.c. voltage superimposed on the a.c. voltage.
Accessories such as insulators, switches, instrument transformers, fuses, etc., should be in
accordance with the relevant IEC standards and are not covered by the scope of this part of
IEC 60831.
The object of this part of IEC 60831 is to:
a) formulate uniform rules regarding performances, testing and rating;
b) formulate specific safety rules;
c) provide a guide for installation and operation.

– 8 – IEC 60831-1:2014 RLV © IEC 2014
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 60050(436):1990, International Electrotechnical Vocabulary (IEV) – Chapter 436: Power
capacitors
IEC 60060-1:19892010, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60110:1973, Recommendation for capacitors for inductive heat generating plants
operating at frequencies between 40 and 24 000 Hz
IEC 60143:1992, Series capacitors for power systems
IEC 60252:1993, A.C. motor capacitors
IEC 60269-1:19862006, Low-voltage fuses – Part 1: General requirements
IEC 60358:1990, Coupling capacitors and capacitor dividers
IEC 60695-2-12:2010, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
IEC 60831-2:19952013, 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
IEC 60871-1:1987, Shunt capacitors for a.c. power systems having a rated voltage above
*
1000 V – Part 1: General – Performance, testing and rating – Safety requirements – Guide
for installation and operation
IEC 60931-1:1996, Shunt power capacitors of the non-self-healing type for a.c. systems
having a rated voltage up to and including 1000 V – Part 1: General – Performance, testing
and rating – Safety requirements – Guide for installation and operation
IEC 60931-3:1996, Shunt power capacitors of the non-self-healing type for a.c. systems
having a rated voltage up to and including 1000 V – Part 3: Internal fuses
IEC 61000-2-2:19902002, Electromagnetic compatibility (EMC) – Part 2-2: Environment –
Compatibility levels for low-frequency conducted disturbances and signalling in public low-
voltage power supply systems
IEC 61000-4-1:19922006, Electromagnetic compatibility (EMC) – Part 4-1: Testing and
measurement techniques – Overview of immunity tests. Basic EMC publication Overview of
IEC 61000-4 series
IEC 61048:1991, Capacitors for use in tubular fluorescent and other discharge lamp circuits –
General and safety requirements
IEC 61049:1991, Capacitors for use in tubular fluorescent and other discharge lamp circuits –
Performance requirements
IEC 61071-1:1993, Power electronic capacitors – Part 1: General
________
*
According to Amendment 1 (1991).

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
capacitor element
element
device consisting essentially of two electrodes separated by a dielectric
[SOURCE: IEC 60050-436:1990, 436-01-03]
3.2
capacitor unit
unit
assembly of one or more capacitor elements in the same container with terminals brought out
[SOURCE: IEC 60050-436:1990, 436-01-04]
3.3
self-healing capacitor
capacitor of which the electrical properties, after local breakdown of the dielectric, are rapidly
and essentially restored
[SOURCE: IEC 60050-436:1990, 436-03-12]
3.4
capacitor bank
bank
number of capacitor units connected so as to act together
[SOURCE: IEC 60050-436:1990, 436-01-06]
3.5
capacitor
generic term, encompassing the notions of capacitor unit and capacitor bank
Note 1 to entry: In this part of IEC 60831, the word capacitor is used when it is not necessary to lay particular
stress upon the different meanings of the words capacitor unit or capacitor bank.
3.6
capacitor installation
one or more capacitor banks and their accessories
[SOURCE: IEC 60050-436:1990, 436-01-07]
3.7
discharge device of a capacitor
device which may be incorporated in a capacitor, capable of reducing the voltage between the
terminals practically to zero, within a given time, after the capacitor has been disconnected
from a network
[SOURCE: IEC 60050-436:1990, 436-03-15, modified ("intended to reduce … value" has been
replaced by "capable of reducing … zero")]
3.8
internal fuse of a capacitor
fuse connected inside a capacitor unit, in series with an element or a group of elements

– 10 – IEC 60831-1:2014 RLV © IEC 2014
[SOURCE: IEC 60050-436:1990, 436-03-16]
3.9
overpressure disconnector for a capacitor
disconnecting device designed to switch off the capacitor in the case of abnormal increase of
the internal pressure
[SOURCE: IEC 60050-436:1990, 436-03-17, modified ("to interrupt … in the event" has been
replaced by "to switch off … in the case")]
3.10
overtemperature disconnector for a capacitor
disconnecting device designed to switch off the capacitor in the case of abnormal increase of
the internal temperature
3.11
line terminal
terminal intended for connection to a line conductor of a network
Note 1 to entry: In polyphase capacitors, a terminal intended to be connected to the neutral conductor is not
considered to be a line terminal.
[SOURCE: IEC 60050-436:1990, 436-03-01]
3.12
rated capacitance of a capacitor
C
N
capacitance value for which the capacitor has been designed
added and "the r.m.s. value
[SOURCE: IEC 60050-436:1990, 436-01-12, modified (symbol C
N
of the alternating current" has been replaced by "capacitance value")]
3.13
rated output of a capacitor
Q
N
reactive power derived from the rated values of capacitance, frequency and voltage
[SOURCE: IEC 60050-436:1990, 436-01-16, modified (symbol Q added and "for which the
N
capacitor has been designed" has been replaced by "derived … voltage")]
3.14
rated voltage of a capacitor
U
N
r.m.s. value of the alternating voltage for which the capacitor has been designed
Note 1 to entry: In the case of capacitors consisting of one or more separate circuits (such as single-phase units
intended for use in polyphase connection, or polyphase units with separate circuits), U refers to the rated voltage
N
of each circuit.
For polyphase capacitors with internal electrical connections between the phases, and for polyphase capacitor
banks, U refers to the phase-to-phase voltage.
N
[SOURCE: IEC 60050-436:1990, 436-01-15]
3.15
rated frequency of a capacitor
f
N
frequency for which the capacitor has been designed

