Breaking capacity and making capacity

[honglien]

Could any one tell me the different between the terms using in shortcircuit calculation:
1. Breaking capacity (Icu) (or Ultimate breaking capacity) vs 2. Making capacity (Icm) (or Service breaking capacity (Ics))
Thank all of you very much!

 

[desertfox]

Hi honglien

Haver a look at this site:-

http://electricalandelectronics.org/2008/10/09/circuit-breaker-ratings/

desertfox

 

[TurbineGen]

Making capacity is the maximum allowable inrush current that the breaker can withstand in a CLOSE operation without excessive contact bounce.

Breaking capacity is the maximum fault current the breaker is capable of interrupting on an OPEN operation.

------------------------------------------------------------------------
If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[Kiribanda]

honglien,
The terms Icm, Ics & Icu are some parameters defined for LV circuit breakers per IEC 60947-2 used by the designer to slect appropriate circuit breaker for his application.But these terms are not used in any SC calculation method.

 

[honglien]

Thank you very much!deserfox, turbingen and also kiribanda.
I agree with you, Kiribanda, they are not used in SC cal. They are specified through some type test of LVCB.

 

[desertfox]

honglien

your welcome