SIST IEC 60481:1997

SLOVENSKI STANDARD
SIST IEC 60481:1997
01-avgust-1997
Coupling devices for power line carrier systems
Coupling devices for power line carrier systems
Groupes de couplage pour systèmes à courants porteurs sur lignes d'énergie
Ta slovenski standard je istoveten z: IEC 60481
ICS:
29.240.20 Daljnovodi Power transmission and
distribution lines
SIST IEC 60481:1997 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST IEC 60481:1997

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SIST IEC 60481:1997
NORME CEI
INTERNATIONALE
IEC
481
INTERNATIONAL
Première édition
STANDARD
First edition
1974
Groupes de couplage pour systèmes
à courants porteurs sur lignes d'énergie
Coupling devices for power line
carrier systems
© CEI 1974 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 pro- any form or by any means, electronic or mechanical,
cédé, électronique ou mécanique, y compris la photocopie et including photocopying and microfilm, without permission
les microfilms, sans l'accord écrit de l'éditeur. in writing from the publisher.
Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé
Genève, Suisse
Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission
PRICE CODE IVI
IEC
Me»wyHapopHaa 3netcrporexHH4ecKan iiomucci R
•
• Pour prix, voir catalogue en vigueur
For price, see current catalogue

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SIST IEC 60481:1997
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CONTENTS
Page
5
FOREWORD
PREFACE 5
SECTION ONE — GENERAL
Clause
7
1. Scope
7
2. Object
Service conditions 7
3.
SECTION Two — DEFINITIONS
4. Methods of coupling 9
5. Coupling device 9
Communication terms for coupling devices 9
6.
SECTION THREE — REQUIREMENTS
11
7. Safety and protection requirements of the coupling device
13
8. Insulation requirements
9. Carrier-frequency requirements 13
SECTION FOUR — RATING PLATE
Rating plate of the coupling device 15
10.
SECTION FIVE — TESTS
15
11. General conditions
17
12. Type tests
19
13. Sampling tests
19
14. Routine tests
FIGURES 20

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SIST IEC 60481:1997
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
COUPLING DEVICES FOR POWER LINE CARRIER SYSTEMS
FOREWORD
The formal decisions or agreements of the I EC on technical matters, prepared by Technical Committees on which all the National
1)
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
recommendations and the corresponding national rules should, as far as possible, be clearly indicated in the latter.
PREFACE
This recommendation has been prepared by IEC Technical Committee No. 57, Power Line Carrier Systems.
It is based on a report of CIGRE Study Committee No. 14, dated May 1968.
Drafts were discussed at the meetings held in Zurich in 1971 and in Athens in 1972. As a result of this latter
meeting, a new draft, document 57(Central Office)8, was submitted to the National Committees for approval
under the Six Months' Rule in March 1973.
The following countries voted explicitly in favour of publication:
Australia Norway
Austria Poland
Belgium Romania
Czechoslovakia Spain
Denmark Sweden
Switzerland
Finland
France Turkey
Germany Union of Soviet
Israel Socialist Republics
Italy United Kingdom
Japan United States
Korea (Republic of) of America

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SIST IEC 60481:1997
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COUPLING DEVICES FOR POWER LINE CARRIER SYSTEMS
SECTION ONE — GENERAL
1. Scope
This recommendation applies to coupling devices for power line carrier (PLC) systems which are connected
between the coupling capacitor(s) and the carrier-frequency connection to the PLC terminal (or to a similar coupling
device, directly or via additional equipment, in the case of retransmission).
The coupling device, in conjunction with the coupling capacitor(s) ensures:
a) the efficient transmission of carrier-frequency signals between the carrier-frequency connection and the
power line;
the safety of personnel and the protection of the low-voltage parts of the installation against the effects of
b)
the power-frequency voltage and transient overvoltages.
This recommendation also applies to coupling devices used in conjunction with PLC systems which are required
to operate over power cables.
2. Object
The object of this recommendation is to establish definitions, requirements, methods of testing and rated values
for coupling devices.
3. Service conditions
This recommendation gives detailed requirements for use under the following conditions.
3.1 Standard conditions
The standard conditions shall be those for outdoor service. Coupling devices shall be capable of their function
whether exposed to sunshine, rain, fog, hail, frost, snow, ice, etc.
3.2 Altitude
The height above sea level shall not exceed 1 000 m.
3.3 Ambient temperature
Unless otherwise agreed between manufacturer and purchaser, the ambient temperature shall be between —25 °C
and +40 °C and shall not exceed the following limits:
+30 °C for the daily average,
+20 °C for the annual average.
3.4 Power frequency
Power systems shall have a rated frequency between zero (d.c.) and 60 Hz inclusive.
3.5 Operating voltage
The rated operating voltage of the power line shall be not less than 1 000 V.
Provision for unusual service conditions
3.6
In all cases where the above conditions are not met and severe atmospheric conditions such as salt spray and
industrial pollution are to be expected, special arrangements should be made between manufacturer and purchaser.

