EN 60931-1:1996
(Main)Shunt power capacitors of the non-self-healing type for a.c. systems having a rated voltage up to and including 1 kV - Part 1: General - Performance, testing and rating - Safety requirements - Guide for installation and operation
Shunt power capacitors of the non-self-healing type for a.c. systems having a rated voltage up to and including 1 kV - Part 1: General - Performance, testing and rating - Safety requirements - Guide for installation and operation
Applies to non-self-healing capacitor units and capacitor banks intended to be used for power-factor correction of a.c. power systems having a rated voltage up to and including 1000 V and frequencies 15 Hz to 60 Hz. Also applies to capacitors intended for use in power filter circuits.
Nichtselbstheilende Leistungs-Parallelkondensatoren für Wechselstromanlagen mit einer Nennspannung bis 1 kV - Teil 1: Allgemeines - Leistungsanforderungen, Prüfung und Bemessung - Sicherheitsanforderungen - Anleitung für Errichtung und Betrieb
Condensateurs shunt de puissance non autorégénérateurs pour réseaux à courant alternatif de tension assignée inférieure ou égale à 1 kV - Partie 1: Généralités - Caractéristiques fonctionnelles, essais et valeurs assignées - Règles de sécurité - Guide d'installation et d'exploitation
S'applique aux condensateurs unitaires et aux batteries de condensateurs non autorégénérateurs devant servir en particulier à la correction du facteur de puissance des réseaux à courant alternatif de tension assignée égale ou inférieure à 1000 V et à fréquences comprises entre 15 Hz et 60 Hz. S'applique également aux condensateurs destinés à être utilisés dans des circuits de filtrage.
Shunt power capacitors of the non-self-healing type for a.c. systems having a rated voltage up to and including 1 kV - Part 1: General - Performance, testing and rating - Safety requirements - Guide for installation and operation (IEC 60931-1:1996)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-1999
Shunt power capacitors of the non-self-healing type for a.c. systems having a
rated voltage up to and including 1 kV - 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 1 kV -- Part 1: General - Performance, testing and rating -
Safety requirements - Guide for installation and operation
Nichtselbstheilende Leistungs-Parallelkondensatoren für Wechselstromanlagen mit einer
Nennspannung bis 1 kV -- Teil 1: Allgemeines - Leistungsanforderungen, Prüfung und
Bemessung - Sicherheitsanforderungen - Anleitung für Errichtung und Betrieb
Condensateurs shunt de puissance non autorégénérateurs pour réseaux à courant
alternatif de tension assignée inférieure ou égale à 1 kV -- Partie 1: Généralités -
Caractéristiques fonctionnelles, essais et valeurs assignées - Règles de sécurité - Guide
d'installation et d'exploitation
Ta slovenski standard je istoveten z: EN 60931-1:1996
ICS:
31.060.70 0RþQRVWQLNRQGHQ]DWRUML Power capacitors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
NORME CEI
INTERNATIONALE IEC
931-1
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
1996-11
Condensateurs shunt de puissance non
autorégénérateurs 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
Shunt power capacitors of the non-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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931-1 © IEC:1996
CONTENTS
Page
FOREWORD 7
SECTION 1: GENERAL
Clause
1 Scope and object 9
2 Normative references
3 Definitions
4 Service conditions
SECTION 2: QUALITY REQUIREMENTS AND TESTS
5 Test requirements 19
6 Classification of tests 21
7 Capacitance measurement and output calculation
8 Measurement of the tangent of the loss angle (tan 8) of the capacitor
9 Voltage tests between terminals
10 Voltage tests between terminals and container
11 Test of internal discharge device
12 Sealing test 29
13 Thermal stability test 29
14 Measurement of the tangent of the loss angle (tan 8) of the capacitor at elevated
temperature
15 Lightning impulse voltage test between terminals and container
16 Discharge test
17 Ageing test
18 Self-healing test
19 Destruction test
SECTION 3: OVERLOADS
20 Maximum permissible voltage
21 Maximum permissible current
SECTION 4: SAFETY REQUIREMENTS
22 Discharge device 39
23 Container connections
24 Protection of the environment
25 Other safety requirements
931-1 ©IEC:1996 – 5 –
Clause Page
SECTION 5: MARKINGS
26 Marking of the unit 41
27 Marking of the bank 43
SECTION 6: GUIDE FOR INSTALLATION AND OPERATION
28 General 43
29 Choice of the rated voltage
30 Operating temperature
31 Special service conditions
32 Overvoltages 49
33 Overload currents 51
34 Switching and protective devices and connections 53
35 Choice of creepage distance 55
36 Capacitors connected to systems with audio-frequency remote control 55
37 Electromagnetic compatibility (EMC) 57
Annexes
A Additional definitions, requirements and tests for power filter capacitors 61
B Formulae for capacitors and installations 65
931-1 © IEC:1996 — 7 —
INTERNATIONAL ELECTROTECHNICAL COMMISSION
SHUNT POWER CAPACITORS OF THE NON-SELF-HEALING TYPE
FOR AC 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
FOREWORD
1)
The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and
electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.
