The dc bus to be measured passed through the center of the toroidal iron core saturable reactor and 120vac excitation was applied to the winding around the iron core. As the current in the dc bus increased, the iron saturated more and more, which in turn allowed a higher level of ac current to flow.
The direct current bus passing through the center of the toroidal iron core saturable reactor was subjected to 120vac excitation applied to the winding around the iron core. As the DC bus current increased, the iron saturated more and more, enabling a higher level of alternating current to flow.