IEC 63210:2021

Shunt power capacitors of the self-healing type for AC systems having a rated voltage above 1 000 V

IEC 63210:2021 is applicable to both self-healing capacitor units and self-healing capacitor banks intended to be used, particularly, for power-factor correction of AC power systems having a rated voltage above 1 000 V and fundamental frequencies of 15 Hz to 60 Hz.
The following capacitors are excluded from this document:
- shunt power capacitors of the self-healing type for AC systems having a rated voltage up to and including 1 000 V (IEC 60831-1, -2);
- shunt power capacitors of the non-self-healing type for AC systems having a rated voltage up to and including 1 000 V (IEC 60931-1, -2 and -3);
- shunt capacitors of the non-self-healing type for AC 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 (IEC 60143-1, -2, -3 and -4);
- AC motor capacitors (IEC 60252-1 and -2);
- coupling capacitors and capacitor dividers (IEC 60358-1, -2, -3, -4);
- capacitors for power electronic circuits (IEC 61071);
- small AC capacitors to be used for fluorescent and discharge lamps (IEC 61048 and IEC 61049);
- capacitors for suppression of radio interference;
- capacitors intended to be used in various types of electrical equipment, and thus considered as components;
- capacitors intended for use with DC voltage superimposed on the AC voltage.
Requirements for accessories such as insulators, switches, instrument transformers and external fuses are given in the relevant IEC standards and are not covered by the scope of this document.
The object of this document is to:
a) formulate uniform rules regarding performances, testing and rating;
b) formulate specific safety rules;
c) provide a guide for installation and operation.

Condensateurs-shunt de puissance autorégénérateurs destinés aux réseaux à courant alternatif de tension assignée supérieure à 1 000 V

L'IEC 63210:2021 s'applique tant aux condensateurs unitaires autorégénérateurs qu'aux batteries de condensateurs autorégénérateurs destinés plus particulièrement à la correction du facteur de puissance des réseaux à courant alternatif de tension assignée supérieure à 1 000 V et de fréquences fondamentales comprises entre 15 Hz et 60 Hz.
Les condensateurs suivants sont exclus du présent document:
- condensateurs-shunt de puissance autorégénérateurs destinés aux réseaux à courant alternatif de tension assignée inférieure ou égale à 1 000 V (IEC 60831-1, IEC 60831-2);
- condensateurs-shunt de puissance non-autorégénérateurs destinés aux réseaux à courant alternatif de tension assignée inférieure ou égale à 1 000 V (IEC 60931-1, IEC 60931-2 et IEC 60931-3);
– condensateurs-shunt non-autorégénérateurs destinés aux réseaux à courant alternatif de tension assignée supérieure à 1 000 V (IEC 60871-1, IEC 60871-2, IEC 60871-3 et IEC 60871-4);
- condensateurs pour les installations de génération de chaleur par induction fonctionnant à des fréquences comprises entre 40 Hz et 24 000 Hz (IEC 60110-1 et IEC 60110-2);
- condensateurs série (IEC 60143-1, IEC 60143-2, IEC 60143-3 et IEC 60143-4);
- condensateurs des moteurs à courant alternatif (IEC 60252-1 et IEC 60252-2);
- condensateurs de couplage et diviseurs capacitifs (IEC 60358-1, IEC 60358-2, IEC 60358 3, IEC 60358-4);
- condensateurs pour circuits électroniques de puissance (IEC 61071);
- petits condensateurs à courant alternatif destinés à être utilisés dans des lampes à fluorescence et des lampes à décharge (IEC 61048 et IEC 61049);
- condensateurs pour la suppression des interférences radio;
- condensateurs destinés à être utilisés dans différents types de matériels électriques et étant donc considérés comme des composants;
- condensateurs destinés à être utilisés avec une tension continue superposée à une tension alternative.
Les exigences relatives aux accessoires tels que les isolateurs, les commutateurs, les transformateurs de mesure et les fusibles externes sont spécifiées dans les normes IEC correspondantes et ne relèvent pas du domaine d'application du présent document.
Le présent document a pour objet:
a) de formuler des règles uniformes en matière de performances, d'essais et de caractéristiques assignées;
b) de formuler des règles de sécurité spécifiques;
c) de fournir un guide d'installation et d’exploitation.

