SIST EN 60255-151:2010

Measuring relays and protection equipment -- Part 151: Functional standard for over/under current protection

This part of IEC 60255 specifies minimum requirements for over/under current relays. This standard includes a specification of the protection function, measurement characteristics and time delay characteristics. This part of IEC 60255 defines the influencing factors that affect the accuracy under steady state conditions and performance characteristics during dynamic conditions. The test methodologies for verifying performance characteristics and accuracy are also included in this standard. The over/under current functions covered by this standard are the following: IEEE/ANSI C37.2 IEC 61850-7-4 Function Numbers Logical nodes Instantaneous phase overcurrent protection 50 PIOC Time delayed phase overcurrent protection 51 PTOC Instantaneous earth fault protection 50N/50G PIOC Time delayed earth fault protection 51N/51G PTOC Negative sequence overcurrent or current unbalance protection 46 PTOC Phase undercurrent protection 37 PTUC Voltage-dependent overcurrent protection 51V PVOC This standard excludes thermal electrical relays as specified in IEC 60255-8. General requirements for measuring relays and protection equipment are specified in IEC 60255-1.

Messrelais und Schutzeinrichtungen - Teil 151: Funktionsanforderungen für Über-/Unterstromschutz

Relais de mesure et dispositifs de protection -- Partie 151: Norme fonctionnelle pour protection à maximum/minimum de courant

La CEI 60255-151:2009 spécifie les exigences minimales relatives aux relais à maximum/minimum de courant. Cette norme inclut la spécification de la fonction de protection, les caractéristiques de mesure et les caractéristiques de temporisation. Elle définit les facteurs d'influence affectant la précision, en conditions de régime établi et les caractéristiques de performance en conditions dynamiques.

Merilni releji in zaščitna oprema - 151. del: Funkcionalni standard za pod- in nadtokovno zaščito (IEC 60255-151:2009)

Ta del IEC 60255 opredeljuje minimalne zahteve za nad- in podtokovne releje. Ta standard vključuje specifikacijo zaščitne funkcije, lastnosti merjenja in lastnosti časovnega zamika. Ta del IEC 60255 določa dejavnike vplivanja, ki vplivajo na natančnosti v stabilnih pogojih in lastnosti delovanja v dinamičnih pogojih. V ta standard so vključene tudi preskusne metodologije za preverjanje lastnosti delovanja in natančnosti. Ta standard zajema naslednje nad- in podtokovne funkcije: IEEE/ANSI C37.2 IEC 61850-7-4. Funkcija. Števila. Logična vozlišča. Trenutna nadtokovna zaščita 50 PIOC. Zadržana nadtokovna zaščita 51 PTOC. Trenutna zaščita zemeljskih stikov 50N/50G PIOC. Zadržana zaščita zemeljskih stikov 51N/51G PTOC. Nadtokovna zaščita ali zaščita tokovne nestabilnosti negativnega zaporedja 46 PTOC. Podtokovna zaščita 37 PTUC. Od napetosti odvisna nadtokovna zaščita 51V PVOC. Ta standard izključuje termične električne releje, opredeljene v IEC 60255-8. Splošne zahteve za merilne releje in zaščitno opremo opredeljuje IEC 60255-1.

General Information

• Status: Published
• Publication Date: 14-Dec-2009
• ICS: 29.120.70 - Relays
• Technical Committee: ISS EIT.ERE - All-or-nothing electrical relays
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 09-Nov-2009
• Due Date: 14-Jan-2010
• Completion Date: 15-Dec-2009
• Ref Project: EN 60255-151:2009 - Measuring relays and protection equipment - Part 151: Functional requirements for over/under current protection

