Space charge measurements: electrode effects and prebreakdown

The authors discuss the measurement of space charge in insulating polymers using a nondestructive method called the thermal step method (TSM). The principles of the TSM are first described. Using this method, the authors study the influence of semiconducting electrodes which assure the electric contact between the insulating polymers and metal electrodes as used in high-voltage cables. Under certain conditions, they measure the prebreakdown electric field values. The prebreakdown experiment clearly shows that space charge is the main reason for polymer performance degradation. These results show that the migration and space charge installation in XLPE (cross-linked polyethylene) depend on the nature of the electrode