In order to solve the problem of maintenance and operation risk of existing drop out fuse

a kind of new type of 12 kV drop out fuse with repeated operation without replacing the fuse is designed by using the temperature deformation function of shape memory alloy（SMA）. The design is based on the two-way memory effect of SMA

the structure of the original drop-out fuse is improved and the operating principle of existing drop-out fuse is changed

by using the deformation characteristics of SMA with temperature

into a“combined apparatus”of air break load switch and drop-out fuse in series which is controlled by shape memory alloy. The fuse is retained as backup protection

which improves the operation reliability of the drop-out fuse. It is proved by the test that the produced sample has good mechanical and electrical performance

can achieve its short-circuit or overload protection function through reliable action. The design improves both safety and convenience of the drop-out fuse

reduces the loss of fuse and has a wide application prospect.