A New Approach to Study Partial Discharge Inception due to Particles in Transformer Oil Using Electric Field Analysis

The presence of particle in transformer oil can cause significant deterioration to breakdown voltage and partial discharge inception voltage of transformer insulation. Although many studies are carried to understand the effect of particle in oil primarily concentrated on breakdown and discharge inception activities, contribution towards understanding the electric field stress distribution due to particle in oil are very limited. Electric stress distribution in transformer oil due to particle presence in oil gap between winding and pressboard barrier is simulated and studied using Finite Element Method (FEM). An attempt is made to correlate partial discharge (PD) inception caused by the local electric field distribution in transformer oil with respect to variation in conductivity of the particle. Effect of variation in size and shape of the particle on the electric field distribution is also considered in this study. The result of this new approach will be useful to understand partial discharge inception caused by electric field stress enhancement in transformer oil due to particle presence in oil gap between winding and pressboard barrier.