Surge Protective Device (SPD) , also known as Surge Protector, lightning arrester, is a kind of electronic protection equipment used to suppress the“Surge voltage”(instantaneous overvoltage) in power systems and signal lines, it can quickly lead the instantaneous high voltage beyond the tolerance range of the equipment into the earth, and avoid the damage of the back-end electrical equipment or communication equipment due to overvoltage and overcurrent, is the electrical system and electronic equipment lightning protection, anti-electromagnetic interference, one of the core components.