Design and Implementation of A novel High-frequency Current Transformer for Partial Discharge Measurements

This study focuses on the improvement of the performance of high-frequency current transformer (HFCT) for Partial Discharge Measurement and thus reveals a new design method of HFCT. An annular nickel-zinc ferrite is used as the magnetic core of the HFCT, and the parameters such as the number of winding turns and the diameter of the enameled wire are optimized. To test the HFCT, an experimental test platform is built according to the technical specifications of high-frequency partial discharge charged detection equipment. The test contents of the HFCT include transmission impedance, sensitivity, anti-interference characteristics, etc. The test results show that the new HFCT has a good response performance from 1MHz to 25MHz, the maximum transmission impedance value can reach 16.4mV/mA, the apparent charge of 5pC can be measured and signal-to-noise ratio is greater than 2:1. In addition, the designed HFCT also has good anti-interference and stability. With the self-designed low-power portable high-voltage cable insulation tester (mainly including signal conditioning circuit and data acquisition circuit), in the high-voltage laboratory, built a simulated discharge experimental circuit on the plate-pin, ball-ball two discharge models for high-voltage testing, the use of the developed HFCT to detect the partial discharge of the insulating polyethylene medium. The test results show that the HFCT can detect the partial discharge pulse signals before breakdown, with accurate data and reliable performance.