SIST EN 60255-5:2002

SLOVENSKI SIST EN 60255-5:2002
prva izdaja
STANDARD
julij 2002
Electrical relays - Part 5: Insulation coordination for measuring relays and protection
equipment - Requirements and tests
ICS 29.120.70 Referenčna številka
SIST EN 60255-5:2002(en)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------

EUROPEAN STANDARD EN 60255-5
NORME EUROPÉENNE
EUROPÄISCHE NORM April 2001
ICS 29.120.70
English version
Electrical relays
Part 5: Insulation coordination for measuring relays
and protection equipment -
Requirements and tests
(IEC 60255-5:2000)
Relais électriques Elektrische Relais
Partie 5: Coordination de l'isolement Teil 5: Isolationskoordination für
des relais de mesure et des dispositifs Meßrelais und Schutzeinrichtungen -
de protection - Anforderungen und Prüfungen
Prescriptions et essais (IEC 60255-5:2000)
(CEI 60255-5:2000)
This European Standard was approved by CENELEC on 2001-03-01. 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, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,
Portugal, 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
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60255-5:2001 E

---------------------- Page: 2 ----------------------

EN 60255-5:2001 - 2 -
Foreword
The text of document 95/98/FDIS, future edition 2 of IEC 60255-5, prepared by IEC TC 95, Measuring
relays and protection equipment, was submitted to the IEC-CENELEC parallel vote and was approved
by CENELEC as EN 60255-5 on 2001-03-01.
This standard should be read in conjunction with HD 625.1 S1:1996.
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) 2001-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-03-01
Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annex ZA is normative and annexes A to D are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60255-5:2001 was approved by CENELEC as a European
Standard without any modification.
__________

---------------------- Page: 3 ----------------------

- 3 - EN 60255-5:2001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-151 1978 International Electrotechnical --
Vocabulary (IEV)
Chapter 151: Electrical and magnetic
devices
IEC 60050-448 1995 Chapter 448: Power system protection - -
IEC 60060-1 1989 High-voltage test techniques HD 588.1 S1 1991
+ corr. March 1990 Part 1: General definitions and test
requirements
IEC 60085 1984 Thermal evaluation and classification of HD 566 S1 1990
electrical insulation
IEC 60112 1979 Method for determining the comparative HD 214 S2 1980
and the proof tracking indices of solid
insulating materials under moist
conditions
IEC 60255 Series Electrical relays EN 60255 Series
IEC 60255-21-1 1988 Part 21: Vibration, shock, bump and EN 60255-21-1 1995
seismic tests on measuring relays and
protection equipment -- Section 1:
Vibration tests (sinusoidal)
IEC 60255-21-2 1988 Part 21: Vibration, shock, bump and EN 60255-21-2 1995
seismic tests on measuring relays and
protection equipment -- Section 2:
Shock and bump tests
IEC 60255-21-3 1993 Part 21: Vibration, shock, bump and EN 60255-21-3 1995
seismic tests on measuring relays and
protection equipment -- Section 3:
Seismic tests
IEC 60664-1 1992 Insulation coordination for equipment HD 625.1 S1 1996
(mod) within low-voltage systems + corr. November 1996
Part 1: Principles, requirements and
tests

---------------------- Page: 4 ----------------------

EN 60255-5:2001 - 4 -
Publication Year Title EN/HD Year
IEC 61000-4-5 1995 Electromagnetic compatibility (EMC) EN 61000-4-5 1995
Part 4-5: Testing and measurement
techniques - Surge immunity test
IEC 61180-1 1992 High-voltage test techniques for low- EN 61180-1 1994
voltage equipment
Part 1: Definitions, test and procedure
requirements
IEC 61180-2 1994 Part 2: Test equipment EN 61180-2 1994

---------------------- Page: 5 ----------------------

NORME CEI
INTERNATIONALE IEC
60255-5
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2000-12
Relais électriques –
Partie 5:
Coordination de l'isolement des relais de mesure
et des dispositifs de protection –
Prescriptions et essais
Electrical relays –
Part 5:
Insulation coordination for measuring relays
and protection equipment –
Requirements and tests
 IEC 2000 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
V
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue

