EN 60099-1:1994

SLOVENSKI STANDARD
01-april-1998
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Surge arresters - Part 1: Non-linear resistor type gapped surge arresters for a.c. systems
Überspannungsableiter - Teil 1: Überspannungsableiter mit nichtlinearen Widerständen
und Funkenstrecken für Wechselspannungsnetze
Parafoudres - Partie 1: Parafoudres à résistance variable avec éclateurs pour réseaux à
courant alternatif
Ta slovenski standard je istoveten z: EN 60099-1:1994
ICS:
29.120.50 9DURYDONHLQGUXJD Fuses and other overcurrent
PHGWRNRYQD]DãþLWD protection devices
29.240.10 Transformatorske postaje. Substations. Surge arresters
Prenapetostni odvodniki
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEI
NORME
IEC
INTERNATIONALE
99-1
INTERNATIONAL
Troisième édition
STANDARD
Third edition
1991-05
Parafoudres
Partie 1:
Parafoudres à résistance variable avec
éclateurs pour réseaux à courant alternatif
Surge arresters
Part 1:
Non-linear resistor type gapped surge arresters
for a.c. systems
de reproduction réservés — Copyright — all rights reserved
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99-1 ©IEC
CONTENTS
Page
FOREWORD
INTRODUCTION
Clause
SECTION 1: GENERAL
1.1 Scope
15 1.2 Normative references
SECTION 2: DEFINITIONS
2.1 Surge arrester
17 2.2 Non-linear resistor type gapped arrester
17 2.3 Series gap of an arrester
17 2.4 Non-linear series resistor of an arrester
2.5 Section of an arrester 17
2.6 Unit of an arrester
2.7 Pressure-relief device of an arrester
Rated voltage of an arrester 17
2.8
Rated frequency of an arrester 2.9
17 2.10 Disruptive discharge
2.11 Puncture
2.12 Flashover
2.13 Sparkover of an arrester
2.14 Impulse
2.15 Rectangular impulse
2.16 Peak (crest) value of an impulse
2.17 Front of an impulse 19
2.18 Tail of an impulse
2.19 Full-wave voltage impulse
2.20 Chopped voltage impulse 19
2.21 Prospective peak (crest) value of a chopped voltage Impulse
2.22 Virtual origin of an impulse 19
2.23 Virtual front time of an impulse (T1 )
2.24 Virtual steepness of the front of an impulse
2) 21
2.25 Virtual time to half value on the tail of an impulse (T
2.26 Designation of an impulse shape
2.27 Standard lightning voltage impulse
2.28 Switching voltage impulse 21
2.29 Virtual duration of the peak of a rectangular impulse

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99-1 ©IEC
Clause Page
2.30 Virtual total duration of a rectangular impulse 21
2.31 Peak (crest) value of opposite polarity of an impulse
2.32 Discharge current of an arrester
2.33 Nominal discharge current of an arrester
2.34 Follow-current of an arrester 23
2.35 Residual voltage (discharge voltage) of an arrester
23 2.36 Power-frequency sparkover voltage of an arrester
2.37 Impulse sparkover voltage of an arrester
2.38 Front-of-wave impulse sparkover of an arrester
23 2.39 Standard lightning impulse sparkover voltage of an arrester
2.40 Time to sparkover of an arrester
2.41 Impulse sparkover-voltage/time curve
2.42 Prospective current
2.43 Type tests (design tests)
2.44 Routine tests
23 2.45 Acceptance tests
25 2.46 Protective characteristics of an arrester
2.47 Arrester disconnector
SECTION 3: IDENTIFICATION AND CLASSIFICATION
3.1 Arrester identification 25
3.2 Arrester classification
SECTION 4: STANDARD RATINGS
4.1 Standard voltage ratings
4.2 Standard rated frequencies
4.3 Standard nominal discharge currents
4.4 Service conditions
4.4.1 Normal service conditions
4.4.2 Abnormal service conditions
SECTION 5: REQUIREMENTS
5.1 Power-frequency sparkover voltage 29
5.2 Standard lightning impulse sparkover voltage
5.3 Front-of-wave impulse sparkover vo ltage 29
5.4 Switching impulse sparkover voltage
5.5 Lightning impulse residual voltage 31
5.6 31
Switching impulse residual voltage
5.7 High-current impulse withstand 31
5.8 Long-duration current withstand 31
5.9 Operating-duty 31
99-1 ©IEC – 7 –
Page
Clause
5.10 Pressure-relief
5.11 Disconnectors
5.11.1 Disconnector withstand
5.11.2 Disconnector operation
SECTION 6: GENERAL TESTING PROCEDURE
33 Test samples and measurements 6.1
6.2 Power-frequency voltage tests
6.3 Wet tests
6.4 Artificial-pollution tests
SECTION 7: ROUTINE AND ACCEPTANCE TESTS
7.1 Routine tests
7.2 Acceptance tests
SECTION 8: TYPE TESTS (DESIGN TESTS)
8.1 General
8.2 Power-frequency voltage sparkover tests
8.3 Voltage impulse sparkover tests
8.3.1 General 41
8.3.2 Standard lightning impulse sparkover test
8.3.3 Lightning impulse sparkover-voltage/time curve test
43 8.3.4 Front-of-wave impulse sparkover test
8.3.5 Switching impulse sparkover-voltage/time curve test
8.4 Measurement of residual voltage 47
