Electronic – Working house main Control Miniature Circuit Breaker(25A) instead of transfuse (16A)

circuit breakertransformer

I have two Miniature Circuit Breaker, so one is ordinary main Miniature Circuit Breaker(house main MCB) in range of 25A and the other is my device (Auto-Transformer) in range of 16A, So when i run the Device some times first Miniature Circuit Breaker(25A) work and cut the power line, So my question is why not the second Miniature Circuit Breaker working first, dose it's come back to that quality or any other setting like it's Trip characteristics?

The MCB 25 A:

MCB 25 A

The MCB's 16A:


Thanks a Lot.

Best Answer

Looks to me like both of those are 16A actually, but one is a B curve and one is a C curve, the C curve breaker is normally used for motor and transformer loads precisely because it has a curve that suits these loads.

A type B will usually trip before a type C on a startup surge.

Type B is normally seen in domestic applications where very large inrush is less of a problem.