[SOURCE: IEC 60050-436:1990, 436-01-14]
3.16
rated current of a capacitor
I
N
r.m.s. value of the alternating current for which the capacitor has been designed
[SOURCE: IEC 60050-436:1990, 436-01-13]
3.17
capacitor losses
active power dissipated in the capacitor
Note 1 to entry: All loss-producing components should be included, for example:
– for a unit, losses from dielectric, internal fuses, internal discharge resistor, connections, etc.;
– for a bank, losses from units, external fuses, busbars, discharge and damping reactors, etc.
[SOURCE: IEC 60050-436:1990, 436-04-10]
3.18
tangent of the loss angle of a capacitor
tan δ
ratio between the equivalent series resistance and the capacitive reactance of the capacitor at
specified sinusoidal alternating voltage and frequency
[SOURCE: IEC 60050-436:1990, 436-04-11]
3.19
maximum permissible a.c. voltage of a capacitor
maximum r.m.s. alternating voltage which the capacitor can sustain for a given time in
specified conditions
[SOURCE: IEC 60050-436:1990, 436-04-07]
3.20
maximum permissible a.c. current of a capacitor
maximum r.m.s. alternating current which the capacitor can sustain for a given time in
specified conditions
[SOURCE: IEC 60050-436:1990, 436-04-09]
3.21
ambient air temperature
temperature of the air at the proposed location of the capacitor
3.22
cooling air temperature
temperature of the cooling air measured at the hottest position in the bank, under steady-state
conditions, midway between two units
Note 1 to entry: If only one unit is involved, it is the temperature measured at a point approximately 0,1 m away
from the capacitor container and at two-thirds of the height from its base.
3.23
steady-state condition
thermal equilibrium attained by the capacitor at constant output and at constant ambient air
temperature
– 12 – IEC 60831-1:2014 RLV © IEC 2014
3.24
residual voltage
voltage remaining on the terminals of a capacitor at a certain time following disconnection
4 Service conditions
4.1 Normal service conditions
This standard gives requirements for capacitors intended for use under the following
conditions:
a) Residual voltage at energization
Not to exceed 10 % rated voltage (Clause 22, Clause 32, and Annex B).
b) Altitude
Not exceeding 2 000 m.
c) Ambient air temperature categories
Capacitors are classified in temperature categories, each category being specified by a
number followed by a letter. The number represents the lowest ambient air temperature at
which the capacitor may operate.
The letters represent upper limits of temperature variation ranges, having maximum values
specified in Table 1. The temperature categories cover the temperature range of –50 °C to
+55 °C.
The lowest ambient air temperature at which the capacitor may be operated should be chosen
from the five preferred values +5 °C, –5 °C, –25 °C, –40 °C, –50 °C.
For indoor use, a lower limit of –5 °C is normally applicable.
Table 1 is based on service conditions in which the capacitor does not influence the ambient
air temperature (for example outdoor installations).
Table 1 – Letter symbols for upper limit of temperature range
Ambient temperature
°C
Symbol
Highest mean over any period of
Maximum
24 h 1 year
A 40 30 20
B 45 35 25
C 50 40 30
D 55 45 35
NOTE 1 The temperature values according to Table 1 can be found in the
meteorological temperature table covering the installation site.
NOTE 2 Higher temperature values than those indicated in Table 1 can be
considered in special applications by mutual agreement between manufacturer and
purchaser. In that case, the temperature category should be indicated by the
combination of minimum and maximum temperature values, for example, –40/60.

If the capacitor influences the air temperature, the ventilation and/or choice of capacitor shall
be such that the Table 1 limits are maintained. The cooling air temperature in such an
installation shall not exceed the temperature limits of Table 1 by more than 5 °C.

