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IEVref:442-05-60ID:
Language:enStatus: Standard
Term: selectivity-limit current
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Symbol: Is
Definition: value of the current corresponding to the intersection between the total time–current characteristic of the protective device on the load side and the pre-arcing (for fuses) or tripping (for circuit-breakers) time–current characteristic of the other protective device

Note 1 to entry: The selectivity-limit current is a limiting value of current:

  • below which, in the presence of two overcurrent protective devices in series, the protective device on the load side completes its breaking operation in time to prevent the other protective device from starting its operation (i.e. selectivity is ensured);
  • above which, in the presence of two overcurrent protective devices in series, the protective device on the load side could not complete its breaking operation in time to prevent the other protective device from starting its operation (i.e. selectivity is not ensured).

Note 2 to entry: I2t characteristics can be used instead of time–current characteristics.


Publication date:2019-05
Source:IEC 62873-2:2016, 3.6.1
Replaces:442-05-60:1998-11
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