How Surge Protectors Work

Some electrical technicians don't know much about surge protectors. They only know that this thing can prevent lightning, and they don't know much about other things. This situation is quite common and normal. After all, surge protection device are common national standard products, so they can be used. As a professional lightning protection equipment manufacturer, the editor here briefly popularizes science for everyone, and let's understand the working principle of surge protectors together, so as not to be complained that electrical professionals don't understand lightning protectors.

1. The role of surge protective device

As we all know, transient overvoltage surges in the line consist of small voltage peaks with a short duration (less than 1 millisecond) and can reach tens of times the standard power supply voltage. Resistance to transient surges (called "pulse withstand voltage") is very important in electrical and electronic equipment.

SPD or surge protector, its role is to protect electrical systems and equipment from transient surges and pulses, such as those caused by lightning and grid operations. Surge protectors contain at least one nonlinear element (varistor or spark gap), whose function is to divert discharge or impulse current and limit overvoltage of downstream equipment.

2. Working principle of surge protector

During normal operation (for example, in the absence of surge), the surge protector has no effect on the system in which it is installed. It acts like an open circuit and maintains isolation between the active conductor and the earth.

Working principle of surge protector, when a voltage surge occurs, the surge protector reduces its impedance and diverts the impact current in a few nanoseconds. At this time, the surge protector behaves like a closed circuit, the overvoltage is short-circuited and limited to an acceptable value for the downstream electrical equipment, and once the pulse surge stops, the surge protector will restore its original impedance and return to the open circuit state.

Working principle of surge protector, if there is no surge protector, the surge will reach the electrical equipment. If the surge exceeds the impulse withstand voltage of the electrical equipment, the impact current flows freely through the equipment and immediately damages the equipment.

By using a surge protector between the active conductor and the earth (TT network), the overvoltage can be limited and the discharge current can be safely diverted, thereby establishing an equipotential connection between the phase and the ground, and when the surge comes, the equipment is safe and sound.

After reading the above content, do you have a clear understanding of the working principle of surge protectors? Lightning protection is no small matter. Surge protectors are necessary when there is electricity. How to correctly install surge protectors? How to choose lightning arresters? How to carry out effective lightning protection design?