IEC TR 61912-1:2007

Low-voltage switchgear and controlgear - Overcurrent protective devices - Part 1: Application of short-circuit ratings

This technical report, which serves as an application guide for the short-circuit ratings given in IEC standards for low-voltage switchgear and controlgear and assemblies, summarises the definitions of the ratings and provides examples of their application. This edition cancels and replaces the first edition of IEC 61912, published in 2006, and corrigendum 1 (May 2006). The changes are only editorial.

Appareillage à basse tension - Dispositifs de protection contre les surintensités - Partie 1: Application des caractéristiques de court-circuit

Le présent rapport technique, qui sert de guide d'application pour les caractéristiques de court-circuit données dans les normes CEI de l'appareillage à basse tension et des ensembles d'appareillage, résume les définitions des caractéristiques et donne des exemples de leur application. Cette édition annule et remplace la première édition de la CEI 61912, publiée en 2006, et le corrigendum 1 (mai 2006).Les modifications ne sont que rédactionnelles.

General Information

• Status: Published
• Publication Date: 22-Aug-2007
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.130.20 - Low voltage switchgear and controlgear
• Technical Committee: SC 121A - Low-voltage switchgear and controlgear
• Drafting Committee: MT 9 - TC 121/SC 121A/MT 9
• Current Stage: PPUB - Publication issued
• Start Date: 31-Oct-2007
• Completion Date: 23-Aug-2007

Relations

• Replaces: IEC TR 61912:2006 - Application of the short-circuit ratings of low-voltage switchgear and controlgear
• Effective Date: 05-Sep-2023
• Replaces: IEC TR 61912:2006/COR1:2006 - Corrigendum 1 - Application of the short-circuit ratings of low-voltage switchgear and controlgear
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC/TR 61912-1
Edition 1.0 2007-08
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Low-voltage switchgear and controlgear – Overcurrent protective devices –
Part 1: Application of short-circuit ratings

Appareillage à basse tension – Dispositifs de protection contre les surintensités –
Partie 1: Application des caractéristiques de court-circuit

IEC/TR 61912-1:2007
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IEC/TR 61912-1
Edition 1.0 2007-08
TECHNICAL
REPORT
RAPPORT
TECHNIQUE
Low-voltage switchgear and controlgear – Overcurrent protective devices –
Part 1: Application of short-circuit ratings

Appareillage à basse tension – Dispositifs de protection contre les surintensités –
Partie 1: Application des caractéristiques de court-circuit
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
S
CODE PRIX
ICS 29.130 ISBN 2-8318-9273-2
– 2 – TR 61912-1 © IEC:2007
CONTENTS
FOREWORD.4
INTRODUCTION.6

1 Scope.7
2 Normative references .7
3 Alphabetical list of definitions and characteristics .8
4 Principle of application – Installation .9
5 Characteristics – Low-voltage assemblies (switchboard, distribution board, etc.).9
6 Characteristics – Switching devices.10
6.1 General .10
6.2 Switching devices – Self-protection against short-circuit.10
6.3 Switching devices – Application as SCPD.11
6.3.1 Fuse-combination units and fuses as SCPD .11
6.3.2 Circuit-breakers to IEC 60947-2 as SCPD .11
6.3.3 Control and protective switching devices (CPS) according to
IEC 60947-6-2 as SCPD .12
6.3.4 Circuit-breakers according to IEC 60898-1 (MCBs) and residual
current operated circuit-breaker with integral overcurrent protection
(RCBOs) according to IEC 61009-1 as SCPD .12
7 Examples of the practical application of the product characteristics.13
7.1 General .13
7.2 Protection of cables.13
7.3 Short-circuit protection for LV assemblies.13
7.3.1 Switchgear and controlgear assemblies (switchboard/motor-control
centre (MCC)).13
7.3.2 Busbar trunking systems (BTS) .13
7.4 Short-circuit protection for contactors and starters .14
7.4.1 General .14
7.4.2 Protected switching device and protected starter .14
7.4.3 Control and protective switching device (CPS) according to
IEC 60947-6-2 .
7.5 Short-circuit protection using circuit-breakers for household and similar
installations according to IEC 60898-1 (usually known as MCBs) and residual
current operated circuit-breakers with integral overcurrent protection
(RCBOs) according to IEC 61009-1 .15

Annex A (informative) Interpolation of the suitability of an alternative SCPD for the
protection of contactors and starters (substitution).21

Bibliography.22

Figure 1 – Example of the I t characteristic of a fuse.17
Figure 2 – Example of the I t characteristic of a circuit-breaker .17
Figure 3 – Example of SCPDs in combination .18
Figure 4 – Example of the derivation of a conditional rating from type-test parameters .19
Figure 5a – Co-ordination of a motor-starter with a fuse.20

TR 61912-1 © IEC:2007 – 3 –
Figure 5b – Co-ordination of a motor-starter with circuit-breaker.20
Figure 5 – Illustration of co-ordination between motor-starter and SCPD.20

Table 1 – Ratio k between service short-circuit capacity (I ) and rated short-circuit
cs
capacity (I ) for an MCB according to IEC 60898-1 .16
cn
Table 2 – Value of the prospective test current according to the rated operational
current .16

– 4 – TR 61912-1 © IEC:2007
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
OVERCURRENT PROTECTIVE DEVICES –

Part 1: Application of short-circuit ratings

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 61912-1, which is a technical report, has been prepared by subcommittee 17B: Low-
voltage switchgear and controlgear, of IEC technical committee 17: Switchgear and
controlgear.
This edition cancels and replaces the first edition of IEC 61912, published in 2006, and
corrigendum 1 (May 2006). The changes are only editorial.

TR 61912-1 © IEC:2007 – 5 –
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
17B/1547/DTR 17B/1564/RVC
Full information on the voting for the approval
...