EN 60143-1:2004

SLOVENSKI SIST EN 60143-1:2004

STANDARD
september 2004
Zaporedni kondenzatorji za elektroenergetske sisteme – 1. del: Splošno
Series capacitors for power systems - Part 1: General
ICS 31.060.70 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 60143-1
NORME EUROPÉENNE
EUROPÄISCHE NORM March 2004
ICS 31.060.70 Supersedes EN 60143-1:1993

English version
Series capacitors for power systems
Part 1: General
(IEC 60143-1:2004)
Condensateurs série destinés  Reihenkondensatoren
à être installés sur des réseaux für Starkstromanlagen
Partie 1: Généralités Teil 1: Allgemeines
(CEI 60143-1:2004) (IEC 60143-1:2004)

This European Standard was approved by CENELEC on 2004-03-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60143-1:2004 E
Foreword
The text of document 33/400/FDIS, future edition 4 of IEC 60143-1, prepared by IEC TC 33, Power
capacitors, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60143-1 on 2004-03-01.
This European Standard supersedes EN 60143-1:1993 + corrigendum October 1994.
The main changes with respect to the previous edition regard in particular the old section 3 "Insulation
level" that has been deeply modified and the new subclause 6.3 "Air clearances" has been added. In
addition, many technical changes have been introduced throughout the text regarding tests and
operation.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2004-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2007-03-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60143-1:2004 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60273 NOTE Harmonized as HD 578 S1:1992 (not modified).
IEC 60060-2 NOTE Harmonized as EN 60060-2:1994 (not modified).
IEC 60721-2-6 NOTE Harmonized as HD 478.2.6 S1:1993 (not modified)
IEC 60110-1 NOTE Harmonized as EN 60110-1:1998 (not modified).
IEC 60252-1 NOTE Harmonized as EN 60252-1:2001 (not modified).
IEC 61048 NOTE Harmonized as EN 61048:1993 (modified).
IEC 61049 NOTE Harmonized as EN 61049:1993 (modified).
IEC 61071 NOTE Harmonized in EN 61071 series (partly modified).

- 3 - EN 60143-1:2004
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application 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.
NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60060-1 1989 High-voltage test techniques HD 588.1 S1 1991
+ corr. March 1990 Part 1: General definitions and test
requirements
IEC 60071-1 1993 Insulation co-ordination EN 60071-1 1995
Part 1: Definitions, principles and rules

IEC 60071-2 1996 Part 2: Application guide EN 60071-2 1997

IEC 60143-2 1994 Series capacitors for power systems EN 60143-2 1994
Part 2: Protective equipment for series
capacitor banks
IEC 60143-3 1998 Part 3: Internal fuses EN 60143-3 1998

IEC 60549 1976 High-voltage fuses for the external - -
protection of shunt power capacitors

IEC 60815 1986 Guide for the selection of insulators in - -
respect of polluted conditions

IEC 60871-2 1999 Shunt capacitors for a.c. power systems - -
having a rated voltage above 1kV
Part 2: Endurance testing
IEEE Std 693 1997 IEEE Recommended Practice for Seismic - -
Design of Substations
NORME CEI
INTERNATIONALE IEC
60143-1
INTERNATIONAL
Quatrième édition
STANDARD
Fourth edition
2004-01
Condensateurs série destinés
à être installés sur des réseaux –
Partie 1:
Généralités
Series capacitors for power systems –
Part 1:
General
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CODE PRIX
XA
Commission Electrotechnique Internationale PRICE CODE
International Electrotechnical Commission
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Pour prix, voir catalogue en vigueur
For price, see current catalogue