Their preparation is entrusted to technical committees; any IEC National Committee interested in
the subject dealt with may participate in this preparatory work. International, governmental and
non-governmental organizations liaising with the IEC also participate in this preparation. The IEC
collaborates closely with the International Organization for Standardization (ISO) in accordance with
conditions determined by agreement between the two organizations.
2)
The formal decisions or agreements of the 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 National Committees.
3)
The documents produced have the form of recommendations for international use and are published in the
form of standards, technical reports or guides and they are accepted by the National Committees in that
sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6)
Attention is drawn to the possibility that some of the elements of this International Standard may be the
subject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 931-1 has been prepared by IEC technical committee 33:
Power capacitors.
This second edition cancels and replaces the first edition published in 1989 and its
amendment 1 (1991), and constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
33/235/FDIS
33/250/RVD
33/235A/FDIS
Full information on the voting for the approval of this standard can be found in the report
on voting indicated in the above table.
Annexe A forms an integral part of this standard.
Annex B is for information only.
931-1 © IEC:1996 - 9 -
SHUNT POWER CAPACITORS
OF THE NON-SELF-HEALING TYPE
FOR AC 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
Section 1: General
1 Scope and object
This part of IEC 931 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 1000 V and frequencies 15 Hz to 60 Hz.
This part of IEC 931 also applies to capacitors intended for use in power filter circuits.
Additional definitions, requirements, and tests for filter capacitors are given in annex A.
Additional requirements for capacitors protected by internal element fuses, as well as
requirements for the same, are given in IEC 931-3.
The following capacitors are excluded from this part of IEC 931:
-
Shunt power capacitors of the self-healing type for a.c. systems having a rated volt-
age up to and including 1000 V (IEC 831).
- Shunt capacitors for a.c. power systems having a rated voltage above 1000 V
(IEC 871).
- Capacitors for inductive heat-generating plants operating at frequencies between
40 Hz and 24 000 Hz (IEC 110).
Series capacitors (IEC 143).
- Capacitors for motor applications and the like (IEC 252).
- Coupling capacitors and capacitor dividers (IEC 358).
- Capacitors to be used in power electronic circuits (IEC 1071).
- Small a.c. capacitors to be used for fluorescent and discharge lamps (IEC 1048 and
IEC 1049).
- 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., are to be in
accordance with the relevant IEC standards.
- 11 -
931-1 ©IEC:1996
a) to formulate uniform rules regarding performances, testing and rating;
b) to formulate specific safety rules;
c) to provide a guide for installation and operation.
2 Normative references
The following normative documents contains provisions which, through reference in this
text, constitute provisions of this part of IEC 931. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties to
agreements based on this part of IEC 931 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. Members
of IEC and ISO maintain registers of currently valid International Standards.
IEC 50(436): 1990, International Electrotechnical Vocabulary (lEV) - Chapter 436: Power
capacitors
IEC 60-1: 1989, High voltage test techniques - Part 1: General definitions and test
requirements
IEC 110: 1973, Recommendation for capacitors for inductive heat generating plants
operating at frequencies between 40 and 24 000 Hz
IEC 143: 1992, Series capacitors for power systems
A.C. motor capacitors
IEC 252: 1993,
IEC 269-1: 1986, Low-voltage fuses - Part 1: General requirements
IEC 358: 1990, Coupling capacitors and capacitor dividers
IEC 831-1: 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
IEC 871-1: 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 931-2: 1995, Shunt power capacitors of the non-self-healing type for a.c. systems
having a rated voltage up to and including 1000 V - Part 2: Ageing test and destruction
test
* According to Amendment No. 1 (1991).
