transformer - Working house main Control Miniature Circuit Breaker(25A) instead of transfuse (16A)?

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:

The MCB's 16A:

Thanks a Lot.