Relations

• Replaces: SIST EN 60255-3:2001 - Electrical relays -- Part 3: Single input energizing quantity measuring relays with dependent or independent time
• Effective Date: 01-Jan-2010
• Replaces: SIST EN 60255-3:2001 - Electrical relays -- Part 3: Single input energizing quantity measuring relays with dependent or independent time
• Effective Date: 29-Jan-2023
• Revised: SIST EN 60255-3:2001 - Electrical relays -- Part 3: Single input energizing quantity measuring relays with dependent or independent time
• Effective Date: 07-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60255-151:2010
01-januar-2010
1DGRPHãþD
SIST EN 60255-3:2001
0HULOQLUHOHMLLQ]DãþLWQDRSUHPDGHO)XQNFLRQDOQLVWDQGDUG]DSRGLQ
QDGWRNRYQR]DãþLWR,(&
Measuring relays and protection equipment -- Part 151: Functional standard for
over/under current protection
Messrelais und Schutzeinrichtungen - Teil 151: Funktionsanforderungen für Über
-/Unterstromschutz
Relais de mesure et dispositifs de protection -- Partie 151: Norme fonctionnelle pour
protection à maximum/minimum de courant
Ta slovenski standard je istoveten z: EN 60255-151:2009
ICS:
29.120.70 Releji Relays
SIST EN 60255-151:2010 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60255-151:2010

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SIST EN 60255-151:2010

EUROPEAN STANDARD
EN 60255-151

NORME EUROPÉENNE
October 2009
EUROPÄISCHE NORM

ICS 29.120.70 Supersedes EN 60255-3:1998 + corr. Jan.1998


English version


Measuring relays and protection equipment -
Part 151: Functional requirements
for over/under current protection
(IEC 60255-151:2009)


Relais de mesure  Messrelais und Schutzeinrichtungen -
et dispositifs de protection - Teil 151: Funktionsanforderungen
Partie 151: Exigences fonctionnelles für Über-/Unterstromschutz
pour les protections à maximum (IEC 60255-151:2009)
et minimum de courant
(CEI 60255-151:2009)




This European Standard was approved by CENELEC on 2009-09-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: Avenue Marnix 17, B - 1000 Brussels


© 2009 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60255-151:2009 E

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SIST EN 60255-151:2010
EN 60255-151:2009 - 2 -
Foreword
The text of document 95/255/FDIS, future edition 1 of IEC 60255-151, prepared by IEC TC 95, Measuring
relays and protection equipment, was submitted to the IEC-CENELEC parallel vote and was approved by
CENELEC as EN 60255-151 on 2009-09-01.
This European Standard supersedes EN 60255-3:1998 + corrigendum January 1998.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2010-06-01
– latest date by which the national standards conflicting
(dow) 2012-09-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60255-151:2009 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60044 NOTE  Harmonized in EN 60044 series (partially modified).
IEC 60255-8 NOTE  Harmonized as EN 60255-8:1998 (modified).
IEC 61850 NOTE  Harmonized in EN 61850 series (not modified).
IEC 61850-7-4 NOTE  Harmonized as EN 61850-7-4:2003 (not modified).
__________

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SIST EN 60255-151:2010
- 3 - EN 60255-151:2009
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

1)
IEC 60050-447 200X International Electrotechnical Vocabulary - - -
Part 447: Measuring relays


2) 3)
IEC 60255-1 - Measuring relays and protection equipment - EN 60255-1 200X
Part 1: Common requirements




1)
To be published.
2)
Undated reference.
3)
To be ratified.

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SIST EN 60255-151:2010

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SIST EN 60255-151:2010
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


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
V
CODE PRIX
ICS 29.120.70 ISBN 2-8318-1060-0
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60255-151:2010
– 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

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SIST EN 60255-151:2010
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

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SIST EN 60255-151:2010
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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-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
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 technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60255-151 has been prepared by IEC technical committee 95:
Measuring relays and protection equipment.
This first edition cancels and replaces IEC 60255-3, published in 1989.
The text of this standard is based on the following documents:
FDIS Report on voting
95/255/FDIS 95/258/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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SIST EN 60255-151:2010
60255-151 © IEC:2009 – 5 –
A list of all parts of the IEC 60255 series, published under the general title Measuring relays
and protection equipment, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition; or
• amended.

