UHV transmission line monitoring terminal is used for fault location and diagnosis

and its energy acquisition is implemented by an instrument transformer. However

there exist problems of big starting current and narrow current range of energy acquisition. This paper proposes a single-coil energy acquisition circuit that adopts a double threshold thyristor closed-loop protection circuit and a high starting voltage flyback converter to realize low starting current and the wide current range of energy acquisition. The working principle of the single-coil energy acquisition circuit is described

and calculation and simulation are carried out.An energy acquisition circuit with the current range of 15～1 500 A and the minimum output power of 3 W is designed. The monitoring terminal with the energy acquisition circuit has passed the experimental verification and been put into field operation.