931-1 ©IEC:1996 - 13 -
IEC 931-3: 1996, Shunt power capacitors of the non-self-healing type for a.c. systems
having a rated voltage up to and including 1000 V - Pa
rt 3: Internal fuses
IEC 1000-2-2: 1990, Electromagnetic compatibility (EMC) - Part 2: Environment -
Section 2: Compatibility levels for low-frequency conducted disturbances and signalling in
public low-voltage power supply systems
IEC 1000-4-1: 1992, Electromagnetic compatibility (EMC) - Part 4: Testing and measure-
ment techniques - Section 1: Overview of immunity tests - Basic EMC publication
IEC 1048: 1991, Capacitors for use in tubular fluorescent and other discharge lamp
circuits - General and safety requirements
IEC 1049: 1991, Capacitors for use in tubular fluorescent and other discharge lamp
circuits - Performance requirements
IEC 1071-1: 1993, Power electronic capacitors - Part 1: General
3 Definitions
For the purpose of this part of IEC 931, the following definitions apply:
3 1 capacitor element (or element): A device consisting essentially of two electrodes
separated by a dielectric. [IEV 436-01-03]
3.2 capacitor unit (or unit): An assembly of one or more capacitor elements in the
same container with terminals brought out. [IEV 436-01-04]
3.3 non-self-healing capacitor: A capacitor in which the dielectric, after local break-
down, is not restored.
3.4 capacitor bank (or bank): A number of capacitor units connected so as to act
together. [IEV 436-01-06]
3.5 capacitor: In this part of IEC 931, the word capacitor is used when it is not neces-
sary to lay particular stress upon the different meanings of the words capacitor unit or
capacitor bank.
One or more capacitor banks and their accessories.
3.6 capacitor installation:
[IEV 436-01-07]
3.7 discharge device of a capacitor: A device which may be incorporated in a capaci-
tor, capable of reducing the voltage between the terminals practically to zero, within a
given time, after the capacitor has been disconnected from a network. [IEV 436-03-15
modified]
931-1 ©IEC:1996 –15 –
3.8 internal fuse of a capacitor: A fuse connected inside a capacitor unit, in series
with an element or a group of elements. [IEV 436-03-16]
3.9 overpressure disconnector for a capacitor:
A disconnecting device designed
to switch off the capacitor in the case of abnormal increase of the internal pressure.
[IEV 436-03-17 modified]
3.10 overtemperature disconnector for a capacitor:
A disconnecting device designed
to switch off the capacitor in the case of abnormal increase of the internal temperature.
3.11
line terminal: A terminal intended for connection to a line conductor of a network.
[IEV 436-03-01]
NOTE – In polyphase capacitors, a terminal intended to be connected to the neutral conductor is not con-
sidered to be a line terminal.
3.12
rated capacitance of a capacitor (CN): The capacitance value for which the
capacitor has been designed. [IEV 436-01-12 modified]
3.13
rated output of a capacitor (O N): The reactive power derived from the rated
values of capacitance, frequency and voltage. [IEV 436-01-16 modified]
3.14 rated voltage of a capacitor (U N): The r.m.s. value of the alternating voltage for
which the capacitor has been designed. [IEV 436-01-15]
NOTE – 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), UN refers to the rated
voltage of each circuit.
For polyphase capacitors with internal electrical connections between the phases, and for polyphase capaci-
tor banks, UN refers to the phase-to-phase voltage.
3.15 rated frequency of a capacitor (fN): The frequency for which the capacitor has
been designed. [IEV 436-01-14]
3.16 rated current of a capacitor (IN):
The r.m.s. value of the alternating current for
which the capacitor has been designed. [IEV 436-01-13]
3.17
capacitor losses: The active power dissipated in the capacitor. [IEV 436-04-10]
NOTE – 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.
3.18
tangent of the loss angle (tan 6) of a capacitor: The ratio between the equivalent
series resistance and the capacitive reactance of the capacitor at specified sinusoidal
alternating voltage and frequency. [IEV 436-04-11]
3.19 maximum permissible a.c. voltage of a capacitor: The maximum r.m.s. alter-
nating voltage which the capacitor can sustain for a given time in specified conditions.
