Types And Structures Of Surge Protectors

The type and construction of surge protectors vary depending on the application, but they contain at least a non-linear voltage limiting element. Commonly used surge protectors include MOV (Metal Oxide Varistor) and gas discharge tubes. Electrical surges contain powerful energy and therefore cannot be stopped. For this reason, the strategy for protecting sensitive electrical equipment from surge damage is to shunt the surge away from the equipment and into the ground.

Indicators of the pros and cons of surge protector MOV: (1) Clamping voltage: Indicates the voltage value that will cause the MOV to connect to the ground wire. The lower the clamping voltage, the better the protection performance. (2) Energy absorption/dissipation capacity: This nominal value indicates how much energy the surge protector can absorb before burning out, in joules. The higher the value, the better the protection performance. (3) Response time: Surge protectors do not disconnect immediately, there is a slight delay in their response to the surge.

Another common surge protection device is a gas discharge tube. These gas discharge tubes do the same thing as an MOV, they move excess current from the hot wire to the ground wire. They do this by using an inert gas as a conductor between the two wires. The composition of the gas makes it a poor conductor when the voltage is within a certain range. If the voltage surges beyond this range, the current will be strong enough to ionize the gas, making the gas discharge tube a very good conductor. It will conduct current to the ground wire until the voltage returns to normal levels, then become a poor conductor again.