How does a fuse protect electrical circuits differently from a circuit breaker?

A fuse protects electrical circuits by melting its internal conductor when overcurrent occurs, which effectively interrupts the flow of electricity. This action is a result of the heat generated by excessive current, causing the fuse element to physically break, thus preventing further current from flowing through the circuit. This method of protection is straightforward, as once the fuse has melted, it must be replaced to restore functionality.

In contrast, a circuit breaker uses an electromechanical mechanism to detect overcurrents and trip, thereby interrupting current flow without the need to replace any part. The ability to simply reset a circuit breaker after tripping is a significant operational difference from a fuse, as circuit breakers provide a way to restore service without replacement after a protective action has occurred. This distinction is crucial in understanding their different operational principles and practical applications in electrical systems.