Partial discharge detection using acoustic camera

Problems related to PD activity within dielectric systems stressed by high voltage have been known for over a hundred years. This phenomenon over the years caused numerous fails of electric machinery and equipment. Therefore, the detection of the presence of this phenomenon became crucial. Over the years different measuring techniques have been developed and tested. Eg. electric methods allow PD quantification and using phase resolved characteristics determination of PD type. The problem with localization leads to developing other methods like acoustics and optical (UV detection). Since method using UV localization of PDs is not usable in all cases, the method of acoustic camera has been developed and tested. This study describes an acoustic camera and its possibilities to detect, localize and identify the PD event at different voltages and frequencies such as 50 Hz, 0,1 Hz and DC. In addition, the camera extracts a PD pattern depicting the phase-unresolved discharge behaviour from the acoustic signal emitted by the localized PD event. The experiments were performed in the lab with the focus on its capability to detect different types of PD such as corona and surface discharges using different setups. For the comparison of acoustic and global PD test techniques, the PD Smart device (from Doble) and a standardized PD circuit according to IEC 60 270 were used. The PD detection at 50 Hz, 0,1Hz and DC was performed. The inception voltage level is equal when using the conventional method detection (PD Smart) and NL Camera (for presented arrangements and conditions). PD patterns produced using the acoustic camera for different types of PD are compared with the PRPD produced by the PD Smart. The acoustic camera and its PD detection and localization were compared to the IEC 60270 PD test method. The PRPD of IEC 60270 and acoustic camera are comparable at 50 Hz voltage source.