Surge Protector Protection Mode Selection

A represents a surge protector consisting of four varistor modules, suitable for TN-S system, representative models AM40A, AM80A, etc.;
B represents a surge protector consisting of three varistor modules and one discharge gap module, the three varistor modules are connected between the phase line and the neutral line, and the discharge gap module is connected between the neutral line and the ground line, suitable for TT system, representative models AM40B, AM80B, etc.;
C represents a surge protector consisting of two varistor modules, suitable for single-phase TN power supply system, representative models AM40C, AM80C, etc.;
D represents a surge protector consisting of one varistor module and one discharge gap module, suitable for single-phase TT power supply system, representative models AM40D, AM80D, etc.;
E represents a surge protector consisting of three varistor modules, the three varistors are connected between the phase line and the ground line, suitable for IT system and TN-C system, representative models AM40E, AM80E, etc.;