scope:

This part of IEC 60050 defines terms related to specified-time relays.

In the past, IEC 60050-446 (Part 446 of the IEV) listed the terminology for all types of electrical relays. In order to improve the precision of terms and definitions as well as the general visibility of relay terminology, it had been decided to split that part of the IEV into three separate parts optimised for the specific relay types covered.

Therefore, this part of IEC 60050 gives terms and definitions for (specified) time relays superseding the terminology of IEC 60050-446 for such relays.

The terminology for elementary relays (non-specified time all-or-nothing relays) is contained in IEC 60050-444. A new part for measuring relays (IEC 60050-447) is also under preparation. When all these three parts are published, IEC 60050-446 shall be withdrawn.

This standard is intended to define the most common time relay functions, and not all possible combinations.