Miniature Circuit Breakers (MCB)
A miniature circuit breaker is an electromagnetic device that carries a complete molded insulating material. The primary function of this device is to switch the circuit. This means to automatically open the circuit (which has been connected to it) when the current passing through the circuit goes beyond a set value or limit. The device can be manually switched ON or OFF just like normal switches whenever necessary.
MCBs are time-delay tripping devices. In these devices, the operating time is controlled by the magnitude of overcurrent passing through it, which means that the device functions whenever there is an overload existing for long periods, long enough to endanger the circuit being protected. MCBs do not respond to transients such as motor starting currents or switch surges. Typically, these devices are designed to operate at less than 2.5 milliseconds when there are short circuit faults and between 2 seconds to 2 minutes in case of overloads.