Abstract: Alternating current carried in a high voltage conductor is sensed by a toroidal coil to produce a first low level signal representative of the alternating current signal. Transmitter means operating at or near the potential of the conductor and remote from electrical ground receives the low level signal and in response produces a series of modulated pulses containing amplitude and phase angle replica information representative of the high voltage alternating current signal. Advantageously, the transmitter may be powered by a power supply deriving power from the high voltage conductor. The pulses produced by the transmitter may be transmitted to a receiver operating at or near ground potential, which receiver then converts the pulses into a second low level signal representative of the high voltage alternating current signal in both amplitude and phase angle.