Pre-breakdown streamer propagation and breakdown characteristics of refined bleached and deodorized palm oil under lightning impulse voltage

Vegetable oils are considered nowadays as a potential alternative to Mineral Oil (MO) for dielectric insulation fluids in transformers due to its high biodegradability, non-toxicity and high fire resistance. This paper presents an experimental investigation on the streamer propagation and breakdown of Refined, Bleached and Deodorized Palm Oil (RBDPO) under both positive and negative lightning impulse voltages. The streamer shape, stopping length, velocity and breakdown voltage of 2 types of RBDPO were examined. Needle-plane electrodes configuration with 50 mm gap was used in this study and streamer images were captured by a high speed camera. It is observed that the negative streamer shape patterns are thicker than positive streamer for both RBDPO and MO. At the same applied voltage level and polarity, both RBDPO have longer streamer stopping lengths and the streamers propagate faster than MO.