A New Current Transducer for On-Line Monitoring of Leakage Current on HV Insulator Strings

Abstract

This paper presents the design, implementation and testing of a transducer to measure and monitor in real time leakage currents on high-voltage insulators. The new proposed transducer has the particularity of not affecting the insulation capacity of the insulator strings and can be installed without the need to de-energize the power system. The transducer is made up of a toroidal current transformer with a high permeability magnetic core, and an amplifier circuit, the output voltage of which is acquired, processed and transmitted by a dedicated device installed in the lower part of the HV tower. The leakage current is reconstructed from the transducer output voltage by applying the FFT technique and its own inverse transfer function. The transducer makes it possible to obtain the leakage current with its characteristic harmonics and the technique presented here reduces the electromagnetic noise present in the power systems. The proposed transducer was tested on an insulator inside an artificial fog chamber, built according to the IEC 60507 standard. Finally, the transducer was tested on an insulator string in a 220 kV substation. The results obtained show that the designed transducer correctly measures the leakage current on HV insulator strings and can be used for the on-line monitoring of pollution levels of insulator strings.