Basic Structure And Application Considerations Of Surge Protector

The type and structure of surge protective device vary according to different uses, but surge protector should contain at least one nonlinear voltage limiting element. The basic components used for surge protection device are: discharge gap, gas-filled discharge tube, varistor, suppression diode and choke coil.

I. Maximum continuous operating voltage Uc

When selecting SPD in a 220/380V three-phase system, its maximum continuous operating voltage Uc should be selected according to different grounding system forms.

(1) When the power supply adopts the TN system, the distribution lines and branch lines drawn from the main distribution board (box) in the building must adopt the TN-S system;

(2) In the following places, the Uc value of the zinc oxide varistor SPD should be increased according to the specific situation:

① Places where the power supply voltage deviation exceeds the specified 10%;

② Places where harmonics increase the voltage amplitude.