Several electrical engineering applications require measuring complex current signals containing high frequency periodic components (MHz) or short duration pulses (nanoseconds) added to a low frequency carrier signal (usually power line frequency). For the overall measurement of such complex signals, high frequency wide band current transformers (HFCT) are currently used. Unfortunately, they have usually limited capability to measure large low frequency currents because of the core saturation. The paper develops a solution to extend the current measuring capability at low frequencies only, together with a corresponding decrease of sensitivity, while the sensitivity at high frequencies remains unchanged. The proposed method does not in any way alter the device original construction.

Keywords: High frequency current transformer, Frequency-dependent sensitivity, Magnetic saturation