60143-1 © IEC:2004 – 3 –
CONTENTS
FOREWORD.4
1 Scope and object .11
2 Normative references.13
3 Terms and definitions .13
4 Service conditions.25
4.1 Normal service conditions.25
4.2 Ambient air temperature categories .25
4.3 Abnormal service conditions .27
4.4 Abnormal power system conditions .27
5 Quality requirements and tests.27
5.1 Test requirements for capacitor units .27
5.2 Classification of tests.33
5.3 Capacitance measurement (routine test).35
5.4 Capacitor loss measurement (routine test) .37
5.5 Voltage test between terminals (routine test).37
5.6 AC voltage test between terminals and container (routine test).39
5.7 Test on internal discharge device (routine test) .39
5.8 Sealing test (routine test).39
5.9 Thermal stability test (type test) .39
5.10 AC voltage test between terminals and container (type test) .43
5.11 Lightning impulse voltage test between terminals and container (type test).43
5.12 Cold duty test (type test) .45
5.13 Discharge current test (type test) .47
5.14 Endurance test ( special test).49
6 Insulation level.49
6.1 Insulation voltages.49
6.2 Creepage distance.61
6.3 Air clearances.63
7 Overloads, overvoltages and duty cycles .73
7.1 Currents.73
7.2 Transient overvoltages.73
7.3 Duty cycles.73
8 Safety requirements.73
8.1 Discharge device.73
8.2 Container connection.75
8.3 Protection of the environment .75
8.4 Other safety requirements.75
9 Markings and instruction books .75
9.1 Markings of the unit .75
9.2 Markings of the bank .77
9.3 Instruction book.79

60143-1 © IEC:2004 – 5 –
10 Guide for selection of ratings, installation and operation .79
10.1 General .79
10.2 Reactance per line, rated reactance per bank and number of modules per bank .81
10.3 Current ratings for the bank .85
10.4 Overvoltage protection requirements.89
10.5 Voltage limitations during power system faults .89
10.6 Protective and switching devices.93
10.7 Choice of insulation level .93
10.8 Other application considerations .93
Annex A (normative) Test requirements and application guide for external fuses and
units to be externally fused. 101
Annex B (informative) Economic evaluation of series capacitor bank losses. 107
Annex C (informative) Capacitor bank fusing and unit arrangement . 109
Annex D (informative) Examples of typical connection diagrams for large series
capacitor installations for transmission lines . 115
Annex E (informative) Precautions to be taken to avoid pollution of the environment by
polychlorinated biphenyls . 117
Bibliography . 119
Figure 1 – Typical nomenclature of a series capacitor installation .19
Figure 2 – Classification of overvoltage protection .31
Figure 3 – Time and amplitude limits for an overvoltage period .47
Figure 4 – Air clearance versus a.c. withstand .71
Figure 5 – Typical current-time profile of an inserted capacitor bank following the fault
and clearing of parallel line typical bank overload and swing current capabilities .85
Figure C.1 – Typical connections between capacitor units in a segment or phase. 113
Figure C.2 – Typical connections between elements within a capacitor unit. 113
Table 1 – Letter symbols for upper limit of temperature range.25
Table 2 – Ambient air temperature in thermal stability test .41
Table 3 – Standard insulation levels for range I (1 kV < U ≤ 245 kV) .57
m
Table 4 – Standard insulation levels for range II (U > 245 kV) .59
m
Table 5 – Typical insulation levels for platform-to-ground insulators.61
Table 6 – Specific creepage distances.63
Table 7 – Correlation between standard lightning impulse withstand voltages and
minimum air clearances .67
Table 8 – Correlation between standard switching impulse withstand voltages and
minimum phase-to-earth air clearances .69
Table 9 – Correlation between standard switching impulse withstand voltages and
minimum phase-to-phase air clearances.69
Table 10 – Typical bank overload and swing current capabilities .87

60143-1 © IEC:2004 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SERIES CAPACITORS FOR POWER SYSTEMS –
Part 1: General
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). 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. 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 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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 60143-1 has been prepared by IEC technical committee 33: Power
capacitors.
This fourth edition cancels and replaces the third edition, published in 1992, and constitutes a
technical revision.
The main changes with respect to the previous edition regard in particular the old section 3:
“Insulation level” that has been deeply modified and the new subclause 6.3 “Air clearances”
has been added. In addition, many technical changes have been introduced throughout the
text regarding tests and operation.