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SIST EN 60255-151:2010
– 6 – 60255-151 © IEC:2009
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 151: Functional requirements for over/under current protection



1 Scope and object
This part of IEC 60255 specifies minimum requirements for over/under current relays. This
standard includes a specification of the protection function, measurement characteristics and
time delay characteristics.
This part of IEC 60255 defines the influencing factors that affect the accuracy under steady
state conditions and performance characteristics during dynamic conditions. The test
methodologies for verifying performance characteristics and accuracy are also included in this
standard.
The over/under current functions covered by this standard are the following:

IEEE/ANSI C37.2 IEC 61850-7-4
Function Numbers Logical nodes

Instantaneous phase overcurrent protection 50 PIOC
Time delayed phase overcurrent protection 51 PTOC
Instantaneous earth fault protection 50N/50G PIOC
Time delayed earth fault protection 51N/51G PTOC
Negative sequence overcurrent or current unbalance protection 46 PTOC
Phase undercurrent protection 37 PTUC
Voltage-dependent overcurrent protection 51V PVOC
This standard excludes thermal electrical relays as specified in IEC 60255-8. General
requirements for measuring relays and protection equipment are specified in IEC 60255-1.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60050-447, International Electrotechnical Vocabulary – Part 447: Measuring relays
IEC 60255-1, Measuring relays and protection equipment – Part 1: Common requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
theoretical curve of time versus characteristic quantity
curve which represents the relationship between the theoretical specified operate time and
the characteristic quantity

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SIST EN 60255-151:2010
60255-151 © IEC:2009 – 7 –
3.2
curves of maximum and minimum limits of the operate time
curves of the limiting errors on either side of the theoretical time versus characteristic quantity
which identify the maximum and minimum operate times corresponding to each value of the
characteristic quantity
3.3
setting value (start) of the characteristic quantity
G
S
reference value used for the definition of the theoretical curve of time versus characteristic
quantity
3.4
threshold value of the characteristic quantity
G
T
lowest value and highest value for dependent time overcurrent and undercurrent relays,
respectively, of the input quantity for which the relay is guaranteed to operate
3.5
start time
duration of the time interval between the instant when the characteristic quantity of the
measuring relay in reset condition is changed, under specified conditions, and the instant
when the start signal asserts
3.6
operate time
duration of the time interval between the instant when the characteristic quantity of the
measuring relay in reset condition is changed, under specified conditions, and the instant
when the relay operates
[IEV 447-05-05]
3.7
disengaging time
duration of the time interval between the instant a specified change is made in the value of
input energizing quantity which will cause the relay to disengage and instant it disengages
[IEV 447-05-10, modified]
3.8
reset time
duration of the time interval between the instant when the characteristic quantity of the
measuring relay in operate condition is changed, under specified conditions, and the instant
when the relay resets
[IEV 447-05-06]
3.9
overshoot time
difference between the operate time of the relay at the specified value of the input energizing
quantity and the maximum duration of the value of input energizing quantity which, when
suddenly reduced (for the overcurrent relay)/increased (for the undercurrent relay) to a
specified value below (for the overcurrent relay)/above(for the undercurrent relay) the setting
value is insufficient to cause operation
3.10
time multiplier setting
TMS
setting which describes an adjustable factor that may be provided by a relay manufacturer
which is applicable to the theoretical curve of time versus characteristic quantity

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SIST EN 60255-151:2010
– 8 – 60255-151 © IEC:2009
NOTE Its purpose is to allow adjustment of the relay operating times. This adjustable TMS factor is usually
expressed in “per unit”. The preferred reference setting of TMS for declaration of relay characteristic is 1,0.
3.11
threshold of independent time operation
G
D
value of the characteristic quantity at which the relay operate time changes from dependent
time operation to independent time operation
3.12
reset ratio
disengaging ratio
ratio between the point where the relay just ceases to start (start signal changes from ON to
OFF) and the actual start current of the element
NOTE It is usually defined as a percentage such that for an overcurrent element the reset ratio is less than 100 %
and for an undercurrent element the reset ratio is greater than 100 %.
3.13
transient overreach
measure of the effect of the d.c. component of a waveform on the start signal of the functional
element. Generally this d.c. component will result in the relay reaching further than the setting
should permit, or specifically in the terms of an overcurrent relay, starting at a value of a.c.
current below the set threshold
4 Specification of the function
4.1 General
The protection function with its inputs, outputs, measuring element, time delay characteristics
and functional logic is shown in Figure 1. The manufacturer shall provide the functional block
diagram of the specific implementation.