8.4.1 Lightning impulse residual voltage
8.4.2 Switching impulse residual voltage
8.5 Current impulse withstand tests
8.5.1 General
8.5.2 High-current impulse test
8.5.3 Long-duration current impulse test 53
8.6 Operating-duty test 57
8.7 Pressure-relief tests 63
8.7.1 General
8.7.2 High-current pressure-relief tests
8.7.3 Low-current pressure-relief tests 67

99-1 ©IEC — 9 —
Page
Clause
8.8 Tests of arrester disconnectors
8.8.1 General
8.8.2 Current impulse withstand and operating-duty tests
69 8.8.3 Disconnector operation
Annexes
A Abnormal service conditions
77 B Typical information given with enquiries and tenders
Selection of the long-duration discharge class of heavy-duty
C
arresters
Typical circuit for a distributed-constant impulse generator for the
D
87 long-duration current impulse test according to 8.5.3
Typical circuit for operating-duty test according to 8.6 91
E
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99-1 © IEC
INTERNATIONAL ELECTROTECHNICAL COMMISSION
SURGE ARRESTERS
Part 1: Non-linear resistor type gapped surge arresters
for a.c. systems
FOREWORD
1) The formal decisions or agreements of the IEC 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.
2) They have the form of recommendations for international use and they are accepted by the National
Committees in that sense.
3) In order to promote international unification, the IEC expresses the wish that all National Committees
should adopt the text of the IEC recommendation for their national rules in so far as national conditions will
permit. Any divergence between the IEC recommendation and the corresponding national rules should, as
far as possible, be clearly indicated in the latter.
This part of International Standard IEC 99 has been prepared by IEC Technical Committee
No. 37: Surge arresters.
It forms the third edition of IEC 99-1 and supersedes the second edition issued in 1970.
The text of this part is based on the following documents:
Six Months' Rule Reports on Voting
37(BC)23 and 23A 37(BC)28
37(BC)34 37(BC)36
37(BC)35 37(BC)37
37(BC)39 37(BC)42
37(BC)40 37(BC)43
37(BC)41 37(BC)44
Full information on the voting for the approval of this part can be found in the Voting
Reports indicated in the above table.
Annex A forms an integral part of this part of IEC 99-1. Annexes B, C, D, and E are for
information only.
99-1 © IEC -13 -
INTRODUCTION
The major changes to the previous edition affect the following subjects:
measurement of residual voltage;
operating-duty test;
pressure-relief test;
standardized sparkover and residual voltages;
- addition of annex for information to be given on enquiries and tenders.
The changes introduced are limited to the agreed upon subjects. Additional work was not
considered due to the changing technology and the present limited use of gapped surge
arresters.
Appendix D of the second addition of this standard has been deleted and issued as a
separate Report, IEC 99-3.
The present developing gapless surge arresters using metal oxide resistors will be the
subject of the future IEC 99-4.
An application guide is under revision and will be published as IEC 99-5. It will supersede
IEC 99-1A.
IEC -15 -
99-1 ©
SURGE ARRESTERS
Part 1: Non-linear resistor type gapped surge arresters
for a.c. systems
SECTION 1: GENERAL
1.1 Scope
This part of International Standard IEC 99 applies to surge protective devices designed for
repeated operation to limit voltage surges on a.c. power circuits and to interrupt
icular, it applies to surge arresters consisting of single or
power-follow current. In part
multiple spark gaps in series with one or more non-linear resistors.
1.2 Normative references
The following standards contain provisions which, through reference in this text, constitute
provisions of this part of International Standard IEC 99. At the time of publication, the
editions indicated were valid. All standards are subject to revision, and pa rties to agree-
ments based on this pa rt are encouraged to investigate the possibility of applying the most
recent editions of the standards indicated below. Members of IEC and ISO maintain regis-
ters of currently valid International Standards.
IEC 60: High-voltage test techniques.
IEC 71-2: 1976, rt 2: Application guide.
Insulation co-ordination - Pa
rt
IEC 99-3: 1990, Surge arresters - Pa 3: Artificial pollution testing of surge arresters.
SECTION 2: DEFINITIONS
For the purpose of this part, the following definitions apply:
2.1 surge arrester*: A device designed to protect electrical apparatus from high
transient voltage and to limit the duration and frequently the amplitude of follow-current.
