Frequently asked questions
What is the rated Short-Circuit Making Capacity (Icm) value for Compact NS MCCB?
FA12111
30 September 2021
The rated Short-Circuit Making Capacity (Icm) for Compact NS Moulded Case Circuit Breaker is as per the table attached and is dependent on the Short-Circuit Breaking Capacity (Icu).
(Note: Table is extracted from IEC 60947-2 document)
Example:
For NS 100 N, 100A MCCB at 440V, Short-Circuit Breaking Capacity (Icu) = 35 KA then, Icm = 2.1 x Icu = 73.5 KA.
Note:
According to the IEC 60947-2, if the Rated Making capacity (Icm) is equal to the value specified in the IEC paragraph 4.3.5.3, it is not imperative to have a marking on the circuit breaker.
This is the reason for not publishing this information concerning the marking on the circuit breaker and the values in catalogue.
Icm can be calculated by the instruction as per the table provided in the IEC document.