Fuses are simple safety devices used to provide overcurrent protection for electrical circuits. The essential component in a fuse is a metal wire or strip that links two contact terminals together. If too much current flows through the fuse, the metal link will melt and interrupt the circuit. A fuse can only trip and open the circuit once, so it must be replaced or repaired to complete the circuit again.
Today, thousands of different fuse designs are used to achieve basic circuit protection requirements using specific current and voltage ratings, breaking capacities and response times. The operating characteristics for any given fuse are chosen to satisfy the needs of the application to protect a circuit without needless interruption.
Circuit breakers are alternative solutions to fuses, but because of their different characteristics choosing one over the other depends largely on the needs of the application.