Phase-angle measurements are carried out simultaneously. The outputs of both the voltage channel and the current channel are amplifier and each output is connected to a Schmitt trigger circuit. The Schmitt trigger circuit produce a positive going spike every time the input sine wave goes through a zero crossing. These positive spikes are applied to a binary phase detector circuit. The phase detector consists of a bistable multivibrator, a differential amplifier, and an integrating capacitor. The positive going pulse form the constant voltage channel sets the multivibrator, and the pulse from the constant voltage channel resets the multivibrator. The “set” time of the MV is therefore determined by the zero crossings of the voltage and current waveforms. The “set” and “reset” outputs of the MV are applied to the differential amplifier. Which applies the difference voltage to an integrating capacitor. The capacitor voltage is directly proportional to the zero-crossing time interval and is applied to the phase-angle meter which then indicates the phase difference, in degrees, between the voltage and current waveform.