APPARATUS FOR MEASURING SINGLE PHASE REACTIVE POWER IN AN AC CIRCUIT

摘要

Apparatus for measuring single reactive power in an electric AC circuit operating at an angular frequency W, the apparatus comprising a multiplier circuit having one input connected via a p/2 phase shafter to receive an image of the instantaneous value of the voltage in said circuit, and another input connected to receive an image of the instantaneous value of the current in said circuit, the output signal from the multiplier being applied to a notch filter for removing signal components at an angular frequency of 2W, wherein the filter is an active filter in the form of a double bridged T with a first T branch being driven by a first amplifier and being constituted by first and second series-connected resistors making up the cross bar of the T with a first separator making the upright of the T, and with a second T branch being driven by a second amplifier and being constituted by second and third series-connected capacitor making up the cross bar of the T with a third resistor making the upright of the T, the stop frequency of the filter being adjustable by varying the gain of said first and second amplifiers.