Any combination of minimum and maximum values can be chosen for the standard
temperature category of a capacitor, for example –40/A or –5/C.
Preferred temperature categories are:
–40/A, –25/A, –5/A and –5/C.
4.2 Unusual service conditions
Unless otherwise agreed between manufacturer and purchaser, this standard does not apply
to capacitors, the service conditions of which, in general, are incompatible with the require-
ments of the present standard.
Section 2: Quality requirements and tests
5 Test requirements
5.1 General
Clause 5 gives the test requirements for capacitor units and, when specified, for capacitor
elements.
Supporting insulators, switches, instrument transformers, fuses, etc, shall be in accordance
with relevant IEC standards.
5.2 Test conditions
Unless otherwise specified for a particular test or measurement, the temperature of the
capacitor dielectric at the start of the test shall be in the range of +5 °C to +35 °C.
It may be assumed that the dielectric temperature is the same as the ambient temperature,
provided that the capacitor has been left in an unenergized state at constant ambient
temperature for an adequate period. When a correction has to be applied, the reference
temperature to be used is +20 °C, unless otherwise agreed between the manufacturer and the
purchaser.
The a.c. tests and measurements shall be carried out at a frequency of 50 Hz or 60 Hz inde-
pendent of the rated frequency of the capacitor, if not otherwise specified.
Capacitors having a rated frequency below 50 Hz shall be tested and measured at 50 Hz or
60 Hz, if not otherwise specified.
6 Classification of tests
The tests are classified as:
6.1 Routine tests
The following tests are routine tests. For details, reference should be made to the relevant
clauses or subclauses:
a) capacitance measurement and output calculation (see Clause 7);
b) measurement of the tangent of the loss angle (tan δ) of the capacitor (see Clause 8);
c) voltage test between terminals (see 9.1);
d) voltage test between terminals and container (see 10.1);

– 14 – IEC 60831-1:2014 RLV © IEC 2014
e) test of the internal discharge device (see Clause 11);
f) sealing test (see Clause 12).
Routine tests shall have been carried out by the manufacturer on every capacitor before
delivery. If the purchaser so requests, he shall be supplied with a certificate detailing the
results of such tests.
In general, the indicated sequence of the tests is not mandatory.
6.2 Type tests
The following tests are type tests. For details, reference should be made to the relevant
clauses or subclauses:
a) thermal stability test (see Clause 13);
b) measurement of the tangent of the loss angle (tan δ) of the capacitor at elevated
temperature (see Clause 14);
c) voltage test between terminals (see 9.2);
d) voltage test between terminals and container (see 10.2);
e) lightning impulse voltage test between terminals and container (see Clause 15);
f) discharge test (see Clause 16);
g) ageing test (see Clause 17);
h) self-healing test (see Clause 18);
i) destruction test (see Clause 19).
Type tests are carried out in order to ascertain that, as regards design, size, materials and
construction, the capacitor complies with the specified characteristics and operation
requirements detailed in this standard.
Unless otherwise specified, every capacitor sample to which the type test is applied shall first
have withstood satisfactorily the application of all the routine tests.
The type tests shall have been carried out by the manufacturer, and the purchaser shall,
on request, be supplied with a certificate detailing the results of such tests.
The successful completion of each type test is also valid for units having the same rated
voltage and lower output, provided that they do not differ in any way that may influence the
properties to be checked by the test. It is not essential that all type tests be carried out on the
same capacitor sample.
The number of samples for the type test shall be subjected to agreement between the
manufacturer and user.
6.3 Acceptance tests
Some or all of the routine and/or type tests may be repeated by the manufacturer in
connection with any contract by agreement with the purchaser. The kind of tests, the number
of samples that may be subjected to such repeated tests, and the acceptance criteria shall be
subject to agreement between manufacturer and purchaser, and shall be stated in the
contract.
7 Capacitance measurement and output calculation
7.1 Measuring procedure
The capacitance shall be measured at the voltage and at the frequency chosen by
the manufacturer. The method used shall not include errors due to harmonics, or to acces-
sories external to the capacitor to be measured, such as reactors and blocking circuits in the
measuring circuit. The accuracy of the measuring method and the correlation with the values
measured at rated voltage and frequency shall be given.
The capacitance measurement shall be carried out after the voltage test between terminals
(see Clause 9).
Measurement at a voltage between 0,9 and 1,1 times the rated voltage, and at a frequency
between 0,8 and 1,2 times the rated frequency, shall be performed on the capacitor
previously used for the thermal stability test (see Clause 13), the ageing test (see Clause 17),
and the self-healing test (see Clause 18 before these tests), and could be performed on other
capacitors at the request of the purchaser in agreement with the manufacturer.
7.2 Capacitance tolerances
The capacitance shall not differ from the rated capacitance by more than
–5 % to +1510 % for units and banks up to 100 kvar;
0–5 % to +105 % for units and banks above 100 kvar.
The capacitance value is that measured under the conditions of 7.1.
In three-phase units, the ratio of maximum to minimum value of the capacitance measured
between any two-line terminals shall not exceed 1,08.
NOTE A formula for the calculation of the output of a three-phase capacitor from a single-phase capacitance
measurement is given in Annex B.
8 Measurement of the tangent of the loss angle (tan δ) of the capacitor
8.1 Measuring procedure
The capacitor losses (or tan δ) shall be measured at the voltage and at the frequency chosen
by the manufacturer. The method used shall not include errors due to harmonics, or to
accessories external to the capacitor to be measured, such as reactors and blocking circuits
in the measuring circuit. The accuracy of the measuring method and the correlation with the
values measured at the rated voltage and frequency shall be given.
The measurement of the capacitor losses shall be carried out after the voltage test between
terminals (see Clause 9).
Measurement at a voltage between 0,9 and 1,1 times the rated voltage, and at a frequency
between 0,8 and 1,2 times the rated frequency shall be performed on the capacitor before the
thermal stability test (see Clause 13), and may be performed on other capacitors upon
request of the purchaser in agreement with the manufacturer.
NOTE 1 When testing a large number of capacitors, statistical sampling may be used for
measuring tan δ. The statistical sampling plan should be by agreement between manufacturer
and purchaser.
– 16 – IEC 60831-1:2014 RLV © IEC 2014
NOTE 2 The tan δ value of certain types of dielectric is a function of the energization time
before the measurement. In that case, test voltage and energization time should be by
agreement between manufacturer and purchaser.
8.2 Loss requirements
The value of tan δ, measured in accordance with 8.1, shall not exceed the value declared by
the manufacturer for the temperature and voltage of the test, or the value agreed upon
between manufacturer and purchaser.
9 Voltage tests between terminals
9.1 Routine test
Each capacitor shall be subjected to an a.c. test at U = 2,15 U for a minimum time of 2 s.
t N
The a.c. test shall be carried out with a substantially sinusoidal voltage at a frequency
between 15 Hz and 100 Hz, and preferably as near as possible to the rated frequency.
During the test, no permanent puncture or flashover shall occur. Self-healing breakdowns are
permitted.
When the unit is composed of a number of elements, or a group of elements connected in
parallel, and which are tested separately, it is not necessary to repeat the test on the unit.
NOTE 1 For polyphase capacitors, the test voltages should be adjusted as appropriate.
NOTE 2 Operation of internal element fuses is permitted, provided the capacitance tolerances are still met and
that not more than two fuses have operated per unit.

