1. The requirements that must be met when selecting the arrester are: the VS characteristics and VA characteristics of the arrester should be correctly matched with the VS characteristics and VA characteristics of the protected equipment; The arc extinguishing voltage of lightning arrester should be correctly matched with the highest power frequency phase voltage at the installation site. In this way, even in the case of grounding fault in the system, the lightning arrester can effectively extinguish the power frequency aftercurrent arc and avoid the explosion of the lightning arrester. Second, when choosing tube arrester, it should be noted that tube arrester can not be used as overvoltage protection for electrical equipment with windings, but can only be used for incoming line protection of lines, power plants and substations; The upper limit of breaking current of tubular arrester should not be less than the maximum value of short-circuit current at the installation place, and the lower limit should not be greater than the minimum value of short-circuit current at the installation place. Three, valve arrester is divided into two categories: ordinary type and magnetic blowing type. It should be noted that the protection ratio Kb of lightning arrester should be selected according to the rated voltage. Pay attention to check the rated voltage, power frequency discharge voltage, impulse discharge voltage and residual voltage of lightning arrester, and pay attention to the distance from the protected electrical equipment. Four, choose zinc oxide arrester, to calculate or measure the long-term maximum working voltage of arrester installation. The rated voltage of lightning arrester should be greater than or equal to the amplitude of transient power frequency overvoltage at the installation point of lightning arrester. Pay attention to the cooperation between residual voltage and insulation level of protected equipment.