SIST IEC 60353:1997

Line traps for a.c. power systems

Applies to line traps inserted into high-voltage a.c. transmission lines that prevent undue loss of carrier signal power in the range 30 kHz to 500 kHz under all power system conditions, and that minimize interference from carrier signalling systems on adjacent transmission lines.

Circuits-bouchons pour réseaux alternatifs

S'applique aux circuits-bouchons insérés dans les lignes de transmission à haute tension à courant alternatif pour éviter toute perte excessive de puissance des signaux à courant porteur, spécialement dans la gamme comprise entre 30 kHz et 500 kHz, quelle que soit la configuration du réseau et pour minimiser les interférences pouvant provenir de courants porteurs sur des lignes électriques adjacentes.

Line traps for a.c. power systems

General Information

• Status: Published
• Publication Date: 31-Jul-1997
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: PSE - Power systems management
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Aug-1997
• Due Date: 01-Aug-1997
• Completion Date: 01-Aug-1997
• Ref Project: IEC 60353 - Definition and value of L, T

Standards Content (Sample)

SLOVENSKI STANDARD
SIST IEC 60353:1997
01-avgust-1997
Line traps for a.c. power systems
Line traps for a.c. power systems
Circuits-bouchons pour réseaux alternatifs
Ta slovenski standard je istoveten z: IEC 60353
ICS:
29.240.20 Daljnovodi Power transmission and
distribution lines
SIST IEC 60353:1997 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST IEC 60353:1997

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SIST IEC 60353:1997
NORME CEI
INTERNATIONALE IEC
60353
INTERNATIONAL
Deuxième édition
STAN DARD
Second edition
1989-10
Circuits-
bouchons pour réseaux alternatifs
Line traps for a.c. power systems
© IEC 1989
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 any form or by any means, electronic or mechanical,
procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in
copie et les
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: [phone] e-mail: [e-mail] IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
W
PRICE CODE
International Electrotechnical Commission
IEC
Mert Pour prix, voir catalogue en vigueur
• • For price, see current catalogue

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SIST IEC 60353:1997
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353©IEC
CONTENTS
Page
FOREWORD 7
PREFACE 7
SECTION ONE- GENERAL
Clause
1. Scope 11
2. Object 11
3. Symbols used in this standard 11.
4. Service conditions 13
4.1 Standard conditions 13
4.2 Altitude 13
13
4.3 Ambient temperature
4.4 Power frequency 13
13
4.5 Wave shape
4.6 Unusual' service conditions 13
SECTION TWO - DEFINITIONS
5. General 15
5.1 Main coil 15
5.2 Tuning device 17
5.3 Protective device 17
5.4 Carrier-frequency characteristics 17
5.5 Currents 21
SECTION THREE - REQUIREMENTS
6. General requirements 21
6.1 Main coil 21
6.2 Tuning device 23
6.3 Protective device 23
7. Blocking requirements 25
8. Continuous service requirements 25
9. Ability to withstand rated short-time current 27
9.1 Mechanical strength 27
9.2 Thermal behaviour 27
10. Insulation level 27
10.1 Insulation across a line trap 27
10.2 System voltage insulation 29
10.3 Line traps for use at high altitudes 29

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SIST IEC 60353:1997
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353 ©IEC
Page
Clause
29
11. Radio influence voltage (RIV)
31 12. Power losses
31
13. Tensile strength of suspension system
33
14. Accessories
33
14.1 Bird barriers
33
14.2 Terminals
SECTION FOUR - RATING PLATES
33
15. Rating plate of the main coil
33
16. Rating plate of tuning device
35 Rating plate information for protective device
17.
SECTION FIVE - TESTS
35
18. General conditions
35
19. Tests
35
Temperature rise test (type test) 19.1
39
Measurement of radio influence voltage (type tests)
19.2
39 19.3 Insulation tests
43
Short-time current tests (type tests) 19.4
Measurement of the rated inductance of the main coil
19.5
47
(type and routine test)
Measurement of power frequency inductance of the main coil
19.6
47
(type and routine test)
Measurement of blocking resistance and blocking impedance
19.7
(type and routine test)  49
Measurement of tapping loss and tapping loss based on
19.8
'49
the blocking resistance (type and routine test)
SECTION SIX RECOMMENDED VALUES
51 20. Rated inductance of main coil (mH)
51
21. Rated continuous current (A)
51
22. Rated short-time current (kA r.m.s.)
Co-ordination of rated continuous current and rated
23.
51
short-time current
55
APPENDIX A
converter
APPENDIX B - Line traps associated with a.c./d.c.
63
stations
70
Figures

