SIST EN IEC 60255-187-1:2021

SLOVENSKI STANDARD
SIST EN IEC 60255-187-1:2021
01-november-2021
Merilni releji in zaščitna oprema - 187-1. del: Funkcijske zahteve za diferenčno
zaščito - Omejena in neomejena diferenčna zaščita motorjev, generatorjev in
transformatorjev
Measuring relays and protection equipment - Part 187-1: Functional requirements for
differential protection - Restrained and unrestrained differential protection of motors,
generators and transformers
Messrelais und Schutzeinrichtungen - Teil 187-1: Funktionsanforderungen für den
stabilisierten und nicht stabilisierten Differentialschutz von Motoren, Generatoren und
Transformatoren
Relais de mesure et dispositifs de protection - Partie 187-1: Exigences fonctionnelles
pour la protection différentielle - Protection différentielle avec et sans caractéristique de
retenue des moteurs, générateurs et transformateurs
Ta slovenski standard je istoveten z: EN IEC 60255-187-1:2021
ICS:
29.120.70 Releji Relays
SIST EN IEC 60255-187-1:2021 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 60255-187-1:2021

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SIST EN IEC 60255-187-1:2021


EUROPEAN STANDARD EN IEC 60255-187-1

NORME EUROPÉENNE

EUROPÄISCHE NORM
September 2021
ICS 29.120.70

English Version
Measuring relays and protection equipment - Part 187-1:
Functional requirements for differential protection - Restrained
and unrestrained differential protection of motors, generators
and transformers
(IEC 60255-187-1:2021)
Relais de mesure et dispositifs de protection - Partie 187-1: Messrelais und Schutzeinrichtungen - Teil 187-1:
Exigences fonctionnelles pour la protection différentielle - Funktionsanforderungen für den stabilisierten und nicht
Protection différentielle avec et sans caractéristique de stabilisierten Differentialschutz von Motoren, Generatoren
retenue des moteurs, générateurs et transformateurs und Transformatoren
(IEC 60255-187-1:2021) (IEC 60255-187-1:2021)
This European Standard was approved by CENELEC on 2021-09-01. 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 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 60255-187-1:2021 E

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SIST EN IEC 60255-187-1:2021
EN IEC 60255-187-1:2021 (E)
European foreword
The text of document 95/465/FDIS, future edition 1 of IEC 60255-187-1, prepared by IEC/TC 95
“Measuring relays and protection equipment” was submitted to the IEC-CENELEC parallel vote and
approved by CENELEC as EN IEC 60255-187-1:2021.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2022-06-01
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2024-09-01
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60255-187-1:2021 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 (series) NOTE Harmonized as EN 61850 (series)
IEC 61850-7-4:2010 NOTE Harmonized as EN 61850-7-4:2010 (not modified)
IEC 61850-9-2 NOTE Harmonized as EN 61850-9-2
2

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SIST EN IEC 60255-187-1:2021
EN IEC 60255-187-1:2021 (E)
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60255-1 - Measuring relays and protection equipment EN 60255-1 -
- Part 1: Common requirements
IEC 61850-8-1 - Communication networks and systems for EN 61850-8-1 -
power utility automation - Part 8–1:
Specific communication service mapping
(SCSM) - Mappings to MMS (ISO 9506-1
and ISO 9506-2) and to ISO/IEC 8802-3
IEC 61869-2 - Instrument transformers - Part 2: Additional EN 61869-2 -
requirements for current transformers
IEC 61869-9 - Instrument transformers - Part 9: Digital EN IEC 61869-9 -
interface for instrument transformers


3

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SIST EN IEC 60255-187-1:2021

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SIST EN IEC 60255-187-1:2021




IEC 60255-187-1

®


Edition 1.0 2021-07




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE
colour

inside










Measuring relays and protection equipment –

Part 187-1: Functional requirements for differential protection – Restrained and

unrestrained differential protection of motors, generators and transformers



Relais de mesure et dispositifs de protection –

Partie 187-1: Exigences fonctionnelles pour la protection différentielle –


Protection différentielle avec et sans caractéristique de retenue des moteurs,

générateurs et transformateurs












INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 29.120.70 ISBN 978-2-8322-1003-9




