Surge arresters. Part 3: Artificial pollution testing of surge arresters

Gives the basic principles of artificial pollution testing of non-linear resistor type (valve type) surge arresters, together with details of pollutant compositions and methods of application and the procedures associated with each mode of pollution.

Parafoudres. Troisième partie: Essais de pollution artificielle des parafoudres

Le présent rapport technique indique les principes fondamentaux des essais de pollution artificielle des parafoudres à résistances variables ainsi que des détails sur les compositions des polluants et les procédés d'application et sur les méthodes d'essai associées à chaque mode de pollution.

Prenapetostni odvodniki - 3. del: Preskušanje prenapetostnih odvodnikov ob umetnem onesnaženju

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SIST IEC/TR 60099-3:1998
Prenapetostni odvodniki - 3. del: Preskušanje prenapetostnih odvodnikov ob
umetnem onesnaženju
Surge arresters. Part 3: Artificial pollution testing of surge arresters
Parafoudres. Troisième partie: Essais de pollution artificielle des parafoudres
Ta slovenski standard je istoveten z: IEC/TR 60099-3
29.120.50 9DURYDONHLQGUXJD Fuses and other overcurrent
PHGWRNRYQD]DãþLWD protection devices
29.240.10 Transformatorske postaje. Substations. Surge arresters
Prenapetostni odvodniki
SIST IEC/TR 60099-3:1998 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST IEC/TR 60099-3:1998
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SIST IEC/TR 60099-3:1998
Première édition
First edition
Partie 3:
Essais de pollution artificielle des parafoudres
Surge arresters
Part 3:
Artificial pollution testing of surge arresters
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No pa of this publication may be reproduced or utilized in any form
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SIST IEC/TR 60099-3:1998
— 3 —
99-3 ©IEC
Foreword 5
I Scope 7
2 Normative references 7
3 Basic principles 7
4 Test objective 9
5 General requirements
6 Voltage application
7 Test procedure
8 Methods of applying pollution
21 9 Solid pollutants for the methods of 8.3 and 8.4
10 Pollutants for t rial use with the methods of 8.3 or 8.4
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SIST IEC/TR 60099-3:1998
99-3©IEC — 5 —
Part 3:
Artificial pollution testing of surge arresters

I) The formal decisions or agreements of the I EC on technical matters, prepared by Technical Committees on which all the

National Committees having a special interest therein are represented, express, as nearly as possible, an international

consensus of opinion on the subjects dealt with.

They have the form of recommendations for international use and they are accepted by the National Committees in that


In order to promote international unification, the I EC expresses the wish that all National Committees should adopt the text

of the I EC recommendation for their national rules in so far as national conditions will permit. Any divergence between the

I EC recommendation and the corresponding national rules should, as far as possible, be clearly indicated in the latter.

This Technical Report has been prepared by IEC Technical Committee No. 37: Surge arresters.

It replaces and cancels Appendix D of Publication 99-1 (1970). A new edition of Publication 99-1 is

being prepared..
The text of this repo
rt is based on the following documents:
Six Months' Rule
Report on Voting
37(CO)24 37(CO)27
Full information on the voting for the approval of this repo
rt can be found in the Voting Repo rt
indicated in the above table.
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SIST IEC/TR 60099-3:1998
99-3 © IEC – 7 –
Part 3: Artificial pollution testing of surge arresters
I Scope

This Technical Report gives the basic principles of artificial pollution testing of non-linear resistor type

(valve type) surge arresters, together with details of pollutant compositions and methods of application

and the test procedures associated with each mode of pollution.
2 Normative references

The following standards contain provisions which, through reference in this text, constitute provisions

of this Technical Repo rt. At the time of publication, the editions indicated were valid. All standards are

subject to revision, and pa rties to agreements based on this Technical Repo rt are encouraged to

investigate the possibility of applying the most recent editions of the standards indicated below.

Members of IEC and ISO maintain registers of currently valid Inte rnational Standards.

IEC 99-1: 1970, Lightning arresters – Pa rt 1: Non-linear resistor type arresters for a.c. systems.

IEC 507: 1975, Artificial pollution tests on high-voltage insulators to be used on a.c. systems.

3 Basic principles

It is well known that a surge arrester can fail at normal service voltage under ce rtain pollution

conditions, owing to the setting up of a very uneven voltage dist ribution on its external surface and/or

because of very rapid changes in this dist ribution. These two stages a ri
se as a consequence of the

formation under such conditions of an initially nearly continuous conducting surface layer consisting

typically of an aqueous solution of electrolyte formed under high humidity by the moisture pick-up of

hygroscopic solid particles or liquid droplets deposited on the surface. Dusts may also be present,

affecting the washing and drying characteristics of the surface. It is well established also that the effect

of leakage current heating the surface layer, when the conductivity is high enough, is to cause "d ry

bands" to form, across which most of the voltage drop occurs and that surges of leakage-current occur

when these bands are temporarily bridged by an arc.

These phenomena can result in the voltage applied across some of the gaps exceeding their sparkover

value, with consequential failure, in some cases, through disturbance of the gap potentials caused by

capacitive coupling between electrodes and wet bands.

