High Voltage DC Electromagnetic Relay (HVDC relay) is a kind of switching device used to control high voltage direct current circuit, its core working principle is through the electromagnetic force to drive the mechanical contact to achieve the circuit on and off. Compared with AC relays or low-voltage DC relays, HVDC relays are unique in design and performance, especially in HVDC environments, which need to solve key issues such as arc, insulation and voltage resistance.