Effect of the presence of metal box on partial discharge detected by internal loop antenna

This paper discusses the measurement and detection of partial discharge (PD) on the metal enclosed power apparatus, mainly on the effect of the presence of metal box on PD induced electromagnetic wave detected by internal loop antenna. The loop antenna was designed, manufactured, and tested using vector network analyzer. The loop antenna shows low return loss and high voltage standing wave ratio. The loop antenna is used for PD measurement. The experimental results show that the presence of metal box gives significant change on the PD signal detected by using loop antenna. Without metal box, the measurement sensitivity decreases because of the high level of background noise. The Metal box acts as electromagnetic wave shielding and reduce the external noise. When the loop antenna placed inside metal box, the measurement sensitivity increases because of the low level of background noise inside metal box.