An improved isolated current sensing device. The invention consists of two magnetizable cores which surround the conductor carrying the current to be measured. The two cores are cyclically saturated in opposite directions by a high-frequency excitation current counter-wound around the two cores. The device then detects through an output winding the asymmetry in the core magnetic fluxes caused by the current-carrying conductor. The output signal is passed through a phase-sensitive detector tuned to twice the original excitation frequency. Negative feedback is used to stabilize the device.
Poul A. Jensen