---------------------- Page: 6 ----------------------

60255-5 © IEC:2000 – 3 –
CONTENTS
Page
FOREWORD . 5
INTRODUCTION .7
Clause
1 Scope and object . 9
2 Normative references. 9
3 Definitions. 11
4 Insulation coordination. 17
4.1 Basic principles. 17
4.2 Voltages and voltage ratings. 19
4.3 Time under voltage stress. 23
4.4 Pollution . 25
4.5 Information to be found on the relay or in the operating instructions. 25
4.6 lnsulation material. 25
5 Dimensioning requirements and rules . 27
5.1 Dimensioning of clearances . 27
5.2 Dimensioning of creepage distances. 27
5.3 Requirements for design of solid insulation. 29
6 Tests and measurements . 31
6.1 Tests . 31
6.2 Measurements . 43
Annex A (informative) Nominal voltages of supply systems . 45
Annex B (informative) Altitude correction factors . 47
Annex C (informative) Guidance for impulse voltage tests . 49
Annex D (informative) Measurement of creepage distances and clearances . 49
Table 1 – Rated insulation voltages. 19
Table 2 – Rated impulse voltages (waveform: 1,2/50 μs) . 23
Table 3 – Minimum clearances in air . 27
Table 4 – Minimum creepage distances. 29
Table 5 – Impulse test voltages . 35
Table 6 − AC test voltages . 39
Table 7 – Symbols for marking of test voltages . 41
Table A.1 – Nominal voltages of supply systems . 45
Table B.1 – Altitude correction factors. 47
Table C.1 – Components of the test generator . 49

---------------------- Page: 7 ----------------------

60255-5 © IEC:2000 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL RELAYS –
Part 5: Insulation coordination for measuring relays and
protection equipment – Requirements and tests
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 co-operation 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 specifications, 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 60255-5 has been prepared by IEC technical committee 95:
Measuring relays and protection equipment.
This second edition cancels and replaces the first edition, published in 1977, and constitutes
a technical revision.
This standard shall be read in conjunction with IEC 60664-1.
The text of this standard is based on the following documents:
FDIS Report on voting
95/98/FDIS 95/108/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 3.
Annexes A to D are for information only.
The committee has decided that the contents of this publication will remain unchanged
until 2004. At this date, the publication will be
reconfirmed;
withdrawn;
replaced by a revised edition, or
amended.

---------------------- Page: 8 ----------------------

60255-5 © IEC:2000 – 7 –
INTRODUCTION
The following points have been considered in the preparation of this standard.
– The application of the insulation coordination according to IEC 60664-1 leads to a graded
range of rated impulse voltages dependent on the nominal voltage of the supply circuit
and the applicable overvoltage category. Further, the impulse test voltages depend on the
air pressure and therefore on the altitude of the test site. Consequently, a wide range of
test voltages becomes necessary.
For an effective test practice, a rationalised test voltage of 5 kV has been specified in this
standard. It is applicable for the normal case of relays directly energised via current and
voltage transformers or directly connected to the station battery supply. It is applicable
independent of the test site altitude, from sea level to 2 000 m.
The existing impulse test generators designed according to IEC 60060-1 remain applicable in
this case.
For other test voltages, the IEC 60060-1 generator can also be used; however components of
the generator must be modified depending on the required test voltage, as described in
annex C. The modifications are necessary to retain the specified output energy of 0,5 J.
It is expected that suitable impulse test generators with variable output voltage and a
fixed output energy of 0,5 J will become available on the market in the near future.
– Reduction of the source impedance of the impulse test generator to 50 Ω has been
considered, because a value of this order would seem to correspond better to the
characteristic impedance of the substation wiring (see also IEC 61000-4-5). However,
considering the satisfactory experience with the current standard and in order to avoid the
existing test generators from becoming obsolete, the 500 Ω value has been retained.
– Impulse withstand testing of circuits containing voltage suppression components may lead
to heavy distortion of the impulse test waveform. This is acceptable, conditional upon the
equipment being undamaged and fully functional after completion of the tests. Withstand
surge testing of circuits is not part of insulation testing and not part of this standard.
– The inclusion of the pollution degree is based on IEC 60664-1 and is a new consideration.

---------------------- Page: 9 ----------------------

60255-5 © IEC:2000 – 9 –
ELECTRICAL RELAYS –
Part 5: Insulation coordination for measuring relays and
protection equipment – Requirements and tests
1 Scope and object
This part of IEC 60255 gives general requirements for the insulation coordination of
measuring relays and protection equipment.
NOTE 1 Unless otherwise stated, the term “relay(s)” is used as an abbreviation for the expression “measuring
relays and protection equipment” in this standard.
In particular, this standard, specifies the following:
– definition of terms;
– guidance for the selection of clearances and creepage distances and other aspects
related to the insulation of measuring relays and protection equipment;
– requirements for voltage tests and insulation resistance measurement.
This standard is applicable to the installation and use at altitudes up to 2 000 m of equipment
having a rated a.c. voltage up to 1 000 V, with a rated frequency up to 65 Hz, or a d.c. voltage
up to 1 500 V.
This standard also applies to associated auxiliary devices such as shunts, series resistors,
transformers, etc., used and tested together with measuring relays and protection equipment
as mentioned above, except where the devices are covered by other IEC publications, for
example communication interfaces.
NOTE 2 Requirements for altitudes exceeding 2 000 m can be derived from table B.1.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 60255. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, parties to
agreements based on this part of IEC 60255 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO
and IEC maintain registers of currently valid International Standards.
IEC 60050(151):1978, International Electrotechnical Vocabulary (IEV) – Chapter 151: Electrical
and magnetic devices
IEC 60050(448):1995, International Electrotechnical Vocabulary – Chapter 448: Power system
protection
IEC 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60085:1984, Thermal evaluation and classification of electrical insulation

