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.