Magnetic Direct-Current-Measuring Circuits
Two circuits measure large direct currents in main conductors by use of magnetic fields produced by currents in glassy metal toroidal ferromagnetic cores surrounding main conductors. In both circuits, direct currents to be measured deduced from transient voltages generated in multiturn windings by transitions between magnetic fields produced by measured currents and saturation magnetic fields of cores.
Sullender, Craig C.↗