The term "surge arrester" includes any external series gap which is essential for the
proper functioning of the device as installed for service, regardless of whether or not it is
supplied as an integral part of the device.
NOTE - Surge arresters are usually connected between the electrical conductors of a network and earth
although they may sometimes be connected across the windings of apparatus or between electrical
conductors.
This ty
pe of equipment may be called "surge diverter" in some countries.

99-1 ©IEC - 17 -
2.2 non-linear resistor type gapped arrester: An arrester having a single or a
multiple spark-gap connected in series with one or more non-linear resistors.
2.3 series gap of an arrester: An intentional gap or gaps between spaced electrodes
in series with the non-linear series resistor or resistors of the arrester.
2.4 non-linear series resistor of an arrester: The pa rt of the surge arrester which, by
its non-linear voltage-current characteristics, acts as a low resistance to the flow of high
discharge currents thus limiting the voltage across the arrester terminals, and as a high
resistance at normal power-frequency voltage thus limiting the magnitude of follow-
current.
2.5 section of an arrester: A complete, suitably housed part of an arrester including
series gaps and non-linear series resistors in such a proportion as is necessary to
represent the behaviour of a complete arrester with respect to a particular test.
2.6 unit of an arrester: A completely housed part of an arrester which may be
connected in series with other units to construct an arrester of higher voltage rating. A
unit of an arrester is not necessarily a section of an arrester.
2.7 pressure-relief device of an arrester: A means for relieving internal pressure in
an arrester and preventing explosive shattering of the housing following prolonged
passage of follow-current or internal flashover of the arrester.
2.8 rated voltage of an arrester: The designated maximum permissible r.m.s. value
of power-frequency voltage between its terminals at which it is designated to operate
correctly. This voltage may be applied to the arrester continuously without changing its
operating characteristics.
2.9 rated frequency of an arrester: The frequency of the power system on which the
arrester is designed to be used.
2.10 disruptive discharge: The phenomena associated with the failure of insulation
under electrical stress which include a collapse of voltage and the passage of current; the
term applies to electrical breakdown in solid, liquid and gaseous dielectrics and
combinations of these.
NOTE - A disruptive discharge in a solid dielectric produces permanent loss of electrical strength; in a
liquid or gaseous dielectric the loss may be only temporary.
2.11
puncture: A disruptive discharge through a solid.
2.12 flashover: A disruptive discharge over a solid su rface.
2.13 sparkover of an arrester: A disruptive discharge between the electrodes of the
gaps of an arrester.
99-1 ©IEC - 19 -
2.14 impulse: A unidirectional wave of voltage or current which, without appreciable
oscillations, rises rapidly to a maximum value and falls, usually less rapidly, to zero with
small, if any, loops of opposite polarity.
The parameters which define a voltage or current impulse are polarity, peak value, front
time, and time to half value on the tail.
2.15 rectangular impulse: An impulse which rises rapidly to a maximum value, remains
substantially constant for a specified period, and then falls rapidly to zero.
The parameters which define a rectangular impulse are polarity, peak value, virtual
duration of the peak, and virtual total duration.
2.16 peak (crest) value of an impulse: The maximum value of voltage or current in an
impulse. In case of superimposed oscillations see 8.3.2, 8.5.2 e), and 8.5.3.2 c).
of an impulse which occurs prior to the peak.
2.17 front of an impulse: That part
2.18 tail of an impulse: That pa rt of an impulse which occurs after the peak.
2.19 full-wave voltage impulse: A voltage impulse which is not interrupted by
sparkover, flashover, or puncture.
2.20 chopped voltage impulse: A voltage impulse which is interrupted on the front,
peak, or tail by sparkover, flashover or puncture causing a sudden drop in the voltage.
2.21 prospective peak (crest) value of a chopped voltage impulse: The peak (crest)
value of the full-wave voltage impulse from which a chopped voltage impulse is derived.
2.22 virtual origin of an impulse: The point on a graph of voltage versus time or
current versus time determined by the intersection between the time axis at zero voltage
or zero current and a straight line drawn through two reference points on the front of the
impulse.
a) For voltage impulses with virtual front times equal to or less than 30 }ts, the
reference points are at 30 % and 90 % of the peak value.
b)
For voltage impulses with virtual front times greater than 30 its, the origin is
generally well defined and needs no artificial definition.
c)
For current impulses, the reference points are 10 % and 90 % of the peak value.
NOTE - This definition applies only when scales of both ordinate and abscissa are linear. See also note
to 2.23.
99-1 ©IEC – 21
2.23 virtual front time of an impulse (T1 ): The time, in microseconds, equal to:
a) for voltage impulses with front durations equal to or less than 30 µs, 1,67 times the
time taken by the voltage to increase from 30 % to 90 % of its peak value;
for voltage impulses with front durations greater than 30 ps, 1,05 times the time
b)
taken by the voltage to increase from 0 % to 95 % of its peak value;
for current impulses, 1,25 times the time taken by the current to increase from 10 %
c)
to 90 % of its peak value.
