Contribution to relationship between space charge injection and dielectric breakdown of low density polyethylene under a divergent field

Low density polyethylene from 0.1 to 1 mm thick samples have been submitted to an increasing divergent field at room temperature until breakdown occurs. The breakdown field has been measured for different voltage waveforms: DC ramp, 50 Hz sine ramp and rectified 50 Hz sine ramp. The observed differences have been attributed to the amount of space charges injected during the voltage ramp application. This amount is strongly dependent on both voltage waveform and needle polarity