9.2 Type test
Each capacitor shall be subjected to an a.c. test at U = 2,15 U for 10 s.
t N
The a.c. test shall be carried out with a substantially sinusoidal voltage.
During the test, no permanent puncture or flashover shall occur. Self-healing breakdowns are
permitted.
NOTE 1 For polyphase capacitors, the test voltages should be adjusted as appropriate.
NOTE 2 Operation of internal element fuses is permitted, provided capacitance tolerances are still met, and that
not more than two fuses have operated per unit.
10 Voltage tests between terminals and container
10.1 Routine test
Units having all terminals insulated from the container shall be subjected to an a.c. voltage
applied between the terminals (joined together) and the container. If the rated voltage of the
cap
...

IEC 60831-1 ®
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 1: General – Performance, testing and rating – Safety requirements – Guide
for installation and operation

Condensateurs shunt de puissance autoregénérateurs pour réseaux à courant
alternatif de tension assignée inférieure ou égale à 1 000 V –
Partie 1: Généralités – Caractéristiques fonctionnelles, essais et valeurs
assignées – Règles de sécurité – Guide d'installation et d'exploitation

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IEC 60831-1 ®
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 1: General – Performance, testing and rating – Safety requirements – Guide

for installation and operation

Condensateurs shunt de puissance autoregénérateurs pour réseaux à courant

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

Partie 1: Généralités – Caractéristiques fonctionnelles, essais et valeurs

assignées – Règles de sécurité – Guide d'installation et d'exploitation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
W
CODE PRIX
ICS 29.120.99; 31.060.70 ISBN 978-2-8322-1391-9

– 2 – 60831-1 © IEC:2014
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 Service conditions . 11
4.1 Normal service conditions . 11
4.2 Unusual service conditions . 12
5 Test requirements. 12
5.1 General . 12
5.2 Test conditions . 13
6 Classification of tests . 13
6.1 Routine tests. 13
6.2 Type tests . 13
6.3 Acceptance tests . 14
7 Capacitance measurement and output calculation . 14
7.1 Measuring procedure . 14
7.2 Capacitance tolerances . 14
8 Measurement of the tangent of the loss angle (tan δ) of the capacitor . 15
8.1 Measuring procedure . 15
8.2 Loss requirements . 15
9 Voltage tests between terminals . 15
9.1 Routine test . 15
9.2 Type test . 15
10 Voltage tests between terminals and container . 16
10.1 Routine test . 16
10.2 Type test . 16
11 Test of internal discharge device . 17
12 Sealing test . 17
13 Thermal stability test . 17
14 Measurement of the tangent of the loss angle (tan δ) of the capacitor at elevated
temperature . 19
14.1 Measuring procedure . 19
14.2 Requirements . 19
15 Lightning impulse voltage test between terminals and container . 19
16 Discharge test . 19
17 Ageing test . 20
18 Self-healing test . 20
19 Destruction test . 20
20 Maximum permissible voltage . 20
20.1 Long-duration voltages . 20
20.2 Switching voltages . 21
21 Maximum permissible current . 21
22 Discharge device . 21
23 Container connections . 22

