The determination of magnitude and phase angle of electrical quantities

Although the three-voltmeter method for measuring the relative magnitude and phase angle of two voltages or currents is well known, the use of vacuum tube voltmeters, which draw negligible amounts of energy from the circuit, permits the use of the method for purposes which previously have not been considered. A further improvement of the scheme by balancing out one component of either voltage or current adds to the accuracy of the results. The method is considered for two purposes, namely: the measurement of the capacitance and power factor of imperfect condensers, and the measurement of the ratio and phase angle of current transformers.