60143-1 © IEC:2004 – 9 –
The text of this standard is based on the following documents:
FDIS Report on voting
33/400/FDIS 33/401/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.
The committee has decided that the contents of this publication will remain unchanged until
2011. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
60143-1 © IEC:2004 – 11 –
SERIES CAPACITORS FOR POWER SYSTEMS –
Part 1: General
1 Scope and object
This part of IEC 60143 applies both to capacitor units and capacitor banks intended to be used
connected in series with an a.c. transmission or distribution line or circuit forming part of an
a.c. power system having a frequency of 15 Hz to 60 Hz.
The primary focus of this standard is on transmission application.
The series capacitor units and banks are usually intended for high-voltage power systems. This
standard is applicable to the complete voltage range.
This standard does not apply to capacitors of the self-healing metallized dielectric type.
The following capacitors, even if connected in series with a circuit, are excluded from this
standard:
– capacitors for inductive heat-generating plants (IEC 60110-1);
– capacitors for motor applications and the like (IEC 60252-1);
– capacitors to be used in power electronics circuits (IEC 61071);
– capacitors for discharge lamps (IEC 61048 and IEC 61049).
Standard types of accessories such as insulators, switches, instrument transformers, external
fuses, etc. should comply with the pertinent IEC standard.
NOTE 1 Additional requirements for capacitors to be protected by internal fuses, as well as the requirements for
internal fuses, are found in IEC 60143-3.
NOTE 2 Additional requirements for capacitors to be protected by external fuses, as well as the requirements for
external fuses, are found in Annex A.
NOTE 3 A separate standard for series capacitor accessories (spark-gaps, non-linear resistors, discharge
reactors, current-limiting damping reactors, damping resistors, circuit-breakers, etc.), IEC 60143-2, was completed
in 1994. A separate standard for internal fuses for series capacitors, IEC 60143-3 (formerly IEC 60595), has been
revised and was completed in 1998.
The object of this standard is:
– to formulate uniform rules regarding performance, testing and rating;
– to formulate specific safety rules;
– to serve as a guide for installation and operation.

60143-1 © IEC:2004 – 13 –
2 Normative references
The following referenced documents are indispensable for the application 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.
NOTE If there is a conflict between this standard and a standard listed below, the test of IEC 60143-1 prevails.
IEC 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60071-1:1993, Insulation co-ordination – Part 1: Definitions, principles and rules
IEC 60071-2:1996, Insulation co-ordination – Part 2: Application guide
IEC 60143-2:1994, Series capacitors for power systems – Part 2: Protective equipment for
series capacitor banks
IEC 60143-3:1998, Series capacitors for power systems – Part 3: Internal fuses
IEC 60549:1976, High-voltage fuses for the external protection of shunt power capacitors
IEC 60815:1986, Guide for the selection of insulators in respect of polluted conditions
IEC 60871-2:1999, Shunt capacitors for a.c. power systems having a rated voltage above
1 000 V – Part 2: Endurance testing
IEEE Std. 693:1997, IEEE Recommended Practice for Seismic Design of Substations
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE Certain terms come from IEC 60050(436) or IEC 60050(604) and where this is the case, the concept from
that publication is referenced in square brackets after the definition.
3.1
ambient air temperature (for capacitors)
temperature of air at the proposed location of the capacitor installation
3.2
bypass switch
device such as a switch or circuit-breaker used in parallel with a series capacitor and its
overvoltage protector to shunt line current for some specified time or continuously
NOTE This device should also have the capability of inserting and bypassing the capacitor into a circuit carrying a
specified level of current.
3.3
capacitor
word used when it is not necessary to distinguish between the different meanings of the words
capacitor unit and the assembly of capacitors associated with a segment