General Information

• Status: Published
• Publication Date: 10-Mar-2021
• ICS: 29.120.99 - Other electrical accessories
• ICS: 31.060.70 - Power capacitors
• Technical Committee: TC 33 - Power capacitors and their applications
• Drafting Committee: WG 23 - TC 33/WG 23
• Current Stage: PPUB - Publication issued
• Start Date: 11-Mar-2021
• Completion Date: 12-Mar-2021

Overview

IEC 63210:2021 is an international standard published by the International Electrotechnical Commission (IEC) that defines the requirements for shunt power capacitors of the self-healing type designed for alternating current (AC) systems with rated voltages above 1,000 V. These capacitors are essential components primarily used for power-factor correction in AC power systems operating at fundamental frequencies between 15 Hz and 60 Hz. This standard establishes uniform rules for the design, performance, testing, and safety of self-healing shunt power capacitors, providing detailed guidance for their installation and operation.

This standard excludes lower voltage capacitors (up to 1,000 V) covered by other standards, non-self-healing capacitor types, series capacitors, motor capacitors, and capacitors intended for other specialized applications such as power electronics or radio interference suppression.

Key Topics

• Scope and Application: Specifies that IEC 63210 applies exclusively to self-healing shunt power capacitors rated above 1,000 V for power-factor correction in AC systems from 15 Hz to 60 Hz.

• Performance and Testing Requirements: Defines testing protocols including routine, type, acceptance, and design tests. Topics covered include:

  • Capacitance and loss angle (tan δ) measurements under various conditions.
  • Voltage withstand and insulation level tests between terminals and to the container.
  • Self-healing capability and internal discharge device testing.
  • Thermal stability and overload tests.
  • Lightning impulse and overvoltage tests.
  • Short-circuit discharge and destruction testing procedures.

• Safety Requirements: Sets specific safety rules covering container connections, discharge devices, environmental protection, and safe operation limits concerning voltage and current overloads.

• Markings and Documentation: Describes mandatory identification and warning plates on capacitor units and banks, including standardized connection symbols and rating plates for clear communication and compliance.

• Installation and Operation Guidance: Offers practical advice for selecting rated voltage, managing operating temperature, coping with overvoltages and overloads, and proper use of switching and protective devices to ensure capacitor longevity and system reliability.

Applications

IEC 63210:2021 applies primarily to electrical engineers, equipment manufacturers, and power system operators dealing with medium- and high-voltage AC power systems requiring power-factor correction. Key applications include:

• Power-Factor Correction: Shunt capacitors improve energy efficiency by compensating reactive power, reducing losses in electrical distribution and generation systems.

• Voltage Regulation: By stabilizing voltage levels in grids, these capacitors support the reliable operation of industrial and utility-scale power networks.

• Grid Equipment Protection: Standards-guided testing and safety requirements help prevent catastrophic failures, ensuring safe integration into substations and industrial plants.

• High-Voltage Equipment Design: Manufacturers use IEC 63210 to design capacitors suitable for high voltage environments, ensuring compliance with international safety and performance benchmarks.

Related Standards

IEC 63210:2021 operates in conjunction with several related IEC standards excluding lower voltage or other types of capacitors, including but not limited to:

• IEC 60831 (Parts 1 & 2): Self-healing shunt power capacitors for AC systems up to 1,000 V.
• IEC 60931 (Parts 1–3): Non-self-healing shunt power capacitors for AC systems up to 1,000 V.
• IEC 60871 (Parts 1–4): Non-self-healing shunt power capacitors above 1,000 V.
• IEC 60110 (Parts 1 & 2): Capacitors for inductive heating plants.
• IEC 60252 (Parts 1 & 2): AC motor capacitors.
• IEC 61071: Capacitors for power electronic circuits.
• IEC 61048/61049: Small AC capacitors for fluorescent and discharge lamps.

Other accessory standards cover insulators, switches, fuses, and instrument transformers, specifying complementary safety and performance requirements.