[IEV 436-04-07]
3.20 maximum permissible a.c. current of a capacitor: The maximum r.m.s. alter-
nating current which the capacitor can sustain for a given time in specified conditions.
[IEV 436-04-09]
931-1 ©IEC:1996 - 17 -
3.21 ambient air temperature:
The temperature of the air at the proposed location of
the capacitor.
3.22 cooling air temperature:
The temperature of the cooling air measured at the
hottest position in the bank, under steady-state conditions, midway between two units. 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: The 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 in the following con-
ditions:
a)
Residual voltage at energization
Not to exceed 10 % rated voltage (clause 22, clause 32, and annex B).
b) Altitude
Not exceeding 2000 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
Maximuum
24 h 1 year
A 40 30 20
B 45 35 25
C 50 40 30
D 55 35
931-1 ©IEC:1996 - 19 -
NOTES
1 The temperature values according to table 1 can be found in the meteorological temperature table cover-
ing the installation site.
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
requirements of the present standard.
Section 2: Quality requirements and tests
5 Test requirements
5.1 General
This clause 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 tempera-
ture, 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
independent of the rated frequency of the capacitor, if not otherwise specified.
931-1 © IEC:1996 – 21 –
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
a) Capacitance measurement and output calculation (see clause 7).
Measurement of the tangent of the loss angle (tan S) of the capacitor
b)
(see clause 8).
c) Voltage test between terminals (see 9.1).
d) Voltage test between terminals and container (see 10.1).
Test of the internal discharge device (see clause 11).
e)
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
a) Thermal stability test (see clause 13).
b) Measurement of the tangent of the loss angle (tan 8) 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).
Lightning impulse voltage test between terminals and container (see clause 15).
e)
f) Discharge test (see clause 16).
g) Ageing test (see clause 17).
h) Self-healing test (see clause 18). Not applicable.
i) Destruction test (see clause 19).
j)
Disconnecting test on internal fuses (see IEC 931-3, subclause 5.3).
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 it is intended to apply the
type test 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.
Oo
- 23 -
931-1 IEC:1996
6.3 Acceptance tests
The routine and/or type tests, or some of them, 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 used
for the thermal stability test (see clause 13) and the ageing test (see clause 17) before
these tests, and may be performed on other capacitors on 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 +15 % for units and banks up to 100 kvar;
0 % to +10 % 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 calculation of the output of a three-phase capacitor from single-phase capacitance
measurement is given in annex B.
8 Measurement of the tangent of the loss angle (tan S) of the capacitor
8.1 Measuring procedure
The capacitor losses (or tan 6) 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 rated voltage and frequency shall be given.
931-1 ©IEC:1996 - 25 -
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 on
request of the purchaser in agreement with the manufacturer.
NOTES
1 When testing a large number of capacitors, statistical sampling may be used for measuring tan S. The
statistical sampling plan should be by agreement between manufacturer and purchaser.
2 The tan S value of certain types of dielectric is a function of the energization time before the measure-
ment. In that case, test voltage and energization time should be by agreement between manufacturer and
purchaser.
8.2 Loss requirements
The value of tan 5, 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
Every capacitor shall be subjected for 10 s to either the test in item a) or the test in
item b). If no prior agreement is reached, the choice is left to the manufacturer. During the
test, neither puncture nor flashover shall occur.
a) An a.c. test, the test voltage being:
Ut =2,15 UN
The a.c. test shall be carried out with a substantially sinusoidal voltage.
b)
A d.c. test, the test voltage being:
Ut =4,3 UN
NOTES
1 For polyphase capacitors, the test voltages should be adjusted as appropriate.
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
Already performed during the routine test according to 9.1. Refer also to the third para-
graph of 6.2.
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 capacitor is UN <_660 V, the voltage to be applied is 3 kV for 10 s or 3,6 kV for a
– 27 –
931-1 © IEC:1996
minimum time of 2 s. If the rated voltage of the capacitor is
UN >660 V, the voltage to be
applied is 6 kV for 10 s or 7,2 kV for a minimum time of 2 s.