NOTE - If oscillations are present on the front, the reference points at 10 %, 30 %, 90 % and 95 % should
be taken on the mean curve drawn through the oscillations.
2.24 virtual steepness of the front of an impulse: The quotient of the peak value and
the virtual front time of an impulse.
2): The time interval
2.25 virtual time to half value on the tail of an impulse (T
between the virtual origin and the instant when the voltage or current has decreased to
half its peak value. This time is expressed in microseconds.
2.26 designation of an impulse shape: A combination of two numbers, the first
) and the second the virtual time to half value of the
representing the virtual front time (T1
tail (T2 1 2, both in microseconds, the sign "/" having no mathematical
). It is written as T /T
meaning.
2.27 standard lightning voltage impulse: An impulse voltage having a waveshape
designation of 1,2/50.
2.28 switching voltage impulse: An impulse having a virtual front time greater than
30 ps.
2.29 virtual duration of the peak of a rectangular impulse: The time during which the
amplitude of the impulse is greater than 90 % of its peak value.
2.30 virtual total duration of a rectangular impulse: The time during which the
amplitude of the impulse is greater than 10 % of its peak value. If small oscillations are
present on the front, a mean curve should be drawn in order to determine the time at
which the 10 % value is reached.
2.31 peak (crest) value of opposite polarity of an impulse: The maximum amplitude
of opposite polarity reached by a voltage or current impulse when it oscillates about zero
before attaining a permanent zero value.
2.32 discharge current of an arrester: The surge or impulse current which flows
through the arrester after a sparkover of the series gaps.
2.33 nominal discharge current of an arrester: The peak value of discharge current,
having an 8/20 waveshape, which is used to classify an arrester. It is also the discharge
current which is used to initiate follow-current in the operating duty test.

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99-1 ©IEC
2.34 follow-current of an arrester: The current from the connected power source
which flows through an arrester following the passage of discharge current.
2.35 residual voltage (discharge voltage) of an arrester: The voltage that appears
between the terminals of an arrester during the passage of discharge current.
power-frequency
the
2.36 power-frequency sparkover voltage of an arrester: The value of
voltage measured as the peak value divided by■ applied between the terminals of an
arrester, which causes sparkover of all the series gaps.
2.37 impulse sparkover voltage of an arrester: The highest value of voltage attained
before sparkover during an impulse of given waveshape and polarity applied between the
terminals of an arrester.
2.38 front-of-wave impulse sparkover of an arrester: The impulse sparkover voltage
obtained on the wavefront the voltage of which increases linearly with time.
2.39 standard lightning impulse sparkover voltage of an arrester: The lowest
prospective peak value of a standard lightning voltage impulse which, when applied to an
arrester, causes sparkover on every application.
2.40 time to sparkover of an arrester: The time interval between virtual origin and the
instant of sparkover of the arrester. The time is expressed in microseconds.
2.41 Impulse sparkover-voltage/time curve: A curve which relates the impulse
sparkover voltage to the time to sparkover.
2.42 prospective current: The current which would flow at a given location in a circuit
if it were short-circuited at that location by a link of negligible impedance.
2.43 type tests (design tests): Tests which are made upon the completion of the
development of a new arrester design to establish representative performance and to
demonstrate compliance with this part of the standard. Once made, these tests need not
be repeated unless the design is so changed as to modify its performance.
rts and materials as required
2.44 routine tests: Tests made on each arrester or on pa
to ensure that the product meets the design specifications.
2.45 acceptance tests: Selected tests which are made when it has been agreed
between the manufacturer and the purchaser that the arresters or representative samples
of an order are to be tested.
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99-1 ©IEC
2.46 protective characteristics of an arrester: The combination of the following:
a) lightning impulse sparkover-voltage/time curve as determined in 8.3.3;
the residual-voltage/discharge-current curve as determined in clause 8.4;
b)
for 10 000 A arresters rated 100 kV and higher, the switching-voltage impulse
c)
sparkover-voltage/time curve as determined in 8.3.5.
2.47 arrester disconnector: A device for disconnecting an arrester from the system in
the event of arrester failure to prevent a persistent fault on the system and to give visible
indication of the failed arrester.
NOTE - Clearing of the fault current through the arrester during disconnection generally is not a function
of the device, and it may not prevent explosive shattering of the housing following internal flashover of the
arrester on high fault currents.
