It can detect the zero sequence current of the milliampere-level line and the alternating short circuit current of 25 times of the rated value, with accurate measurement and control and sensitive action. The same specifications of the product can be applied to different neutral grounding operation mode of power distribution system: vacuum arcing, SF6 insulated outside, the built-in isolation knife and arcing chamber asynchronous linkage, switch points and strong ability, good safety, Latch spring operation type, rod type manual switch, manual or electric points gate, operation simple and convenient: working power supply (voltage transformer) built-in, complete sets of equipment as a whole from high maintainability: all components are fully sealed, strong weatherability, good lon: all aviation plug electrical connections, installation commissioning and quick, convenient, accurate and reliable: generally choose no communication mode to run, it can also configure communication module and flexibly choose wired or wireless communication mode for centralized data management.