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SIST IEC 60353:1997
353 ©IEC -7
INTERNATIONAL ELECTROTECHNICAL
COMMISSION
LINE TRAPS FOR A.C. POWER 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.
PREFACE
This standard has been prepared by IEC Technical Committee No. 57:
Telecontrol, teleprotection and associated telecommunications for electric
power systems.
It forms the second edition of IEC Publication 353 and replaces the first
edition, 1971.
The text of this standard is based on the following documents:
Six Months' Report Two Months'
Report
Rule on Voting Procedure on Voting
57(CO)23 57(CO)28 57(CO)43 57(CO)48
Full information on the voting for the approval of this standard can be
found in the Voting Reports indicated in the above table.

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SIST IEC 60353:1997
353 © IEC
The following publications are quoted in this standard:
Publication Nos. 50: International Electrotechnical Vocabulary (IEV).
71-1 (1976): Insulation co-ordination, Part 1: Terms, defini-
tions, principles and rules.
76-2 (1976): Power transformers, Part 2: Temperature rise.
85 (1957): Thermal evaluation and classification of elec-
trical insulation.
99: Lightning arresters.
99-1 (1970): Part 1: Non-linear resistor type arresters for
a.c. systems.
129 (1975): Alternating current disconnectors (isolators) and
earthing switches.
270 (1981): Partial discharge measurements.
353 (1971): Line traps.
383 (1976): Tests on insulators of ceramic material or glass
for overhead lines with a nominal voltage greater
than 1 000 V.
518 (1975): Dimensional standardization of terminals for
high-voltage switchgear and controlgear.

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SIST IEC 60353:1997
353 © IEC - 11 -
LINE TRAPS FOR A.C. POWER SYSTEMS
SECTION ONE - GENERAL
Scope
1.
This standard applies to line traps inserted into high voltage a.c.
transmission lines to prevent undue loss of carrier signal power,
typically in the range 30 kHz to 500 kHz, under all power system
conditions and to minimize interference from carrier signalling systems
on adjacent transmission lines. It does not apply to inductors which
are connected to high voltage transmission lines for other purposes.
Line traps associated with a.c./d.c. converter stations require to
operate under power system conditions which are not defined in this
standard.
The information which has been provided in Appendix B to assist in
the specification of such line traps is of an advisory nature only and
does not form part of this standard.
Object
2.
The object of this standard is to establish definitions, requirements,
methods of testing and ratings for line traps.
3. Symbols used in this standard
Please note that the symbols used only in the appendixes are not
included.
a = temperature coefficient
At = tapping loss
AtR = tapping loss based on blocking resistance
C = self-capacitance
r
eft bandwidth based on blocking impedance
Afl, =
bandwidth based on blocking resistance
=
Af1R' Af2R
centre frequency
f
c
= centre frequency based on blocking resistance
fcR
= rated power frequency
f P N
/ N = continuous rated current
asymmetrical peak value of first half cycle of short-
=
/ km
circuit currents
I steady state component of short-circuit currents
kN

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J short-circuit current density
L =
power-frequency inductance of the main coil
L = true inductance of the main coil
= rated inductance of the main coil
L tN
R b = blocking resistance
T = inverse of temperature coefficient
U
= voltage developed across the line trap at rated power
frequency by the rated short-time current
U maximum system voltage
m
= blocking impedance
e = temperature
4. Service conditions
4.1 Standard conditions
The standard conditions shall be those for outdoor service. A line
trap shall be capable of carrying out its required function whether
exposed to sunshine, rain, fog, frost, snow, ice, etc. Cases arising
from severe atmospheric conditions such as salt spray, industrial
pollution, etc., shall be covered by special agreement between
manufacturer and purchaser.
4.2 Altitude
A line trap shall not be used at an altitude greater than 1 000 m
above sea-level without special agreement with the manufacturer and
measure being taken to ensure its suitability.
4.3 Ambient temperature
Unless otherwise agreed between manufacturer and purchaser, a line
trap shall not be used beyond an air temperature range of -40 °C to
+40 °C.
4.4 Power frequency
This standard applies only to power system frequencies between
15 Hz and 60 Hz inclusive.
4.5 Wave shape
For the purpose of this standard, power-frequency currents and
voltages shall be considered to have wave shapes which are approxi-
mately sinusoidal.
4.6 Unusual service conditions
In the event that the requirements of Sub-clauses 4.2 and 4.3
cannot be met, reference should be made to Clause 8 and
Sub-clause 10.3.

