IEC 60255-1:2022

Measuring relays and protection equipment - Part 1: Common requirements

IEC 60255-1:2022 specifies common rules and requirements applicable to measuring relays and protection equipment, including any combination of equipment to form a distributed protection scheme for power system protection such as control, monitoring and process interface equipment, to obtain uniformity of requirements and tests. This document covers the main technologies in use today; other emerging technologies present specific EMC and safety issues but the philosophy in this document will be applied.
This second edition cancels and replaces the first edition published in 2009. This edition includes the following significant technical changes with respect to the previous edition:
a. scope of document clarified;
b. merging units and communications as an integral part of the protection added;
c. binary output clarification expanded;
d. environmental operating conditions added (Annex B);
e. test reference conditions added;
f. multiple changes to improve understanding across most clauses;
g. derating by manufacturer added;
h. safety and EMC tests removed from document and referenced only;
i. relay setting and type test guidelines modified (Annex A)
j. battery monitor port and low power instrument transformers added.

Relais de mesure et dispositifs de protection - Partie 1: Exigences communes

lEC 60255-1:2022 spécifie les exigences et les règles communes applicables aux relais de mesure et aux dispositifs de protection, y compris toute combinaison de matériel pour former un système de protection distribué pour la protection des réseaux d'alimentation, tel que des dispositifs de commande, de surveillance et d'interface de processus, afin d'obtenir l'uniformité des exigences et des essais. Le présent document couvre les principales technologies utilisées actuellement. D'autres technologies émergentes présentent des problèmes de CEM et de sécurité spécifiques, mais la philosophie du présent document est appliquée.
Cette deuxième édition annule et remplace la première édition parue en 2009. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a. clarification du domaine d'application du document;
b. ajout des concentrateurs et des communications en tant que partie intégrante de la protection;
c. extension de la clarification des sorties binaires;
d. ajout des conditions d'environnement de fonctionnement (Annexe B);
e. ajout des conditions de référence pour les essais;
f. apport de modifications multiples qui visent à améliorer la compréhension à la plupart des articles;
g. ajout du détarage par le fabricant;
h. suppression des essais de sécurité et de CEM du document, auxquels il est seulement fait référence;
j. modification des lignes directrices relatives au réglage des relais et aux essais de type (Annexe A);
k. ajout de l'accès de surveillance de batterie et des transformateurs de mesure de faible puissance.

General Information

• Status: Published
• Publication Date: 14-Dec-2022
• ICS: 29.120.70 - Relays
• Technical Committee: TC 95 - Measuring relays and protection equipment
• Drafting Committee: MT 3 - TC 95/MT 3
• Current Stage: PPUB - Publication issued
• Start Date: 15-Dec-2022
• Completion Date: 30-Dec-2022

Relations

• Revises: IEC 60255-1:2009 - Measuring relays and protection equipment - Part 1: Common requirements
• Effective Date: 05-Sep-2023

Overview

IEC 60255-1:2022 is the latest international standard establishing common requirements for measuring relays and protection equipment used in electrical power systems. Published by the International Electrotechnical Commission (IEC), this standard ensures uniformity in the design, testing, and performance of relay devices crucial for protection, control, and monitoring in power utilities. It applies broadly to devices that can be configured individually or as part of a distributed protection scheme, encompassing various control, process interface, and monitoring equipment widely used in modern power system protection.

The 2022 edition supersedes the 2009 version, introducing significant clarifications and technical updates such as expanded environmental conditions, updated relay setting guidelines, and enhanced communication and binary output requirements. Importantly, it integrates modern technologies, addressing cybersecurity and interoperability concerns while referring safety and EMC testing requirements to specialized documents.

