Intro：Drop-out fuses and pull-load drop-out fuses are outdoor high-voltage protection appliances. It is installed on the high-voltage side of the distribution transformer or on the branch and trunk lines of the distribution line, and is used for short-circuit and overload protection of the transformer and the line, as well as the split and combined load current. The drop fuse is composed of two parts: an insulating bracket and a fuse tube. The static contact is installed at both ends of the insulating bracket, and the moving contact is installed at both ends of the fuse tube. The fuse tube consists of an inner arc suppression tube and an outer layer. phenolic paper tube or epoxy glass cloth tube. The load drop type fuse enhances the elastic auxiliary contact and arc extinguishing cover to divide and combine the load current.