The fuse is a kind of passive electrical safety element based on“Current heat effect” to realize short-circuit and overload protection. Its core principle is the use of low melting point conductive melt (such as lead-tin alloy, copper) , in the circuit overload or short circuit caused by excessive current, melt due to heat fusing, thereby cutting off the circuit, it is the basic protection device with the simplest structure and the lowest cost in the electrical system to prevent the back-end equipment and wires from overheating and burning or causing fire.