Key Topics

• Scope and Application: Defines the boundaries for inclusion, covering measuring relays and protection equipment with control and monitoring functions in power systems.
• Environmental Conditions: Specifies typical operating, storage, and transport conditions to ensure equipment reliability in diverse climates and situations.
• Ratings and Performance: Covers rated voltage, current, frequency, burden, and temperature ranges, establishing baseline expectations for equipment operation.
• Design and Construction: Details mandatory aspects like marking, dimensions, enclosure protection, functional performance, product safety, and mechanical robustness including vibration and seismic tolerance.
• Communication and Cybersecurity: Addresses modern communication protocols integration and introduces cybersecurity considerations vital to today's interconnected protection systems.
• Testing Procedures: Outlines standardized test conditions and methodologies to validate burden measurements, climatic endurance, and functional accuracy.
• Documentation: Identifies requirements for marking, labeling, packaging, and comprehensive technical documentation essential for compliance verification.

Applications

IEC 60255-1:2022 serves as an essential framework for manufacturers, engineers, and utilities involved in the development, deployment, and maintenance of electrical protection and measuring equipment. Key applications include:

• Power System Protection: Ensuring high reliability and standardized performance for relays protecting generators, transformers, transmission lines, and other critical infrastructure.
• Distributed Protection Schemes: Facilitating coordination among multiple protection devices with common communication and input/output standards.
• Control and Monitoring Interfaces: Enhancing integration of protection equipment with control centers and process monitoring systems via unified port definitions and communication protocols.
• Product Safety and Compliance: Assisting manufacturers in meeting international safety, environmental, and electromagnetic compatibility requirements.
• Environmental Resilience: Guiding design choices for equipment installed in harsh or specialized environments to maintain dependable operation.

Related Standards

To complement IEC 60255-1:2022, stakeholders often reference these related IEC standards to fully comply with safety, EMC, and other detailed requirements:

• IEC 60255 Series: Other parts in the 60255 series address specific relay types, measuring methods, and advanced protection functions.
• IEC 61000: Covers electromagnetic compatibility (EMC) testing and requirements for electrical and electronic equipment.
• IEC 61850: Defines communication networks and systems for power utility automation, enhancing interoperability.
• IEC 62443: Provides guidelines for cybersecurity in industrial automation and control systems, crucial for protecting modern relay communication.
• IEC 60068: Specifies environmental testing methods including temperature, humidity, and mechanical stress tests relevant to relay equipment.

Conclusion

Adhering to IEC 60255-1:2022 guarantees consistent quality, interoperability, and safety in measuring relays and protection equipment globally. By meeting common requirements for environmental resilience, functional accuracy, and communication capabilities, this standard plays a pivotal role in advancing reliable and secure power system protection technologies. Manufacturers and power utilities benefit from streamlined testing processes, enhanced product documentation, and clear guidance for modern protection systems integration to support a resilient and efficient electrical grid.

Keywords: IEC 60255-1:2022, measuring relays, protection equipment, power system protection, relay testing, environmental conditions, relay design, communication protocols, cybersecurity, IEC standards, electrical protection devices.

Standards Content (Sample)

IEC 60255-1 ®
Edition 2.0 2022-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measuring relays and protection equipment –
Part 1: Common requirements
Relais de mesure et dispositifs de protection –
Partie 1: Exigences communes
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IEC 60255-1 ®
Edition 2.0 2022-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measuring relays and protection equipment –

Part 1: Common requirements
Relais de mesure et dispositifs de protection –

Partie 1: Exigences communes
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.70 ISBN 978-2-8322-6120-0

– 2 – IEC 60255-1:2022 © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 15
4 Environmental conditions . 15
4.1 General . 15
4.2 Normal environmental conditions . 16
4.3 Special environmental conditions . 16
4.4 Environmental storage conditions . 16
4.5 Transport conditions . 16
5 Ratings . 16
5.1 General . 16
5.2 Rated voltage . 17
5.2.1 Input energizing voltage. 17
5.2.2 Auxiliary power supply port energizing voltage. 17
5.2.3 Rated insulation voltage . 17
5.3 Rated current – Input energizing current . 17
5.3.1 Primary relay . 17
5.3.2 Secondary relay . 17
5.4 Binary input and output port . 18
5.4.1 Binary input port . 18
5.4.2 Binary output port . 18
5.5 Transducer analogue input and output port . 19
5.5.1 Transducer analogue input port . 19
5.5.2 Transducer analogue output port . 19
5.6 Frequency . 19
5.6.1 Rated frequency . 19
5.6.2 Frequency operating range . 19
5.7 Rated burden . 19
5.8 Rated ambient temperature range . 20
6 Design and construction . 20
6.1 Marking . 20
6.2 Dimensions . 20
6.3 Enclosure protection . 20
6.4 Product safety requirements . 20
6.5 Functional performance requirements . 20
6.5.1 General . 20
6.5.2 Intrinsic accuracy . 21
6.5.3 Operating accuracy. 22
6.5.4 Performance under system conditions . 22
6.5.5 Performance of multifunctional protection equipment . 22
6.5.6 Internal user programmable logic . 22
6.6 Communication protocols . 22

