IEC 60255-22-2:2008

IEC 60255-22-2
Edition 3.0 2008-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measuring relays and protection equipment –
Part 22-2: Electrical disturbance tests – Electrostatic discharge tests

Relais de mesure et dispositifs de protection –
Partie 22-2: Essais d’influence électrique – Essais de décharge électrostatique

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: inmail@iec.ch
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: csc@iec.ch
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
ƒ Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
ƒ Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
ƒ Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: csc@iec.ch
Tél.: +41 22 919 02 11
Fax: +41 22 919 03 00
IEC 60255-22-2
Edition 3.0 2008-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measuring relays and protection equipment –
Part 22-2: Electrical disturbance tests – Electrostatic discharge tests

Relais de mesure et dispositifs de protection –
Partie 22-2: Essais d’influence électrique – Essais de décharge électrostatique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
M
CODE PRIX
ICS 29.120.70 ISBN 2-8318-9709-2

– 2 – 60255-22-2 © IEC:2008
CONTENTS
FOREWORD.3
1 Scope and object.5
2 Normative references .5
3 Terms and definitions.6
4 Test severity level .6
5 Test equipment.7
6 Test set-up .7
7 Test procedures .9
8 Criteria for acceptance .11
9 Test report.11
Annex A (informative) .12

Figure 1 – Example of test set-up with EUT .9

Table 1 – Test severity classes.7
Table 2 – Criteria for acceptance .11

60255-22-2 © IEC:2008 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 22-2: Electrical disturbance tests –
Electrostatic discharge tests
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 60255-22-2 has been prepared by IEC technical committee 95:
Measuring relays and protection equipment.
This third edition cancels and replaces the second edition published in 1996. It constitutes a
technical revision.
The main changes with respect to the previous edition are listed below:
• the improvement of the scope and object,
• the improvement of the test severity level, test set-up and test report.

– 4 – 60255-22-2 © IEC:2008
The text of this part is based on the following documents:
FDIS Report on voting
95/227/FDIS 95/232/RVD
Full information on the voting for the approval of this standard can be found in the voting on
report indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 60255 series, published under the general title Measuring relays and
protection equipment, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
60255-22-2 © IEC:2008 – 5 –
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 22-2: Electrical disturbance tests –
Electrostatic discharge tests
1 Scope and object
This part of IEC 60255-22 is based on IEC 61000-4-2, referring to that publication where
applicable, and specifies the general requirements for electrostatic discharge tests for
measuring relays and protection equipment for power system protection, including the control,
monitoring and process interface equipment used with those systems.
The object of the tests is to confirm that the equipment being tested will not maloperate when
energized and subjected to an electrostatic discharge.
The requirements are applicable only to relays and protection equipment in new condition,
and all tests specified are type tests only.
The object of this standard is to state:
• definitions of terms used;
• test severity level;
• test equipment;
• test set-up;
• test procedures;
• criteria for acceptance;
• test report requirements.
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.
IEC 60050-161, International Electrotechnical Vocabulary – Chapter 161: Electromagnetic
compatibility
IEC 60050-446, International Electrotechnical Vocabulary – Chapter 446: Electrical relays
IEC 60050-448, International Electrotechnical Vocabulary – Chapter 448: Power system
protection
IEC 60255-6:1988, Electrical relays – Part 6: Measuring relays and protection equipment
IEC 61000-4-2:1995, Electromagnetic compatibility (EMC) – Part 4-2: Testing and
measurement techniques – Electrostatic discharge immunity test
Amendment 1 (1998)
Amendment 2 (2000)
– 6 – 60255-22-2 © IEC:2008
3 Terms and definitions
For the purposes of this document, the terms and definitions in IEC 60050-161, IEC 60050-
446 and IEC 60050-448 apply and, for special terms, IEC 61000-4-2 applies.
3.1
equipment under test
EUT
equipment which may be either a measuring relay or a protection equipment
3.2
contact discharge method
method of testing, in which the electrode of the test generator is held in contact with the EUT,
and the discharge to the EUT actuated by the discharge switch within the generator
3.3
air discharge method
method of testing, in which the charged electrode of the test generator is approached to the
EUT, and the discharge actuated by a spark to the EUT
3.4
direct application
application of the test directly to the EUT
3.5
indirect application
application of the test to a coupling plane in the vicinity of the EUT, and simulation of personal
discharge to objects which are adjacent to the EUT
3.6
auxiliary equipment
equipment necessary to provide the EUT with the signals required for normal operation, and
equipment used to verify the performance of the EUT
4 Test severity level
IEC 61000-4-2 makes reference to two test methods and two methods of application. These
are:
• test methods:
– contact discharge,
– air discharge;
• applications:
– direct,
– indirect.
Tests shall be applied as follows:
• the contact discharge method is the preferred method;
• the air discharge method shall only be used when the accessible surfaces of the EUT are
non-conducting;
• the direct application test method shall be used;
• the indirect method of application is not applicable when the EUT is intended to be
mounted in a grounded cabinet.