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN IEC 60255-187-1:2021
– 2 – IEC 60255-187-1:2021 © IEC 2021
CONTENTS
FOREWORD . 11
1 Scope . 13
2 Normative references . 14
3 Terms and definitions . 14
4 Specification of the function . 18
4.1 General . 18
4.2 Input energizing quantities/energizing quantities . 19
4.2.1 General . 19
4.2.2 Connections . 19
4.3 Binary input signals. 19
4.4 Functional logic . 22
4.4.1 General . 22
4.4.2 Phase biased differential protection . 22
4.4.3 Biased restricted earth fault protection . 24
4.4.4 Compensation of energizing quantities . 25
4.4.5 Additional restraint or blocking methods . 26
4.5 Binary output signals . 27
4.5.1 General . 27
4.5.2 Start (pick-up) signals . 27
4.5.3 Operate (trip) signals . 27
4.5.4 Other output signals . 27
4.6 Additional influencing functions and conditions . 27
4.6.1 General . 27
4.6.2 Operation during CT saturation . 28
4.6.3 Switch onto fault . 28
4.6.4 Energizing quantity failure (CT supervision) . 28
4.6.5 Off-nominal frequency operation . 28
4.6.6 Geomagnetically induced currents (GIC) . 28
5 Performance specification . 29
5.1 General . 29
5.2 Effective and operating ranges. 29
5.3 Steady state accuracy tests in the effective range . 29
5.3.1 General . 29
5.3.2 Test related to the declared thermal withstand current . 30
5.3.3 Basic characteristic accuracy . 30
5.3.4 Ratio compensation accuracy . 30
5.3.5 Phase (vector) compensation validity . 31
5.3.6 Zero sequence compensation validity . 31
5.3.7 Harmonic restraint basic accuracy . 31
5.3.8 Basic accuracy of time delay settings . 31
5.3.9 Disengage time. 31
5.4 Dynamic performance in operating range . 32
5.4.1 General . 32
5.4.2 Typical operate time . 32
5.4.3 Relay stability for external faults . 32
5.4.4 Relay behaviour for internal fault preceded by an external fault . 33
5.5 Stability during magnetizing inrush conditions . 33

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SIST EN IEC 60255-187-1:2021
IEC 60255-187-1:2021 © IEC 2021 – 3 –
5.6 Stability during overexcitation conditions . 33
5.7 Presence of harmonics on load . 33
5.8 Performance during saturation of current transformers . 33
5.9 Behaviour of differential protection with digital interface for the energizing
quantities . 34
6 Functional tests . 34
6.1 General . 34
6.2 Test related to the declared thermal withstand current . 35
6.3 Steady state accuracy tests in effective range . 35
6.3.1 General . 35
6.3.2 Basic characteristic accuracy . 37
6.3.3 Ratio (magnitude) compensation accuracy . 44
6.3.4 Phase (vector) compensation validity . 45
6.3.5 Zero sequence compensation validity . 47
6.3.6 Harmonic restraint basic accuracy test under steady state conditions at

nominal frequency . 50
6.3.7 Accuracy related to time delay setting . 52
6.3.8 Determination and reporting of the disengage time . 54
6.4 Dynamic performance tests . 55
6.4.1 General . 55
6.4.2 Operate time for double infeed network model (restrained operation) . 57
6.4.3 Operate time for double infeed network model (unrestrained operation) . 68
6.4.4 Operate time for radial single infeed network model (restrained
operation) . 73
6.4.5 Operate time for radial single infeed network model (unrestrained
operation) . 86
6.4.6 Reporting of typical operate time . 89
6.4.7 Stability for external faults . 95
6.5 Relay behaviour for internal fault preceded by an external fault . 112
6.5.1 General . 112
6.5.2 Application specific considerations: transformer differential . 112
6.5.3 Application specific considerations: biased restricted earth fault . 115
6.5.4 Application specific considerations: generator differential . 119
6.5.5 Reporting . 122
6.6 Stability during inrush conditions. 123
6.6.1 General . 123
6.6.2 Application specific considerations: transformer differential . 123
6.7 Stability during overexcitation conditions . 128
6.7.1 General . 128
6.7.2 Application specific considerations: transformer differential . 128
6.8 Performance with load harmonics . 133
6.8.1 General . 133
6.8.2 Application specific considerations: transformer differential . 133
6.8.3 Application specific considerations: generator or motor differential . 137
6.8.4 Application specific considerations: biased restricted earth fault . 140
6.8.5 Reporting . 142
7 Documentation requirements . 143
7.1 Type test report . 143
7.2 Other user documentation . 143

