Method and apparatus for adjusting overload compensation for a watthour meter

摘要

An apparatus for electrically setting the overload compensating magnetic reluctance in a single phase induction watthour meter includes a moveable magnetic shunt positioned adjacent the poles of a current core of a current stator circuit. An electrical parameter of the current stator circuit is sensed and changes in this parameter are used to set the air gap between the magnetic shunt and the current core poles. In one embodiment, a programmable controller controls a motor to move the shunt in response to variation of the sensed electrical parameter from a predetermined value. In one method, the sensed electrical parameter is the voltage induced in a first current coil when a second current coil is energized. In other methods, the sensed electrical parameter is the flux induced in the magnetic shunt or the self inductance of a current coil. A further method is to determine the ration of a harmonic voltage to a fundamental voltage which corresponds to the desired degree of magnetic saturation of the overload compensator at the control point.