Abstract: An electronic current transducer for high voltage transmission lines including a fast analog data channel for providing effective relaying information which is stablized by a slow, highly accurate, channel which is insensitive to changes in gain. In addition for dc transmission lines where polarity may reverse, offsetting or biasing allows for bipolar measurement.

Abstract: An optical data transmission system for use with current sensors on ac high voltage transmission lines comprises a light-emitting diode transmitter at line potential and a silicon photodiode receiver at ground potential. Signals are conducted from the transmitter to receiver along a fiber optic light pipe. A silicon photodiode in a feedback configuration produces a linear ac output light from the light-emitting diode in response to line current. A dc reference signal is superimposed on the ac current data signal to provide system gain calibration. The dc signal is utilized, in a feedback loop, to control the gain of an ac signal amplifier in the receiver and to thus stabilize system calibration.