During the test, neither puncture nor flashover shall occur.
The test shall be performed, even if, in service, one of the terminals is intended to be
connected to the container.
Three-phase units having separate phase capacitance can be tested with respect to the
container with all the terminals joined together. Units having one terminal permanently
connected to the container shall not be subjected to this test.
When the unit container consists of insulating material, this test shall be omitted.
If a capacitor has separate phases or sections, a test of the insulation between phases or
sections shall be made at the same voltage value as for the terminals-to-container test.
10.2 Type test
Units having all terminals insulated from the container shall be subjected to a test
according to 10.1 for a duration of 1 min with a voltage of 3 kV if the rated voltage of the
<
capacitor is UN --660 V or with a voltage of 6 kV if UN >660 V.
The test on units having one terminal permanently connected to the container shall be
limited to the bushing(s) and container (without elements).
If the capacitor container is of insulating material, the test voltage shall be applied
between the terminals and a metal foil wrapped closely round the surface of the container.
The test shall be made under dry conditions for indoor units and with artificial rain
(see IEC 60-1) for units to be used outdoors.
During the test, neither puncture nor flashover shall occur.
NOTES
1 Units intended for outdoor installation may be subjected to a d ry test only.
The manufacturer should in such a case supply a separate type test repo rt showing that the bushing with
enclosure, if used, will withstand the wet test voltage.
2 For filter capacitors, the voltage appearing at the capacitor terminals is always higher than the network
voltage.
For filter capacitors, and provided the arithmetic sum of the r.m.s values of the harmonic voltages does not
exceed 0,5 times the nominal network voltage, the test voltage between terminals and container refers to the
nominal network voltage to which the filter is connected (and not to the voltage appearing at the capacitor
terminals).
If the factor of 0,5 times is exceeded then the normal rule should apply, that is the test voltage between
terminals and container refers to the rated voltage of the capacitor.
931-1 ©IEC:1996 - 29 -
11 Test of internal discharge device
The resistance of the internal discharge device, if any, shall be checked either by a
resistance measurement or by measuring the self-discharging rate (see clause 22). The
choice of the method is left to the manufacturer.
The test shall be made after the voltage tests of clause 9.
12 Sealing test
The unit (in non-painted state) shall be exposed to a test that will effectively detect any
leak of the container and bushing(s). The test procedure is left to the manufacturer, who
shall describe the test method concerned.
If no procedure is stated by the manufacturer, the following test procedure shall apply:
Unenergized capacitor units shall be heated throughout so that all parts reach a tem-
perature not lower than 20 °C above the maximum value in table 1 corresponding to the
capacitor symbol, and shall be maintained at this temperature for 2 h. No leakage shall
occur.
It is recommended that a suitable indicator is used.
NOTE - If the capacitor contains no liquid materials at the test temperature, the test may be omitted as a
routine test.
13 Thermal stability test
The capacitor unit subjected to the test shall be placed between two other units of the
same rating, which shall be energized at the same voltage as the test capacitor. Alter-
natively, two dummy capacitors each containing resistors may be used. The dissipation in
the resistors shall be adjusted to a value so that the container temperatures of the dummy
capacitors near the top opposing faces are equal to, or greater than, those of the test ca-
pacitor. The separation between the units shall be equal to, or less than, the normal spac-
ing.
The assembly shall be placed in still air in a heated enclosure in the most unfavourable
thermal position according to the manufacturer's instructions for mounting on site. The
ambient air temperature shall be maintained at or above the appropriate temperature
shown in table 2. It shall be checked by means of a thermometer having a thermal time
constant of approximately 1 h.
The ambient air thermometer should be shielded so that it is subjected to the minimum
possible thermal radiation from the three energized samples.
Table 2 - Ambient air temperature for the thermal stability test
Ambient air temperature
Symbol
oc
A 40
B 45
C 50
D
931-1 © IEC:1996 -31 -
After all parts of the capacitor have attained the temperature of the ambient air, the
capacitor shall be subjected for a period of at least 48 h to an a.c. voltage of substantially
sinusoidal form. The magnitude of the voltage troughout the last 24 hours of the test shall
be adjusted to give a calculated output, using the measured capacitance (see 7.1), of at
least 1,44 times its rated output.
