What is ics,icu,icw of load breaker

Answer Posted / mike evans

Circuit breakers are designed with withstand short circuit
currents for a short period of time, defined as Icw for a
period of 1 second. This is designed to guarantee
selectivity of breakers and other devices providing short
circuit current protection. The ultimate breaking capacity
of the breaker is the highest symmetrical short circuit
fault current that the breaker is designed to break, and the
breaker manufacture is required to guarantee this level of
performance for one time only. Ics or service breaking
capacity must be guaranteed at least 3 times.
Realistically, the value of Icu is not practical when
considering fault calculations in a distribution system, and
often manufacturers aim for achieving Ics=Icu.

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