The third line of defensing against surges
The goal is to ultimately protect the equipment by reducing the value of the remaining surge voltage below 1000V so that the surge energy will damage the equipment. When the power surge protector is installed on the ac power supply of imported electronic information equipment as a third level of protection, it shall be of a series voltage-limited power arrester type and its lightning current capacity shall not be less than 10 kA.
A final line of defense can be to use a built-in power shield on the internal power portion of the power supply unit to completely eliminate minor transient overvoltages. The power surge protector used here requires that the maximum impact capacity of each phase does not exceed 20KA and the limit voltage does not exceed 1000V.
For particularly critical or sensitive electronic equipment, there must be a third level of protection, as well as protection of electrical equipment from transient overvoltages generated within the system. For the rectifier power supply used by microwave communication equipment, mobile base station communication equipment and radar equipment, according to the protection needs of the working voltage, it is advisable to choose the DC power arrester adapted to the working voltage as the non-horizontal protection.