60255-22-2 © IEC:2008 – 7 –
To cover different environmental conditions, this standard includes different severity classes.
General guidance for the selection of severity classes is given in Annex A.
The test severity class shall be chosen from the following table. In this standard, the severity
is expressed as the charging voltage of the energy storing capacitor in the discharge
generator.
Table 1 – Test severity classes
Class Test voltage (±5 %)
Contact discharge Air discharge
0 – –
1 2 kV 2 kV
2 4 kV 4 kV
3 6 kV 8 kV
4 8 kV 15 kV
Class 3 is the normal test severity class for measuring relays and protection equipment.
Testing shall also be satisfied at the lower levels given in Table 1.
NOTE 1 For situations involving a very severe electrostatic environment, testing with higher voltage levels than
those specified in Class 4 is subject to agreement between the user and manufacturer, or as defined by the
manufacturer. If higher voltages than those shown are specified, special test equipment may be required.
NOTE 2 For Classes 3 and 4, the test voltage levels for the contact discharge method are less than those for the
air discharge method, due to the characteristics of the two test methods. It is not intended to imply that the test
severity is equivalent between test methods.
5 Test equipment
The recommended test equipment is described in IEC 61000-4-2.
6 Test set-up
The test set-up consists of the test generator, the EUT, and auxiliary instrumentation
necessary to perform direct discharges to the EUT, as applicable, in the following manner:
a) contact discharge to conductive surfaces;
b) air discharge at insulating surfaces.
All tests shall be conducted in a test laboratory under the environmental reference conditions
outlined in Clause 7.
The EUT shall be tested in as close to installed conditions as possible. Wiring shall be
consistent with the manufacturer's recommended procedures, and the EUT shall be tested in
its case or housing. All parts intended to be earthed shall be connected to the ground
reference plane with copper straps (or copper braid) of at least 20 mm width.
A ground reference plane shall be provided on the floor of the laboratory or on the work
bench. It shall be a metallic sheet (copper or aluminium) of 0,25 mm minimum thickness;
other metallic materials may be used, but they shall be of at least 0,65 mm thickness. The
minimum size of the reference plane is 1 m , the exact size depending on the dimensions of
the EUT. It shall project beyond the EUT, or the coupling plane, by at least 0,5 m on all sides,

– 8 – 60255-22-2 © IEC:2008
and shall be connected to the protective ground system. Local safety regulations shall always
be met.
The EUT shall be placed on the ground reference plane, but distanced from it by means of at
least 0,1 m thick insulation supports. The distance to walls and metallic structures shall be at
least 1 m.
Cables interconnecting the various parts of the EUT shall be kept at a distance of at least
0,1 m from the ground plane.
The discharge generator shall be earthed via its discharge return cable directly to the
ground reference plane, close to the EUT. The total length of this cable is in general 2 m.
Where coupling planes are specified, for example to allow indirect application of the
discharge, they shall be constructed from the same material type and thickness as that of the
ground reference plane, and shall be connected to the ground reference plane via a cable
with a 470 kΩ resistor located at each end. These resistors shall be capable of withstanding
the discharge voltage and shall be insulated to avoid short circuits to the ground reference
plane when the cable lies on the ground reference plane. An example of a test set-up is given
in IEC 61000-4-2.
If monitoring equipment is required, it should be decoupled in order to reduce the possibility of
erroneous failure indication.
An example of a test set-up is given in Figure 1.

