Wiring methods of surge protectors in different power supply systems

TN-C-S system:

The TN-C-S system is a three-phase five-wire system, and the colors of the five wires are yellow L1, green L2, red L3, light blue N, and yellow-green PE. It is the combined system of the TN-C system and the TN-S system. The neutral conductor N and the protective conductor PE are combined into a protective protective conductor PEN line, and the neutral conductor N and the protective conductor PE are structurally separated in the secondary circuit.

TN-S system(4P):

The TN-S system is a three-phase five-wire system, and the colors of the five wires are yellow L1, green L2, red L3, light blue N, and yellow-green PE. In the power supply system, the working neutral line and the protection line are separated.

TN-S system(3+NPE):

TT system(3+NPE):

IT system(3P):