6.7 Cybersecurity . 22
6.8 Binary input and output port . 23
6.8.1 Binary input port . 23
6.8.2 Binary output port . 23
6.9 Transducer analogue input and output port . 23
6.9.1 Transducer analogue input port . 23
6.9.2 Transducer analogue output port . 23
6.10 Input circuit for measurement quantities . 23
6.10.1 Analogue voltage port . 23
6.10.2 Analogue current port . 23
6.10.3 Communication port . 24
6.11 Binary output performance (mechanical and static) . 24
6.12 Climatic performance . 24
6.12.1 General . 24
6.12.2 Verification procedure . 24
6.12.3 Climatic environmental tests . 25
6.13 Mechanical requirements . 29
6.13.1 Vibration response and endurance (sinusoidal) . 29
6.13.2 Shock response, shock withstand and bump . 29
6.13.3 Seismic risk . 29
6.14 Pollution . 29
6.15 Electromagnetic compatibility (EMC) . 29
7 Tests . 29
7.1 Test reference conditions . 29
7.2 Test overview . 30
7.3 Burden measurements . 32
7.3.1 Burden for analogue voltage inputs . 32
7.3.2 Burden for analogue current inputs . 32
7.3.3 Burden for AC power supply . 32
7.3.4 Burden for DC power supply . 32
7.3.5 Burden for binary input . 33
7.4 Type test report content . 33
8 Marking, labelling and packaging . 34
9 Product documentation and technical data . 34
Annex A (normative) Type testing guidelines . 35
A.1 General . 35
A.2 Protection setting . 35
A.2.1 Introductory remark . 35
A.2.2 Test philosophy . 35
A.2.3 Overcurrent and undercurrent . 36
A.2.4 Overvoltage and undervoltage . 37
A.2.5 Over frequency and under frequency . 38
A.2.6 Functions set around current, voltage and frequency . 38
A.2.7 Other functions . 39
Annex B (informative) Environmental operating locations . 40
B.1 Operating environment . 40
B.2 Operating conditions . 40
Bibliography . 44

– 4 – IEC 60255-1:2022 © IEC 2022

Figure 1 – Ports for measuring relays and protection equipment . 13
Figure 2 – Binary output parameters . 19
Figure A.1 – Settings selection criteria . 36

Table 1 – Normal environmental conditions . 16
Table 2 – Contact performance requirements . 18
Table 3 – Hot and cold temperatures . 20
Table 4 – Dry heat test – Operational. 25
Table 5 – Cold test – Operational . 26
Table 6 – Dry heat test, storage temperature . 26
Table 7 – Cold test, storage temperature . 27
Table 8 – Change of temperature test . 27
Table 9 – Damp heat steady state test . 28
Table 10 – Cyclic temperature with humidity test . 28
Table 11 – Test reference conditions . 30
Table 12 – Test overview . 31
Table B.1 – Operating locations . 40
Table B.2 – Climatic conditions . 41
Table B.3 – Mechanical conditions . 41
Table B.4 – EMC conditions . 42
Table B.5 – Chemically active substance conditions . 42
Table B.6 – Mechanically active substance conditions . 42
Table B.7 – Biological conditions . 43

