According to the type classification, SPD can be divided into two kinds of surge protectors, power line and signal line. In the power line, the main function of the surge protector is to connect the protected line to the equipotential system in the first time. Let each port of the device be equipotential, and discharge the huge pulse energy generated by the lightning strike on the circuit into the ground, so that the potential of each port of the device is reduced, thereby protecting the device; the signal line surge protector is in the signal Installed in the line, the function is to protect the subsequent equipment, which is generally installed at the front end of the equipment. The low-frequency signal SPD, the antenna feed SPD, etc. are all signal line surge protectors.
When selecting the surge protector, attention should be paid to factors such as the average voltage protection between the devices and the conductor interface of the connecting wires. The types of surge protectors are selected through different kinds of conditions of the low voltage system.