Time correlation of light intensity, voltage and current waveforms in breakdown of transformer oil under steep-fronted impulse excitation

Time-correlated specimen voltage, current, and light-intensity waveforms are related to tree initiation, onset of conduction, and tree propagation. Results on breakdown voltage and time of initiation relative to waveforms are also given. It is demonstrated that the breakdown phenomena in polymethylmethacrylate, as indicated by waveforms and self-luminosity, are similar to those described for breakdown in transformer oil.<>