Experimental investigation of partial discharge detection in medium-voltage switchgear based on Ultra-High-Frequency sensor

Partial discharge (PD) detection is the important research topic in the safe operation of electric equipment and power grid. Experimental investigation of partial discharge detection was carried out in a 12 kV switchgear by Ultra-High-Frequency (UHF) method. Two kinds of typical artificial fault models, namely suspended-metal model and voids-in-dielectric model were used as discharge sources. The UHF antenna was placed in the vicinity of joints for better capture efficiency. High-voltage probe was used to synchronize with the input voltage wave form, which determined the phase distributions of different defect models. Signal's amplitude rose with the increasing of input voltage till fully breaking down resulting in fatal damages to discharge models. Relations between the models' dimensions and discharge amplitude were also investigated. Further study focused on the frequency spectrums of these discharge signals. It revealed that the signal's frequency components were located mainly in less than 200 MHz and 520 MHz~540 MHz. These results might contribute to a better understanding of partial discharge detection by UHF method.