SIST EN 60255-127:2014

SLOVENSKI STANDARD
SIST EN 60255-127:2014
01-marec-2014
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SIST EN 60255-3:2001
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Measuring relays and protection equipment - Part 127: Functional requirements for
over/under voltage protection
Relais de mesure et dispositifs de protection -- Partie 127: Exigences fonctionnelles pour
les protections à minimum et maximum de tension
Ta slovenski standard je istoveten z: EN 60255-127:2014
ICS:
29.120.70 Releji Relays
SIST EN 60255-127:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60255-127:2014

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SIST EN 60255-127:2014

EUROPEAN STANDARD
EN 60255-127

NORME EUROPÉENNE
January 2014
EUROPÄISCHE NORM

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


English version


Measuring relays and protection equipment -
Part 127: Functional requirements for over/under voltage protection
(IEC 60255-127:2010)


Relais de mesure et dispositifs de protection -  Messrelais und Schutzeinrichtungen -
Partie 127: Exigences fonctionnelles pour les Teil 127: Funktionsnorm für Über-
protections à minimum et maximum de tension /Unterspannungsschutz
(CEI 60255-127:2010) (IEC 60255-127:2010)





This European Standard was approved by CENELEC on 2013-09-19. 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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same status as the official versions.

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

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

CEN-CENELEC Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2014 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60255-127:2014 E

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SIST EN 60255-127:2014
EN 60255-127:2014 - 2 -
Foreword
The text of document 95/254/CDV, future edition 1 of IEC 60255-127, prepared by IEC/TC 95
"Measuring relays and protection equipment" was submitted to the IEC-CENELEC parallel vote and
approved by CENELEC as EN 60255-127:2014.
The following dates are fixed:
– latest date by which the document has to be implemented at (dop) 2014-07-10
national level by publication of an identical national
standard or by endorsement
– latest date by which the national standards conflicting with (dow) 2016-09-19
the document have to be withdrawn

This document supersedes EN 60255-3:1998.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 60255-127:2010 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 61850 NOTE Harmonized in EN 61850 series.
IEC 61850-7-4 NOTE Harmonized as EN 61850-7-4.
IEC 61850-9-2 NOTE Harmonized as EN 61850-9-2.

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SIST EN 60255-127:2014
- 3 - EN 60255-127:2014
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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
IEC 60044 series Instrument transformers EN 60044 series
IEC 60255-1 - Measuring relays and protection EN 60255-1 -
equipment
Part 1: Common requirements

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SIST EN 60255-127:2014

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SIST EN 60255-127:2014
IEC 60255-127
®
Edition 1.0 2010-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Measuring relays and protection equipment –
Part 127: Functional requirements for over/under voltage protection

Relais de mesure et dispositifs de protection –
Partie 127: Exigences fonctionnelles pour les protections à minimum et
maximum de tension

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
T
CODE PRIX
ICS 29.120.70 ISBN 978-2-88910-077-4
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60255-127:2014
– 2 – 60255-127 © IEC:2010
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 energising quantities/Energising quantities .8
4.3 Binary input signals .9
4.4 Functional logic .9
4.4.1 Operating characteristics .9
4.4.2 Reset characteristics .13
4.5 Binary output signals .14
4.5.1 Start (pick-up) signal .14
4.5.2 Operate (trip) signal.15
4.5.3 Other binary output signals.15
5 Performance specification .15
5.1 Accuracy related to the characteristic quantity.15
5.2 Accuracy related to the operate time .15
5.3 Accuracy related to the reset time .16
5.4 Transient performance .16
5.4.1 Overshoot time .16
5.4.2 Response to time varying value of the characteristic quantity .16
5.5 Voltage transformer requirements .16
6 Functional test methodology.16
6.1 General .16
6.2 Determination of steady state errors related to the characteristic quantity .17
6.2.1 Accuracy of setting (start) value .17
6.2.2 Reset ratio determination.18
6.3 Determination of steady state errors related to the start and operate time .18
6.4 Determination of steady state errors related to the reset time.19
6.5 Determination of transient performance .20
6.5.1 Overshoot time for undervoltage protection .20
6.5.2 Response to time varying value of the characteristic quantity for
dependent time relays .20
7 Documentation requirements .21
7.1 Type test report.21
7.2 Other user documentation .22
Annex A (informative) Reset time determination for relays with trip output only.23
Bibliography.24

8
Figure 1 – Simplified protection function block diagram.
Figure 2 – Overvoltage independent time characteristic .9
Figure 3 – Undervoltage independent time characteristic .10
Figure 4 – Dependent time characteristic for overvoltage protection .11
Figure 5 – Dependent time characteristic for undervoltage protection .12