60143-1 © IEC:2004 – 15 –
3.4
capacitor unit
unit
assembly of one or more capacitor elements in the same container with terminals brought out
[IEC 60050, 436-01-04]
3.5
(capacitor) element
device consisting essentially of two electrodes separated by a dielectric
[IEC 60050, 436-01-03]
3.6
capacitor losses
active power dissipated in the capacitor
[IEC 60050, 436-04-10]
NOTE All loss-producing components should be included. For a unit, this includes losses from the dielectric,
discharge device, internal fuses (if applicable) and internal connections. For the bank, this includes losses from the
units, external fuses (if applicable) and busbars. See Annex B for additional discussion.
3.7
cooling air temperature
temperature of cooling air measured at the hottest position in the capacitor assembly of a
segment, under rated current and 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
3.8
degree of compensation
k
degree of series compensation, k (of a line section) is
k = 100 (X / X ) %
c L
where
X is the capacitive reactance of the series capacitor;
c
X is the total positive sequence inductive reactance of the transmission line section on which
L
the series capacitor is applied.
3.9
discharge device (of a capacitor)
device connected across the terminals of the capacitor or built into the capacitor unit, capable
of reducing the residual voltage across the capacitor effectively to zero after the capacitor has
been disconnected from the supply
[IEC 60050, 436-03-15, modified]
NOTE Further requirements on the size of the discharge device are found in 8.1
3.10
external fuse (of a capacitor)
fuse connected in series with a capacitor unit or with a group of parallel units

60143-1 © IEC:2004 – 17 –
3.11
fuseless capacitor bank
capacitor bank without any fuses, internal or external, constructed of parallel strings of
capacitor units. Each string consists of capacitor units connected in series
NOTE See Annex C for an explanation of “string”.
3.12
highest voltage of a three-phase system
highest r.m.s. phase-to-phase voltage which occurs under normal operating conditions at any
time and at any point of the system
NOTE It excludes voltage transients (such as those due to system switching) and temporary voltage variations due
to abnormal system conditions (such as due to faults or sudden disconnection of large loads).
3.13
highest voltage for equipment
U
m
highest r.m.s. value of phase-to-phase voltage for which the equipment is designed in respect
of its insulation as well as other characteristics which relate to this voltage in the relevant
equipment standards
[IEC 60050, 604-03-01]
NOTE This voltage is the maximum value of the highest voltage of the system for which the equipment may be
used.
3.14
insulation level
U
i
non-simultaneous combination of test voltages (power-frequency (U ) or switching impulse,
ipf
and lightning impulse) which characterizes the insulation of the capacitor with regard to its
capability of withstanding the electric stresses between terminals and earth, between phases
and between terminals and metalwork (e.g. platform) not at earth potential
3.15
internal fuse of a capacitor
fuse connected inside a capacitor unit, in series with an element or group of elements
[IEC 60050, 436-03-16]
3.16
limiting voltage
U
lim
maximum peak of the power frequency voltage occurring between capacitor unit terminals
immediately before or during operation of the overvoltage protector, divided by 2 (see 5.1.4)
3.17
line terminal
terminal to be connected to the power system
[IEC 60050, 436-03-01, modified]

60143-1 © IEC:2004 – 19 –
3.18
module (of a series capacitor)
switchable step of a series capacitor consisting of identical segments in each phase (see
Figure 1), which furthermore are also equipped with provisions for a common operation of the
bypass switch of each of these segments
NOTE The bypass switch of a module is normally operated on a three-phase basis. However, in some applications
for protection purposes, the bypass switch may be required to temporarily operate on an individual phase basis.
SC installation
SC
Module 1 Module N
bank
Phase A
11 2-7 11
Segment A1 Segment AN
Phase B
11 11
Segment B1 Segment BN
9 9
Phase C
11 11
Segment C1 Segment CN
IEC  2904/03
Key
1 assembly of capacitor units
2-7 main protective equipment (Figure 2/M2 and Annex D)
9 isolating disconnector
10 bypass disconnector
11 earth switch
Figure 1 – Typical nomenclature of a series capacitor installation
3.19
overvoltage protector (of a series capacitor)
quick-acting device which limits the voltage across the capacitor to a permissible value when
that value would otherwise be exceeded as a result of a circuit fault or other abnormal power
system conditions
[IEC 60050, 436-03-14, modified]
3.20
power frequency withstand voltage
U
ipf
wet power frequency withstand voltage of bushings and insulators