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 1: Common requirements
FOREWORD
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60255-1 has been prepared by IEC technical committee 95: Measuring relays and
protection equipment. It is an International Standard.
This second edition cancels and replaces the first edition published in 2009. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) scope of document clarified;
b) merging units and communications as an integral part of the protection added;
c) binary output clarification expanded;
d) environmental operating conditions added (Annex B);
e) test reference conditions added;
f) multiple changes to improve understanding across most clauses;
g) derating by manufacturer added;

– 6 – IEC 60255-1:2022 © IEC 2022
h) safety and EMC tests removed from document and referenced only;
i) relay setting and type test guidelines modified (Annex A)
j) battery monitor port and low power instrument transformers added.
The text of this International Standard is based on the following documents:
Draft Report on voting
95/513/FDIS 95/521/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 60255 series, published under the general title Measuring relays
and protection equipment, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
The following explains the numbering of documents falling under the responsibility of TC 95:
The numbering of documents follows the following principle:
• common standards start with IEC 60255–XX;
• protection functional standards fall into IEC the 60255-1XX series.
The IEC 60255 series consists of the following parts:
a) Common standards:
Part 1: Common requirements
Part 21: Vibration, shock, bump and seismic tests
Part 24: Common format for transient data exchange (COMTRADE) for power systems
Part 26: Electromagnetic compatibility requirements
Part 27: Product safety requirements
b) Protection functional standards:
Part 1XX: Functional requirements
NOTE The last two digits of the part of the proposed functional standard new numbering correspond to function
TM 1
numbers as established in IEEE Std C37.2 -2008 [3] .

___________
Numbers in square brackets refer to the Bibliography.

– 8 – IEC 60255-1:2022 © IEC 2022
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 1: Common requirements
1 Scope
This part of IEC 60255 specifies common rules and requirements applicable to measuring relays
and protection equipment, including any combination of equipment to form a distributed
protection scheme for power system protection such as control, monitoring and process
interface equipment, to obtain uniformity of requirements and tests. This document covers the
main technologies in use today; other emerging technologies present specific EMC and safety
issues but the philosophy in this document will be applied.
All measuring relays and protection equipment used for protection within the power system
environment are covered by this document. Other documents in this series can define their own
requirements which in such cases take precedence. The typical locations for measuring relays
and protection equipment are where protection of electrical equipment is required: generally
power stations, substations and industrial locations.
Measuring relays and protection equipment installed in special applications (marine, railways,
aerospace, explosive atmospheres, computer centres, etc.) could be enhanced by additional
requirements required by that application.
2 Normative references
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.
IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-14, Environmental testing – Part 2-14: Tests – Test N: Change of temperature
IEC 60068-2-30, Environmental testing – Part 2-30: Tests – Test Db: Damp heat, cyclic
(12 h + 12 h cycle)
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady state
IEC 60255-21-1, Electrical relays – Part 21: Vibration, shock, bump and seismic tests on
measuring relays and protection equipment – Section One: Vibration tests (sinusoidal)
IEC 60255-21-2, Electrical relays – Part 21: Vibration, shock, bump and seismic tests on
measuring relays and protection equipment – Section Two: Shock and bump tests
IEC 60255-21-3, Electrical relays – Part 21: Vibration, shock, bump and seismic tests on
measuring relays and protection equipment – Section 3: Seismic tests
IEC 60255-26, Measuring relays and protection equipment – Part 26: Electromagnetic
compatibility requirements
IEC 60255-27, Measuring relays and protection equipment – Part 27: Product safety
requirements
IEC 60255-1XX (all parts), Measuring relays and protection equipment – Part 1XX: Functional
requirements
IEC 60688, Electrical measuring transducers for converting AC and DC electrical quantities to
analogue or digital signals
IEC 61810-1, Electromechanical elementary relays – Part 1: General and safety requirements
IEC 61869-2, Instrument transformers – Part 2: Additional requirements for current transformers
IEC 61869-3, Instrument transformers – Part 3: Additional requirements for inductive voltage
transformers
IEC 61869-5, Instrument transformers – Part 5: Additional requirements for capacitor voltage
transformers
IEC 61869-10, Instrument transformers – Part 10: Additional requirements for low-power
passive current transformers
IEC 61869-11, Instrument transformers – Part 11: Additional requirements for low-power
passive voltage transformers
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
absolute error
difference between a measured value and its declared value
[SOURCE: IEC 60050-447:2020 [5], 447-08-01]
3.1.2
analogue input port
port intended for current or voltage input whose values are directly proportional to physical
measured quantities, i.e. transducer input (measuring temperature, light, etc.)
3.1.3
analogue output port
port that generates an analogue output signal to drive actuators, analogue panel meters, etc.
Note 1 to entry: Typically a current or voltage less than or equal to 20 mA or 10 V DC respectively.