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SIST EN 60255-127:2014
60255-127 © IEC:2010 – 3 –
Figure 6 – Definite time reset characteristic .14
Figure 7 – Definite time reset characteristic (alternative solution with instantaneous
reset after relay operation).14
Figure 8 – Test waveform .21
Figure A.1 – Dependent reset time determination .23

Table 1 – Test points for overvoltage elements .19
Table 2 – Test points for undervoltage elements .19
Table 3 – Test points for overvoltage elements .20
Table 4 – Test points for undervoltage elements .20
Table 5 – Recommended values for the test .21

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 127: Functional requirements for over/under voltage 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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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 60255-127 has been prepared by IEC technical committee 95:
Measuring relays and protection equipment.
The text of this standard is based on the following documents:
CDV Report on voting
95/254/CDV 95/261/RVC

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.
A list of all parts of the IEC 60255 series can be found, under the general title Measuring
relays and protection equipment, on the IEC website.

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SIST EN 60255-127:2014
60255-127 © IEC:2010 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the stability 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 60255-127:2014
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MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 127: Functional requirements for over/under voltage protection



1 Scope
This part of IEC 60255 specifies minimum requirements for over/under voltage relays. The
standard includes specification of the protection function, measurement characteristics and
time delay characteristics.
This standard 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 voltage functions covered by this standard are as follows:

IEEE/ANSI C37.2 IEC 61850-7-4

Function numbers Logical nodes

Phase undervoltage protection 27 PTUV
Positive sequence undervoltage protection 27D PTUV
Phase overvoltage protection 59 PTOV
Residual/zero-sequence overvoltage protection 59N/59G PTOV
Negative sequence/ unbalance overvoltage protection 47 PTOV

The 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 60044 (all parts), Instrument transformers
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 definition 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 60255-127:2014
60255-127 © IEC:2010 – 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 vs. 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
the reference value used for the definition of the theoretical curve of time vs. characteristic
quantity
3.4
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
3.5
operate time
duration of the time interval between the instant when the characteristic quantity of a
measuring relay in reset condition is changed, under specified conditions, and the instant
when the relay operates
[IEC 60050-447:2010, 447-05-05]
3.6
disengaging time
duration of the time interval between the instant a specified change is made in the value of
the input energizing quantity which will cause the relay to disengage and the instant it
disengages
[IEC 60050-447:2010, 447-05-10]
3.7
reset time
duration of the time interval between the instant when the characteristic quantity of a
measuring relay in operate condition is changed, under specified conditions, and the instant
when the relay resets
[IEC 60050-447:2010, 447-05-06]
3.8
overshoot time
the difference between the operate time of the relay at the specified value of the input
energising quantity and the maximum duration of the value of input energising quantity which,
when suddenly reduced (for the overvoltage relay)/increased(for the undervoltage relay) to a
specified value below(for the overvoltage relay)/above(for the undervoltage relay) the setting
value, is insufficient to cause operation
3.9
threshold of independent time operation
G
D
the value of the characteristic quantity at which the relay operate time changes from
dependent time operation to independent time operation

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SIST EN 60255-127:2014
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3.10
reset ratio
disengaging ratio
ratio between the voltage value at the point where the relay just ceases to start (start signal
changes from ON to OFF) and the actual start voltage of the element.
NOTE It is usually defined as a percentage such that for an overvoltage element the resetting ratio shall be less
than 100 % and for an undervoltage element the reset ratio shall be greater than 100 %.
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  743/10
Figure 1 – Simplified protection function block diagram
4.2 Input energising quantities/Energising quantities
The input energising quantities are the measuring signals, e.g. voltages. Their ratings and
relevant standards are specified in IEC 60255-1. Input energising quantities can come with
wires from voltage transformers or as a data packet over a communication port using an
appropriate communication protocol (such as IEC 61850-9-2).
The energising quantities used by the protection function need not be directly the voltage at
the secondary side of the voltage transformers. Therefore, the measuring relay documentation
shall state the type of energising quantities used by the protection function. Examples are:
• single phase voltage measurement;
• three phase voltage (phase to phase or phase to earth) measurement;
• neutral to earth voltage or residual voltage measurement;
• positive, negative or zero sequence voltage measurement.
The type of measurement of the energising quantity shall be stated. Examples are:
• RMS value of the signal;

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SIST EN 60255-127:2014
60255-127 © IEC:2010 – 9 –
• 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 energising 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 overvoltage relays, t = t when G > G . The independent time characteristic is
(G) op S
presented in Figure 2.
IEC  744/10

Figure 2 – Overvoltage independent time characteristic

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SIST EN 60255-127:2014
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For undervoltage relays, t = t when G < G . The independent time characteristic is
(G) op S
presented in Figure 3.


