Sensitivities and noise-resistant performances of various PD sensors located outside a GIS

This paper deals with the method of PD detection with the sensor (antenna) put at the outside of the GIS tank. It pays attention to the flange of the spacer as a leakage place of the PD electromagnetic radiation. Three kinds of antennas are proposed and made for trial purposes. And comparative study of the three antennas with the internal PD sensor (disc coupler) used worldwide so far is made from the viewpoint of the sensitivity characteristic and the noise-resistant performance. As a result, it is concluded that one kind of antenna has equal or even higher sensitivity to/than the internal disc coupler, without remarkable inferiority about the noise-resistant performance in the frequency range from 1.2 GHz to 2.7 GHz.