Modifying the Windings of HFCT Restrain Magnetic Saturation and Harmonics Interference

The ferrite core design for HFCT sensor uses the small signal current sampling as the basis. The non-linear loads, such as system unbalance or interphase ground fault, produces considerable harmonic induction, thus leading to magnetic saturation of the ferrite core. The aliasing of high and low frequency signals distorts the extracted waveform or damages the HFCT. To address the above problem, this study used sensors to improve two sets of windings, whereby the forward winding and backward winding were connected in series in the coil position. As the low frequency signal neutralized the increase of induced potential through the backward winding loop path, the low frequency response hazard generated was reduced by a low frequency signal. The experimental results showed that the unmodified sensor correlation coefficient quantized value R=0.94137 was positively correlated, which validates the excellent ability to suppress magnetic saturation and harmonic interference.