PD IEC/TR 61912-2:2009
Current
The latest, up-to-date edition.
Low-voltage switchgear and controlgear. Over-current protective devices Selectivity under over-current conditions
Hardcopy , PDF
English
13-05-2009
FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms, definitions and abbreviated terms
3.1 Alphabetical index of terms
3.2 Terms and definitions
3.3 Abbreviated terms
4 Scope of selectivity requirements
4.1 General
4.2 Motor protection circuit-breaker/Manual motor starter
5 Selectivity determination
5.1 Circuit-breaker as UD
5.1.1 Selectivity between circuit-breakers
5.1.2 Selectivity between a circuit-breaker (UD) and
a fuse to IEC 60269-1 (DD)
5.1.3 CB/CPS - Selectivity between a circuit-breaker
to IEC 60947-2 (UD) and a CPS to IEC 60947-6-2
(DD)
5.1.4 Circuit-breaker/MOR - Selectivity between a
circuit-breaker (UD) and a motor protection
overload relay to IEC 60947-4-1 or
IEC 60947-4-2 (DD)
5.2 Fuse(s) to IEC 60269-1 as UD
5.2.1 Fuse/circuit-breaker - Selectivity between a fuse
to IEC 60269-1 (UD) and a circuit-breaker (DD)
5.2.2 FU/FU - Selectivity between fuses to IEC 60269-1
(UD and DD)
5.2.3 FU/CPS - Selectivity between fuse(s) to IEC 60269-1
(UD) and a CPS to IEC 60947-6-2 (DD)
5.2.4 FU/MOR - Selectivity between fuse(s) to IEC 60269-1
(UD) and a motor overload protection relay to
IEC 60947-4-1 or IEC 60947-4-2 (DD)
6 Residual current devices (RCDs)
6.1 General
6.2 Selectivity - RCD/RCD
6.2.1 Selectivity between RCDs in the case of
earth-leakage current
6.2.2 Selectivity between RCDs in the case of
earth-fault (ground-fault) current
7 Zone Selective Interlocking (ZSI)
7.1 General
7.2 Operating principle
7.3 Example
8 Over-current protection relay (OCR) - Single input energizing
quantity measuring relays with dependent or independent time
Annex A (informative) - Examples of selectivity between
over-current protection devices Examples of the grades
of selectivity applicable to circuit-breakers
Annex B (informative) - Standing loads - Effect of standing
loads on selectivity in the overload zone
Bibliography
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