Characteristics of Discharge Inception across Barrier in the Oil/Pressboard Composite Insulation System

Abstract

This paper deals with discharge characteristics in the oil/pressboard composite insulation system under application of lightning impulse voltage. Large oil gaps in power transformer are often subdivided by insulating barriers into small ones. We observed partial discharge at an oil gap across the barrier without puncturing it in a test sample and also evaluated the voltage required for the phenomenon. As a result, we conclude that the discharge occurred in the oil gap due to the electric field enhancement along with discharge propagation.