Effect of thin solid layer coating on creepage discharge characteristics in oil/pressboard composite insulation system

This paper deals with experimental characterization of creepage discharge to improve the electrical characteristics of oil/pressboard (PB) composite insulation system by thin solid layer coating such as epoxy resin and Teflon on PB surface under positive standard impulse voltage (1.2/50 μs) using a rod-plane electrode arrangement in mineral oil. To evaluate the creepage discharge properties according to surface condition, the number of discharge branches, discharge final length (ld) and partial discharge inception voltage (PDIV) are investigated versus the type of solid layer coating for different applied voltage using a digital camera. As a results, it is found that solid layer coating of PB surface significantly influences the PDIV and creepage discharge properties.