The MCB (Miniature Circuit Breaker) is a distribution box that is fixed or provided in every apartment in modern society. Instead of an mcb box, a 32 Ampere DP switch was fixed that had an on-off switch. The mcb box concept didn't exist as they were not aware of such a thing as MCB. In India, there are many mcb distribution box manufacturers but if you find the best among the best then you must check out Star India Electricals
As always, be careful debugging any electricity problems. Shock is always a possibility. If electrically challenged, please call a professional.
There are different types of mcb boxes, but the idea is to protect against as many faults as possible by breaking the power supply if a problem is detected. Things can go wrong with an appliance that causes too much current to flow or a connection to be made to the protective earth. The circuit breaker, therefore, has detection systems that monitor the amount of current flowing through live and neutral. If there's an imbalance between the two then it knows current must be flowing to earth so it trips. If more than the set maximum current flows then it also trips.