SURGE PROTECTION CIRCUIT AND APPARATUS FOR GROUND RESISTANCE TESTER

摘要

A surge protection circuit and apparatus for a ground resistance tester (10). The surge protection circuit comprises: a first clamping module (21), a second clamping module (22), and a third clamping module (23). By connecting the first clamping module (21) between a ground electrode (301) and an auxiliary voltage electrode (302) of the ground resistance tester (10), connecting the second clamping module (22) between the auxiliary voltage electrode (302) and an auxiliary current electrode (303) of the ground resistance tester (10), and connecting the third clamping module (23) between the ground electrode (301) and the auxiliary current electrode (303) of the ground resistance tester (10), potential differences among said three electrodes of the ground resistance tester (10) are clamped within a preset range, thereby solving the existing problem that during the testing of a ground resistance using a three-electrode method, due to that the auxiliary electrodes are connected to the ground, when a lightning stroke or surge happens, a potential difference would be generated between any two of the three electrodes, and if the potential difference reaches a given degree, the ground resistance tester (10) would be damaged.