This is a ABB B50 brand contactor,it is written Ith=125A ,
IeAC-1=100A & not mentioned continuous current ,
I don't understand what do they mean & which one is the exact current that it can handles?
Thanks!!!

 

This is a ABB B50 brand contactor,it is written Ith=125A ,
IeAC-1=100A & not mentioned continuous current ,
I don't understand what do they mean & which one is the exact current that it can handles?
Thanks!!!

Ith = Thermal Rated Current
IeAC may have something to do with Auxiliary Contacts current..

 

http://www.clrwtr.com/ABB-Contactor-Technical-Terms.htm

 

The Ith figure is it's continuous, steady-state carrying capacity.

AC1 and AC3 are 'real world' ratings for when it's switching power to various categories of load.

eg. a when the contactor closes to start a big three phase motor, the start current will be much higher than the maximum running current, while it gets up to speed. When it opens to stop the motor, there will be some level of arcing at the contacts due to switching an inductive load (the motor windings).

One of the ratings (AC3?) gives the maximum motor current rating, which is rather lower than the Ith figure to allow for the starting & stopping loads and still maintain the rated life of the contactor.