60831-1 © IEC:2014 – 3 –
24 Protection of the environment . 22
25 Other safety requirements . 22
26 Marking of the unit . 22
26.1 Rating plate . 22
26.2 Standardized connection symbols . 23
26.3 Warning plate . 23
27 Marking of the bank . 23
27.1 Instruction sheet or rating plate . 23
27.2 Warning plate . 23
28 General . 24
29 Choice of the rated voltage . 24
30 Operating temperature . 25
30.1 General . 25
30.2 Installation . 25
30.3 High ambient air temperature . 25
30.4 Evaluation of losses . 25
31 Special service conditions . 26
32 Overvoltages . 26
33 Overload currents . 27
34 Switching and protective devices and connections . 27
35 Choice of creepage distance . 28
36 Capacitors connected to systems with audio-frequency remote control . 29
37 Electromagnetic compatibility (EMC) . 29
37.1 Emission . 29
37.2 Immunity . 29
37.2.1 General . 29
37.2.2 Low-frequency disturbances . 29
37.2.3 Conducted transients and high-frequency disturbances . 29
37.2.4 Electrostatic discharges . 29
37.2.5 Magnetic disturbances . 30
37.2.6 Electromagnetic disturbances . 30
Annex A (normative) Additional definitions, requirements and tests for power filter
capacitors . 31
A.1 Terms and definitions . 31
A.2 Quality requirements and tests . 31
A.2.1 Capacitance tolerance . 31
A.2.2 Voltage test between terminals (see Clause 9) . 32
A.2.3 Thermal stability test (see Clause 13) . 32
A.3 Overloads – Maximum permissible current (see Clause 21) . 32
A.4 Markings – Instruction sheet or rating plate (see 27.1) . 32
A.5 Guide for installation and operation – Choice of the rated voltage (see
Clause 29) . 32
Annex B (informative) Formulae for capacitors and installations . 33
B.1 Computation of the output of three-phase capacitors from three single-
phase capacitance measurements . 33
B.2 Resonance frequency . 33
B.3 Voltage rise . 33

– 4 – 60831-1 © IEC:2014
B.4 Inrush transient current . 34
B.4.1 Switching in of single capacitor . 34
B.4.2 Switching of capacitors in parallel with energized capacitor(s) . 34
B.4.3 Discharge resistance in single-phase units or in one-phase or
polyphase units . 34
Bibliography . 36

Figure B.1 – k values depending on the method of connection of the resistors with the
capacitor units . 35

Table 1 – Letter symbols for upper limit of temperature range . 12
Table 2 – Ambient air temperature for the thermal stability test . 18
Table 3 – Admissible voltage levels in service . 20

60831-1 © IEC:2014 – 5 –
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 1: General – Performance, testing and rating –
Safety requirements – Guide for installation and operation

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
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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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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60831-1 has been prepared by IEC technical committee 33: Power
capacitors and their applications.
This third edition cancels and replaces the second edition published in 1996 and Amendment
1:2002. 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) Test conditions have been clarified;
c) Thermal stability test has been clarified;
d) Maximum permissible voltage and current have been clarified;

– 6 – 60831-1 © IEC:2014
e) The protection of the environment has been amended with safety concerns and plastic
quality requirements.
The text of this standard is based on the following documents:
FDIS Report on voting
33/543/FDIS 33/550/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 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.
The contents of the corrigendum of May 2014 have been included in this copy.

60831-1 © IEC:2014 – 7 –
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

1 Scope
This part of the IEC 60831 series is applicable to both capacitor units and capacitor banks
intended to be used, particularly, for power-factor correction of a.c. power systems having a
rated voltage up to and including 1 000 V and frequencies of 15 Hz to 60 Hz.
This part of IEC 60831 also applies to capacitors intended for use in power filter circuits.
Additional definitions, requirements, and tests for power filter capacitors are given in Annex A.
The following capacitors are excluded from this part of IEC 60831:
– Shunt power capacitors of the non-self-healing type for a.c. systems having a rated
voltage up to and including 1 000 V (IEC 60931-, -2 and -3).
– Shunt capacitors for a.c. power systems having a rated voltage above 1 000 V
(IEC 60871-1, -2, -3 and -4).
– Capacitors for inductive heat-generating plants operating at frequencies between 40 Hz
and 24 000 Hz (IEC 60110-1 and -2)
– Series capacitors (IEC60143-1, -2, -3 and -4)
– AC motor capacitors (IEC 60252-1 and -2)
– Coupling capacitors and capacitor dividers (IEC 60358-1)
– Capacitors for power electronic circuits (IEC 61071).
– Small a.c. capacitors to be used for fluorescent and discharge lamps (IEC 61048 and
IEC 61049).
– Capacitors for suppression of radio interference (under consideration).
– Capacitors intended to be used in various types of electrical equipment, and thus
considered as components.
– Capacitors intended for use with d.c. voltage superimposed on the a.c. voltage.
Accessories such as insulators, switches, instrument transformers, fuses, etc., should be in
accordance with the relevant IEC standards and are not covered by the scope of this part of
IEC 60831.
The object of this part of IEC 60831 is to:
a) formulate uniform rules regarding performances, testing and rating;
b) formulate specific safety rules;
c) provide a guide for installation and operation.