During the last six hours, the temperature of the container near the top shall be measured
at least four times. Throughout this period of 6 h, the temperature rise shall not increase
by more than 1 °C. Should a greater change be observed, the test may be continued until
the above requirement is satisfied for four consecutive measurements during a 6 h period.
At the end of the thermal stability test, the difference between the measured temperature
of the container and the ambient air temperature shall be recorded.
Before and after the test, the capacitance shall be measured (see 7.1) within the standard
temperature range for testing (see 5.2), and these two measurements shall be corrected to
the same dielectric temperature. No change of capacitance greater than 2 % shall be
apparent from these measurements.
A measurement of the tangent of the loss angle (tan 6) shall be made before and after the
thermal stability test, at a temperature of approximately 20 °C.
The value of the second measurement of the tangent of the loss angle shall be not greater
than that of the first by more than 2 x 10-4.
When interpreting the results of the measurements, two factors shall be taken into
account:
- the repeatability of the measurements;
the fact that internal change in the dielectric may cause a small change of capaci-
-
tance, without puncture of any element of the capacitor or blowing of an internal fuse
having occurred.
NOTES
1 When checking whether the capacitor losses or temperature conditions are satisfied, fluctuations of
voltage, frequency and ambient air temperature during the test should be taken into account. For this reason,
it is advisable to plot these parameters, the tangent of the loss angle, and the temperature rise as a function
of time.
2 Units intended for 60 Hz installation may be tested at 50 Hz, and units intended for 50 Hz may be tested
at 60 Hz provided that the specified output is applied. For units rated below 50 Hz, the test conditions should
be agreed between purchaser and manufacturer.
3 For polyphase units, two possibilities are allowed:
- use of a three-phase source;
modification of the internal connections in order to have only one phase with the same output.
-
931-1 ©IEC:1996 - 33 -
14 Measurement of the tangent of the loss angle (tan
8) of the capacitor
at elevated temperature
14.1 Measuring procedure
The capacitor losses (tan 8) shall be measured at the end of the thermal stability test
(see clause 13). The measuring voltage shall be that of the thermal stability test.
14.2
Requirements
The value of tan 8, measured in accordance with 14.1, 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.
15 Lightning impulse voltage test between terminals and container
Only units having all terminals insulated from the container and intended for exposed
installations shall be subjected to this test.
Unless otherwise agreed between manufacturer and purchaser, the impulse test shall be
performed with a wave of 1,2/50 gs to 5/50 µs, having a peak value of 15 kV if the rated
voltage of the capacitor is
UN <660 V, or having a peak value of 25 kV if UN >660 V. Three
impulses of positive polarity followed by three impulses of negative polarity shall be
applied between terminals joined together and the container.
After the change of polarity, it is permissible to apply some impulses of lower amplitude
before the application of the test impulses.
The absence of failure during the test shall be verified by a cathode ray oscillograph,
which is used to record the voltage and to check the wave shape.
If the capacitor container is of insulating material, the test voltage shall be applied be-
tween the terminals and a metal foil wrapped closely round the su
rface of the container.
NOTE –
Partial discharge in the insulation to the container may be indicated by the modification of the wave-
shapes between the different impulses.
16 Discharge test
The unit shall be charged by means of d.c. and then discharged through a gap situated as
close as possible to the capacitor.
It shall be subjected to five such discharges within 10 min.
The test voltage shall be equal to 2
UN.
Within 5 min after this test, the unit shall be subjected to a voltage test between terminals
(see 9.1).
931-1 ©IEC:1996 — 35 —
The capacitance shall be measured before the discharge test and after the voltage test.
The measurements shall not differ by an amount corresponding either to breakdown of an
element, or to blowing of an internal fuse, or by more than 2 %.
For polyphase units, the test shall be carried out in the following manner:
— In the case of units with three-phase delta connection, two terminals shall be short-
circuited and the test carried out between the third terminal and the short-circuited
terminals at 2 UN.
— In the case of units with three-phase star connection, the test shall be carried out
between two terminals with the third terminal left unconnected. The test voltage shall
be 4 UN/'3 to achieve the same test voltage across the elements.
If the first peak of the test current exceeds the value of 200 /N (r.m.s.), it may be kept at
this limit by means of an external coil.
