Characteristics of discharge progress across barrier in the oil/pressboard composite insulation system under impulse voltage application

It is crucial for reasonable transformer insulation design to understand the characteristics of discharge progress under the application of a standard lightning impulse voltage. This paper deals with the fundamental discharge characteristics of oil/pressboard (PB) composite insulation system. We obtained discharge images using a digital camera equipped with an image intensifier. In this research, we focused on the route of discharge progress along pressboard barrier. Furthermore, we evaluated the discharge velocity as well as the time required for the successive discharge generation across the barrier PB.