How To Choose A Surge Protector Model?

Most people have heard of surge protectors in daily life, but few understand their working principles or how to select the right model. How should one choose the appropriate surge protective device for lightning protection of building power supplies?

1. Class I and II Lightning Protection Buildings

Class I surge protectors need to be installed at the main distribution box. The voltage must be controlled and cannot exceed 2.5 kV. However, if the impulse current value for Class I protection mode cannot be determined, then the value should be set to greater than 12.5 kA.

2. Class III Lightning Protection Buildings

The selection requirements for surge protectors are basically the same as for Class I and II, except that there is no specific requirement for the impulse current value. If the current value cannot be determined, the same impulse current formula as for Class I and II lightning protection buildings can be used for calculation. Furthermore, we can understand the requirements for surge protectors as follows: only after the primary surge protector is determined can the secondary surge protection device be determined, and so on.

Surge protectors primarily operate in two modes: common mode and differential mode. The former mainly refers to protection between phase-to-ground (L-PE) and neutral-to-ground (N-PE). The latter differs, primarily referring to protection between phase-to-neutral (L-N) and phase-to-phase (L-L). If protection is implemented at the second, third, or fourth level on the low-voltage side, preparations for both modes are necessary.