Dynamic observation of space charge formation in XLPE using pulsed electro-acoustic method

Short interval measurement of space charge formation in XLPE under DC and AC voltage stress is carried out using the pulsed electro-acoustic (PEA) method. To obtain a signal of the space charge distribution using an ordinary PEA system, it takes more than 30 s to average the measured signals of from 1000 to 2000, transfer and store the averaged data to memory. On the other hand, the improved system makes it possible to measure the space charge formation within the interval of less than 1 second by reducing the noise and employing a computer controlled DC or AC high voltage power supply and a pulse generator. Using the improved system, a dynamic space charge formation in XLPE was observed within the interval of 1 second during the stepwise DC voltage application. It is found that, within the first 10 seconds, the hetero space charges appeared, and then increased in XLPE. In addition to the above observation, the space charge formations under various frequencies (ca. 0.0001-50 Hz) of AC voltage was also observed. This report is presented as the introduction of the improved system and the typical dynamic space charge formation obtained using the improved system