The fast fuse is a kind of fuse, and it is mainly used for short circuit protection of semiconductor rectifier or rectifier. Because of the overload capacity of semiconductor components is very low. Can withstand large overload current in a very short period of time, thus requiring fast fuse circuit protection. The structure of the quick fuse is basically the same as that of the packing closed fuse, but the material and shape of the melt is different. It is a kind of variable cross-section melt with a V shaped deep groove.