Novel low-cost electronic power-factor meter

This paper describes the construction and operation of a low-cost electronic power-factor meter that can replace the conventional electrodynamic type. The alternating voltage and current signals are passed through a zero-crossing detector. The voltage signal is passed through an integrator through an inverting/non-inverting amplifier. The inversion is selected by an electronic switch controlled by the current zero-crossing signal. The output voltage from the integrator is proportional to the p.f. Any analogue d.c. meter calibrated for the power-factor can directly read the power-factor. An electronic circuit with two flip-flops indicates the lead/lag nature of the power-factor.