What is Ics & Icu of a Circuit Breaker? What is breaking capacity of circuit breaker?

Icu & Ics Details sheet of a circuit breaker
breaking capacity Icu, Ics of Circuit Breaker

Breaking capacity Icu:

 The rated breaking capacity (Icu) or (Icn) is the maximum fault-current a circuit-breaker can successfully interrupt without being damaged. The probability of such a current occurring is extremely low, and in normal circumstances the fault-currents are considerably less than the rated breaking capacity (Icu) of the CB. Normally the value of Icu for Miniature Circuit Breaker (MCB) is between 6kA to 10kA and the Value of Moulded Case Circuit Breaker (MCCB) may be 200kA.

Ics

The rated breaking capacity (Icu) or (Icn) of a circuit breaker is the maximum fault current a circuit-breaker can successfully interrupt without being damaged. The probability of such a current occurring is extremely low, and in normal circumstances the fault-currents are considerably less than the rated breaking capacity (Icu) of the CB.

On the other hand it is important that high currents (of low probability) be interrupted under good conditions, so that the CB is immediately available for reclosure, after the faulty circuit has been repaired. It is for these reasons that a new characteristic (Ics) has been created, expressed as a percentage of Icu, viz: 25, 50, 75, 100% for industrial circuit-breakers.


Asif Malik

A young Electrical Engineer having more than 5 years of experience in Electrical Power System, Construction and Execution of different projects, Project Management, Electrical Inspection. He is a article Writer as well on the different topic related to Electrical Engineering and Information Technology.

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