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SIST IEC 60353:1997
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SECTION TWO - DEFINITIONS
For the purpose of this standard, the following definitions shall
apply. Other terms used have the meanings attributed to them in IEC
Publication 50, unless otherwise stated.
5. General
A line trap, consisting of a main coil in the form of an inductor, a
tuning device and a protective device, is intended for insertion in a
high voltage power transmission line between the point of connection of
carrier-frequency signals and adjacent power system elements such as
busbars, transformers, etc. The tuning device connected across the
main coil ensures, with proper adjustment, that the line trap presents
a relatively high impedance at one or more carrier frequencies or
carrier-frequency bands, whereas the impedance of the line trap at
power frequencies is negligible. A line trap may also be used to limit
the loss of carrier-frequency at a power system tee point.
Untuned line traps are sometimes used where there is a requirement
for a wideband coupling. However, attention is drawn in Sub-
clause 5.4 to the possibility of series resonance occurring under
certain power system conditions, leading to an unacceptable shunting
effect of the carrier-frequency signal path.
Figures la and lb show the circuit diagrams of typical line traps.
5.1 Main coil
An inductor which carries the power-frequency current of the high
voltage transmission line.
5.1 .1
Apparent inductance
The reactance of the main coil divided by the angular frequency at
which the reactance was determined, uncompensated for the effect of
self-capacitance.
5.1 .2
Power-frequency inductance
The inductance L at power-frequency.
5.1.3
True inductance
The self-inductance Lt of the main coil at a specified frequency
compensated for the effect of self-capacitance.

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SIST IEC 60353:1997
353©IEC -17-
5.1.4 Rated inductance
The value of true inductance L tN at 100 kHz.
5.1 .5 Self-capacitance
which, together with the true inductance, causes
The capacitance C
the main coil to "resonate at self-resonant frequency. The self-
capacitance is a function of the design of the main coil.
5.1.6 Self-resonant frequency
The frequency at which the combination of true inductance and self-
capacitance becomes resonant.
5.1.7 Resistance of main coil
The value of resistance at d.c. current.
5.1 .8 Temperature coefficient
The ratio a of the change in resistivity due to a change in tempera-
ture of 1 °C relative to the resistivity at 0 °C.
5.1.9 Rated power frequency
The frequency f of the high voltage power transmission system to
pN
which the line trap is connected.
Tuning device
5.2
The combination of capacitors, inductors and resistors connected
across the main coil. All of these components may not be present at
any one time, depending on the carrier-frequency requirements of the
line trap.
5.3 Protective device
The device connected across the main coil and tuning device which
prevents the line trap from being damaged by transient overvoltages
which may occur across it. Additional protective devices may be fitted
to protect individual components of the tuning device.
Carrier-frequency characteristics
5.4
Power system elements such as transformers, busbars, lines, etc.,
represent an impedance connected beyond the line trap between line
and earth. This impedance, in series with the impedance of the line
trap, may shunt the carrier-frequency signal path. The loss in signal
power resulting from this shunt depends upon the vectorial sum of the
two impedances.

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SIST IEC 60353:1997
353 © IEC - 19 -
In the most unfavourable case, the reactive components of the two
impedances may neutralise each other thus reducing the total shunt
impedance to an unacceptably low value.
In order to eliminate this possibility and the further possibility of
varying shunting effects arising out of power system switching, the
blocking impedance of the line trap should always include a resistive
component. The line trap performance can therefore be assessed in
terms of its resistive component only.
Blocking impedance
5.4.1
The complex impedance Z b of the complete line trap within a
specified carrier-frequency range.
5.4.2 Blocking resistance
of the blocking impedance.
The resistive component R b
5.4.3 Tapping loss
The loss At sustained by a carrier-frequency signal due to the finite
blocking ability of the line trap. It is defined in terms of the ratio of
the signal voltages across an impedance equal to the characteristic
impedance of the transmission line with and without the shunt
connection of the line trap and is expressed in decibels.
Tapping loss based on blocking resistance
5.4.4
expressed in decibels, sustained by a carrier-
The loss
AtR,
frequency signal due to the shunt connection of the resistive com-
ponent of the line trap impedance.
5.4.5 Bandwidth based on blocking impedance
The carrier-frequency bandwidth Af 1 or oft within which the module
of the blocking impedance does not fall below a specified value or the
tapping loss At does not exceed a specified value (see Figures 2a
and 2b).
5.4.6 Bandwidth based on blocking resistance
The bandwidth and based on the resistive component
6f1R Af2R
expressed in terms of the blocking resistance (see Figures 2a and 2b).
5.4.7 Centre frequency
The geometric mean frequency of the bandwidth limit frequencies.
f

