MT 3 - TC 95/MT 3

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.

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.

IEC 60255-27:2013 describes the product safety requirements for measuring relays and protection equipment having a rated a.c. voltage up to 1 000 V with a rated frequency up to 65 Hz, or a rated d.c. voltage up to 1 500 V. Above these limits, IEC 60664-1 is applicable for the determination of clearance, creepage distance and withstand test voltage. This standard details essential safety requirements to minimize the risk of fire and hazards caused by electric shock or injury to the user. This new edition includes the following significant technical changes with respect to the previous edition:
- the removal of tables and diagrams which are from other standards and referring instead directly to the source standard;
- all aspects of IEC 60255-5 have been covered and this standard will be withdrawn.

IEC 60255-1:2009 specifies common rules and requirements applicable to measuring relays and protection equipment including any combination of devices to form schemes for power system protection such as control, monitoring and process interface equipment in order to obtain uniformity of requirements and tests. Covers all measuring relays and protection equipment used for protection within the power system environment.