避雷器是保护雷电过电压的，避免器件遭受雷击瞬时高压的损坏，这种过电压波形前端很陡，频率很高，但后续电流很小，避雷器可以将雷电波的峰值泄放从而保证其后面的电器安全 。通常避雷器正常情况下是处于断路，在经过雷击高压时导通将其释放到大地上。避雷器不负责引雷，如果雷电击中输电线路，雷电过电压会随着输电线路流向变压器或者流过配电装置时，此时避雷器泄流，防止配电装置被击坏。
The lightning arrester protects the lightning overvoltage and avoids the damage caused by the instantaneous high pressure of the lightning stroke. The front end of the overvoltage waveform is very steep, the frequency is very high, but the follow-up current is very small. The lightning arrester can release the peak of the lightning wave and ensure the safety of the electric appliance behind it. Usually, the lightning arrester is in a normal circuit, and is released to the earth by lightning high voltage. Lightning arrestor is not responsible for lightning. If lightning strikes a transmission line, lightning overvoltage will flow to the transformer or flow through the distribution device. At this time, the lightning arrester is discharged to prevent the distribution device from being damaged.