Dennis Bryan Ardin

US Patent:

43215297, Mar 23, 1982

Filed:

Oct 2, 1979

Appl. No.:

6/081244

Inventors:

Charles W. Simmonds - Salt Lake City UT
Dennis B. Ardin - Salt Lake City UT

International Classification:

G01R 2500

US Classification:

324 83R

Abstract:

A power factor metering device. The power factor metering device includes a novel electronic circuit for deriving the power factor from a detected voltage and current. The device includes a current clamp that may be clamped onto any conductor of a three-phase or single-phase circuit. Voltage clips are used to detect the circuit's voltage. The current clamp induces a voltage that lags the detected current by 90 electrical degrees. An amplifier stage is coupled to the induced voltage through a low input variable resistance so that the input voltage to the amplifier stage may be adjusted to correct for errors induced in the phase relationship between the detected voltage and current. The output from the amplifier stage is input into a zero crossing detector stage that changes its output state each time the output of the amplifier stage passes through zero. The output of the zero crossing detector stage is applied to one side of a pair of EXCLUSIVE-OR gates, and is also applied to one of the inputs of a bistable multivibrator. The voltage detected by the voltage clips is stepped down by a transformer and is input to a second zero crossing detector stage.