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SIST IEC 60353:1997
353 © IEC -21 -
5.4.8 Centre frequency based on blocking resistance
The geometric mean frequency derived from the bandwidth limit
fcR
frequencies based on blocking resistance. For band-tuned line traps fc
is equivalent to
fcR•
5.4.9 Q factor
The ratio of reactance to resistive component of the main coil at a
specified frequency.
5.5 Currents
5.5.1 Continuous rated current
/N
The maximum r.m.s. value of the current flowing continuously
through the main coil at specified power frequency which does not
cause the specified temperature rise limits to be exceeded.
5.5.2 Rated short-time current
The r.m.s. value of the steady state component of the short-circuit
current /kN flowing through the main coil for a specified time without
causing thermal or mechanical damage. The asymmetrical peak
value /km of the first half-cycle of the short-circuit current shall be
assumed to be 2.55 times the r.m.s. value.
5.5.3 Emergency overload current
The amount of current which the main coil can sustain for a
specified period without suffering permanent damage or a significant
reduction in useful life.
SECTION THREE - REQUIREMENTS
6. General requirements
6.1 Main coil
The rated inductance of the main coil shall be chosen from the
recommended values given in Clause 20 and shall not be less than 90%
of the stated value.
Where there is a requirement for interchangeability, a suitable upper
limit shall be agreed between manufacturer and purchaser. Otherwise,
an upper limit does not require to be specified.
Note.- For calculations of blocking resistance or bandwidth based on
blocking resistance, the lower tolerance should be used.

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6.1.1 Self-resonant frequency
This frequency shall always be higher than 500 kHz except for line
traps having a rated inductance greater than 0.5 mH where it may not
be possible to achieve such a high frequency because of the physical
construction of the main coil.
6.1.2 Q factor
Where interchangeability is of prime importance, a Q factor of not
less than 30 at 100 kHz must be assured. The physical construction of
the main coil can have an influence on the Q factor.
6.1.3 Current ratings
The continuous and short-time current ratings shall be in accordance
with Clauses 21 and 22.
6.2 Tuning device
The tuning device shall be so arranged as to permit interchange
without removing the line trap. It shall be so designed that neither
significant alteration in the line trap blocking requirements nor
physical damage shall result from either the temperature rise or the
magnetic field of the main coil at continuous rated current, rated
short-time current or emergency overload current.
6.3 Protective device
It is recommended that non-linear resistor type arresters for a.c.
systems in accordance with IEC Publication 99 or an equivalent national
standard, whichever is more appropriate, be used for insulation co-
ordination and that the nominal discharge current be equal to or
greater than that of the station arresters installed behind the line
trap. In no case shall this current be taken as less than 5 kA.
The protective device shall be so designed and arranged that neither
a significant alteration in its protective function nor physical damage
shall result either from the temperature rise or the magnetic field of
the main coil at continuous rated current, rated short-time current or
from emergency overload current. It shall neither enter into operation
as a result of the power-frequency voltage developed across the line
trap by the rated short-time current nor shall it remain in operation
after a response to a transient overvoltage which is immediately
followed by the power-frequency voltage developed across the line trap
by the rated short-time current.

