Partial discharge detection of free moving particles in GIS by the UHF method: recognition pattern depending on the particle movement and location

Partial discharge detection by the UHF method has become a powerful tool to guarantee GIS reliability. This paper presents new experimental results regarding the study of the most common discharge source in a GIS, which is provoked by free metal particles. Particles of different size and material were introduced in an experimental GIS bus and AC voltage applied. The movement of the particles was observed by a video camera and simultaneously the partial discharges were registered by a UHF monitoring system. Several discharge patterns were identified depending on the particle movement and location (ground metal chamber or spacer). These patterns were then used by the monitoring system for defect location and risk assessment for the GIS. Finally, based on more than 10 years experience with UHF monitoring, an overview of HV commissioning procedures and online monitoring systems is presented.