Closeup of toroidal inductors and electrolytic capacitors on electronic PCB

Copper commutator bar of the electric motor close up electric motor rotor

Shot of an electronics factory workers assembling circuit boards by hand while it stands on the assembly line high tech factory facility

Small AC on Large DC Currents

Rogowski current probes do not measure the DC component of a current. However unlike a current transformer or a fluxgate device they contain no magnetic materials so are unaffected by the DC current. Therefore it is possible to use a small, flexible, Rogowski coil to measure a small AC current in the presence of a large DC current, whereas a sensor based on a magnetic principle would be expensive and bulky to prevent saturation effects. One such common application is measuring the ripple current in capacitors where the main current is DC or slow time varying.