oSIST prEN IEC 60255-27:2022

Measuring relays and protection equipment - Part 27: Product safety requirements

IEC 60255-27:2023 specifies the product safety requirements for measuring relays and protection equipment having a rated AC voltage up to 1 000 V, or a rated DC voltage up to 1 500 V. This document specifies essential safety requirements to minimize the risk of fire and hazards caused by electric shock or injury to the user and property. This document specifies only product safety requirements; functional performance of the equipment is not covered. This document covers all the ways in which the equipment can be mounted and used in cabinets, racks and panels. This document also applies to auxiliary devices such as shunts, series resistors, transformers, auxiliary control panels, display devices, etc., that are used in conjunction with measuring relays and protection equipment and are tested together.

Messrelais und Schutzeinrichtungen - Teil 27: Anforderungen an die Produktsicherheit

Relais de mesure et dispositifs de protection - Partie 27: Exigences de sécurité

L'IEC 60255-27:2023 spécifie les exigences de sécurité des produits pour les relais de mesure et les dispositifs de protection avec une tension assignée en courant alternatif inférieure ou égale à 1 000 V ou avec une tension assignée en courant continu inférieure ou égale à 1 500 V. Le présent document spécifie les exigences de sécurité fondamentales pour réduire le plus possible les risques d'incendie et de dangers causés par un choc électrique ou les risques de blessure de l'utilisateur et de dégradation matérielle. Le présent document spécifie uniquement les exigences de sécurité des produits; les performances fonctionnelles du matériel ne sont pas couvertes. En revanche, le présent document couvre tous les modes qui peuvent être utilisés pour le montage et l'utilisation du dispositif dans des baies, des racks ou des panneaux. Le présent document s'applique aussi aux dispositifs auxiliaires comme les shunts, résistances série, transformateurs, panneaux de commande auxiliaires, dispositifs d'affichage, etc., qui sont utilisés conjointement avec les relais de mesure et les dispositifs de protection et sont soumis à l'essai ensemble.

Merilni releji in zaščitna oprema - 27. del: Zahteve za varnost izdelka

General Information

• Status: Not Published
• Public Enquiry End Date: 23-Feb-2022
• ICS: 29.120.70 - Relays
• Technical Committee: ISS EIT.ERE - All-or-nothing electrical relays
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 10-Dec-2021
• Due Date: 29-Apr-2022
• Completion Date: 25-Feb-2022
• Directive: 2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
• Mandate: M/511 - Mandate to CEN, CENELEC and ETSI relating to harmonised standards in the field of the Low Voltage Directive
• Ref Project: FprEN IEC 60255-27:2022 - Measuring relays and protection equipment - Part 27: Product safety requirements

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN IEC 60255-27:2022
01-februar-2022
Merilni releji in zaščitna oprema - 27. del: Zahteve za varnost izdelka
Measuring relays and protection equipment - Part 27: Product safety requirements
Messrelais und Schutzeinrichtungen - Teil 27: Anforderungen an die Produktsicherheit
Relais de mesure et dispositifs de protection - Partie 27: Exigences de sécurité
Ta slovenski standard je istoveten z: prEN IEC 60255-27:2021
ICS:
29.120.70 Releji Relays
oSIST prEN IEC 60255-27:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 60255-27:2022

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oSIST prEN IEC 60255-27:2022
95/482/CDV

COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60255-27 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2021-12-03 2022-02-25
SUPERSEDES DOCUMENTS:
95/464/CD, 95/479/CC

IEC TC 95 : MEASURING RELAYS AND PROTECTION EQUIPMENT
SECRETARIAT: SECRETARY:
France Mr Thierry BARDOU
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

TC 14, TC 17, TC 38, TC 57, TC 77
Other TC/SCs are requested to indicate their interest, if any, in this
CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of CENELEC,
is drawn to the fact that this Committee Draft for Vote (CDV) is
submitted for parallel voting.
The CENELEC members are invited to vote through the CENELEC
online voting system.

This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are aware
and to provide supporting documentation.

TITLE:
Measuring relays and protection equipment – Part 27: Product safety requirements

PROPOSED STABILITY DATE: 2028

NOTE FROM TC/SC OFFICERS:


Copyright © 2021 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

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CONTENTS

FOREWORD . 8
INTRODUCTION . 10
1 Scope . 11
2 Normative references . 11
3 Terms and definitions . 13
4 Protection against electric shock . 21
4.1 Protection from contact with hazardous-live-parts . 21
4.1.1 General . 21
4.1.2 Insulation . 21
4.1.3 Equipment enclosure and barriers . 21
4.1.4 Hazardous live terminations using stranded wire . 22
4.2 Protective impedance . 22
4.3 Accessible parts . 23
4.3.1 General . 23
4.3.2 Determination of accessible parts . 23
4.3.3 Permissible limits for accessible parts . 24
4.4 Earthing and protective bonding requirements . 25
4.4.1 General . 25
4.4.2 Insulation between live parts and accessible conductive parts . 25
4.4.3 Protective bonding . 26
4.5 Functional earthed circuits . 26
4.6 Protective conductor connection . 27
4.7 High leakage current . 27
4.8 Solid insulation . 27
4.8.1 General . 27
4.8.2 Requirements . 27
4.9 Clearances and creepage distances. 28
4.9.1 General . 28
4.9.2 Clearances . 28
4.9.3 Creepage distances . 29
4.10 Single fault conditions . 29
4.10.1 Testing in single fault condition. 29
4.10.2 Application of single fault condition . 30
4.10.3 Duration of tests . 31
4.10.4 Compliance . 32
5 Mechanical aspects . 33
5.1 Protection against mechanical hazards . 33
5.1.1 Stability . 33
5.1.2 Moving parts . 33
5.1.3 Edges and corners. 33
5.2 Mechanical requirements . 33
5.3 Mechanical security of terminations . 33
6 Flammability and resistance to fire . 33
6.1 General . 33

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6.2 Requirements for protection against the spread of fire . 33
6.3 General hazards from overheating and fire . 35
6.3.1 Surface temperature limits for protection against burns . 35
6.3.2 Temperature of insulation . 36
6.3.3 Hazardous gases and chemicals . 36
6.4 Minimization of fire risk . 37
6.4.1 General . 37
6.4.2 Eliminating or reducing the sources of ignition within the equipment . 37
6.5 Cabling and fusing . 37
6.6 Flammability of materials and components . 38
6.6.1 General . 38
6.6.2 Materials for components and other parts inside fire enclosures . 38
6.6.3 Materials for fire enclosures. 38
6.6.4 Materials for components and other parts outside fire enclosures . 39
6.7 Fire ignition sources . 40
6.8 Conditions for a fire enclosure . 40
6.8.1 Parts requiring a fire enclosure . 40
6.8.2 Parts not requiring a fire enclosure . 40
6.9 Fire enclosures and flame barriers . 41
6.9.1 General . 41
6.9.2 Fire enclosures and flame barrier requirements . 41
6.10 Assessment of the fire risk due to a single fault condition . 43
6.10.1 Guidelines for maximum acceptable temperatures when subjecting a
circuit or component to a single fault condition . 43
6.10.2 Temperature of windings under normal use or a single fault condition . 43
6.10.3 Compliance of equipment with requirements for protection against the
spread of fire . 43
6.11 Limited-energy circuit . 43
7 General and fundamental design requirements for safety . 44
7.1 Climatic conditions for safety . 44
7.2 Electrical connections . 45
7.3 Components . 45
7.3.1 General . 45
7.3.2 High-integrity part or component . 45
7.4 Connection to other equipment . 45
7.5 High intensity light sources . 46
7.6 Explosion . 46
7.6.1 General . 46
7.6.2 Components at risk of explosion . 46
8 Marking, documentation and packaging . 47
8.1 Marking . 47
8.1.1 General . 47
8.1.2 Identification . 47
8.1.3 Auxiliary supplies, Measurands, Inputs and Outputs . 47
8.1.4 Fuses . 49
8.1.5 Measuring circuit terminals . 49
8.1.6 Terminals and operating devices . 50

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8.1.7 Equipment protected by double or reinforced insulation . 50
8.1.8 Batteries . 50
8.1.9 Test voltage marking . 53
8.1.10 Warning markings . 53
8.1.11 Marking durability . 54
8.2 Documentation . 54
8.2.1 General . 54
8.2.2 Equipment ratings . 54
8.2.3 Equipment installation . 55
8.2.4 Equipment commissioning and maintenance . 55
8.2.5 Equipment operation . 56
8.3 Packaging . 56
9 Type tests and routine tests . 56
9.1 General . 56
9.2 Safety type tests . 58
9.3 Routine testing . 58
9.4 Conditions for testing . 58
9.5 Verification procedure . 58
9.6 Tests . 59
9.6.1 Climatic environmental tests . 59
9.6.2 Mechanical tests . 59
9.6.3 Clearances and creepage distances . 60
9.6.4 Safety-related electrical tests . 60
9.6.5 Electrical environment and flammability . 65
9.6.6 Reverse polarity and slow ramp test . 67
9.6.7 Resistance to mechanical stress . 67
Annex A (normative)  Isolation class requirements and example diagrams . 70
A.1 Introduction . 70
A.1.1 General . 70
A.1.2 Hazardous live voltage (HLV) . 70
A.1.3 Symbols . 71
A.2 Typical insulation examples complying with the requirements of Table A.2 . 75
Annex B (normative) Rated impulse voltages . 79
Annex C (normative) Guidance for the determination of clearance, creepage distance
and withstand voltages . 80
C.1 General . 80
C.1.1 Introductory remark . 80
C.1.2 Rated insulation voltages . 80
C.1.3 Determination of rated insulation voltage . 81
C.1.4 Determination of rated impulse voltage . 81
C.1.5 Switching overvoltages generated by equipment . 82
C.1.6 lnsulation material . 82
C.1.7 Overvoltage categories . 82
C.2 Determination of clearances, creepage distances and withstand voltages . 84
C.2.1 Guidance for determination of clearances, creepage distances and
withstand voltages . 84