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SIST IEC 60481:1997
-9
SECTION TWO — DEFINITIONS
For the purpose of this recommendation, the following definitions apply.
4. Methods of coupling
Coupling is usually effected to one or more phase conductors of the power line (poles in the case of a d.c. power
line), phase-to-earth and phase-to-phase being the most common forms of coupling. Coupling to all three phases
of a circuit may be required in certain cases. Coupling to one or more associated insulated earth-wire conductors
is also employed.
4.1 Phase-to-earth coupling
la
Coupling to the power line effected between the conductor(s) of one phase of the line and earth (see Figures
and 2, pages 20 and 22).
4.2 Phase-to-phase coupling
Coupling to the power line effected between the conductor(s) of one phase and the conductor(s) of another
page 21). The two phases may belong to the same circuit or
phase of the same line (see Figures lb and 1 e,
to different circuits of the power line (intercircuit coupling).
Note. — Coupling between individual conductors of a phase bundle is a special application.
5. Coupling device
An arrangement of elements which contribute to ensure, together with one or more associated coupling capacitors,
the transmission, under prescribed conditions, of carrier-frequency signals between one or more conductors of
the power line and the carrier-frequency connection (see Figures 1 and 2).
These elements, alone or together, contribute to all, or part of, the following functions:
Note. —
tuning, designed to compensate for the reactive component of the coupling capacitor(s) impedance, in order to promote
—
tuning device,
the efficient transmission of carrier-frequency signals. This function may be performed by a
impedance matching between the power line and the carrier-frequency connection. This function may be performed by a
—
transformer or autotransformer,
galvanic isolation between primary and secondary terminals of the coupling device. This function may be performed by
—
the above-mentioned transformer, if present,
draining to earth of the power-frequency current derived by the coupling capacitor(s). This function may be performed
—
of the previously mentioned transformer, if present,
drain coil, or by the primary winding
by an inductance, termed
limitation of voltage surges coming from the power line, at the terminals of the coupling device. This function may be
—
lightning arresters suitably arranged in the coupling device,
performed by
direct and efficient earthing, when necessary, of the primary terminal(s) of the coupling device. This function may be
—
performed by an earthing switch.
5.1 Earth terminal
A terminal of the coupling device which is intended to be connected directly to the local station earth.
5.2 Primary terminal
A terminal of the coupling device which is intended to be connected to the low-voltage terminal of the coupling
capacitor.
5.3 Secondary terminal
A terminal of the coupling device which is intended to be connected to the carrier-frequency connection.
6. Communication terms for coupling devices
6.1 Nominal line-side impedance (Z1)
The impedance which the coupling device, together with the associated coupling capacitor(s), is designed to
match on the line side, and to which the requirements refer (see Figure 3, page 22).