60143-1 © IEC:2004 – 21 –
3.21
protective level
U
pl
magnitude of the maximum peak of the power frequency voltage appearing across the
overvoltage protector during a power system fault
NOTE The protective level may be expressed in terms of the actual peak voltage across a segment or in terms of
the per unit of the peak of the rated voltage across the capacitor (see 5.1.4, 10.4 and 10.5)
3.22
rated capacitance (of a capacitor)
C
N
capacitance value for which the capacitor has been designed
[IEC 60050, 436-01-12, modified]
3.23
rated current of a capacitor
I
N
r.m.s. value of the alternating current for which the capacitor has been designed
[IEC 60050, 436-01-13]
3.24
rated frequency (of a capacitor)
f
N
frequency of the system in which the capacitor is intended to be used
[IEC 60050, 436-01-14, modified]
3.25
rated output (of a capacitor)
Q
N
reactive power derived from rated reactance and rated current
[IEC 60050, 436-01-16, modified]
NOTE For the bank, the rated three-phase reactive power rating in Mvar (Q ) is defined by the equation:
N
Q = 3 × I × X
N N N
where
I is the rated current, in kA;
N
X is the rated reactance, in Ω.
N
3.26
rated reactance (of capacitor)
X
N
reactance of each phase of the series capacitor at rated frequency and 20 °C dielectric
temperature
3.27
rated voltage (of the bank)
power system phase-to-phase voltage for which the phase-to-ground insulation system is
designed
3.28
rated voltage (of a capacitor)
U
N
r.m.s. value of the voltage between the terminals, derived from rated reactance and rated
current U = X × I
N N N
[IEC 60050, 436-01-15, modified]

60143-1 © IEC:2004 – 23 –
3.29
residual voltage (of a capacitor)
voltage remaining between terminals of a capacitor at a given time following disconnection of
the supply
3.30
segment (of a series capacitor)
where each phase of a bank is divided into one or more series connected parts, of which each
part contains its own assembly of capacitor units, overvoltage protector, protective functions
and bypass switch, each such complete part is called segment (see Figure 1)
NOTE Segments are not normally separated by isolating disconnectors. More than one segment can be on the
same insulated platform.
3.31
series capacitor bank (or bank)
three-phase assembly of capacitors with the associated protection and insulated support
structure
NOTE The bank may include one or more modules (see Figure 1).
3.32
series capacitor installation
series capacitor bank and its accessories including the bypass and isolating disconnectors
[IEC 60050, 436-01-07, modified]
3.33
steady-state condition
thermal equilibrium attained by the capacitor at constant output and at constant ambient air
temperature
3.34
sub-segment
where a segment is divided into more than one series connected part, and each part includes
an assembly of capacitors with an overvoltage protector and selected protective functions,
each part is called a sub-segment
NOTE A sub-segment does not have its own bypass switch.
3.35
tangent of loss angle (of a capacitor)
tan δδδδ
ratio between the equivalent series resistance and the capacitive reactance of a capacitor at
specified sinusoidal alternating voltage and frequency
NOTE Tangent of loss angle can also be expressed as the capacitor losses divided by the reactive power of the
capacitor.
3.36
varistor coordinating current
magnitude of varistor current associated with the protective level
NOTE The varistor coordinating current waveform is considered to have a virtual front time of 30–50 µs. The tail of
the waveform is not significant in establishing the protective level voltage.

