The electric fuse is an overcurrent protective device that interrupts a circuit when current exceeds the maximum amount permitted. The thermal effect of the current destroys the melting fuse, which must then be replaced.
Device and micro fuses (G-fuses) comprise a small glass or ceramic tube that houses a fuse element and are covered with a metal cap at both ends.
The nominal current and maximum voltage as well as the speed at which the fuse responds to overcurrent are indicated on the metal contacts ("FF" stands for "fast fuse"). See Fig. 1 Electric fuse
A miniature circuit breaker is an overcurrent protective device used in electrical installations. It protects an electrical circuit from being damaged by excessive heat caused as a result of overcurrent. Although miniature circuit breakers can be reused, they do not reset themselves and can automatically interrupt a circuit in the event of an overload or short circuit as is the case with a fuse.