Wattmeter calibration at zero power factor using digitally generated sinewaves

A two-phase digital sinewave generator with provision for accurate phase shifts has been constructed. A system using this generator for the calibration of power frequency wattmeters at zero power factor is described. This method relies mainly on the phase angles of three terminal gas dielectric capacitors and a four terminal current shunt for quadrature accuracy between current and voltage. An intercomparison with a high-quality air-cored mutual inductor gives phase agreement within ±50 μrad