60255-22-2 © IEC:2008 – 9 –
Equipment under test
Supply and monitoring equipment
Discharge
generator
≥ 0,2 m
Power supply
≥ 0,1 m
Insulating support
Ground reference plane IEC  529/08

Figure 1 – Example of test set-up with EUT
7 Test procedures
The tests shall be carried out with the equipment under reference conditions, as stated in the
applicable clauses of IEC 60255-6.
The tests shall be carried out with auxiliary energizing quantities and loading applied to the
appropriate circuits, having values equal to rated conditions (see Note 1 below).
The value of the input energizing quantity shall be as close as possible to the transitional
state, but not closer than the claimed variation due to electrostatic discharge disturbance.
The settings and appropriate variations associated with the tests shall be declared by the
manufacturer.
NOTE 1 The thermal withstand capability should be taken into consideration.
NOTE 2 Since the coincidence of electrostatic discharge and a fault is considered to be extremely unlikely, the
effect of the discharge on the relay in its transitional or operating condition is not considered.
The points selected for the application of the test shall be those which are accessible to the
operator under normal service conditions, including communication ports and those points for

– 10 – 60255-22-2 © IEC:2008
setting adjustments that can only be accessed by removing the relay cover. Setting
adjustments which necessitate any action other than removal of the cover, such as removal of
a module, are not included.
The application of discharge to any point of the equipment which is accessible only for repair
and maintenance purposes is outwith the scope of this standard.
In the selection of test points, attention shall be given to the following:
• knobs, push-buttons, switches, communication interface, etc., accessible under normal
service;
• points on covers of insulating material where conducting parts are close to the inside of
the cover;
• points on conducting parts not belonging to, but placed in the vicinity of, the EUT, when
this has an insulating cover.
To achieve reproducible results, it is recommended that the selected test points are specified
by the manufacturer.
The contact discharge method of testing (the preferred method) shall be applied to conductive
surfaces of the EUT.
The air discharge method shall only be used when the accessible surfaces of the EUT are
non-conducting.
The test voltage shall be increased from the minimum to the selected test level, in order to
determine any threshold of failure.
It is recommended that the discharge generator includes a monitor device for indication of the
actual application of the discharge at the corresponding level.
The test shall be performed with single discharges. It shall be repeated on each selected test
point at least 10 times with positive polarity and 10 times with negative polarity of test voltage.
The recommended time interval between successive single discharges is 1 s, although longer
intervals may be necessary to determine whether a failure has occurred.
NOTE The points to which the discharges should be applied may be selected by means of an exploration carried
out at a repetition rate of 20 discharges per second, or more.
The discharge generator shall be held perpendicular to the surface to which the discharge is
applied. This improves repeatability of the test results.
The discharge return cable of the generator shall be kept at a distance of at least 0,2 m from
the EUT and metal surfaces, other than the ground plane, whilst the discharge is being
applied.
For contact discharge tests, the tip of the discharge electrode shall touch the EUT before the
discharge switch is operated.
In the case of painted surfaces covering a conducting substrate at the intended point of test,
the following procedure shall be adopted:
• where the coating is not declared to be an insulating coating by the equipment
manufacturer, then the pointed tip of the generator shall penetrate the coating so as to
make contact with the conducting substrate;

60255-22-2 © IEC:2008 – 11 –
• where the coating is declared as insulating and has a declared voltage withstand
exceeding the appropriate test voltage level for air discharge tests, the contact discharge
test shall not be applied to such surfaces.
For air discharge tests, the discharge tip of the discharge electrode shall approach and touch
the EUT as fast as possible without causing mechanical damage. After each discharge, the
discharge electrode shall be removed from the EUT, and the generator shall be retriggered in
readiness for the next single discharge. This procedure shall be repeated until the discharges
are completed.
For test method of ungrounded equipment see IEC 61000-4-2.
8 Criteria for acceptance
The criteria for acceptance shall be given in Table 2. The applicable functions shall be
monitored during the test.
The EUT has passed the test if it fulfils the criteria for acceptance according to Table 2 and,
after the test has been completed, still complies with the relevant performance specification.
Table 2 – Criteria for acceptance
Function Criterion for acceptance
Protection Normal performance within the specification limits
Command and control Normal performance within the specification limits
Measurement Temporary degradation during test, with self-recovery at the end of the
test. No loss of stored data
Integral human-machine interface and Temporary degradation or loss of function during test, with self-recovery
visual alarms at the end of the test. No loss of stored data
Data communication Possible bit error rate increase but no loss of transmitted data
9 Test report
The test report shall include those items listed in 60255-6 and also the following:
• the identification and configuration of the EUT;
• the test conditions;
• the mounting and orientation of the EUT;
• the type(s) and number of interconnecting wires used and the interface port (of the EUT)
to which these are connected;
• the operating conditions of the EUT, for example relay settings and values of input
energizing quantities;
• the test severity level;
• the test equipment used;
• the test conclusion (pass/fail).

