Lightning impulse breakdown performance of an inhibited Gas-To-Liquid (GTL) hydrocarbon transformer oil

In this paper, breakdown voltages and acceleration voltages of an inhibited Gas-To-Liquid (GTL) based transformer oil were investigated under both positive and negative lightning impulse voltages. A conventional inhibited mineral oil was also tested as a benchmark. Both point-sphere and point-plane configurations were used. Rising voltage method was used to conduct the breakdown tests, and the breakdown voltage was obtained as the average of ten tests. Results show that both positive and negative impulse breakdown voltages of the GTL based oil are higher than those of the conventional mineral oil. This is thought to be due to the significantly lower aromatic content in the GTL based oil, since aromatic molecules tend to have low ionization potentials that promote the positive streamer propagation and electron scavenging properties that accelerate the negative streamer propagation. In addition, the paper also discusses streamer propagation velocity and acceleration voltages of the GTL based oil under both positive and negative polarities.