Due to the inherent inaccuracy during the manufacrure of DC fuses

only part of narrow necks arc are likely to occur under low overcurrent

which leads to the malfunction of fuse

such as overheating and arc spray

thus it is difficult for melt design to judge whether the melt will have uneven arc and break short circuit current under uneven arc. To solve this problem

a mathematical model of the DC fuse arcing process and a thermoelectric coupling model of the DC fuse pre-arcing process are established to calculate the number of arcing narrow necks under different conditions. The results of the calculation will provide a solution to set stepped narrow neck to ensure the successful breaking of current. A DC fuse with the rated 800 V/300 A is improved and designed

and the fault current breaking tests are carried out. It is proved that the testing products have successful broken 500 A

1 kA and 10 kA overcurrent. The results verify the feasibility and effectiveness of the design

and the relevant conclusion can be used to guide the design of the DC fuse.