SECTION 3: IDENTIFICATION AND CLASSIFICATION
3.1 Arrester identification
Surge arresters shall be identified by the following minimum information which shall
appear on the rating plate (nameplate):
rated voltage;
rated frequency, if other than one of the standard frequencies, see 4.2;
nominal discharge current (specifying for the 5 000 A arrester whether series A or
series 6*, and for the 10 000 A arrester, whether light or heavy duty);
- long-duration discharge class (for 10 000 A heavy-duty arresters), see 8.5.3.2;
- pressure-relief class (for arresters fitted with pressure-relief devices), see 8.7.2;
- manufacturer's name or trademark, type and identification;
- year of manufacture.
NOTES
1 Information to be given by inquiry or tender may be guided by annex B.
2 In some countries, it is customary to classify arresters as:
station for 10 000 A arresters;
intermediate (series A) or distribution (series B) for 5 000 A arresters`;
secondary for 1 500 A arresters.
are based
Series A arresters are based on performance characteristics in practice in all countries. Series B arresters
on performace characteristics in Canada and the United States of America and other countries.

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99-1 ©IEC
3.2 Arrester classification
Surge arresters are classified by their standard nominal discharge currents and they shall
ormance characteristics listed in table 3.
meet at least the test requirements and pe rf
Arresters having more favorable performance characteristics or lower protective levels
than those required in this part shall be considered to have met this standard.
SECTION 4: STANDARD RATINGS
4.1 Standard voltage ratings
Standard values of rated voltages for arresters shall be as listed in Table 1.
Table 1 - Standard voltage ratings (kV r.m.s.)
36 75 126
0,175 6 18
0,280 7,5 21 39 84
42 96 150
0,500 9 24
10,5 27 51 102
0,660
108 186
3 12 30 54
60 120 198
4,5 15 33
For voltage ratings above 198 kV, the arrester ratings shall be divisible by 6.
4.2 Standard rated frequencies
The standard rated frequencies are 50 Hz and 60 Hz.
4.3 Standard nominal discharge currents
The standard nominal discharge currents are: 10 000 A, 5 000 A, 2 500 A and 1 500 A,
having an 8/20 waveshape.
NOTE - For the 10 000 A arrester (see 3.2) there are two types, light-duty and heavy-duty, which are
differentiated by the amplitude of the long-duration impulse current which they are capable of withstanding.
See 8.5.3.
4.4 Service conditions
4.4.1 Normal service conditions
Surge arresters which conform to this part of the standard shall be suitable for operation
under the following normal service conditions:
a) ambient temperature within the range of -40 °C to +40 °C;
b) altitude not exceeding 1 000 m;

99-1 ©IEC - 29 -
c) frequency of the a.c. power supply not less than 48 Hz and not exceeding 62 Hz;
power-frequency voltage applied between the line and earth terminals of the
d)
arrester not exceeding its rated voltage.
4.4.2 Abnormal service conditions
Arresters subjected to other than normal application or service conditions may require
special consideration in manufacture or application and each case should be discussed
with the manufacturer. See annex A: Abnormal service conditions and annex C: Selection
of the long-duration discharge class of heavy-duty arresters.
SECTION 5: REQUIREMENTS
5.1 Power-frequency sparkover voltage
For all classes of surge arresters, except the 10 000 A heavy-duty class, the lowest value
of power-frequency sparkover voltage shall be not less than 1,5 times the rated voltage of
the arrester. For the 10 000 A heavy-duty class arresters, the lowest value of power-
frequency sparkover is subject to agreement between the manufacturer and the
purchaser.
power-frequency sparkover test is the minimum
It should be noted that the dry
requirement for routine tests to be made by the manufacturer as specified in 6.1.
5.2 Standard lightning impulse sparkover voltage
With the lightning impulse voltage specified in 8.3.2 and table 8 the arrester shall
sparkover on every impulse of a series of five positive and five negative impulses.
If in either series of five impulses, the gaps fail to sparkover once only, an additional ten
impulses of that polarity shall be applied and the gaps shall sparkover on all of these
impulses.
5.3 Front-of-wave impulse sparkover voltage
With voltage impulses having a virtual steepness of front equal to that specified in table 8,
the sparkover voltage shall not exceed the value given in table 8. This is verified
according to 8.3.4 by a test with five positive and five negative impulses, or by using the
lightning impulse sparkover voltage/time curve described in 8.3.3.
5.4 Switching impulse sparkover voltage
This voltage is determined on 10 000 A arresters having a rated voltage above 100 kV
according to 8.3.5. No limits for the maximum switching impulse sparkover voltage have
been specified.
99-1 ©IEC -31 -
5.5 Lightning impulse residual voltage
The residual voltage for nominal discharge current is determined from the curve drawn
according to 8.4.1. This voltage shall not be higher than the maximum residual voltage of
the arrester specified in table 8.
5.6 Switching impulse residual voltage
This requirement applies to 10 000 A, light or heavy duty, or 5 000 A series A arresters,
having a rated voltage above 100 kV and with active gaps (an active gap is defined as a
gap which generates at least 100 V/kV of rating during the switching impulse test).