– 10 – IEC 60255-1:2022 © IEC 2022
3.1.4
assigned error
error limits within which the manufacturer declares that any measuring relay or protection
equipment of a given type will perform under reference conditions of influence quantities
[SOURCE: IEC 60050-447:2020 [5], 447-08-13, modified – the term “declared error” has been
removed.]
3.1.5
auxiliary power supply port
AC or DC auxiliary energizing input
Note 1 to entry: Some modern relays have a single auxiliary power supply port that can be energized with both AC
and/or DC.
3.1.6
battery monitor port
port intended for connection to the station battery for the purpose of battery voltage monitoring
3.1.7
binary input port
port intended for inputs which have an on or off state given by direct connection to an energizing
quantity without any communications protocol
3.1.8
binary output port
port intended for outputs which have an on or off state given by direct connection without any
communications protocol
3.1.9
substation control room
room of a substation in which are located facilities necessary to monitor and control substation
items
[SOURCE: IEC 60050-605:1983 [7], 605-02-34]
3.1.10
communication port
interface on measuring relays and protection equipment used for transfer of information in
digital format pertaining to, for example, current or voltage inputs or outputs, binary inputs,
binary outputs, data files
3.1.11
dynamic performance
set of characteristics defining the ability of a measuring relay or protection equipment to achieve
the intended functions under fault conditions (for example, single phase to earth fault) and/or
abnormal system conditions which occur at the power system frequency (for example, power
swings, harmonics)
[SOURCE: IEC 60050-447:2020 [5], 447-07-15]
3.1.12
earth port
point where a cable intended for connection to earth for functional or safety purposes can be
connected
3.1.13
energizing quantity
quantity itself or signal representing the information corresponding to the quantity that, applied
to a measuring relay or protection equipment under specified conditions, enables it to operate
Note 1 to entry: Both input energizing quantity and auxiliary energizing quantity are energizing quantities.
[SOURCE: IEC 60050-447:2020 [5], 447-03-01]
3.1.14
equipment
single apparatus or set of devices or apparatuses, or a set of main devices of an installation,
or all devices necessary to perform a specific task
Note 1 to entry: Examples of equipment are a power transformer and the equipment of a substation.
Note 2 to entry: For this document, equipment is a measuring relay or protection equipment.
[SOURCE: IEC 60050-151:2001 [4], 151-11-25, modified – Note 2 to entry has been added.]
3.1.15
equipment under test
EUT
equipment submitted to a test, including any accessories such as communication modules, plug
in power supplies, unless otherwise specified
3.1.16
human machine interface
HMI
user interface or dashboard that allows a person to access and operate a system, or device
3.1.17
influence quantity
quantity not essential for the performance of an EUT but affecting its performance
Note 1 to entry: For electric devices, typical influence quantities may be temperature, humidity, pressure.
[SOURCE: IEC 60050-151:2001 [4],151-06-31, modified – the term “item” has been replaced
by “EUT”.]
3.1.18
input port
port through which the EUT is energized or controlled in order to perform its function(s)
EXAMPLE Analogue current transformer (LPCT or CT) input, analogue voltage transformer (LPVT or VT) input,
binary input, battery monitor input, etc.
3.1.19
intrinsic accuracy
quality that characterizes the ability of a measuring relay or protection equipment, when used
under reference conditions of influence quantities, to operate both at the value of characteristic
quantity and at the time close to their declared values (e.g. setting values)
[SOURCE: IEC 60050-447:2020 [5], 447-08-18]
3.1.20
low-power instrument transformer
LPIT
arrangement, consisting of one or more current or voltage transformer(s) which may be
connected to transmitting systems and secondary converters, all intended to transmit a low-