---------------------- Page: 10 ----------------------

60255-5 © IEC:2000 – 11 –
IEC 60112:1979, Method for determining the comparative and the proof tracking indices of
solid insulating materials under moist conditions
IEC 60255 (all parts), Electrical relays
IEC 60255-21-1:1988, Electrical relays – Part 21: Vibration, shock, bump and seismic tests on
measuring relays and protection equipment – Section 1: Vibration tests (sinusoidal)
IEC 60255-21-2:1988, Electrical relays – Part 21: Vibration, shock, bump and seismic tests on
measuring relays and protection equipment – Section 2: Shock and bump tests
IEC 60255-21-3:1993, Electrical relays – Part 21: Vibration, shock, bump and seismic tests on
measuring relays and protection equipment – Section 3: Seismic tests
IEC 60664-1:1992, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 61000-4-5:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 5: Surge immunity test
IEC 61180-1:1992, High-voltage test techniques for low-voltage equipment – Part 1:
Definitions and test procedure requirements
IEC 61180-2:1994, High-voltage test techniques for low-voltage equipment – Part 2: Test
equipment
3 Definitions
For the purpose of this part of IEC 60255, the following definitions together with those of
IEC 60050(448), IEC 60664-1 and the relevant parts of IEC 60255 apply.
3.1
hazardous live part
part at a voltage in excess of 50 V r.m.s. or 75 V d.c.
3.2
exposed conductive part
conductive part which can be readily touched and is normally not hazardous live but may be
at hazardous live voltage under a single fault condition
NOTE 1 For relays which are not enclosed, the frame, the fixing devices, etc., form the exposed conductive parts.
NOTE 2 For relays which are enclosed, the conductive parts which are accessible when the relay is mounted in
its normal position of use, including those of its fixing surface, form the exposed conductive parts. Small parts such
as inscription plates, screws and rivets which are isolated from the circuits are not taken into consideration.
3.3
clearance
shortest distance in air between two conductive parts
[IEC 60664-1]
3.4
solid insulation
solid insulating material interposed between any two conductive parts
[IEC 60664-1]

---------------------- Page: 11 ----------------------

60255-5 © IEC:2000 – 13 –
3.5
creepage distance
shortest distance along the surface of the insulating material between two conductive parts
[IEV 151-03-37]
3.6
rated voltage
value of voltage assigned by the manufacturer to a component, device or equipment and to
which operation and performance characteristics are referred
[IEC 60664-1]
3.7
rated insulation voltage
r.m.s. withstand voltage value assigned by the manufacturer to the relay or to a part of it,
characterising the specified (long term) withstand capability of its insulation and to which
dielectric tests and creepage distances are referred
NOTE The rated insulation voltage is not necessarily equal to the rated voltage of equipment which is primarily
related to functional performance.
3.8
rated impulse voltage
impulse withstand voltage value assigned by the manufacturer to the relay or to a part of it,
characterising the specified withstand capability of its insulation against transient over-
voltages and to which clearances are referred
3.9
overvoltage
any voltage having a peak value exceeding the corresponding peak value of the maximum
steady-state voltage at normal operating conditions
[IEC 60664-1]
3.10
overvoltage category
numeral defining a transient overvoltage condition
[IEC 60664-1]
NOTE Overvoltage categories I, II, III, IV are used, see 4.2.2.1.
3.11
macro-environment
environment of the room or other location in which the relay is installed or used
[IEC 60664-1]
3.12
micro-environment
immediate environment of the insulation which particularly influences the dimensioning of the
creepage distances
[IEC 60664-1]
3.13
pollution
any addition of foreign matter, solid, liquid or gaseous, that can result in a reduction of
electric strength or surface resistivity of the insulation
[IEC 60664-1]
3.14
pollution degree
numeral characterising the expected pollution of the micro-environment
[IEC 60664-1]
NOTE Degrees 1 to 4 are defined in 4.4.

