A rectifier meter for the indication and measurement of phase angles

This paper shows how it is possible to use certain combinations of metal-rectifier elements, together with a dynamometer-type instrument, to indicate and measure phase angles. Full-wave or half-wave circuits, involving quite distinct principles of measurement, can be used. Formulae relating meter readings and phase angles are deduced theoretically, and practical results are compared. Provided certain compensating resistances are introduced to overcome imperfect rectifier performance, close agreement is found. The method is shown to be particularly suitable for measuring phase angles near to 90°. The application of this principle to three-phase circuits, and the effects of waveform harmonics, are also discussed. It is shown that the same principles can be used to construct a synchroscope, and tests on this type of instrument are recorded. Methods by which the phase-meter might be made to read phase angle directly are also discussed.