Online Detection and Early Warning of Condenser Layer Breakdown in RIP Bushings: An Experimental Investigation

The reliable operation of high voltage direct current (HVDC) bushings is critical for power grid safety. Condenser layer breakdown stands as a particularly destructive failure mechanism in resin-impregnated paper (RIP) bushings, yet its development process remains inadequately understood due to detection challenges. This paper proposes a novel experimental method to simulate and study the condenser layer breakdown process. The failure development process is divided into five distinct stages through continuous monitoring of multiple electrical parameters. For the first time, two characteristic transitions in discharge behavior are identified: from magnitudedominated to frequency-dominated discharge parameters, and from outline variations to concentrated discharge bands in phase-resolved partial discharge (PRPD) patterns. The physical mechanism of breakdown development is revealed through the analysis of parameter coupling, where periodic high-energy discharges coincide with synchronized variations in capacitance and dissipation factor, indicating progressive formation of permanent conductive channels. These findings not only enhance understanding of the failure mechanism but also provide new criteria for condition monitoring, including the identification of critical transition points and the correlation analysis of multiple parameters for early warning in practical applications.