The switching impulse residual voltage determined according to 8.4.2 shall not exceed
the value indicated in table 8.
5.7 High-current impulse withstand
Arresters shall withstand the high-current impulse test according to 8.5.2. The average
dry power-frequency sparkover voltage (see 8.2) recorded before and after this test shall
not have changed by more than 10 %. Examination of the test samples shall reveal no
evidence of puncture or flashover of the non-linear resistors or significant damage to the
series gaps or grading circuit.
5.8 Long-duration current withstand
Arresters shall withstand the long-duration current impulse test according to 8.5.3 and
tables 5 (heavy-duty) or 6 (light-duty). The average dry power-frequency sparkover
voltage of 8.2 recorded before and after this test shall not have changed by more
than 10 %.
5.9 Operating-duty
Arresters shall withstand the operating-duty test described in 8.6 during which:
- follow-current shall be established by each test impulse and the test sample shall
interrupt the follow-current each time;
- final interruption of the follow-current shall occur at least at the end of the half-cycle
following that in which the impulse is applied.
Following the operating-duty test and after the test sample has cooled to near ambient
temperature, the power-frequency sparkover test and the residual voltage test which were
made before the operating-duty test are repeated and the average values shall not have
changed by more than 10 %.
5.10 Pressure-relief
When an arrester is fitted with a pressure-relief device, the failure of the arrester shall not
cause explosive shattering of the housing. This is verified by the tests described in 8.7.
The test sample is deemed to have passed the test if the housing remains intact or if it
breaks sufficiently non-explosively and if all parts of the sample are contained within the
circular enclosure.
99-1 © IEC - 33 -
5.11 Disconnectors
5.11.1 Disconnector withstand
When an arrester is fitted or associated with a disconnector, this device shall withstand,
without operating, each of the following tests:
- high-current impulse test (8.8.2.1);
long-duration current impulse test (8.8.2.2);
- operating-duty test (8.8.2.3).
5.11.2 Disconnector operation
The time delay for the operation of the disconnector is determined for three values of
10 % according to 8.8.3. There shall be clear
current: 20 A, 200 A and 800 A r.m.s., f
ective and permanent disconnection by the device.
evidence of eff
SECTION 6: GENERAL TESTING PROCEDURE
and measurements
6.1 Test samples
Except. when specified otherwise, all tests shall be made on the same arresters, arrester
sections or arrester units. They shall be new, clean, completely assembled, and arranged
as nearly as possible as in service and shall be fitted with grading rings, if used.
The measuring equipment shall meet the requirements of IEC 60, and the values obtained
shall be accepted as accurate for the purpose of compliance with the relevant test
clauses.
6.2 Power-frequency voltage tests
All power-frequency tests shall be made with an alternating voltage having a frequency
waveshape.
sinusoïdal
between the limits of 48 Hz and 62 Hz, and an approximately
6.3 Wet tests
This clause is in agreement with the recommendations on wet tests contained in IEC 60.
It is generally recognized that wet tests are not intended to reproduce actual operating
conditions but to provide a criterion based on accumulated experience that satisfactory
service operation will be obtained.
The test shall give reproducible results in the same and in different laboratories.
The tests shall be made only on arresters designed for use outdoors. Where such a test
is specified, the test object shall be subjected to a spray of water of prescribed resistivity
provided by a properly located nozzle or nozzles. The spray, consisting of small drops,
shall fall on the test object at an angle approximately 45° to the vertical as determined by
visual obse
rvation or by measurements of the vertical and horizontal components of the
precipitation rate.
99-1 © IEC - 35 -
The vertical component of the spray shall be measured with a collecting vessel having a
ical and horizontal
horizontal opening of area 100 cm 2 to 750 cm 2. When both vert
components are required, the horizontal component will be measured with a collecting
vessel having a similar vertical opening directed towards the nozzles. The collecting
vessel shall be located on the side of the test object facing the nozzles and as close to the
test object as is possible without collecting splashes from it.
For test objects of height greater than 50 cm, measurements of the rate of precipitation
shall be made near the ends and the middle and values obtained for any one position shall
not differ by more than 25 % from the average for the three positions; for test objects of
50 cm height or less, the measurement shall be made near the middle only.
The test object shall be sprayed for at least 1 min before the application of voltage. (Alter-
natively, more consistent results may be obtained if the test object is thoroughly wetted
with water of the prescribed resistivity and temperature before the application of voltage.)
The characteristics of the spray shall be as given in table 2. Two sets are given, one in
general accordance with European practice, the other with practice in Canada and in the
United States of America. It is recommended that each National Committee use only one
of these practices.
Table 2 - Parameters for wet tests
Practice
Characteristics
Canada and
Europe
United States of America
1.
