Experimental investigations on surface discharge characteristics over oil/pressboard interface based on a rod-to-plane electrode

Partial discharge (PD) measurement and recognition is of great importance to assess the health condition of power transformers. Surface discharge is a typical PD event often happened within oil-paper insulation system. In this work, surface discharge over oil/pressboard interface is observed in laboratory using a digital PD measurement system. Accelerated aging experiment is performed to obtain aged oil and pressboards with different aging degrees. Then, the influences of insulation aging, electrode size as well as applied voltage on surface discharge characteristic are analyzed. Experimental results relevant to surface discharge measurements performed on lab-scale rod-to-plane electrode under different circumstances are presented with the purpose to spotlight surface discharge distributions aimed at identifying the basic nature of surface discharge over oil/pressboard interface. The obtained results would provide useful information to condition diagnosis of transformers.