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IEC 60255-12 1st Edition, January 1, 1980
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Electrical Relays Part 12: Directional Relays and Power Relays with Two Input Energizing Quantities
Additional Comments: BILINGUAL
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This standard specifies the performance requirements of directional relays and power relays with two input energizing quantities, which constitute a particular sub-family of measuring relays with more than one input energizing quantity as defined in IEC Publication 255-6, Electrical Relays, Part 6: Measuring Relays with More than One Input Energizing Quantity, and the parameters whose values are to be declared by the manufacturer of such relays. It also specifies methods of presenting the characteristics and performance of these relays.

This standard excludes impedance relays and deals specifically with:

- relays measuring phase angle (direction);

- relays measuring power.

The requirements in this standard relating to phase angle (direction) can be combined with requirements relating to other characteristics (e. g. current) specified in other parts of the IEC 255 series publications, so as to cover combinations such as “directional current relays”.

For particular cases, supplementary requirements may be agreed between the manufacturer and the user or may be specified in national standards.

All tests in this standard are type tests.

This standard applies only to the relays in new condition.