– 12 – IEC 60255-1:2022 © IEC 2022
power analogue or digital output signal to measuring instruments, meters and protective or
control devices or similar apparatus
EXAMPLE An arrangement consisting of three current sensors, three voltage sensors connected to one merging
unit delivering one digital output is considered an LPIT.
Note 1 to entry: LPITs are commonly called non-conventional instrument transformers (NCIT).
Note 2 to entry: The output power produced by these devices is typically lower or equal to 1 VA.
[SOURCE: IEC 61869-6:2016 [20], 3.1.601, modified – Note 3 to entry has been removed.]
3.1.21
low-power current transformer
LPCT
low-power instrument transformer for current measurement
[SOURCE: IEC 61869-6:2016 [20], 3.1.602, modified – Note 1 to entry has been removed.]
3.1.22
low-power voltage transformer
LPVT
low-power instrument transformer for voltage measurement
[SOURCE: IEC 61869-6:2016 [20], 3.1.603, modified – Note 1 to entry has been removed.]
3.1.23
merging unit
physically independent unit collecting multi-channel digital signals, analogue outputs from
current and voltage transformers synchronously, and which transmits these signals digitally
3.1.24
multifunction protection equipment
single apparatus taking a range of input measurements and performing a multitude of protection
functions on these measurements
3.1.25
non-weatherprotected
location in which the equipment is exposed to all environmental conditions and is not protected
from direct sunlight
3.1.26
operating accuracy
quality that characterizes the ability of a measuring relay or protection equipment to minimize
the absolute error, when influence quantity(ies) is(are) different from its reference value(s)
Note 1 to entry: The operating accuracy of measuring relays and protection equipment depends on intrinsic
accuracy and uncertainty associated with the variation of the performance of components due to influence quantities.
[SOURCE: IEC 60050-447:2020 [5], 447-08-17, modified – Note 1 to entry has been added.]
3.1.27
output port
port through which the EUT produces predetermined changes
3.1.28
overall system accuracy
accuracy of a protection system, considering intrinsic accuracy and operating accuracy of the
equipment, to which are added uncertainties and variations due to external sensors accuracy
and to external wires
3.1.29
partially weather protected
location in which the equipment is protected from precipitation and direct sunlight but is exposed
to the outside air through ventilation or louvres
3.1.30
port
interface on measuring relays and protection equipment
SEE: Figure 1.
Figure 1 – Ports for measuring relays and protection equipment
3.1.31
primary relay
electric relay directly energized by the current or voltage in a main circuit, without any
intermediate instrument transformer, shunt or transducer
Note 1 to entry: The main circuit includes all the conductive parts, and is intended for transmitting electrical energy.
[SOURCE: IEC 60050-447:2020 [5], 447-01-20]
3.1.32
product family
range of products based on a common hardware and/or software platform
3.1.33
programmable logic device
integrated circuit that consists of logic elements with an interconnection pattern, parts of which
are user programmable
[SOURCE: IEC 60050-521:2002 [6], 521-11-01]
3.1.34
rated value
value of a quantity used for specification purposes, established for a specified set of operating
conditions of a component, device, equipment, or system
[SOURCE: IEC 60050-151:2001 [4], 151-16-08]

