scope:

This part of IEC 60255 specifies common rules and requirements applicable to measuring relays and protection equipment including any combination of devices 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. All measuring relays and protection equipment used for protection within the power system environment are covered by this standard. Other standards in this series may define their own requirements which in such cases shall take precedence. The typical locations for measuring relays and protection equipment are power stations and medium (MV) and high voltage (HV) substations. Measuring relays and protection equipment installed in special applications (marine, railways, aerospace, explosive atmospheres, computers, etc.), may need to be enhanced by additional requirements required by that application. The requirements are routine tests and type tests (as declared in Table 13) and are applicable only to relays in a new condition