Consideration of reference impedances and public supply network impedances for use in determining the disturbance characteristics of electrical equipment having a rated current ≤75 A per phase

IEC/TR 60725:2012, which is a technical report, records the information that was available and the factors that were taken into account in arriving at the reference impedances that were incorporated in IEC 60555 and which are now incorporated in some parts of IEC 61000-3. In addition, information is given on the impedances of public supply networks associated with service current capacities ≤100 A per phase. The third edition includes brings two mainly significant technical changes with respect to the previous edition:
- a new survey and other data from countries with public supply networks operating at 60 Hz have been included; and
- recommendations that were applicable to 50 Hz systems are now mirrored by new recommendations that are relevant to 60 Hz systems.

Etude des impédances de référence et des impédances des réseaux publics d'alimentation aux fins de la détermination des caractéristiques de perturbation des équipements électriques utilisant un courant nominal ≤75 A par phase

La CEI/TR 60725:2012 est un rapport technique qui comprend les informations disponibles et les facteurs pris en compte lors de l'établissement des impédances de référence intégrées dans la CEI 60555 et qui sont désormais intégrés dans certaines parties de la CEI 61000-3. De plus, les informations fournies concernent les impédances des réseaux publics d'alimentation associés à des capacités utiles de courant ≤100 A par phase. Cette troisième édition apporte principalement deux modifications techniques majeures par rapport à l'édition précédente:
- une nouvelle enquête comparative et d'autres données en provenance de pays ayant des réseaux de distribution publique fonctionnant à 60 Hz ont été incluses; et
- les recommandations qui étaient applicables aux systèmes à 50 Hz sont maintenant complétées par des recommandations équivalentes pour les systèmes à 60 Hz.

General Information

Status
Published
Publication Date
26-Jun-2012
Current Stage
PPUB - Publication issued
Start Date
15-Sep-2012
Completion Date
27-Jun-2012
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IEC/TR 60725 ®
Edition 3.0 2012-06
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Consideration of reference impedances and public supply network impedances
for use in determining the disturbance characteristics of electrical equipment
having a rated current ≤75 A per phase

Étude des impédances de référence et des impédances des réseaux publics
d’alimentation aux fins de la détermination des caractéristiques de perturbation
des équipements électriques utilisant un courant nominal ≤75 A par phase
IEC/TR 60725:2012
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IEC/TR 60725 ®
Edition 3.0 2012-06
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Consideration of reference impedances and public supply network impedances

for use in determining the disturbance characteristics of electrical equipment

having a rated current ≤75 A per phase

Étude des impédances de référence et des impédances des réseaux publics

d’alimentation aux fins de la détermination des caractéristiques de perturbation

des équipements électriques utilisant un courant nominal ≤75 A par phase

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX U
ICS 33.100.01 ISBN 978-2-83220-161-9

– 2 – TR 60725 © IEC:2012
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Systems of low-voltage supply . 6
3.1 Three-phase supply systems . 6
3.2 Single-phase two-wire supply systems . 7
3.3 Single-phase three-wire supply systems . 7
4 Supply impedances . 7
4.1 Typical residential premises . 7
4.2 Large residential, commercial and light industrial premises . 10
4.2.1 General . 10
4.2.2 Supply impedance relevant to the connection of three-phase
equipment . 11
4.2.3 Supply impedances relevant to the connection of single-phase
equipment . 11
5 Reference impedances . 12
5.1 General . 12
5.2 Reference impedances for equipment with current ratings ≤16 A . 12
5.2.1 Overview . 12
5.2.2 50 Hz and 60 Hz low-voltage supply systems . 13
5.3 Reference impedance for 50 Hz and 60 Hz equipment with current ratings
>16 A and ≤75 A per phase . 15
6 Impedance at frequencies above the supply frequency . 15
Annex A (informative) Methods for determining the maximum modulus values of public
electricity supply low-voltage network impedances relevant to three-phase services of
more than 100 A per phase at 50 Hz . 16
Annex B (informative) Methods for determining the maximum modulus values of public
electricity supply low-voltage network impedances relevant to three-phase services of
more than 100 A per phase at 60 Hz . 24
Annex C (informative) Measurement of supply impedance and survey method . 26
Bibliography . 29

Figure 1 – Representation of a single-phase three-wire supply system . 7
Figure A.1 – Model used for determining the impedance of a network line conductor
from a transformer to a three-phase service cut-out . 18
Figure A.2 – Three-phase impedance diagram of a typical 500 kVA transformer and
mains cable . 19
Figure B.1 – Model used for determining the impedance of a network line conductor
from a transformer to a three-phase service cut-out . 24
Figure C.1 – Measurement of impedance at a customer’s premises . 27

Table 1 – Residential consumers' complex supply impedances at 50 Hz . 8
Table 2 – Single-phase device capacities <100 A per phase . 9
Table 3 – Three-phase service capacities <100 A per phase . 9

TR 60725 © IEC:2012 – 3 –
Table 4 – Single or two-phase service capacities ≥100 A per phase. 10
Table 5 – Three-phase service capacities ≥100 A per phase . 10
Table 6 – Modulus values of supply impedance, in ohms at 50 Hz, relevant to the
connection of three-phase equipment and having a 95 % probability of not being
exceeded . 11
Table 7 – Modulus values of supply impedance, in ohms at 50 Hz, relevant to the
connection of single-phase equipment and having a 95 % probability of not being
exceeded . 12
Table 8 – Reference impedances for testing purposes . 13
Table 9 – Reference impedances for 100 V/200 V and 120 V/240 V supply systems
<100 A . 14
Table 10 – Reference impedances for 200 V to 240 V supply systems <100 A . 14
Table 11 – Reference impedances for 200 V to 240 V supply systems, ≥100 A per
phase . 15
Table 12 – Reference impedances for testing purposes, for 200 V to 240 V supply
systems, ≥100 A . 15
Table A.1 – Modulus values of the maximum supply impedance, in ohms, of the line-
conductors of 230 V/400 V, 50 Hz, public electricity supply networks, relevant to
three-phase services having service capacities of 200 A per phase . 21
Table A.2 – Modulus values of the maximum supply impedance, in ohms, of the line
and neutral conductors of 230 V/400 V, 50 Hz, public electricity supply networks,
relevant to three-phase services having service capacities of 200 A per phase . 22
Table C.1 – Impedance values for copper conductor installation wiring . 28

– 4 – TR 60725 © IEC:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CONSIDERATION OF REFERENCE IMPEDANCES AND PUBLIC SUPPLY
NETWORK IMPEDANCES FOR USE IN DETERMINING THE DISTURBANCE
CHARACTERISTICS OF ELECTRICAL EQUIPMENT HAVING A RATED
CURRENT ≤75 A PER PHASE
FOREWORD
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Committees in that sense. While all reasonable efforts are ma
...

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