Methods of eliminating conversion factor drift effects in a clip-on hall-effect ammeter

摘要

A clip-on ammeter includes a magnetic frame, which is designed as a clamp and accommodates a winding and a Hall element in an air gap, a reference current source and a commutating switch for connecting the current source to the winding. Methods of operating include taking measurements with reference current flowing in each of the two possible directions in the winding and secondly with reference current flowing to oppose the effect of the current under measurement and with no reference current flowing. The conversion factor is calculated for use in obtaining readings free of conversion factor drift.