A perspective of low-voltage circuit breaker interrupting rating

This paper reviews application of all three types of low-voltage circuit breakers for three-phase fault interrupting duty by reference to the circuit breaker´s interrupting requirement and rating. After a discussion of the rating process for circuit breaker design and the fault-current evaluation process for circuit breaker application, it then considers the effect of the erroneous assumption that the load-side bolted fault interrupting let-through current of all circuit breakers is equal to the calculated line-side prospective fault current