60143-1 © IEC:2004 – 25 –
4 Service conditions
4.1 Normal service conditions
Series capacitor banks shall be suitable for operation at their specified current, voltage, and
frequency ratings and specified fault sequences under the following conditions:
a) The elevation does not exceed 1 000 m above sea level.
b) The indoor and outdoor ambient temperatures are within the limits specified by the
purchaser.
c) The ice load does not exceed 19 mm (if applicable).
d) Wind velocities are no greater than 128 km/h.
e) The horizontal seismic acceleration (if applicable) of the equipment does not exceed 0,2 g
and the vertical acceleration does not exceed 0,16 g when applied simultaneously at the
base of the support insulators. For the purposes of this requirement, the values of
acceleration are static.
NOTE This is the “low seismic qualification level” defined in IEEE Std 693. The seismic acceleration and the
maximum wind do not have to be considered to occur simultaneously.
f) The snow depth (if applicable) does not exceed the height of the foundations for the
platform support insulators. (A typical maximum height is 1 m.)
g) The solar radiation does not exceed 1 000 W/ m .
4.2 Ambient air temperature categories
Capacitors are classified in temperature categories, each category being specified by one
number followed by one letter. The number represents the lowest ambient air temperature at
which the capacitor may operate. The letter represents the upper limit of temperature variation
range, having the maximum value specified in Table 1.
Table 1 – Letter symbols for upper limit of temperature range
Ambient air 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
The temperature categories cover a total temperature range from –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 and –50 °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.

60143-1 © IEC:2004 – 27 –
Table 1 is based on service conditions in which the capacitor does not influence the ambient
air temperature (e.g. outdoor installations). If the capacitor influences the air temperature, the
ventilation and/or choice of capacitor shall be such that the limits of Table 1 are maintained.
The cooling air temperatures in such installations shall not exceed the temperature limits of
Table 1 by more than 5 °C.
NOTE The temperature values according to Table 1 can be found in the meteorological temperature tables
covering the installation site.
4.3 Abnormal service conditions
The application of series capacitor banks at other than the normal service conditions shall be
considered as special and shall be identified in the purchaser’s specification. Examples of such
conditions are as follows:
a) Service conditions other than those listed in 4.1.
b) Exposure to excessively abrasive and conducting dust.
c) Exposure to salt, damaging fumes, or vapors.
d) Swarming insects.
e) Flocking birds.
f) Conditions requiring over-insulation or extra leakage distance on insulators.
g) Seismic accelerations at the “moderate or high seismic qualification levels” as defined in
IEEE Std 693.
4.4 Abnormal power system conditions
Abnormal power system conditions include:
a) Continuous harmonic currents in the power system.
b) The transmission line on which the series capacitor bank is located does not have phase
transpositions so the reactances of each phase of the line are not approximately equal.
5 Quality requirements and tests
5.1 Test requirements for capacitor units
5.1.1 General
This clause gives the test requirements for capacitor units.
NOTE Test requirements for other equipment is found in IEC 60143-2, IEC 60143-3 and Annex A of this standard.
Supporting insulators, switches, instrument transformers, external fuses, etc., shall be in
accordance with the pertinent IEC standard.

60143-1 © IEC:2004 – 29 –
5.1.2 Test conditions
Unless otherwise specified for a particular test or measurement, the temperature of the
capacitor dielectric shall be in the range +5 °C to +35 °C. When a correction has to be applied,
the reference temperature to be used is +20 °C, unless otherwise agreed between the manu-
facturer and the purchaser. It may be assumed that the dielectric temperature of the capacitor
unit is the same as the ambient air temperature, provided that the capacitor has been left in an
non-energized state in a constant ambient air temperature for an adequate period.
The a.c. tests and measurements shall be carried out at a frequency of 50 Hz or 60 Hz irrespective
of the rated frequency of the capacitor unless otherwise specified.
5.1.3 Voltage limits as established by overvoltage protector
a) Purpose
The overvoltage protector is a quick-acting device which limits the voltage across the series
capacitor to a permissible value when that value would otherwise be exceeded as a result
of a power-system fault or other abnormal network condition.
b) Classification
Four common alternatives are listed below (see Figure 2):
– single protective spark gap (type K1),
– two different set single-protective spark gaps forming a dual-gap system (type K2),
– non-linear resistor (type M1),
– non-linear resistor with bypass gap (type M2).
NOTE 1 If the sparkover voltage of an overvoltage protector is dependent on air density, U is understood to
pl
correspond to the conditions resulting in the highest sparkover voltage, i.e. to the highest air pressure and the
lowest temperature. Also, the tolerance on sparkover voltage should be taken into account when determining U .
pl
NOTE 2 For scheme K2 (dual gap) U and consequently all test voltages and insulation levels should be
pl
determined by the high set gap.