Precipitation rate
(vertical component) 3 mm/min ±10 % 5 mm/min ±10 %
2. Resistivity of water 10 000 S2 • cm ±10 % 17 800 S2 • cm ±10 %
3. Temperature of water Ambient temperature ±15 °C Ambient temperature ±15 °C
4. Type of nozzle See figure 1 x See figure 2
5.
Water pressure See figure 1 See figure 2f
*
Figure numbers refer to IEC 60 (1962).
6.4 Artificial-pollution tests
Artificial-pollution tests are described in IEC 99-3. This report gives the basic principles of
artificial-pollution testing of non-linear resistor type gapped surge arresters, together with
details of pollutant compositions and methods of application and the test procedures
associated with each mode of pollution.

99-1 ©IEC - 37 -
SECTION 7: ROUTINE AND ACCEPTANCE TESTS
7.1 Routine tests
The minimum requirement for routine tests to be made by the manufacturer shall be the
dry power-frequency sparkover test, (see 8.2). If the arrester is constructed with a number
of self-contained units, the tests may be made on the units.
7.2 Acceptance tests
When the purchaser specifies acceptance tests in the purchase agreement, the following
tests shall be made on the nearest highest whole number to the cube root of the number
of arresters to be supplied:
a) d power-frequency voltage sparkover test on the complete arrester (see 8.2);
ry
standard lightning impulse sparkover test on the complete arrester (see 8.3.2);
b)
only when specifically agreed between the manufacturer and the purchaser,
c)
residual voltage shall be determined at a discharge current of not less than 0,25 times
the nominal discharge current on the complete arrester or on each of the individual
units of the arrester or sections (see 8.4). When the tests are made on sections, the
tests shall apply to all types of elements of the arrester, and the elements of the tested
sections shall be distinct.
Any alteration in the number of samples or type of tests shall be specifically negotiated
between the manufacturer and the purchaser.
SECTION 8: TYPE TESTS (DESIGN TESTS)
8.1 General
The following type tests shall be made as far as required in table 3:
1) Measurement of power-frequency sparkover voltage (8.2).
2) Standard lightning impulse sparkover test (8.3.2).
3) Lightning impulse sparkover-voltage/time curve test (8.3.3).
4) Measurement of front-of-wave impulse sparkover-voltage (8.3.4).
5) Switching impulse sparkover-voltage/time curve test (8.3.5).
6)
Measurement of residual voltages (8.4).
7) Current impulse withstand tests (8.5).
8) Operating-duty test (8.6).
9) Pressure-relief tests (when the arrester is fitted with a pressure-relief
device) (8.7).
10)
Tests of arrester diisconnectors (8.8).

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99-1 ©IEC
Table 3 - Arrester classification and test requirements
Standard nominal discharge current
A
10 000 5 000
10 000
Heavy-duty Light-duty
2 500 1 500
Series A Series B
Up to 0,660
3 to 138 3 to 39 Up to 36
1. Voltage ratings (kV r.m.s.) 3 or more 3 or more
2. Power-frequency voltage
8.2
8.2 8.2 82 82
sparkover test 8.2
8.32,
8.32, 82.2, 8.3.2,
3. Standard lightning-voltage 8.3.2,
table 8, table 8, Not required
impulse sparkover test table 8, table 8, table 8,
column 3 column 3 column 3 column 3
column 2
4. Front-of-wave-voltage
82.4 8.3.4 8.3.4
sparkover test 8.3.4 8.3.4 8.3.4
5. Switching impulse
Not Not Not
sparkover-voltage/time 8.3.5 8.3.5 Not
required
(above required required required
curve test (above
100 kV) 100 kV)
8.4,
6. 8.4, 8.4, 8.4, 8.4,
Residual voltage test
table 8, 8.4
table 8, table 8, table 8, table 8,
column 9 column 9 column 9
column 8 column 9
7. Current impulse withstand:
8.52 8.52 8.5.2
a) High-current 8.52 8.52 8.5.2
8.5.3.3 8.5.3.3 Not required
b) Long-duration 8.5.3.2 8.5.3.3 8.5.3.3
8.6 8.6 8.6 8.6 8.6
8. Operating-duty test 8.6
Not Not Not
9. Pressure-relief test (when
required
8.7 8.7 8.7 appropriate required
fitted with relief device)
Not Not
10. Arrester disconnector
8.8 8.8 8.8
(when fitted) appropriate appropriate 8.8
The required number of samples is specified in the individual subclauses. Arresters which
differ only in methods of mounting or arrangement of the supporting structure, and which
rformance
are otherwise based on the same components with similar construction and pe
characteristics are considered to be of the same design.
Tests 1, 2, 3, 4 and 5 in the foregoing list shall be made on the same samples; these
same samples may also be used for test 6 and then shall be considered to have been
made on new arresters. For tests 7, 8, 9 and 10 see the recommendations in the specific
subclauses.