It is consequently the primary purpose of artificial pollution testing of surge arresters to simulate

relevant pollution conditions, representative of those occurring in se
rvice and establishing that when

subjected to these, the surge arrester, energized at appropriate power-frequency voltage does not suffer

gap sparkover.
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SIST IEC/TR 60099-3:1998
– 9 –
99-3 © IEC

Pollution flashover of the surge arrester surface is a serious matter operationally, and the performance

in this respect also must be determined. This is discussed in the following paragraphs.

ice and testing that the pollution conditions which may result in
There is now evidence both from se rv

surge arrester sparkover can be generally different from those leading to surface flashover. The latter is

associated typically with severe conditions characterized by frequent high-amplitude leakage-current

surges, whereas gap sparkover is typically associated with pollution onset or d rying-out of the pollutant.

Accordingly, separate tests for these two distinct modes of failure may be needed, at least with some test


Some artificial pollution test methods for surface flashover of high-voltage insulators have been

developed to a stage where they are generally accepted as giving a valid indication of pollution

performance. These are fully described in IEC 507. The essential common feature of the tests, even

though there are differences in the polluting techniques, are the repeatable production of various

degrees or "severities" of pollution, measured, for example, in terms of specific conductance of the

pollutant, application of a suitable test voltage and consequent determination of the performance in

terms of a given severity.

The mode of operation of surge arresters, however, is such that the methods used for insulator testing

are not directly applicable to surge arresters, especially in respect of arrester sparkover. The tests

, though broadly based on those of I EC 507, are essentially aimed at meeting the

described in this repo rt

special requirements for surge arrester operation and bear specifically on gap sparkover.

C 507 are directly applicable to surface flashover of insulation, and it is accordingly

The methods of I E
recommended that they should be used to determine performance in this respect.

It should be noted that the tests according to IEC 507 with respect to such surface flashover perfor-

mance and those proposed here to check sparkover performance are recommended only for surge

arresters exposed to natural pollution, possibly with live washing, and not for those subject to periodic

cleaning or greasing.

From the foregoing account of the failure mechanism it follows that for pollution tests of both kinds, it

is essential that they be performed on a complete se rvice surge arrester assembly.

When sufficient experience has been gained from the tests described in the following clauses, this

experience will form the basis of a type test.

ice, surge arresters sometimes suffer long-term deterioration associated with internal corona discharges.

NOTE – In serv

The tests described in this repo rt do not demonstrate the performance of the surge arrester in this respect.

4 Test objective

The objective of the test is to establish that the surge arrester can withstand a specified severity of

pollution without sparkover when energized at a specified voltage or voltage-application mode, both

severity and voltage mode being representative of se ice conditions.
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SIST IEC/TR 60099-3:1998
99-3 © I E C – 11 –
5 General requirements
5.1 Test arrester

The test shall be made on a complete arrester, with all normal spark-gaps, grading resistors and any

grading ring, etc., which may significantly affect the voltage dist
ribution of the arrester. However, for

pollution tests, it is not generally necessary to mount the arrester on a pedestal. This is because the

conductive surface layer and the internal processes determine the voltage distribution and its vari-

ations in this case, as opposed to that of tests for impulse sparkover performance in the normal

unpolluted state, for example, where the distribution, though partly controlled by grading resistors,

series capacitance of the gaps, etc., can also be affected by the distributed capacitance to the earth plane

and high-voltage lead, etc.
The dry

arrester power-frequency sparkover value and grading current measured at the operating

voltage should be measured prior to and after the test.
5.2 Cleaning

Before the arrester is tested for the first time, the surface shall be carefully cleaned (using a detergent

solution such as trisodium phosphate) and thoroughly rinsed (using tap or mains water) so that all

traces of surface contamination, particularly grease, are removed before testing. Care must be taken to

avoid touching the cleaned arrester.

NOTE — It may be necessary in some cases, particularly when spraying salt pollutants, to paint the metal pa rts and

cement to ensure that no corrosion products wash down onto the insulating surface during the test.

5.3 Installation

The cleaned arrester shall be erected so that the minimum distance between any pa rt of it and any.

earthed object other than the jets, and a ceiling or a wall is not less than one-half of the length of the

arrester. The arrester shall be in thermal equilibrium with the ambient air at the start of the test and the

temperature shall be noted. The temperature shall not be below 5 °C or greater than 40 °C.

Arrangements for arrester current monitoring

For test result diagnostic purposes according to 7.5 the surface leakage and internal current paths shall

be separately connected to the earth terminal of the test voltage source so that the surface leakage and

internal currents can be separately monitored. If the arrester is not provided with an internal current

lead isolated from the bottom flange, a surface leakage current collecting band is fitted above the flange

and the insulation surface between the band and the flange should be greased. Band/flange spacing

should be as small as possible, subject to provision of the necessary insulation, to minimize encroach-

ment on the leakage path. For most designs of arrester housing these requirements are met by fitting the

band immediately above the bottom shed.

In the case of a. multi-unit arrester, the band is applied only to the bottom unit.

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SIST IEC/TR 60099-3:1998
99-3 ©IEC – 13 –
5.5 Test circuit requirements

The impedance of the whole circuit, including the transformer and regulator, should not be so great that

sparkover is inhibited by a drop in the voltage, or distortion of the wave shape.

This condition is met when

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