Electronic solid state q-hour meter and/or combination q-hour and

Abstract

An electronic solid state Q-hour meter for measuring leading and lagging VARS quantities of electric power over a defined range of power factor. The Q-hour meter comprises first and second time division/pulse width-amplitude modulated/analog multiplier circuits. First and second current transformers are coupled to first and second phases of a multi-phase power supply to be monitored for deriving first and second analog circuit indicating signals which are supplied to respective analog current input terminals of the analog multipliers. First and second potential transformers are coupled across the first and second phases of the multi-phase power supply for deriving first and second analog voltage indicating signals that are supplied to respective input terminals of the first and second analog multiplier circuits. An electronic phase shifting circuit is connected intermediate the output of one of the potential transformers and the input terminal to one of the analog multiplier circuits for shifting the phase of the voltage indicating signal supplied thereto sixty degrees lagging. The outputs of the analog multiplier circuits are summed together to derive an output analog signal representative of a leading and lagging VARS quantities of electric power. By combining the solid state Q-hour meter with an electronic solid state kilowatt-hour meter a combination meter capable of measuring both kilowatt hours and Q-hours is provided.