Measurement of space charge distribution in XLPE cable insulation at high temperature

This paper presents experimental results of space charge distribution in cross-linked polyethylene (XLPE) cable insulation measured with Pulsed Electro-Acoustic method. The measurement results obtained show that the space charge formation process in XLPE cable insulation can be explained as follows; Under low electric field (-15 kV/mm) at high temperature, carrier sources were generated in the insulation and moved toward the anode, resulting in accumulation of heterocharges near the anode. Under medium electric field (-35 kV/mm) at high temperature, the accumulated heterocharges decreased gradually. It is considered that this phenomenon occurs due to the increased electrical field by the heterocharges, which causes charge injection from the anode. Under high electric field (-100 kV/mm) at high temperature, both negative and positive packet charges were generated in the middle of insulation, and they moved while decaying. In this way, process for space charge formation in XLPE cable insulation is observed and the distribution of the space charges shows drastic change under various electric fields