---

By adhering to IEC 63210:2021, power system designers and operators ensure that high-voltage self-healing shunt power capacitors meet stringent international standards for reliability, safety, and performance-enabling enhanced power-factor correction and system stability in AC electrical networks.

Standards Content (Sample)

IEC 63210 ®
Edition 1.0 2021-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Shunt power capacitors of the self-healing type for AC systems having a rated
voltage above 1 000 V
Condensateurs-shunt de puissance autorégénérateurs destinés aux réseaux à
courant alternatif de tension assignée supérieure à 1 000 V

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IEC 63210 ®
Edition 1.0 2021-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Shunt power capacitors of the self-healing type for AC systems having a rated

voltage above 1 000 V
Condensateurs-shunt de puissance autorégénérateurs destinés aux réseaux à

courant alternatif de tension assignée supérieure à 1 000 V

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.99; 31.060.70 ISBN 978-2-8322-9464-2

– 2 – IEC 63210:2021 © IEC 2021
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Service conditions . 13
4.1 Normal service conditions . 13
4.2 Unusual service conditions . 14
5 Quality requirements and tests . 14
5.1 General . 14
5.2 Test conditions . 14
6 Classification of tests. 15
6.1 Routine tests. 15
6.2 Type tests and design tests . 15
6.3 Acceptance tests . 16
7 Capacitance measurement . 16
7.1 Measuring procedure . 16
7.2 Capacitance tolerances . 17
8 Measurement of the tangent of the loss angle (tan δ) of the capacitor . 17
8.1 Measuring procedure . 17
8.2 Loss requirements . 17
9 Voltage tests between terminals . 17
9.1 General for routine test . 17
9.2 AC test . 17
9.3 DC test . 18
9.4 Type test . 18
10 Voltage tests between terminals and container . 18
10.1 Routine test . 18
10.2 Type test . 19
11 Test of internal discharge device . 19
12 Sealing test . 19
13 Thermal stability test (type test) . 20
13.1 General . 20
13.2 Measuring procedure . 20
14 Measurement of the tangent of the loss angle (tan δ) of the capacitor at elevated
temperature (type test) . 21
14.1 Measuring procedure . 21
14.2 Requirements . 21
15 Lightning impulse test between terminals and container (type test) . 21
16 Overvoltage test (design test) . 22
16.1 General . 22
16.2 Conditioning of the sample before the test . 22
16.3 Test procedure . 23
16.4 Acceptance criteria . 23
16.5 Validity of test . 23
16.5.1 General . 23

16.5.2 Element design . 23
16.5.3 Test unit design . 23
16.5.4 Waveform of overvoltage . 24
17 Short-circuit discharge test (type test) . 24
18 Self-healing test (type test) . 25
18.1 General . 25
18.2 Test setup . 25
18.3 Acceptance criteria . 25
19 Destruction test (design test) . 25
19.1 General . 25
19.2 Test setup for capacitors without actively monitored safety device (internally

protected) . 26
19.3 Acceptance criteria . 26
19.4 Test setup for capacitors with actively monitored safety device (externally
protected) . 27
19.5 Acceptance criteria . 27
20 Insulation levels . 27
20.1 Standard insulation values . 27
20.2 General requirements . 28
20.2.1 General . 28
20.2.2 Adjacent insulating components and equipment . 28
20.2.3 Capacitors insulated from ground . 28
20.2.4 Capacitors with neutral connected to ground . 29
20.3 Test between terminals and container of capacitor units . 29
20.4 Capacitors in single-phase systems . 29
21 Overloads – Maximum permissible voltage . 32
21.1 Long duration voltages . 32
21.2 Switching overvoltages . 32
22 Overloads – Maximum permissible current. 32
23 Safety requirements for discharge devices . 33
24 Safety requirements for container connections . 33
25 Safety requirements for protection of the environment . 33
26 Other safety requirements . 33
27 Markings of the capacitor unit . 34
27.1 Rating plate . 34
27.2 Standardized connection symbols . 34
27.3 Warning plate . 35
28 Markings of the capacitor bank . 35
28.1 Instruction sheet or rating plate . 35
28.2 Warning plate . 35
29 Guide for installation and operation . 35
29.1 General . 35
29.2 Choice of the rated voltage . 36
29.3 Operating temperature . 36
29.3.1 General . 36
29.3.2 Installation . 37
29.3.3 High ambient air temperature. 37
29.4 Special service conditions . 37

