OMICRON Magazine

What is partial discharge? Partial discharge (PD) is a localized dielectric breakdown of an insulation system under electrical stress. It can lead to dielectric failure if left undetected or if it’s not rectified in a timely manner. This is because PD weakens the insulation’s strength over time, making it unable to withstand operational stress. Therefore, detecting, measuring and locating PD inside of high-voltage (HV) asset insulation, such as in rotating machines, transformers, switchgear and power cables, is essential. PD measurement is a sensitive and non-invasive method accepted worldwide for detecting insulation weakness in HV assets. It’s used to assess the insulation condition during quality control at the factory and on-site commissioning after the asset has been installed. Once in service, PD measurement is performed periodically to ensure the reliable operation of assets in the grid. As with other high-voltage (HV) assets, partial discharge (PD) activity in Gas-Insulated Switchgear (GIS) is an indication of developing and potential failure-causing defects in the insulation. Typical problems inside of GIS that can cause PD are sharp conductive objects or particles deposited on the outer conductor, inner conductor, or attached to the insulating spacers. Such particles need to be found inside of the GIS and removed, especially during onsite commissioning to ensure reliable in-service operation. PARTIAL DISCHARGE TESTING ON GAS-INSULATED SWITCHGEAR With multiple ultra-high frequency measurement modes, our UHF 800 system provides you with sensitive on-site partial discharge measurements on GIS 20