A miniature circuit breaker (MCB) is an essential component of any modern electrical installation. It provides protection against the consequences of sudden faults, short circuits, and overloads in electrical equipment, while also helping to extend the service life of the installation. To perform its function effectively, a circuit breaker must possess high sensitivity, rapid response, precision, and the ability to maintain its performance characteristics even after repeated operation.
Various types of miniature circuit breakers are available on the market. For residential installations, circuit breakers with a "B" tripping characteristic are recommended; in these units, the overload release is set to trigger at 1.13–1.45 times the rated current. An example of such a device is the SZ203 modular circuit breaker from ABB, which complies with the IEC/EN 60898-1 standard and features a maximum breaking capacity of 6 kA.