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C.2.2 Determination of clearances, creepage distances and withstand
voltages . 85
Annex D (informative) Components . 91
D.1 General . 91
D.2 Introductory remark . 91
D.3 Transformers . 91
D.4 Equipment primary circuit capacitors . 91
D.5 Coil devices – transformers, instrument transformers and transducers,
reactors, and operating coils of relays and contactors with multiple
windings/screen . 92
D.5.1 Coil windings . 92
D.5.2 Insulating foil . 93
D.5.3 Interposing protective screen . 93
D.5.4 Safety isolation transformers . 93
D.6 Electromechanical components . 93
D.7 Semiconductor components and semiconductor configurations . 93
D.8 Connectors and terminal blocks . 93
D.9 Voltage dependent resistors (VDRs) . 94
D.10 Intentional radio transmitters . 95
Annex E (normative) External wiring terminations . 96
E.1 General . 96
E.2 Permanently connected equipment . 96
E.3 Conductors . 96
E.4 Terminals . 97
Annex F (informative) Examples of battery protection . 98
Annex G (informative) Risk assessment . 99
G.1 Risk assessment procedure . 99
G.2 Achieving tolerable risk . 100
G.3 An application of risk assessment procedures . 101
Bibliography . 103


Figure 1 – Flow chart showing requirements for protection against the spread of fire . 35
Figure 2 – Baffle . 41
Figure 3 – Location and extent of a flame barrier . 42
Figure 4 – Voltage ramp test . 67
Figure 5 – Impact test with sphere . 69
Figure A.1 – Equipment with SELV input/output (I/O) . 75
Figure A.2 – Equipment with PELV input/output (I/O) . 76
Figure A.3 – Equipment with PEB input/output (I/O) . 77
Figure A.4 – Equipment with ELV input/output (I/O) . 78
Figure C.1 – Guidance for determination of clearances, creepage distances and
withstand voltages . 85
Figure F.1 – Non-rechargeable battery protection . 98
Figure F.2 – Rechargeable battery protection . 98
Figure G.1 – Iterative process of RISK assessment and RISK reduction . 99

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Figure G.2 – Risk reduction . 101

Table 1 – Equipment enclosure requirements for protection against electric shock . 21
Table 2 – Current levels under normal use . 25
Table 3 – Charge or energy of capacitance levels under normal use . 25
Table 4 – Altitude multiplication factor . 28
Table 5 – Current levels in single fault condition . 32
Table 6 – Maximum temperature under normal use and at an ambient temperature of
40 °C . 36
Table 7 – Maximum temperature for insulation materials . 36
Table 8 – Acceptable perforation in the bottom of an equipment case . 42
Table 9 – Insulation material of windings . 43
Table 10 – Limits of maximum available current . 44
Table 11 – Overcurrent protective device . 44
Table 12 – Fuse types . 49
Table 13 – Symbols . 52
Table 14 – Symbols for marking of test voltage(s) . 53
Table 15 – Overview of tests . 56
Table 16 – Impulse generator characteristics . 61
Table 17 – Guidance for routine dielectric voltage testing for safety – Informative . 64
Table 18 – Limiting dynamic values . 66
Table 19 – Impact energy levels, test height and corresponding IK codes . 69
Table A.1 – Circuit isolation class for product circuits/groups . 70
Table A.2 – Insulation requirement between any two circuits . 73
Table B.1 – Rated impulse voltages (waveform: 1,2/50 µs) . 79
Table C.1 – Comparative tracking index (CTI) . 82
Table C.2 – Functional insulation, pollution degree 1, overvoltage category I . 85
Table C.3 – Functional insulation, pollution degree 2, overvoltage category I . 86
Table C.4 – Functional, basic or supplementary insulation, pollution degree 1,
overvoltage category II . 86
Table C.5 – Functional, basic or supplementary insulation, pollution degree 2,
overvoltage category II . 87
Table C.6 – Functional, basic or supplementary insulation, pollution degree 1,
overvoltage category III . 87
Table C.7 – Functional, basic or supplementary insulation, pollution degree 2,
overvoltage category III . 88
Table C.8 – Double or reinforced insulation, pollution degree 1, overvoltage category
II 88
Table C.9 – Double or reinforced insulation, pollution degree 2, overvoltage category
II 89
Table C.10 – Double or reinforced insulation, pollution degree 1, overvoltage category
III 89
Table C.11 – Double or reinforced insulation, pollution degree 2, overvoltage category
III 90

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Table C.12 – Test voltage multiplication factor for proving the clearance in air . 90
Table C.13 – Reduction of the pollution degree of internal environment through the
use of additional protection within the equipment . 90
Table E.1 – Range of conductor sizes to be accepted by terminals . 97
Table E.2 – Sizes of terminal studs or screws directly securing supply conductors. 97
Table G.1 – Severity of harm . 101
Table G.2 – Probability of harm . 101
Table G.3 – Risk category. 102

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 27: Product safety requirements


FOREWORD
1) The International Electrotechnical Commission (IEC
...