Check that the outgoing circuit breakers are connected correctly. Perhaps they were not selected according to the load and ruined by current, as a result, the outgoing groups are not disconnected from the overloads and the input machine takes over the entire overload.
It is also possible the introductory machine is chosen weaker than necessary, and therefore does not withstand the load.
If you are sure that the introductory machine knocks out for no reason, then the matter is in it, possibly defective. You can read about the reasons for tripping a circuit breaker here. https://our.electricianexp.com/en/pochemu-srabatyvaet-avtomaticheskij-vyklyuchatel.html
Check that the outgoing circuit breakers are connected correctly. Perhaps they were not selected according to the load and ruined by current, as a result, the outgoing groups are not disconnected from the overloads and the input machine takes over the entire overload.
It is also possible the introductory machine is chosen weaker than necessary, and therefore does not withstand the load.