IEC  745/10
Figure 3 – Undervoltage independent time characteristic
4.4.1.3 Standard dependent time characteristics
For overvoltage protection, the characteristic curves of dependent time relays shall follow a
law of the form:
T
t = (1)

(G)
⎛ ⎞
G
⎜ ⎟
−1
⎜ ⎟
G
S
⎝ ⎠
where:
t is the theoretical operate time with constant value of G in seconds;
(G)
T is the time setting (theoretical operate time for G = 2 × G );
S
G is the measured value of the characteristic quantity;
G is the setting value (see 3.3).
S
This dependent time characteristic is shown in Figure 4.

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SIST EN 60255-127:2014
60255-127 © IEC:2010 – 11 –
t
(G)
T
Effective range
G
G
G
S 2G D
S
IEC  746/10
1,2 ´ G
S

Figure 4 – Dependent time characteristic for overvoltage protection
The effective range of the characteristic quantity for the dependent time portion of the curve
shall lie between 1,2 × G and G . The value of G shall be stated by the manufacturer for
S D D
the upper limit of the setting range.
For undervoltage protection, the characteristic curves of dependent time relays shall follow a
law of the form:
T
t = (2)
(G)
⎛ ⎞
G
⎜ ⎟
1−
⎜ ⎟
G
⎝ S ⎠
where:
t is the theoretical operate time in seconds with constant value of G;
(G)
T is the time setting (theoretical operate time for G = 0);
G is the measured value of the characteristic quantity;
G is the setting value (see 3.3).
S
This dependent time characteristic is shown in Figure 5.

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SIST EN 60255-127:2014
– 12 – 60255-127 © IEC:2010
t
(G)
T
G
0 G
S
Effective range
IEC  747/10

Figure 5 – Dependent time characteristic for undervoltage protection
The effective range of the dependent time portion of the characteristic quantity shall lie
between 0 and G .
S
Power system fault conditions can produce time varying voltages. To ensure proper
coordination between dependent time relays under such conditions, relay behaviour shall be
of the form described by the integration given by Equation 3.
For G > G (overvoltage protection) or G < G (undervoltage protection):
S S
T
0
1
dt = 1 (3)
∫
t(G)
0
where:
T is the theoretical operate time where G varies with time;
0
t(G) is the theoretical operate time with constant value of G in seconds;
G is the measured value of the characteristic quantity.
Operate time is defined as the time instant when the integral in Equation 3 becomes equal to
or greater than one.

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SIST EN 60255-127:2014
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4.4.2 Reset characteristics
4.4.2.1 General
To allow users to determine the behaviour of the relay in the event of repetitive intermittent
faults or for faults which may occur in rapid succession, relay resetting characteristics shall be
defined by the manufacturer. The recommended reset characteristics are defined below.
4.4.2.2 No intentional delay on reset
For undervoltage relays, for G > (reset ratio) × G , the relay shall return to its reset state with
S
no intentional delay. This reset option can apply to both dependent and independent time
relays.
For overvoltage relays, for G < (reset ratio) × G , the relay shall return to its reset state with
S
no intentional delay. This reset option can apply to both dependent and independent time
relays.
4.4.2.3 Definite time resetting
This reset characteristic is applicable to overvoltage and undervoltage protection. Here the
definite time reset is described for an overvoltage protection. The principle is the same for an
undervoltage protection.
For G < (reset ratio) × G , the relay shall return to its reset state after a user-defined reset
S
time delay, t . During the reset time, the element shall retain its state value as defined by
r
t
P
1
with t being the transient period during which G > G . If during the reset time period,
dt P S
∫
t()G
0
the characteristic quantity exceeds G , the reset timer t , is immediately reset to zero and the
S r
element continues normal operation starting from the retained value.
Following G > G for a cumulative period causing relay operation, the relay shall maintain its
S
operated state for the reset time period after the operating quantity falls below G as shown in
S
Figure 6. Alternatively, the relay may return to its reset state with no intentional delay as soon
as the operating quantity falls below G after tripping as shown in Figure 7.
S
This reset option can apply to both dependent and independent time elements. A graphical
representation of this reset characteristic is shown in Figures 6 and 7, for partial and complete
operation of the element.

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SIST EN 60255-127:2014
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Start time
Energ
...