IEC  1705/09
Figure 1 – Simplified protection function block diagram
4.2 Input Energizing quantities / energizing quantities
The input energizing quantities are the measuring signals, e.g. currents and voltages (if
required). Their ratings and relevant standards are specified in IEC 60255-1. Input energizing
quantities can come with wires from current and voltage transformers or as a data packet over
a communication port using an appropriate communication protocol (such as IEC 61850-9-2).

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SIST EN 60255-151:2010
60255-151 © IEC:2009 – 9 –
The energizing quantities used by the protection function need not be directly the current at
the secondary side of the current transformers. Therefore, the measuring relay documentation
shall state the type of energizing quantities used by the protection function. Examples are:
• single phase current measurement;
• three phase current measurement;
• neutral current or residual current measurement;
• positive, negative or zero sequence current measurement.
The type of measurement of the energizing quantity shall be stated. Examples are:
• RMS value of the signal;
• RMS value of the fundamental component of the signal;
• RMS value of a specific harmonic component of the signal;
• peak values of the signal;
• instantaneous value of the signal.
4.3 Binary input signals
If any binary input signals (externally or internally driven) are used, their influence on the
protection function shall be clearly described on the functional logic diagram. Additional
textual description may also be provided if this can further clarify the functionality of the input
signals and their intended usage.
4.4 Functional logic
4.4.1 Operating characteristics
4.4.1.1 General
The relationship between operate time and characteristic quantity can be expressed by means
of a characteristic curve. The shape of this curve shall be declared by the manufacturer by an
equation (preferred) or by graphical means.
This standard specifies two types of characteristics:
• independent time characteristic (i.e. definite time delay);
• dependent time characteristic (i.e. inverse time delay).
The time characteristic defines the operate time which is the duration between the instant
when the input energizing quantity crosses the setting value (G ) and the instant when the
S
relay operates.
4.4.1.2 Independent time characteristic
Independent time characteristic is defined in terms of the setting value of the characteristic
quantity G and the operate time t . When no intentional time delay is used, then the
S op
independent time relay is denoted as an instantaneous relay.
For overcurrent relays, t(G) = t when G > G . The independent time characteristic is
op S
presented in Figure 2.

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SIST EN 60255-151:2010
– 10 – 60255-151 © IEC:2009
t(G)
t
op
G
s G

IEC  1706/09
Figure 2 – Overcurrent independent time characteristic
For undercurrent relays, t(G) = t when G < G . The independent time characteristic is
op S
presented in Figure 3.
t(G)
t
op
G
G
s

IEC  1707/09
Figure 3 – Undercurrent independent time characteristic
4.4.1.3 Dependent time characteristics
Dependent time characteristics are only defined for overcurrent relays.
For dependent time relays the characteristic curves shall follow a law of the form:
⎡ ⎤
⎢ ⎥
⎢ ⎥
k
t(G) = TMS + c (1)
⎢ ⎥
α
⎛ ⎞
⎢ G ⎥
⎜ ⎟
−1
⎢ ⎥
⎜ ⎟
G
⎝ S ⎠
⎣ ⎦
where
t(G) is the theoretical operate time with constant value of G in seconds;
k, c, α are the constants characterizing the selected curve;
G is the measured value of the characteristic quantity;

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SIST EN 60255-151:2010
60255-151 © IEC:2009 – 11 –
G is the setting value (see 3.3);
S
TMS is the time multiplier setting (see 3.10).
The constants, k and c, have a unit of seconds, α has no dimension.
The dependent time characteristic is shown in Figure 4.
t(G)
Effective range
G 2x G G
S S D G
G ≤ G ≤ 1,3 x G
S T S
IEC  1708/09

Figure 4 – Dependent time characteristic
The effective range of the characteristic quantity for the dependent time portion of the curve
shall lie between 2 × G and G . The minimum value of G is equal to 20 times the setting
S D D
value G . The manufacturer shall declare the setting value range for which this is applicable.
S
For setting values higher than this range, the manufacturer shall declare the value of G .
D
The threshold value G is the lowest value of the input energizing quantity for which the relay
T
is guaranteed to operate. G lies between G and 1,3 × G . Its value shall be defined by the
T S S
manufacturer.
Dependent time relays shall have a definite minimum operate time. This requirement may
...