IEC 60255-151:2009

IEC 60255-151 ®
Edition 1.0 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measuring relays and protection equipment –
Part 151: Functional requirements for over/under current protection

Relais de mesure et dispositifs de protection –
Partie 151: Exigences fonctionnelles pour les protections à minimum et
maximum de courant
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IEC 60255-151 ®
Edition 1.0 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measuring relays and protection equipement –
Part 151: Functional requirements for over/under current protection

Relais de mesure et dispositifs de protection –
Partie 151: Exigences fonctionnelles pour les protections à minimum et
maximum de courant
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
V
CODE PRIX
ICS 29.120.70 ISBN 978-2-88910-078-1
– 2 – 60255-151 © IEC:2009
CONTENTS
FOREWORD.4
1 Scope and object.6
2 Normative references .6
3 Terms and definitions .6
4 Specification of the function.8
4.1 General .8
4.2 Input Energizing quantities / energizing quantities .8
4.3 Binary input signals .9
4.4 Functional logic .9
4.4.1 Operating characteristics .9
4.4.2 Reset characteristics .12
4.5 Binary output signals .16
4.5.1 Start (pick-up) signal .16
4.5.2 Operate (trip) signal.16
4.5.3 Other binary output signals.16
4.6 Additional influencing functions/conditions .16
4.7 Specific characteristics.16
5 Performance specification .17
5.1 Accuracy related to the characteristic quantity.17
5.2 Accuracy related to the operate time .18
5.3 Accuracy related to the reset time .18
5.4 Transient performance .19
5.4.1 Transient overreach.19
5.4.2 Overshoot time .19
5.4.3 Response to time varying value of the characteristic quantity .19
5.5 Current transformer requirements.19
6 Functional test methodology.20
6.1 General .20
6.2 Determination of steady state errors related to the characteristic quantity .20
6.2.1 Accuracy of setting (start) value .20
6.2.2 Reset ratio determination.22
6.3 Determination of steady state errors related to the start and operate time .23
6.4 Determination of steady state errors related to the reset time.23
6.5 Determination of transient performance .24
6.5.1 General .24
6.5.2 Transient overreach.24
6.5.3 Overshoot time .25
6.5.4 Response to time varying value of the characteristic quantity for
dependent time relays .26
7 Documentation requirements .27
7.1 Type test report.27
7.2 Other user documentation .27
Annex A (normative) Constants for dependent time operating and reset characteristics .29
Annex B (informative) Reset time determination for relays with trip output only.30
Bibliography.31

60255-151 © IEC:2009 – 3 –
Figure 1 – Simplified protection function block diagram.8
Figure 2 – Overcurrent independent time characteristic .10
Figure 3 – Undercurrent independent time characteristic .10
Figure 4 – Dependent time characteristic .11
Figure 5 – Definite time reset characteristic .13
Figure 6 – Definite time reset characteristic (alternative solution with instantaneous
reset after relay operation).14
Figure 7 – Dependent time reset characteristic .15
Figure 8 – Dependent time reset characteristic (alternative solution with instantaneous
reset after relay operation).16
Figure 9 – Voltage restrained characteristics .17
Figure 10 – Voltage controlled characteristics.17
Figure 11 – Typical test waveform for transient overreach .25
Figure 12 – Test waveform .26
Figure B.1 – Dependent reset time determination .30

Table 1 – Multiplier factor on operated time assigned error .18
Table 2 – Multiplier factor on reset time assigned error.19
Table 3 – Test points for overcurrent elements .23
Table 4 – Test points for undercurrent elements .23
Table 5 – Test points for overcurrent elements .24
Table 6 – Test points for undercurrent elements .24
Table 7 – Recommended values for the test .26
Table A.1 – Constants for dependent time operating and reset characteristics.29

– 4 – 60255-151 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 151: Functional requirements for over/under current protection

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on tech
...