– 8 – 60831-1 © IEC:2014
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 60060-1:2010, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60269-1:2006, Low-voltage fuses – Part 1: General requirements
IEC 60831-2:2013, 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
IEC 60695-2-12:2010, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
IEC 61000-2-2:2002, Electromagnetic compatibility (EMC) – Part 2-2: Environment –
Compatibility levels for low-frequency conducted disturbances and signalling in public low-
voltage power supply systems
IEC 61000-4-1:2006, Electromagnetic compatibility (EMC) – Part 4-1: Testing and
measurement techniques – Overview of IEC 61000-4 series
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
capacitor element
element
device consisting essentially of two electrodes separated by a dielectric
[SOURCE: IEC 60050-436:1990, 436-01-03]
3.2
capacitor unit
unit
assembly of one or more capacitor elements in the same container with terminals brought out
[SOURCE: IEC 60050-436:1990, 436-01-04]
3.3
self-healing capacitor
capacitor of which the electrical properties, after local breakdown of the dielectric, are rapidly
and essentially restored
[SOURCE: IEC 60050-436:1990, 436-03-12]
3.4
capacitor bank
bank
number of capacitor units connected so as to act together

60831-1 © IEC:2014 – 9 –
[SOURCE: IEC 60050-436:1990, 436-01-06]
3.5
capacitor
generic term, encompassing the notions of capacitor unit and capacitor bank
Note 1 to entry: In this part of IEC 60831, the word capacitor is used when it is not necessary to lay particular
stress upon the different meanings of the words capacitor unit or capacitor bank.
3.6
capacitor installation
one or more capacitor banks and their accessories
[SOURCE: IEC 60050-436:1990, 436-01-07]
3.7
discharge device of a capacitor
device which may be incorporated in a capacitor, capable of reducing the voltage between the
terminals practically to zero, within a given time, after the capacitor has been disconnected
from a network
[SOURCE: IEC 60050-436:1990, 436-03-15, modified ("intended to reduce … value" has been
replaced by "capable of reducing … zero")]
3.8
internal fuse of a capacitor
fuse connected inside a capacitor unit, in series with an element or a group of elements
[SOURCE: IEC 60050-436:1990, 436-03-16]
3.9
overpressure disconnector for a capacitor
disconnecting device designed to switch off the capacitor in the case of abnormal increase of
the internal pressure
[SOURCE: IEC 60050-436:1990, 436-03-17, modified ("to interrupt … in the event" has been
replaced by "to switch off … in the case")]
3.10
overtemperature disconnector for a capacitor
disconnecting device designed to switch off the capacitor in the case of abnormal increase of
the internal temperature
3.11
line terminal
terminal intended for connection to a line conductor of a network
Note 1 to entry: In polyphase capacitors, a terminal intended to be connected to the neutral conductor is not
considered to be a line terminal.
[SOURCE: IEC 60050-436:1990, 436-03-01]
3.12
rated capacitance of a capacitor
C
N
capacitance value for which the capacitor has been designed

– 10 – 60831-1 © IEC:2014
[SOURCE: IEC 60050-436:1990, 436-01-12, modified (symbol C added and "the r.m.s. value
N
of the alternating current" has been replaced by "capacitance value")]
3.13
rated output of a capacitor
Q
N
reactive power derived from the rated values of capacitance, frequency and voltage
[SOURCE: IEC 60050-436:1990, 436-01-16, modified (symbol Q added and "for which the
N
capacitor has been designed" has been replaced by "derived … voltage")]
3.14
rated voltage of a capacitor
U
N
r.m.s. value of the alternating voltage for which the capacitor has been designed
Note 1 to entry: In the case of capacitors consisting of one or more separate circuits (such as single-phase units
intended for use in polyphase connection, or polyphase units with separate circuits), U refers to the rated voltage
N
of each circuit.
For polyphase capacitors with internal electrical connections between the phases, and for polyphase capacitor
banks, U refers to the phase-to-phase voltage.
N
[SOURCE: IEC 60050-436:1990, 436-01-15]
3.15
rated frequency of a capacitor
f
N
frequency for which the capacitor has been designed
[SOURCE: IEC 60050-436:1990, 436-01-14]
3.16
rated current of a capacitor
I
N
r.m.s. value of the alternating current for which the capacitor has been designed
[SOURCE: IEC 60050-436:1990, 436-01-13]
3.17
capacitor losses
active power dissipated in the capacitor
Note 1 to entry: All loss-producing components should be included, for example:
– for a unit, losses from dielectric, internal fuses, internal discharge resistor, connections, etc.;
– for a bank, losses from units, external fuses, busbars, discharge and damping reactors, etc.
[SOURCE: IEC 60050-436:1990, 436-04-10]
3.18
tangent of the loss angle of a capacitor
tan δ
ratio between the equivalent series resistance and the capacitive reactance of the capacitor at
specified sinusoidal alternating voltage and frequency
[SOURCE: IEC 60050-436:1990, 436-04-11]

