Study of breakdown of transformer oil in the presence of barrier

• Main Authors: Husain, E., Kamaluddin, Ashraf, I., Iqbal, A.
• Format: Conference Proceeding
• Language: English
• Subjects: Dielectrics and electrical insulation; Electric breakdown; Electrodes; Oil insulation; Partial discharges; Petroleum; Power transformer insulation; Space charge; Stress; Testing
• DOI: 10.1109/ICPADM.1994.413942

Barriers can influence the failure-stresses by effectively breaking up a large oil volume into smaller oil volumes, and by interfering with particle motion, and partial discharge activity. However, despite the importance of insulating barriers to oil filled transformers, little has been reported on their effect on failure stresses. The results obtained by experimental investigation into breakdown characteristics of transformer oil under non-homogeneous field conditions (rod-plate electrode system) as well as moderately homogeneous field conditions (sphere-sphere electrode system) under alternating (50 Hz) voltage stresses have been reported in this work. The effect of gap length on breakdown in oil and the influence of electrode covering, and the barrier in the form of a sheet of insulation such as kraft paper, polystyrene and polypropylene is reported. It has been found that as the distance between the barrier and plate electrode increases, the breakdown strength slightly decreases and then increases remarkably, resulting in much higher strength than that with a covered ground electrode. The complicated characteristics of the breakdown have been studied under the rod-plate and sphere-sphere electrode configuration for ac voltage (50 Hz). An attempt has been made to explain the result by considering the space charge effect.< >