– 4 – IEC 63210:2021 © IEC 2021
29.5 Overvoltages . 38
29.5.1 General . 38
29.5.2 Restriking of switches . 38
29.5.3 Lightning . 38
29.5.4 Motor self-excitation . 38
29.5.5 Star-delta starting . 38
29.5.6 Capacitor unit selection . 38
29.6 Overload currents . 39
29.6.1 Continuous overcurrents . 39
29.6.2 Transient overcurrents . 39
29.7 Switching and protective devices . 39
29.7.1 Withstand requirements . 39
29.7.2 Restrike-free circuit-breakers . 40
29.7.3 Relay settings . 40
29.8 Choice of insulation levels . 41
29.8.1 General . 41
29.8.2 Altitudes exceeding 1 000 m . 41
29.8.3 Influence of the capacitor itself . 41
29.8.4 Overhead ground wires . 43
29.9 Choice of creepage distances and air clearance . 43
29.9.1 Creepage distance . 43
29.9.2 Air clearances. 44
29.10 Capacitors connected to systems with audio-frequency remote control . 46
Annex A (normative) Requirements regarding comparable element design and test
unit design . 47
A.1 Test element design criteria . 47
A.2 Test unit design . 47
Annex B (informative) Self-healing breakdown test equipment that may be used . 49
Annex C (normative) Test requirements and application guide for external fuses and
units to be externally fused . 50
C.1 General . 50
C.2 Performance requirements . 50
C.3 Tests on fuses . 50
C.4 Guide for coordination of fuse protection . 50
C.4.1 General . 50
C.4.2 Protection sequence . 51
C.5 Choice of fuses . 52
C.5.1 General . 52
C.5.2 Non current-limiting fuses . 52
C.5.3 Current-limiting fuses. 52
C.6 Information needed by the user of the fuses . 52
Annex D (informative) Formulae for capacitors and installations . 53
D.1 Computation of the output of three-phase capacitors from three single-phase
capacitance measurements . 53
D.2 Resonant frequency . 53
D.3 Voltage increase . 53
D.4 Inrush transient current . 54
D.4.1 Switching in of single capacitor bank . 54
D.4.2 Switching on of a bank in parallel with energized bank(s) . 54

D.5 Discharge resistance in single-phase unit . 54
D.6 Discharge time to 10 % of rated voltage . 55
Bibliography . 56

Figure 1 – Time and amplitude limits for an overvoltage period . 24
Figure 2 – Bank isolated from ground . 42
Figure 3 – Bank isolated from ground (containers connected to ground) . 42
Figure 4 – Bank connected to ground . 43
Figure 5 – Air clearance versus AC withstand . 46
Figure B.1 – Example of self-healing detection equipment . 49

Table 1 – Letter symbols for upper limit of temperature range . 14
Table 2 – Ambient air temperature for the thermal stability test . 20
Table 3 – Standard insulation levels for range I (1 kV < U ≤ 245 kV) . 30
m
Table 4 – Standard insulation levels for range II (U > 245 kV) . 31
m
Table 5 – Admissible voltage levels in service . 32
Table 6 – Insulation requirements . 41
Table 7 – Specific creepage distances . 43
Table 8 – Correlation between standard lightning impulse withstand voltages and
minimum air clearances (Table A.1 from IEC 60071-2:1996) . 45

– 6 – IEC 63210:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SHUNT POWER CAPACITORS OF THE SELF-HEALING TYPE FOR
AC SYSTEMS HAVING A RATED VOLTAGE ABOVE 1 000 V

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
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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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.
IEC 63210 has been prepared by IEC technical committee 33: Power capacitors and their
applications. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
33/651/FDIS 33/653/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.