60831-1 © IEC:2014 – 11 –
3.19
maximum permissible a.c. voltage of a capacitor
maximum r.m.s. alternating voltage which the capacitor can sustain for a given time in
specified conditions
[SOURCE: IEC 60050-436:1990, 436-04-07]
3.20
maximum permissible a.c. current of a capacitor
maximum r.m.s. alternating current which the capacitor can sustain for a given time in
specified conditions
[SOURCE: IEC 60050-436:1990, 436-04-09]
3.21
ambient air temperature
temperature of the air at the proposed location of the capacitor
3.22
cooling air temperature
temperature of the cooling air measured at the hottest position in the bank, under steady-state
conditions, midway between two units
Note 1 to entry: If only one unit is involved, it is the temperature measured at a point approximately 0,1 m away
from the capacitor container and at two-thirds of the height from its base.
3.23
steady-state condition
thermal equilibrium attained by the capacitor at constant output and at constant ambient air
temperature
3.24
residual voltage
voltage remaining on the terminals of a capacitor at a certain time following disconnection
4 Service conditions
4.1 Normal service conditions
This standard gives requirements for capacitors intended for use under the following
conditions:
a) Residual voltage at energization
Not to exceed 10 % rated voltage (Clause 22, Clause 32, and Annex B).
b) Altitude
Not exceeding 2 000 m.
c) Ambient air temperature categories
Capacitors are classified in temperature categories, each category being specified by a
number followed by a letter. The number represents the lowest ambient air temperature at
which the capacitor may operate.
The letters represent upper limits of temperature variation ranges, having maximum values
specified in Table 1. The temperature categories cover the temperature range of –50 °C to
+55 °C.
– 12 – 60831-1 © IEC:2014
The lowest ambient air temperature at which the capacitor may be operated should be chosen
from the five preferred values +5 °C, –5 °C, –25 °C, –40 °C, –50 °C.
For indoor use, a lower limit of –5 °C is normally applicable.
Table 1 is based on service conditions in which the capacitor does not influence the ambient
air temperature (for example outdoor installations).
Table 1 – Letter symbols for upper limit of temperature range
Ambient temperature
°C
Symbol
Highest mean over any period of
Maximum
24 h 1 year
A 40 30 20
B 45 35 25
C 50 40 30
D 55 45 35
NOTE 1 The temperature values according to Table 1 can be found in the
meteorological temperature table covering the installation site.
NOTE 2 Higher temperature values than those indicated in Table 1 can be
considered in special applications by mutual agreement between manufacturer and
purchaser. In that case, the temperature category should be indicated by the
combination of minimum and maximum temperature values, for example, –40/60.

If the capacitor influences the air temperature, the ventilation and/or choice of capacitor shall
be such that the Table 1 limits are maintained. The cooling air temperature in such an
installation shall not exceed the temperature limits of Table 1 by more than 5 °C.
Any combination of minimum and maximum values can be chosen for the standard
temperature category of a capacitor, for example –40/A or –5/C.
Preferred temperature categories are:
–40/A, –25/A, –5/A and –5/C.
4.2 Unusual service conditions
Unless otherwise agreed between manufacturer and purchaser, this standard does not apply
to capacitors, the service conditions of which, in general, are incompatible with the require-
ments of the present standard.
5 Test requirements
5.1 General
Clause 5 gives the test requirements for capacitor units and, when specified, for capacitor
elements.
Supporting insulators, switches, instrument transformers, fuses, etc, shall be in accordance
with relevant IEC standards.
60831-1 © IEC:2014 – 13 –
5.2 Test conditions
Unless otherwise specified for a particular test or measurement, the temperature of the
capacitor dielectric at the start of the test shall be in the range of +5 °C to +35 °C.
It may be assumed that the dielectric temperature is the same as the ambient temperature,
provided that the capacitor has been left in an unenergized state at constant ambient
temperature for an adequate period.
The a.c. tests and measurements shall be carried out at a frequency of 50 Hz or 60 Hz inde-
pendent of the rated frequency of the capacitor, if not otherwise specified.
Capacitors having a rated frequency below 50 Hz shall be tested and measured at 50 Hz or
60 Hz, if not otherwise specified.
6 Classification of tests
6.1 Routine tests
The following tests are routine tests. For details, reference should be made to the relevant
clauses or subclauses:
a) capacitance measurement and output calculation (see Clause 7);
b) measurement of the tangent of the loss angle (tan δ) of the capacitor (see Clause 8);
c) voltage test between terminals (see 9.1);
d) voltage test between terminals and container (see 10.1);
e) test of the internal discharge device (see Clause 11);
f) sealing test (see Clause 12).
Routine tests shall have been carried out by the manufacturer on every capacitor before
delivery. If the purchaser so requests, he shall be supplied with a certificate detailing the
results of such tests.
In general, the indicated sequence of the tests is not mandatory.
6.2 Type tests
The following tests are type tests. For details, reference should be made to the relevant
clauses or subclauses:
a) thermal stability test (see Clause 13);
b) measurement of the tangent of the loss angle (tan δ) of the capacitor at elevated
temperature (see Clause 14);
c) voltage test between terminals (see 9.2);
d) voltage test between terminals and container (see 10.2);
e) lightning impulse voltage test between terminals and container (see Clause 15);
f) discharge test (see Clause 16);
g) ageing test (see Clause 17);
h) self-healing test (see Clause 18);
i) destruction test (see Clause 19).
Type tests are carried out in order to ascertain that, as regards design, size, materials and
construction, the capacitor complies with the specified characteristics and operation
requirements detailed in this standard.

