scope:

This standard specifies the general requirements for impedance measuring relays. These relays constitute a particular sub-family of measuring relays with more than one input energizing quantity as defined in IEC Publication 255-6, Part 6: Measuring Relays with More than One Input Energizing Quantity.

This standard specifies test methods and methods of presenting relay characteristics and performance. It covers multi-input energizing quantity measuring relays in which impedance is a characteristic quantity and for which the operating characteristics are defined in the R-X plane.

This standard applies to independent or dependent specified time relays.

Relays coming within the scope of IEC Publication 255-12, Part 12: Directional Relays and Power Relays with Two Input Energizing Quantities, are excluded.

All tests in this standard are type tests.

This standard applies only to relays in new condition.

Notes 1. - The term relay includes all the additional components which are necessary for its operation and which are tested with it.

2. - The voltage(s) and/or current(s) contributing to the measurement of the impedance can be either simple quantities or combinations of more than one voltage and/or more than, one current, for example the difference of two phase-to-ground voltages, the sum of a phase current and residual current, etc. To obtain specific operating characteristics which may have special properties (e.g. directional) the energizing quantities may be mixed or additional input quantities may be brought into the relay.