– 14 – IEC 60255-1:2022 © IEC 2022
3.1.35
routine test
conformity test made on each individual equipment during or after manufacture
Note 1 to entry: Individual equipment includes complete products and spare parts.
[SOURCE: IEC 60050-151:2001 [4], 151-16-17, modified – the word "item" has been replaced
by the word "equipment" and Note 1 to entry has been added.]
3.1.36
secondary relay
electric relay energized by the quantity (e.g. electric current or voltage) derived from an
instrument transformer or transducer
[SOURCE: IEC 60050-447:2020 [5], 447-01-21]
3.1.37
service port
interface on measuring relays and protection equipment used for temporary connection for the
transfer of information
3.1.38
signal or control port
port intended for the interconnection of components of an EUT, or between an EUT and local
auxiliary equipment, and used in accordance with relevant functional specifications (for
example, for the maximum length of cable connected to it)
Note 1 to entry: Examples include EIA-232, universal serial bus (USB), high-definition multimedia interface (HDMI),
IEEE Standard 1394 ("Fire Wire"), IRIG-B interface.
3.1.39
technical data
product specification made available to a user which could be product specification sheets, user
manuals, etc.
3.1.40
totally weatherprotected
location in which the equipment is isolated from the outdoor environment and is maintained
under stable conditions
3.1.41
transducer
equipment that converts variations in a physical quantity such as temperature, into an electrical
signal
3.1.42
transient response
reaction of a measuring relay or protection equipment under transient system conditions that
occur at off-rated power system frequency (for example, magnetizing inrush, capacitive voltage
transformer transients)
[SOURCE: IEC 60050-447:2020 [5], 447-07-16]
3.1.43
type test
test of one or more devices made to a given design, to check if these devices comply with the
requirements of the standard concerned
[SOURCE: IEC 60050-851:2008 [21], 851-12-05]

3.1.44
wired network port
port for the connection of voice, data and signalling transfers intended to interconnect widely
dispersed systems by direct connection to a single-user or multi-user communication network
Note 1 to entry: Examples of these include CATV, PSTN, ISDN, xDSL, LAN and similar networks.
Note 2 to entry: These ports may support screened or unscreened cables and may also carry AC or DC power (e.g.
PoE) where this is an integral part of the telecommunication specification.
Note 3 to entry: A port generally intended for interconnection of components of a system under test (e.g. EIA-232,
IEEE Standard 1284 (parallel printer), universal serial bus (USB), IEEE Standard 1394 ("Fire Wire"), etc.) and used
in accordance with its functional specifications (e.g. for the maximum length of cable connected to it), is not
considered to be a wired network port.
3.1.45
wireless network port
port for the connection of voice, data and signalling transfers intended to interconnect widely
dispersed systems by radio frequency connection to a single-user or multi-user communication
network
3.2 Abbreviated terms
AE Auxiliary equipment
BI Binary input
CATV Communal (broadcasting) antenna/cable TV network
CT Current transformer
EMC Electromagnetic compatibility
EUT Equipment under test
HMI Human machine interface
HRV Highest rated voltage
ISDN Integrated services digital network
LAN Local area network
LCD Liquid crystal display
LPCT Low-power current transformer
LPIT Low-power instrument transformer
LPVT Low-power voltage transformer
LRV Lowest rated voltage
MCB Miniature circuit breaker
NCIT Non-conventional instrument transformer
PoE Power over Ethernet
PSTN Public switched telephone network
SEF sensitive earth fault
USB Universal serial bus
VT Voltage transformer
xDSL Generic term for all types of DSL (digital subscriber line) technology
4 Environmental conditions
4.1 General
Clause 4 specifies the environmental conditions for stationary use, maintenance and repair.
Additional information on the operating environments can be found in Annex B.

– 16 – IEC 60255-1:2022 © IEC 2022
4.2 Normal environmental conditions
Measuring relays and protection equipment are intended to be used in the normal environmental
conditions listed in Table 1.
Table 1 – Normal environmental conditions
Environmental parameters Conditions
a b
Ambient air temperature Upper limit ≤ +55 °C
b
Lower limit ≥ –10 °C
Solar radiations Negligible
Altitude ≤ 2 000 m
Air pollution by dust, salt, smoke, corrosive and/or flammable gas,
c
No significant air pollution
vapours
d
Relative humidity: 24 h average From 5 % to 95 %
According to IEC 60255-21-1,
Vibration, shocks, bumps and seismic conditions IEC 60255-21-2 and IEC 60255-21-3
environment Class 1 or Class 2
Electromagnetic environment defined by
Electromagnetic disturbances
immunity test levels of IEC 60255-26
a
The ambient air temperature is the maximum or minimum temperatur
...