– 14 – 60831-1 © IEC:2014
Unless otherwise specified, every capacitor sample to which the type test is applied shall first
have withstood satisfactorily the application of all the routine tests.
The type tests shall have been carried out by the manufacturer, and the purchaser shall,
on request, be supplied with a certificate detailing the results of such tests.
The successful completion of each type test is also valid for units having the same rated
voltage and lower output, provided that they do not differ in any way that may influence the
properties to be checked by the test. It is not essential that all type tests be carried out on the
same capacitor sample.
The number of samples for the type test shall be subjected to agreement between the
manufacturer and user.
6.3 Acceptance tests
Some or all of the routine and/or type tests may be repeated by the manufacturer in
connection with any contract by agreement with the purchaser. The kind of tests, the number
of samples that may be subjected to such repeated tests, and the acceptance criteria shall be
subject to agreement between manufacturer and purchaser, and shall be stated in the
contract.
7 Capacitance measurement and output calculation
7.1 Measuring procedure
The capacitance shall be measured at the voltage and at the frequency chosen by
the manufacturer. The method used shall not include errors due to harmonics, or to acces-
sories external to the capacitor to be measured, such as reactors and blocking circuits in the
measuring circuit. The accuracy of the measuring method and the correlation with the values
measured at rated voltage and frequency shall be given.
The capacitance measurement shall be carried out after the voltage test between terminals
(see Clause 9).
Measurement at a voltage between 0,9 and 1,1 times the rated voltage, and at a frequency
between 0,8 and 1,2 times the rated frequency, shall be performed on the capacitor
previously used for the thermal stability test (see Clause 13), the ageing test (see Clause 17),
and the self-healing test (see Clause 18), and could be performed on other capacitors at the
request of the purchaser in agreement with the manufacturer.
7.2 Capacitance tolerances
The capacitance shall not differ from the rated capacitance by more than
–5 % to +10 % for units and banks up to 100 kvar;
–5 % to +5 % for units and banks above 100 kvar.
The capacitance value is that measured under the conditions of 7.1.
In three-phase units, the ratio of maximum to minimum value of the capacitance measured
between any two-line terminals shall not exceed 1,08.
NOTE A formula for the calculation of the output of a three-phase capacitor from a single-phase capacitance
measurement is given in Annex B.

60831-1 © IEC:2014 – 15 –
8 Measurement of the tangent of the loss angle (tan δ) of the capacitor
8.1 Measuring procedure
The capacitor losses (or tan δ) shall be measured at the voltage and at the frequency chosen
by the manufacturer. The method used shall not include errors due to harmonics, or to
accessories external to the capacitor to be measured, such as reactors and blocking circuits
in the measuring circuit. The accuracy of the measuring method and the correlation with the
values measured at the rated voltage and frequency shall be given.
The measurement of the capacitor losses shall be carried out after the voltage test between
terminals (see Clause 9).
Measurement at a voltage between 0,9 and 1,1 times the rated voltage, and at a frequency
between 0,8 and 1,2 times the rated frequency shall be performed on the capacitor before the
thermal stability test (see Clause 13), and may be performed on other capacitors upon
request of the purchaser in agreement with the manufacturer.
When testing a large number of capacitors, statistical sampling may be used for measuring
tan δ. The statistical sampling plan should be by agreement between manufacturer and
purchaser.
The tan δ value of certain types of dielectric is a function of the energization time before the
measurement. In that case, test voltage and energization time should be by agreement
between manufacturer and purchaser.
8.2 Loss requirements
The value of tan δ, measured in accordance with 8.1, shall not exceed the value declared by
the manufacturer for the temperature and voltage of the test, or the value agreed upon
between manufacturer and purchaser.
9 Voltage tests between terminals
9.1 Routine test
Each capacitor shall be subjected to an a.c. test at U = 2,15 U for a minimum time of 2 s.
t N
The a.c. test shall be carried out with a substantially sinusoidal voltage at a frequency
between 15 Hz and 100 Hz, and preferably as near as possible to the rated frequency.
During the test, no permanent puncture or flashover shall occur. Self-healing breakdowns are
permitted.
When the unit is composed of a number of elements, or a group of elements connected in
parallel, and which are tested separately, it is not necessary to repeat the test on the unit.
For polyphase capacitors, the test voltages should be adjusted as appropriate.
NOTE Operation of internal element fuses is permitted, provided t
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