Broken Aptomat

But aptomat is broken

The MCCB isn't broken it looks like it has melted. Even the insulation on the wiring lugs shows signs of overheating.

I don't know enough about your load current profile but I would have expected the MCCB to operate if the problem was related to load current, regardless of the load current profile.

This looks like another case of poor (high resistance) connections between the wiring and the MCCB causing overheating at the joint resulting in eventual failure of the MCCB.

The cause of the overheating could be poor crimp connections, incorrect tightning torque (or loosening over time), surface corrosion between the joints, etc.

I am assuming you removed the bottom two terminal screws not present in the picture after the failure, right.

I don't suppose you've spoken to the manufacturer of the MCB have you?

I'll not hold my breath awaiting an answer going by your previous posts.