Influence of curing by-products on dielectric loss in XLPE insulation

The authors present results on the dielectric loss of PE (polyethylene) insulation systems containing curing by-products of acetophenone, cumyl alcohol, and α-methyl styrene. They also discuss the influence of these curing by-products on dielectric loss of insulation. It is shown that when a layer of curing by-product, especially acetophenone, is placed at the boundary of the PE and the electrode, the dielectric loss tangent increases to an extent which cannot be estimated by the Maxwell-Wagner type polarization of composite dielectrics. This result can be explained by the increase of accumulated charge carriers in PE bulk due to carrier injection from the electrode accelerated by the presence of the curing by-products between the PE and the electrode