Anomalous breakdown phenomena in PMMA immersed in transformer oil

The results of experimental investigations on anomalous breakdown characteristics of polymethylmethacrylate (PMMA) immersed in transformer oil under direct, alternating, lightning impulse ( 1.2 50 μs) and switching surge ( 250 2500 μs) voltage stresses are presented in this paper. The effect of waveshape and polarity of the applied voltage, thickness and size of the specimen and diameter of the high voltage electrode on anomalous breakdown are discussed. © 1982.