60143-1 © IEC:2004 – 31 –
DD
Type K1 Type M1
Single gap Non-linear resistor
DD
Type K2 Type M2
Non-linear resistor
Dual gap
with by-pass gap
IEC  2905/03
Figure 2 – Classification of overvoltage protection
5.1.3.1 Type K overvoltage protector
When the gap sparks over due to an excessive line current caused by a fault in the system, an
arc is sustained until de-energizing the line or closing a bypass switch.
During arcing of the gap, the capacitor is exposed to one voltage peak whose value shall not
exceed U . The capacitor is subjected to a transient discharge once only at every operation of
pl
the gap.
5.1.3.2 Type M overvoltage protector
The non-linear resistor is permanently connected across the capacitor terminals. When the
bank is operated at normal load current, a given but very low current passes through the non-
linear resistor.
In the case of a fault external to the line concerned, the series capacitor becomes
automatically reinserted when the fault is disconnected. Even during such a fault the series
capacitor exerts a certain compensating effect. For this reason, in many cases, the U chosen
pl
with Type M can be lower than with Type K overvoltage protectors. On the other hand, in the
event of a short-circuit at the compensated line itself, the circuit-breakers at the ends of the
line will be opened.
The non-linear resistor shall be designed to withstand the thermal stresses occurring during the
overload conditions and during the system swing according to 10.3, and those of the maximum
line fault current.
60143-1 © IEC:2004 – 33 –
In the event of prolonged duration of an external fault, e.g. due to malfunction of the line
protection, the non-linear resistor may become thermally overloaded. Also short-circuits at the
compensated line may imply such high currents that it is not economical to dimension the non-
linear resistor accordingly. In order to protect the non-linear resistor in such cases, it may be
bypassed by a switch or a forced, triggered spark-gap.
5.1.4 Determination of protective level voltage U and U
pl lim
The value of a test voltage (U ) between terminals depends on the type of the overvoltage
t
protector and its protective level voltage U (see 5.1.3).
pl
The limiting voltage U (kV r.m.s.) for the capacitor unit is related to the protective level
lim
voltage of the actual phase or segment U (kV peak) according to equation (1).
pl
U = U /(s ×2) (1)
lim pl
where s is the number of capacitor units in series which spans U .
pl
Further clarifications are given in 10.4 and 10.5.
5.2 Classification of tests
Tests on equipment that constitute the capacitor bank are designated as routine tests, type
tests and special tests. Additional tests are typically performed after the bank is installed.
These tests are discussed in IEC 60143-2.
5.2.1 Routine tests
a) Capacitance measurement (see 5.3)
b) Capacitor loss measurement (see 5.4)
c) Voltage test between terminals (see 5.5)
d) AC voltage test between terminals and container (see 5.6)
e) Test on internal discharge device (see 5.7)
f) Sealing test (see 5.8)
g) Discharge test of internal fuses (see 3.1.2 of IEC 60143-3).
The test sequence is not necessarily that indicated above.
The routine tests shall be carried out by the manufacturer on every capacitor unit before
delivery.
5.2.2 Type tests
a) Thermal stability test (see 5.9)
b) AC voltage test between terminals and container (see 5.10)
c) Lightning impulse voltage test between terminals and container (see 5.11).
d) Cold duty test (see 5.12)
e) Discharge current test (see 5.13).
The type tests are carried out in order to ensure that the capacitor unit complies with the
contractual characteristics and with the operational requirements as specified in this standard.

60143-1 © IEC:2004 – 35 –
It is not essential that all type tests are carried out on the same capacitor unit.
The above list of type tests does not indicate any test sequence.
Unless otherwise specified, every capacitor sample to which a type test will be applied shall
have first withstood satisfactorily the application of all the routine tests.
When a type test has previously been successfully performed on equipment of similar design at
stress or duty levels that are equal to or greater than t
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