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.
– 8 – IEC 63210:2021 © IEC 2021
SHUNT POWER CAPACITORS OF THE SELF-HEALING TYPE FOR AC
SYSTEMS HAVING A RATED VOLTAGE ABOVE 1 000 V

1 Scope
This document is applicable to both self-healing capacitor units and self-healing capacitor banks
intended to be used, particularly, for power-factor correction of AC power systems having a
rated voltage above 1 000 V and fundamental frequencies of 15 Hz to 60 Hz.
The following capacitors are excluded from this document:
– shunt power capacitors of the self-healing type for AC systems having a rated voltage up to
and including 1 000 V (IEC 60831-1, -2);
– shunt power capacitors of the non-self-healing type for AC systems having a rated voltage
up to and including 1 000 V (IEC 60931-1, -2 and -3);
– shunt capacitors of the non-self-healing type for AC 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 (IEC 60143-1, -2, -3 and -4);
– AC motor capacitors (IEC 60252-1 and -2);
– coupling capacitors and capacitor dividers (IEC 60358-1, -2, -3, -4);
– capacitors for power electronic circuits (IEC 61071);
– small AC capacitors to be used for fluorescent and discharge lamps (IEC 61048 and
IEC 61049);
– capacitors for suppression of radio interference;
– capacitors intended to be used in various types of electrical equipment, and thus considered
as components;
– capacitors intended for use with DC voltage superimposed on the AC voltage.
Requirements for accessories such as insulators, switches, instrument transformers and
external fuses are given in the relevant IEC standards and are not covered by the scope of this
document.
The object of this document is to:
a) formulate uniform rules regarding performances, testing and rating;
b) formulate specific safety rules;
c) provide a guide for installation and operation.
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 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60071-1:2019, Insulation co-ordination – Part 1: Definitions, principles and rules

IEC 60071-2:1996, Insulation co-ordination – Part 2: Application guide
IEC 60549, High-voltage fuses for the external protection of shunt capacitors
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
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
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
capacitor bank
bank
number of capacitor units connected so as to act together
[SOURCE: IEC 60050-436:1990, 436-01-06]
3.4
capacitor
two-terminal device characterized essentially by its capacitance
Note 1 to entry: The term "capacitor" is used when it is not necessary to specify whether a capacitor unit or capacitor
bank is meant.
[SOURCE: IEC 60050-151:2001, 151-13-28, modified – Note 1 to entry has been added.]
3.5
self-healing capacitor
self-healing metallized dielectric capacitor
capacitor (consisting of elements which have at least one electrode made of a metallic deposit
on the dielectric) whose electrical properties, after local breakdown of the dielectric, are rapidly
and essentially restored
[SOURCE: IEC 60050-436:1990, 436-03-12, modified – addition of "(metallized dielectric)" and
"(consisting of elements whose at least one electrode is made of a metallic deposit on the
dielectric)"]
_____________
Withdrawn. IEC 60071-2:1996 has been cancelled and replaced by IEC 60071-2:2018.

– 10 – IEC 63210:2021 © IEC 2021
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 – In the definition, "intended to reduce"
has been replaced by "capable of reducing" and "to a given value" has been replaced by
"practically to zero".]
3.8 Safety device (of a capacitor unit)
3.8.1
overpressure disconnector
disconnecting device designed to switch off the capacitor unit in case of abnormal increase of
the internal pressure
[SOURCE: IEC 60050-436:1990, 436-03-17, modified – "for a capacitor" has been deleted from
the term. In the definition, "to interrupt the current path in the event" has been replaced by "to
switch off the capacitor unit in case".]
3.8.2
overpressure detector
device designed to detect abnormal increase of the internal pressure of the capacitor unit,
usually used to operate an electrical switch and indirectly interrupt the current path of the
capacitor unit
3.8.3
overtemperature disconnector
disconnecting device designed to switch off the capacitor unit in case of abnormal increase of
the internal temperature
3.8.4
segmented metallization design
pattern design of the metal layer over the dielectric shaped in a way to allow a small part of it
to be isolated in case of local short-circuit or breakdown, in order to restore the full functionality
of the unit with a negligible loss of capacitance
3.8.5
special unsegmented metallization design
design of the metal layer over the dielectric shaped in a way that safe self-healing features
guarantee the full functionality of the unit with a negligible loss
operating at a voltage up to U
N
of capacitance
3.8.6
fault detector
device with other safety mechanisms (design measures, sensors or provisions) than those
defined in 3.8.1 to 3.8.5 but utilized with the same purpose to detect an abnormal technical
state of the capacitor unit in order to avoid possible safety risks by indirect interruption of the
current path in the capacitor unit