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SIST IEC 60353:1997
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7. Blocking requirements
Specification of the blocking impedance and the tapping loss are for
agreement between manufacturer and purchaser. This standard does
not give any detailed guidance on the permissible variation of these
two quantities within the bandwidth of the line trap.
Attention is, however, drawn to Clause A3 of Appendix A where the
relationship between rated inductance, blocking resistance and band-
width is discussed.
For the purpose of stating the bandwidth, a maximum loss of 2.6 dB
is suggested for both tapping loss and tapping loss based on blocking
resistance. This corresponds to a line trap blocking resistance of 1.41
times the characteristic impedance of the transmission line. A typical
case is that of a line trap of 570 Q blocking resistance connected to a
transmission line of 400 Q characteristic impedance, this being a typical
value of the phase/earth impedance of a single conductor transmission
line.
8. Continuous service requirements
The temperature rise of any part of a line trap under rated
continuous current conditions shall not exceed the values given in
Table I at altitudes below 1 000 m and the air temperature range given
in Sub-clause 4.3. The temperature rise at the hot spot should be
measured directly and the average temperature rise calculated from the
increase in resistance of the main coil as described in Sub-clause 19.1.
Since a line trap is usually not fully loaded during all its working
life, the values given in Table I are higher than those given in IEC
Publication 85.
Table I
Limits of temperature rise
Insulation class Maximum temperature rise (°C)
and reference
Average value measured
temperature Hot spot measured
by increase
by direct
(°C) methods in resistance
105 (A) 75 65
120 (E) 100 85
130 110 90
(B)
135 115
155 (F)
140
185 (H) 155
160
220 (C) 200
For certain insulating materials outside these classifications,
Note.-
temperature rises in excess of those given in Table I may be
adopted by agreement between manufacturer and purchaser.

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If a line trap is intended for service where the air temperature is
likely to exceed the upper limit of the range given in Sub-clause 4.3
by not more than 10 °C, the allowable temperature rise shall be
reduced by:
- 5 °C if the excess temperature is less than or equal to 5 °C;
- 10 °C if the excess temperature is greater than 5 °C but less than
10 °C.
No recommendations are given regarding the temperature rise where
the air temperature exceeds the upper limit given in Sub-clause 4.3 by
more than 10 °C.
For a line trap intended for use at altitudes greater than 1 000 m
but tested at lower altitudes, the limits of temperature rise given in
Table I must be reduced by 2.5% for each 500 m above 1 000 m.
Note.- Certain parts of a line trap may require, or be capable of
having, individual temperature specifications depending on
their positions relative to the main coil. For bare metallic
parts or windings, the temperature rise shall not exceed the
limits given for adjacent material. For the dimensions of the
terminals, attention is drawn to IEC Publication 129 noting
that the terminals of line traps operate at higher temperatures
due to eddy currents produced by the magnetic field of the main
coil.
9. Ability to withstand rated short-time current
9.1 Mechanical strength
The ability of a line trap to withstand the mechanical forces
produced by the asymmetrical peak value /km of the short-time current
a) of Sub-
shall be verified by carrying out the tests specified in Item
clause 19.4.
9.2 Thermal behaviour
The ability of a line trap to withstand the heating effect of the rated
short-time current /kN shall be verified by carrying out the tests
specified in Item b) of Sub-clause 19.4.
10. Insulation level
10.1 Insulation across a line trap
The insulation level for the insulation between the terminals of a line
trap is governed by the rated voltage of the protective device. The
insulation of the main coil and the tuning device shall be adequately
rated for:

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SIST IEC 60353:1997
353 ©IEC - 29 -
a) the voltage U developed across the line trap at rated power
frequency by the rated short-time current. This voltage U shall
be:
U = 21 • f • Lp •
pN
/kN
where:
f pN = rated power frequency
L = power frequency inductance of the main coil measured in
p
accordance with Clause 19.6
rated short-time current
I kN
The rated voltage of the protective device shall be higher than U.
b) the front of wave impulse sparkover voltage or the residual voltage
caused by the nominal discharge current of the protective device,
whichever is higher.
10.2 System voltage insulation
The system voltage insulation of a line trap is provided by insulator
strings or post insulators. For these IEC Publication 383 applies. The
line trap system voltage insulation shall be consistent with the other
equipment in the associated high voltage transmission network.
10.3 Line traps for use at high altitudes
In the case of line traps intended for use at altitudes between
1 000 m and 3 000 m, but tested at altitudes below 1 000 m, the test
voltage for those insulations which are formed by air distances shall be
increased in accordance with IEC Publication 71-1.
11. Radio influence voltage (RIV)
Radio influence voltage may be generated by corona on the line trap.
It is therefore recommended that the corona inception voltage be at
least 15% higher than the phase to earth voltage (U m/V3) of the trans-
mission network to which the line trap is connected. The maximum
system voltages U given in Table II are in accordance with IEC
m
Publication 71-1. The test voltages (1.15 . 0 /V3 in three-phase supply
networks) relating to each power system voltage, are also given in
Table II. The maximum radio influence voltage is a matter for
agreement between manufacturer and purchaser.

