Lightning arrester is a device to protect substation from lightning shock wave. When the lightning shock wave introduced into the substation along the line exceeds the protection level of the lightning arrester, the lightning arrester discharges first, and the lightning current is safely introduced into the earth through a good conductor, and the lightning voltage amplitude is limited below the lightning shock level of the protected equipment by using the grounding device, thus protecting the electrical equipment. Lightning arrester can be divided into: protection gap-the simplest form of lightning arrester; Tube arrester-also a protective gap, but it can automatically extinguish the arc after discharge; Valve arrester-it divides a single discharge gap into many short series gaps, and at the same time increases nonlinear resistance to improve protection performance; Magnetic blow arrester-using magnetic blow spark gap to improve arc extinguishing ability, and also has the ability to limit internal overvoltage; Zinc oxide arrester-It makes use of the ideal volt-ampere characteristics of zinc oxide valve plate (high nonlinearity, that is, low resistance at high current, which limits the voltage on the arrester, and high resistance at normal power frequency voltage), and has the advantages of no gap, no aftercurrent residual voltage and limited internal overvoltage, so it is widely used.