17 Ageing test
The requirements for this test are given in IEC 931-2.
18 Self-healing test
Not applicable.
19 Destruction test
The requirements for this test are given in IEC 931-2.
Section 3: Overloads
20 Maximum permissible voltage
20.1 Long-duration voltages
Capacitor units shall be suitable for operation at voltage levels according to table 3
(see also clauses 29 and 32).
931-1 © IEC:1996 - 37 -
Table 3 - Admissible voltage levels in service
Voltage
Maximum
Observation
Type factor x UN
duration
r. m.s.
Power frequency 1,00 Continuous Highest average value during any period of
capacitor energization. For energization
periods less than 24 h exceptions apply as
indicated below (see clause 29)
System voltage regulation and fluctuations
1,10 8 h in every 24 h
Power frequency
System voltage regulation and fluctuations
Power frequency 1,15 30 min in every 24 h
1,20 5 min Voltage rise at light load (see clause 29)
Power frequency
1 min
Power frequency 1,30
Such that the current does not exceed the value given in clause 21
Power frequency
(see also clauses 33 and 34)
plus harmonics
The amplitude of the overvoltages that may be tolerated without significant deterioration of
the capacitor depends on their duration, the number of applications, and the capacitor
temperature (see clause 29). It is assumed that the overvoltages given in table 3 and
UN occur 200 times in the life of the capacitor.
having a value higher than 1,15
20.2 Switching voltages
The switching of a capacitor bank by a restrike-free circuit breaker usually causes a
transient overvoltage, the first peak of which does not exceed 2 times the applied
voltage (r.m.s. value) for a maximum duration of 1/2 cycle.
About 5000 switching operations per year are acceptable under these conditions, taking
into account the fact that some of them may take place when the internal temperature of
the capacitors is less than 0 °C but within the temperature category. (The associated peak
N (see clause 33)).
transient overcurrent may reach 100 times the value /
In the case of capacitors that are switched more frequently, the values of the overvoltage
amplitude and duration, and the transient overcurrent shall be limited to lower levels
(see clause 34).
These limitations and/or reductions shall be agreed between manufacturer and purchaser.
21 Maximum permissible current
Capacitor units shall be suitable for continuous operation at an r.m.s. line current
of 1,3 times the current that occurs at rated sinusoidal voltage and rated frequency,
CN, the
excluding transients. Taking into account the capacitance tolerances of 1,15
maximum current can reach 1,5 /N.
These overcurrent factors are intended to take into account the combined effects of
harmonics, overvoltages and capacitance tolerance according to 20.1.
931-1 © IEC:1996 – 39 –
Section 4: Safety requirements
22 Discharge device
Each capacitor unit and/or bank shall be provided with a means for discharging each unit
in 3 min to 75 V or less, from an initial peak voltage of times rated voltage UN.
There shall be no switch, fuse cut-out, or any other isolating device between the capacitor
unit and this discharge device.
A discharge device is not a substitute for short-circuiting the capacitor terminals together
and to earth before handling.
NOTES
1 Capacitors connected directly and permanently to other electrical equipment providing a discharge path
should be considered properly discharged, provided that the circuit characteristics are such as to ensure the
discharge of the capacitor within the time specified above.
2 Attention is drawn to the fact that in some countries smaller discharge times and voltages are required.
In this event, the purchaser should inform the manufacturer.
3 Discharge circuits should have adequate current-carrying capacity to discharge the capacitor from the
peak of the 1,3 UN overvoltage according to clause 20.
4 A formula for the calculation of the discharge resistance is given in annex B.
5 Since the residual voltage at energization should not exceed 10 % of the rated voltage (see 4.1),
discharge resistors with lower resistance or additional switched discharge devices may be needed, if the
capacitors are automatically controlled.
23 Container connections
To enable the potential of the metal container of the capacitor to be fixed, and to be able
to carry the fault current in the event of a breakdown to the container, the metallic
container shall be provided with connection capable of carrying the fault current.
24 Protection of the environment
When capacitors are impregnated with products that shall not be dispersed into the
environment, the necessary precautions shall be taken. In some countries, there exist
legal requirements in this respect (see 26.3). The units and the bank shall be labelled
accordingly, if so required.
25 Other safety requirements
The purchaser shall specify at the time of enqui
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