Phase-Angle Meter

an instrument used to measure the cosine of the phase-shift angle, or the power factor, between voltage and current in electric AC circuits at frequencies specified for mains used by industry or to measure the phase difference of electric oscillations. At normal frequencies, the cosine of the phase-shift angle is measured by direct-reading, electromechanical meters. The measuring mechanism in such meters is a ratio meter of the electrodynamic, ferrodynamic, electromagnetic, or induction type; the deflection of the moving part of the ratio meter depends on the phase shift between the given voltage and current. Electronic counters are used as phase-angle meters for a wide range of frequencies. Such meters measure the time interval between the instants when the correlated oscillations pass through zero. Another type of meter suitable to wide frequency ranges consists of a graduated phase shifter combined with a zero phase-difference indicator, for example, a phase detector. The measuring error is l°–3° for electromechanical phase-angle meters and 0.05°–0.1° for electronic types.