– 41 –
99-1 © IEC
8.2 Power-frequency voltage sparkover tests
Dry and wet tests shall be made in accordance with 7.1, 7.2, 7.3 and 8.1 on three samples
of complete arresters of each voltage rating tested. The performance for other voltage
ratings of the same design (as defined in 8.1) within ±25 % (or 6 kV, whichever is greater)
of a test sample rating can be determined by adjusting the voltage level in proportion to
the voltage ratings. The voltage applied to the arrester shall be switched on at a value low
enough to avoid sparkover of the arrester by the resulting switching surge and raised
rapidly at a uniform rate until sparkover of the series gap occurs. The time during which
the voltage may exceed the rated voltage of the arrester shall be in the range of 2 s to 5 s
when testing arresters using grading resistors which may be damaged by overheating if
the applied voltage exceeds the rated voltage for too long. After sparkover, the test
voltage shall be switched off as rapidly as possible, preferably by automatic tripping and in
any case within 0,5 s. If it is difficult to measure the rapidly increasing voltage with an
indicating type of instrument, a high speed recorder or an oscillograph shall be used. It is
recommended that the manufacturer be consulted about the permissible test procedure.
The load imposed on the testing circuit by a surge arrester having non-linear grading
resistors of high conductivity gives rise to harmonics, and the test-circuit must have a
sufficiently low impedance to maintain the waveform of the voltage across the specimen
within the limits specified in the current edition of IEC 60.
The voltage shall be applied not less than five times, with an interval of about 10 s
between successive applications.
The average sparkover value of the five tests is adopted as the power-frequency spark-
over voltage for purposes of a comparison of tests made before and after other type tests.
8.3 Voltage impulse sparkover tests
8.3.1 General
These tests shall be made in accordance with 7.1 and 8.1 on the same test samples of
complete arresters used for the power-frequency sparkover tests described in 8.2. Spark-
over values and voltage/time curves for other voltage ratings of the same design as
defined in 8.1 within ±25 % (or 6 kV, whichever is greater) of a test sample rating can be
determined by adjusting the voltage level in proportion to the voltage ratings.
8.3.2 Standard lightning impulse sparkover test
With the test sample arrester in the circuit, the impulse generator is adjusted to give a
1,2/50 voltage waveshape and the peak value specified in table 8. With this adjustment,
five positive and five negative impulses shall be applied to the test sample and the series
gaps of the arrester shall spark over on every impulse. If in either series of five impulses,
the gaps fail to spark over once only, an additional ten impulses of that polarity shall be
applied and the gaps must spark over on all of these impulses.

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99-1 ©IEC
The time interval between the start of the wave and the instant of sparkover is immaterial
in this test.
The tolerances on the adjustment of the testing equipment shall be such that the
measured values lie within the following limits:
for the specified peak values;
a) between 97 % and 100 %
b) from 0,85 ps to 1,6 µs for the virtual duration of the wavefront;
c) from 40 µs to 60 µs for the time to half value on the wavetail.
Oscillations on the first part of the wavefront (below 50 %) shall not exceed 10 % of the
peak value. Small oscillations near the peak of the impulse are permissible provided that
their amplitude is less than 5 % of the peak value. Measurement shall be made at the
peak of the oscillations.
8.3.3 Lightning impulse sparkover-voltage/time •curve test
This test shall be made using positive or negative impulses, whichever result in the higher
sparkover voltages. Data for plotting the curve are obtained by applying 1,2/50 voltage
impulses of successively increasing amplitudes in steps beginning at a voltage below
arrester sparkover and increasing the generator charging voltage (and thus the
prospective peak voltage) until the virtual steepness of the front of the impulse equals that
specified in table 8. Alternatively, for times to sparkover of less than 1,2 µs, the data may
be obtained by reducing the virtual front time of the impulse. For times to sparkover of
less than 1,2 ps, the test impulse shall have a substantially uniform rate of rise to arrester
sparkover.
For each sparkover, the highest voltage attained before sparkover shall be plotted against
the time to sparkover measured from virtual origin. Enough data points shall be obtained
to define clearly the curve which should be drawn through the maximum sparkover values.
8.3.4 Front-of-wave impulse sparkover test
Using a voltage impulse with a virtual steepness of front equal to that specified in table 8,
five positive and five negative impulses shall be applied to the arrester and the sparkover
voltage is determined from voltage-time oscillograms made during each test. On none of
the impulses shall the sparkover voltage exceed the value given in the appropriate column
of table 8.
It is permissible to use the point of intersection of the curve specified in 8.3.3 with a line
representing the virtual steepness of front specified in table 8 for determining the
maximum front-of-wave sparkover voltage of the test sample arrester for comparison with
the maximum permissible value given in table 8 provided there are at least five positive
and five negative spar
...