Power surges, also known as voltage surges or surges, are a common phenomenon in power systems, usually referring to sudden fluctuations in current or voltage. Such fluctuations can be caused by lightning strikes, power grid failures, switching operations, or other causes. Power surges can cause serious damage to electrical equipment and electronic equipment, and even lead to safety problems such as fire. Surge protector is used to limit transient overvoltage and discharge inrush current of electrical appliances, mainly by reducing the damage of surge to power equipment and electronic equipment, to ensure the safety of electricity use.

The core components of the surge protection device are generally varistors, gas discharge tubes and graphite gaps, which can be divided into three categories according to the different core components, voltage switching SPD, voltage limiting SPD, and composite SPD. The common point is that when the lightning current intrudes into the system, the lightning current can be discharged to the ground in time, and the lightning overvoltage can be limited. The whole process is in the nanosecond level, and the normal power supply of the equipment will not be affected.