An electronic wattmeter for nonsinusoidal low power factor power measurements

The development of an electronic wattmeter for use in power circuits with very low power factors and nonsinusoidal waveforms is reported. The wattmeter is constructed of commercially available components which include a high-accuracy electronic multiplier and appropriate amplifying, averaging, and compensating circuitry. It is a portable laboratory instrument with provisions for direct reading of both instantaneous and average power. A thermal standard has been used to calibrate the wattmeter over a wide range of current pulse magnitudes and pulsewidths and at power factors down to 0.01. Several applications of power measurements in typical solid-state power controller circuits are discussed.