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SIST EN IEC 60255-187-1:2021
– 4 – IEC 60255-187-1:2021 © IEC 2021
Annex A (informative) Examples of phase (vector) compensation and zero sequence
compensation schemes . 144
A.1 General . 144
A.2 Y→d conversion . 145
A.2.1 Current conversion . 145
A.2.2 Three-phase fault at Y (star/wye) side . 146
A.2.3 Phase-phase fault at Y (star/wye) side . 147
A.2.4 Single-phase fault at Y (star/wye) side . 147
A.2.5 Three-phase fault at delta side . 148
A.2.6 Phase-phase fault at delta side . 149
A.2.7 Single-phase fault at delta side . 149
A.2.8 Ratio between start currents under different fault types . 152
A.3 d→Y conversion . 152
A.3.1 Current conversion . 152
A.3.2 Three-phase fault at Y (star/wye) side . 153
A.3.3 Phase-phase fault at Y (star/wye) side . 153
A.3.4 Single-phase fault at Y (star/wye) side . 153
A.3.5 Three-phase fault at delta side . 154
A.3.6 Phase-phase fault at delta side . 154
A.3.7 Single-phase fault at delta side . 155
A.3.8 Ratio between start currents under different fault types . 155
Annex B (normative) Calculation of mean, median and mode . 156
B.1 Mean . 156
B.2 Median . 156
B.3 Mode . 156
B.4 Example . 156
Annex C (normative) CT requirements . 157
C.1 General . 157
C.2 Transformer differential protection . 161
C.2.1 General . 161
C.2.2 Fault 1 . 161
C.2.3 Fault 2 . 162
C.2.4 Fault 3 . 162
C.3 Transformer restricted earth fault protection . 163
C.3.1 General . 163
C.3.2 Fault 1 . 163
C.3.3 Fault 2 . 164
C.3.4 Fault 3 . 164
C.4 Generator differential protection . 165
C.4.1 General . 165
C.4.2 Fault 2 . 165
C.4.3 Criteria and additional conditions . 166
C.5 Motor differential protection . 166
C.5.1 General . 166
C.5.2 Fault 1 . 166
C.5.3 Criteria and additional conditions . 166
C.5.4 Start of motor, security case . 167
C.5.5 Criteria and additional conditions . 167
C.6 Reporting . 167

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SIST EN IEC 60255-187-1:2021
IEC 60255-187-1:2021 © IEC 2021 – 5 –
Annex D (informative) CT saturation and influence on the performance of differential
relays . 168
Annex E (informative) Guidance on dimensioning of CTs for transformer differential

protection . 173
E.1 General . 173
E.2 Example 1 . 174
E.2.1 General . 174
E.2.2 Verification of CT1 – Internal fault . 175
E.2.3 Verification of CT1 – External fault . 175
E.2.4 Verification of CT2 . 176
E.3 Example 2 . 177
E.3.1 General . 177
E.3.2 Dimensioning of CT1 . 178
E.3.3 Dimensioning of CT2 . 179
Annex F (informative) Examples of test procedures to determine CT sizing
requirements for differential protection . 181
F.1 General . 181
F.2 Test data . 183
F.2.1 General . 183
F.2.2 Network model for CT requirement tests for the transformer differential
protection . 183
F.2.3 Network model for CT requirement tests for the transformer restricted
earth fault protection . 187
F.3 CT data and CT models . 189
F.4 Test summary . 197
Annex G (normative) Ramping methods for testing basic characteristic accuracy . 199
G.1 General . 199
G.2 Pre-fault condition . 199
G.3 Pseudo-continuous ramp . 199
G.4 Ramp of shots. 201
Annex H (informative) Example of COMTRADE file for an evolving fault test case . 203
Annex I (normative) Definition of fault inception angle. 204
Bibliography . 205

Figure 1 – Explanatory diagram for start time, operate time and disengage time . 17
Figure 2 – Simplified biased differential functional block diagram . 18
Figure 3 – Primary current reference direction . 21
Figure 4 – Typical restrained element (biased) characteristic . 23
Figure 5 – Typical unrestrained element characteristic . 23
Figure 6 – Example of combined characteristic using restrained and unrestrained
elements . 24
Figure 7 – Basic error of the operating characteristic . 30
Figure 8 – Example of an operating characteristic in the I /I plane with a
DIFF REST
tolerance band . 37
Figure
...