A magnetic-modulator-type current-dividing highly stable DC current transformer for large currents

A highly stable current-dividing DC current transformer system using a second-harmonic type of magnetic modulator has been developed for a several-hundred-ampere highly regulated current source which is required for nuclear magnetic resonance measurements. The system consists of a resistive current divider, two choke coils, and two magnetic modulator ampere-turn comparators, using relatively small cores, with feedback. The performance of the regulated current source was tested by setting the current supply to 200 A. A temperature drift of 3 p.p.m./ degrees C in the regulated output current was achieved. >