Both the vacuum load switch and the vacuum load switch-fuse combination are based on the vacuum arc extinction principle.

The moving and static contacts are sealed in the vacuum arc extinguishing chamber. When breaking, the vacuum arc diffuses rapidly when the power supply crosses zero and the insulation strength recovers much faster than that of air.

The transfer current of the air load switch (gas-producing or pressure-gas load switch) combination can generally only reach about 1000A, while the transfer current of the vacuum load switch-fuse combination can reach 3150A (can be larger), and the operation safety is more reliable.