---------------------- Page: 12 ----------------------

60255-5 © IEC:2000 – 15 –
3.15
tracking
progressive formation of conductive paths which are produced on the surface of solid
insulating material due to the combined effects of electric stress and electrolytic conta-
mination on the surface
3.16
comparative tracking index
figure that characterises the relative tracking performance of insulating materials
3.17
type test
test of one or more devices made to a certain design to show that the design meets certain
specifications
[IEV 151-04-15]
3.18
routine test
test to which each individual device is subjected during or after manufacture to ascertain
whether it complies with certain criteria
[IEV 151-04-16]
3.19
dielectric test
test of short duration which consists in applying a specified voltage to the insulation to prove
that it is in accordance with the rated insulation voltage of the circuit, as stated by the
manufacturer
3.20
impulse voltage withstand test
test which consists in applying a specified impulse voltage to the insulation to prove the ability
of the measuring relay or protection equipment to withstand without damage overvoltages of
very high values and very short duration
3.21
functional insulation
insulation between conductive parts which is necessary only for the proper functioning of the
relay
[IEC 60664-1]
3.22
basic insulation
insulation applied to live parts to provide basic protection against electric shock
[IEC 60664-1]
NOTE Basic insulation does not necessarily include insulation used exclusively for functional purposes.
3.23
supplementary insulation
independent insulation applied in addition to basic insulation, in order to provide protection
against electric shock in the event of a failure of basic insulation
[IEC 60664-1]
3.24
double insulation
insulation comprising both basic insulation and supplementary insulation
[IEC 60664-1]

---------------------- Page: 13 ----------------------

60255-5 © IEC:2000 – 17 –
3.25
reinforced insulation
single insulation system applied to live parts, which provides a degree of protection against electric
shock equivalent to double insulation under conditions specified in the relevant IEC standard
[IEC 60664-1]
NOTE A single insulation system does not imply that the insulation must be one homogeneous piece. It may
comprise several layers which cannot be tested singly as basic or supplementary insulation.
4 Insulation coordination
4.1 Basic principles
The basic principles of insulation coordination are stated in IEC 60664-1 which provides
guidance for the specification and testing of clearances, creepage distances and solid
insulation.
NOTE The standard insulation for relays is basic insulation. However, there are cases of application in which a
higher level of insulation (e.g. supplementary, reinforced or double insulation) is required. For example, a
communication port connected to a modem may require double insulation.
Clearances shall be dimensioned according to expected overvoltages at the place of
installation.
The following design parameters shall be considered:
– overvoltage category;
– pollution degree;
– geometry of clearances;
– nominal voltage from which the rated insulation voltage is derived.
The overvoltage category takes into account the fact that transient overvoltages, originating
from the supply system, can intrude into the equipment through its terminals. In addition, the
equipment itself may generate overvoltages.
Overvoltage categories are specified that describe the different probabilities of transient
overvoltages occurring to which the equipment will be subjected during operation.
The geometry of clearances plays an important part for flashover, whereby inhomogeneous
fields are to be assumed in the normal case for measuring relays and protection equipment.
The pollution degree is only relevant for small clearances.
Creepage distances shall be dimensioned from the view point of avoiding breakdown as a conse-
quence of tracking. The following parameters shall therefore be taken into consideration:
– nominal voltage from which the rated insulation voltage is derived;
– tracking withstand of insulation material;
– pollution degree.
The rated voltage depends on the nominal voltage of the supply system or the maximum
operating voltage. The pollution degree specified for the equipment depends on its environ-
ment and may be altered within the equipment.
The voltage test for clearances is carried out with transient high-voltage (impulse voltage
withstand test) derived from voltages occurring in practice in low-voltage supply circuits.

---------------------- Page: 14 ----------------------

60255-5 © IEC:2000 – 19 –
Creepage distances cannot be tested but shall be verified by measurement.
For verification of solid insulation, the dielectric test (a.c. power frequency high-voltage test)
is additionally applied.
4.2 Voltages and voltage ratings
4.2.1 Determination of rated insulation voltage
4.2.1.1 Standard values of rated insulation voltages
For each relay, the manufacturer shall declare the rated insulation voltage(s). The rated
insulation voltage of one or all of the circuits of these relays shall be chosen from table 1.
However, for relays directly energised from instrument transformers and for circuits directly
connected to the station battery supply, the rated insulation voltage shall not be below 250 V.
Table 1 – Rated insulation voltages
Nominal voltage of 30 60 110 150 208 220 300 380 440 575 720  960
the supply system
120 230 400 480 600 830 1 000
(see note 1)
127 240 415 500 660
V a.c or d.c.
690
Rated insulation 32 63 125 160 200 250 320 400 500 630 800 1 000
voltage
(see (see
(see note 2) note 3) note 3)
V
NOTE 1 The stated values are standard nominal voltages of low-voltage mains, as derived from tables 3a and 3b
of IEC 60664-1.
NOTE 2 The rated insulation voltage must be at least as high as the rated voltage assigned to the circuit, but a
higher value of rated insulation voltage may be chosen by the manufacturer.
NOTE 3 In these cases, the rated insulation voltage is lower than the nominal voltage due to the rationalisation
of a range of insulation voltages (see table 3b of IEC 6066
...