An optical technique to detect the degradation of electricalinsulation

摘要

An experimental technique which can simultaneously measure theamplitude and phase of the electroluminescence (EL) pulses emitted priorto electrical tree inception is described. A digital oscilloscope isused to acquire the light pulses and 3-D plots of the number of lightpulses versus their amplitude, and phase with respect to the AC waveformare obtained. Long-term aging tests are also performed on polymericinsulation. The results show that the light inception voltage and notthe partial discharge (PD) inception voltage is the thereshold voltageat which the polymer starts to degrade