What is the function of a circuit breaker in power systems?

Circuit breakers protect power systems by interrupting fault currents and enabling safe operation. They detect abnormal conditions (overcurrent, short circuits) and open automatically to isolate faulty sections, preventing damage and fire. Unlike fuses, circuit breakers can be reset and reused. Modern circuit breakers can interrupt currents of 50,000A or more within milliseconds. They are rated by voltage, continuous current, and interrupting capacity.