Current Considerations For Drop-out Fuses

According to operating experience, the rated current of cover drop out fuse should have a large margin, and the rated current of drop fuse should generally be selected at least twice the actual load current. The rated current of drop fuse cutout fuse should also be greater than the actual load current, and should be 1.3~1.5 times the actual load current. According to on-site operating experience, when the load current passing through drop out expulsion fuse often exceeds 90~100A, the contact of drop out fuse 22kv (commonly known as duckbill) is prone to cause local overheating, sparking, and it is easy to expand into an interphase arc fault accident. Therefore, when the normal load current exceeds 90~100A, drop out fuse 33kv is generally not used, and other pole switches are used instead.