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SIST IEC 60481:1997
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6.2 Nominal equipment-side impedance (Z2)
The impedance which the coupling device is designed to match, on the equipment side, and to which the require-
ments refer (see Figure 3, page 22).
6.3 Composite loss
The composite loss (see I.E.V. 55-05-175) brought about by the quadripole made up of the coupling device and
associated coupling capacitor(s) having the specified capacitance and assumed to have no loss, terminated by the
nominal line-side and equipment-side impedance.
6.4 Return loss
The return loss (see I.E.V. 55-05-195) of the quadripole made up of the coupling device and associated coupling
capacitor(s) having the specified capacitance and assumed to have no loss, respectively terminated by the nominal
line-side and equipment-side impedance.
6.5 Available bandwidth
The frequency band within which the composite loss does not exceed, and the return losses do not fall short
of the specified values.
6.6 Carrier frequency working range
The range of carrier frequencies within which the available bandwidth of a coupling device can be set.
6.7 Nominal peak-envelope power
The peak-envelope power for which the coupling device has been designed compatible with the requirements
for intermodulation.
SECTION THREE — REQUIREMENTS
7. Safety and protection requirements of the coupling device
7.1
General
The coupling device shall meet the following requirements irrespective of whether or not the protective devices
of an associated coupling capacitor or capacitor voltage transformer contribute to the safety and protection of
the coupling device. The design of the coupling device shall be such as to prevent the occurrence of dangerous
potentials on the carrier-frequency connection due to the service voltage or transient overvoltages which may
occur on the power line.
Note. — There are two types of transient overvoltages to be taken into account:
a) Overvoltages due chiefly to the operation of switchgear. Such overvoltages may have amplitudes of the same order of
magnitude as the service voltage and be transferred to the low-voltage side of the coupling capacitor because of the steep-
fronted or high-frequency nature of the transients.
b)
Atmospheric overvoltages which are also transferred to the low-voltage side of the coupling capacitor for the same reason.
The coupling device shall be designed and built to ensure that a fault on the power line shall not in general cause
a permanent interruption in the functioning of the coupling device. If, under abnormal power-system conditions,
the values specified in Sub-clauses 7.5, 8.1 and 8.2 are exceeded, this shall be a matter for special agreement between
manufacturer and purchaser.
7.2
Earthing of the primary terminal
The coupling device shall be so designed that the impedance at power frequency between the primary terminal
and the earth terminal is as low as possible and in no case in excess of 20 Q. This low impedance shall be
ensured by a device such as a drain coil or matching transformer winding as specified in Sub-clause 7.3.

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SIST IEC 60481:1997
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Drain coil or matching transformer winding
7.3
The drain coil or matching transformer winding shall:
offer a maximum guarantee of continuity of connection to the earth terminal;
a)
withstand any of the above-mentioned overvoltages which may occur on the power line, taking into account
b)
the effect of the main arrester (Sub-clause 7.5).
7.4 Earthing switch
An earthing switch shall be provided for making a temporary direct connection between the primary and earth
requirements of Sub-clause 7.3 also apply to this device.
terminals. The .
The method of operating the earthing switch shall take due regard of national requirements for safety.
It is recommended that an indication of "on" and "off" positions of the earthing switch be clearly visible.
7.5 Main arrester
A lightning arrester shall be connected as directly as possible between the primary and earth terminals and shall
be capable of protecting the coupling device and the carrier-frequency connection.
Notes 1. — For this purpose, at present, either arresters of the air-gap type or those of the non-linear resistor type are used.
If an air-gap type arrester is used, it must be robust and allow easy maintenance; moreover, it is recommended that its
power-frequency sparkover voltage be of the order of 2 kV r.m.s. and that it be able to sustain an impulse discharge current
of wave shape 8/20 gs of at least 5 kA. It is desirable that the arrester be capable of sustaining a power-frequency current
of at least 5 kA r.m.s. for a period of 0.2 s while ensuring, even if damaged, that the other parts of the coupling device
remain adequately protected.
If a non-linear resistor type arrester is employed, it is recommended that its rated voltage be of the order of 1 kV (corre-
sponding to an impulse sparkover voltage of about 4 kV) and that it be able to sustain an impulse discharge current of
wave shape 8/20.ts of at least 5 kA. See I EC Publication 60, High-voltage Test Techniques, and I EC Publication 99-1,
Lightning Arresters, Part 1: Non-linear Resistor Type Arresters for A.C. Systems, 2nd edition).
Where the coupling capacitor is remote from the coupling device, it may be necessary to provide, at the coupling capacitor,
2. —
an additional arrester, similar to the main arrester.
It may be advisable, both for the protection of the carrier-frequency connection and the PLC terminal, to provide an arrester
3. —
which will limit the voltage across the secondary terminals of the coupling device to a value compatible with the withstand
voltage of the carrier-frequency connection and that of the protection device, if any, at the other end of the carrier-frequency
connection. Gas-type arresters, having a power-frequency sparkover voltage of the order of a few hundred volts are generally
suitable.
8. Insulation requirements
8.1 Power frequency level
If isolation between primary and secondary terminals of the coupling device is required by local operating
conditions, then
...