3.9 Protection (of a capacitor unit)
3.9.1
protected capacitor unit
capacitor unit that meets the requirements for the destruction test as specified in Clause 19
Note 1 to entry: Protected capacitors alone are not sufficient to prevent all possible dangers in case of malfunction.
3.9.2
unprotected capacitor unit
capacitor unit that does not meet requirements for the destruction test as specified in Clause 19
3.10
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, modified – Note 1 to entry has been added.]
3.11
rated capacitance of a capacitor
C
N
capacitance value derived from the values of rated output, voltage and frequency of the
capacitor
[SOURCE: IEC 60050-436:1990, 436-01-12, modified – The symbol "C " has been added.]
N
3.12
rated output of a capacitor
rated power of a capacitor
Q
N
reactive power for which the capacitor has been designed
[SOURCE: IEC 60050-436:1990, 436-01-16, modified – In the term, "(power)" has been added,
and the symbol "Q " has been added.]
N
3.13
rated voltage of a capacitor
U
N
RMS 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 (for example single-phase
units intended for use in polyphase connection, or polyphase units with separate circuits), U refers to the rated
N
voltage 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, modified – The symbol "U " and Note 1 to entry
N
have been added.]
3.14
rated frequency of a capacitor
f
N
frequency for which the capacitor has been designed
[SOURCE: IEC 60050-436:1990, 436-01-14, modified – The symbol "f " has been added.]
N
– 12 – IEC 63210:2021 © IEC 2021
3.15
rated current of a capacitor
I
N
RMS value of the alternating current for which the capacitor has been designed
" has been added.]
[SOURCE: IEC 60050-436:1990, 436-01-13, modified – The symbol "I
N
3.16
total capacitor losses
active power dissipated in the capacitor
Note 1 to entry: All loss-producing components are 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.
Note 2 to entry: The capacitor losses may be recalculated as an equivalent series resistor to the unit and/or bank.
[SOURCE: IEC 60050-436:1990, 436-04-10, modified – In the term, "total" has been added.
Note 1 and Note 2 to entry have been added.]
3.17
loss factor of a capacitor
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, modified. The term "loss factor of a capacitor" has
been added.]
3.18
maximum permissible AC voltage of a capacitor
maximum RMS alternating voltage which the capacitor can sustain for a given time in specified
conditions
[SOURCE: IEC 60050-436:1990, 436-04-07]
3.19
maximum permissible AC current of a capacitor
maximum RMS alternating current which the capacitor can sustain for a given time in specified
conditions
[SOURCE: IEC 60050-436:1990, 436-04-09]
3.20
ambient air temperature
temperature of the air at the proposed location of the capacitor
3.21
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 considering its mounting orientation.

3.22
steady-state condition
thermal equilibrium attained by the capacitor at constant output and at constant ambient air
temperature
3.23
residual voltage
voltage remaining on the terminals of a capacitor at a certain time following disconnection
3.24
test voltage
U
t
voltage to be applied for designated test, which is identified either as AC or DC in the according
description of test
3.25
external fuse
fuse connected outside the capacitor unit(s) and mounted electrically in series with one unit or
one group of parallel units
4 Service conditions
4.1 Normal service conditions
This document gives requirements for capacitors intended for use under the following conditions:
a) Residual voltage at energization
Not exceeding 10 % rated voltage.
b) Altitude
Not exceeding 1 000 m.
In case of installations on altitudes above 1 000 m, correction factors for insulation
(clearance) and correction factors for power reduction (thermal stability) shall be considered.
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).

– 14 – IEC 63210:2021 © IEC 2021
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 tables
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 is 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 document does not apply
to capacitors, the service conditions of which, in general, are incompatible with the requirements
of this document.
5 Quality requirements and tests
5.1 General
Clauses 5 to 19 give the test requirements for capacitor units. Supporting insulators, switches,
...