Pulse Current Characteristics of Creeping Discharge of Oil-Impregnated Pressboard Under DC Voltage

The transformer insulation system is a critical point of vulnerability, with creepage flashover being a significant contributor to transformer failures. Consequently, gaining a thorough understanding and evaluation of parameters that influence creeping discharge behavior is essential. This research aims to investigate the spectral characteristics of creeping discharges occurring in oil-pressboard insulation under different levels of DC voltage using a point-plane electrode model. The study analyzes key parameters such as the discharge count, amplitude, time interval (At), and the mean discharge value. Results from the experiments indicate that with higher DC voltage stress, the interval between consecutive discharges shortens, while the frequency of discharges increases. Moreover, as the voltage rises, the mean discharge value decreases due to the substantial increase in discharge occurrences. These findings imply that charge carriers accumulate more easily before a discharge and migrate rapidly in the direction of the electric field at higher voltage stresses.