– 12 – 60255-22-2 © IEC:2008
Annex A
(informative)
Explanatory notes on electrostatic discharge tests for measuring relays
and protection equipment
A.1 General considerations
Electronic equipment is likely to be affected by electrostatic discharges which are applied
either directly to the equipment, or to metal objects in the proximity of the equipment. The
primary concern of this standard is the effect of these discharges, whose source is the human
body, on protection equipment, particularly static and microprocessor based measuring relays
and protection equipment
The effect of discharge from the operator may be a simple malfunction of the equipment, or
damage of electronic components. The dominant effects can be attributed to the parameters
of the discharge current (rise time, duration, etc.).
Electrostatic charges are easily generated in an environment with dry atmosphere and
synthetic fabrics. The operator's body may be charged either directly, or by electrostatic
induction. There are many possible variations in the charging process. A common situation is
one in which an operator walks over a carpet, and at each step loses or gains electrons
relative to the fabric. An exchange of electrostatic charges can also occur due to friction
between a person's clothing and a seat or chair.
The charges can be carried over a long distance by people wearing insulating shoes. In such
cases, it does not help if the floor where the electronic equipment is placed consists of
conducting material.
Equipment can be subjected to electrostatic discharge both indoors and outdoors.
The most common discharge behaviour can be classified as follows:
• at discharge from a hand or a discharge generator, a part of the charge is tied
capacitively, locally in the region where the discharge occurs. This charge is discharged
with a current pulse of very short duration, which can be of high amplitude, and can
therefore represent a severe condition for the equipment. The remaining discharge causes
a current which is distributed over the equipment subject to the discharge, and via this
equipment, to other units connected to it, and to earth;
• if a good earth connection exists between the cover of the equipment and a conducting
floor, the discharge current will go through the cover to earth. The current shape is
determined by the source capacitance and resistance, and the low inductance in the path
to earth. This generates a current pulse, with a rise time of the order of a few
nanoseconds, and a tail of the order of some tens of nanoseconds;
• if the equipment cover is not earthed, or the earth path has a high impedance, the
discharge current will flow through other parts. The inductance of these can cause a rise
time 10 times as high as in the preceding case. The current shape is a damped oscillatory
wave;
• when a significant amount of the discharge current flows through other parts to earth, the
electronic circuitry can be subjected to inductive coupling or radiation;
• when the discharge current flows from one unit to another along connecting cables, the
signals may be strongly affected by interference.
For further explanatory notes, see Annex A of IEC 61000-4-2.

60255-22-2 © IEC:2008 – 13 –
A.2 Selection of test severity classes
The main carrier of electrostatic charge is the human body. The level to which the human
body is charged depends on the material in the clothing and in the room (specifically the
floor), and on the relative humidity of the room.
The severity class should be chosen so that the expected discharge voltage does not exceed
the test voltage of the class chosen.
The recommended severity class is dependent on the environmental conditions, as follows:
• Class 0: environment where the discharge voltage is kept negligible;
• Class 1: environment where the discharge voltage is kept below 2 kV. For example,
where floors are covered with antistatic material, and the relative humidity is greater than
35 %;
• Class 2: environment where the discharge voltage is kept below 4 kV. For example,
where floors are covered with antistatic material, and the relative humidity is greater than
10 %;
• Class 3: environment where the discharge voltage is kept below 8 kV. For example,
where floors are covered with material which tends to generate static electricity, such as
synthetic material, and the relative humidity is greater than 50 %;
• Class 4: environment where the discharge voltage is kept below 15 kV. For example,
where floors are covered with material which tends to generate static electricity, such as
synthetic material, and the relative humidity is greate
...