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Table II
Relationship between maximum power system voltage
and radio influence test voltage
Maximum power Radio influence
test voltage
system voltage
U 1 . 15•(0 / 33 ) (r.m.s.)
m m
kV kV
52 35
48
72.5
123 83
145 97
113
170
163
245
300 199
242
362
420 280
349
525
765 508
12. Power losses
Power losses occur in the main coil due to the passage of power-
frequency current and the presence of eddy currents. The magnitude
of these losses is a function of the design of the line trap and the
material used in the windings.
If the purchaser requires the losses to be determined, this should
be done by agreement with the manufacturer who should thereafter
declare them. It is pointed out that a requirement for low power losses
can influence the carrier-frequency performance of the line trap.
Since line traps vary widely in design and construction, it is
recommended, for comparison purposes, that the losses should be
corrected for a temperature of 75 °C.
A method of correcting power losses with regard to temperature is
given in Appendix A, Clause A4, for guidance only.
13. Tensile strength of suspension system
The suspension system of a line trap shall be designed for a tensile
stress of at least twice the mass of the line trap in kilograms, multi-
plied by 9.81 to convert to newtons, plus 5 000 N.

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SIST IEC 60353:1997
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14. Accessories
Bird barriers
14.1
The provision of bird barriers is optional. If provided, no entrance
to the line trap shall admit a sphere having a diameter of 16 mm.
14.2 Terminals
The position and type of terminals used is a matter for agreement
between manufacturer and purchaser. Attention is, however, drawn to
IEC Publication 518 and NEMA Standard CC1-1975 for details of
recommended dimensions.
SECTION FOUR - RATING PLATES
The main coil, the tuning device and the protective device shall be
provided with rating plates of weatherproof material fitted so that they
are readily visible. The inscriptions shall be indelibly marked and
include the following data:
15. Rating plate of the main coil
a) Manufacturer's name and year of manufacture.
b) Type.
c) Serial number.
Rated inductance (mH) .
d)
e) Power-frequency inductance (mH).
Rated continuous current (A).
f)
g) Rated power frequency (Hz) .
h) Rated short-time current (kA) and duration (s).
i) Total weight (kg).
16. Rating plate of tuning device
a) Manufacturer's name and year of manufacture.
b) Type.
c) Serial number.
d) Frequency band(s) (kHz).
e) Blocking impedance (minimum value) (Q) .
f) Blocking resistance (minimum value) (Q) .
g) Rated impulse protective level (kV) .
h) Belonging to main coil with rated inductance (mH) and serial
number (optional) .
If additional information is required, this is a matter for agreement
between manufacturer and purchaser.

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SIST IEC 60353:1997
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17. Rating plate information for protective device
This should be in accordance with IEC Publication 99-1.
SECTION FIVE - TESTS
18. General conditions
The tests may be made by the manufacturer at any ambient
temperature between 0 °C and +40 °C, indoors or outdoors.
For the tests, the line tap shall be mounted in a position similar to
what it would be in service unless otherwise stated. The ambient
temperature during the tests should be noted.
Some or all of the type tests may be repeated as sampling tests if
specially agreed to between manufacturer and purchaser. The tests on
the protective device shall be carried out in accordance with IEC
Publication 99-1, or an equivalent national standard.
Note.- For some of the following tests, particular methods are
suggested in the interests of simplicity. Other methods,
including direct read-out instruments which eliminate or reduce
computation, can be used providing their accuracy and suit-
ability can be adequately demonstrated. It is important when
carrying out carrier-frequency measurements, to ensure that the
measuring loop is kept as small as possible in order to exclude
extraneous impedances.
Also, all equipment used in such measurements (including the
line trap) should be kept clear of metallic surfaces and
objects and, where appropriate, the impedance of the test leads
taken into account.
19. Tests
The titles of the following sub-clauses will indicate which are type
tests and which are routine tests.
19.1 Temperature rise test (type test)
This test is designed to prove the thermal behaviour of the line trap
at rated continuous current. The temperature rise of the main coil of
the line tr
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