Effect of water on the space charge formation in XLPE

In this paper, we describe the effect of water on the space charge in crosslinked polyethylene (XLPE). In order to study the effects of water and by-products of crosslinking, we prepared two types of samples. The water in the first one (Type A) is controlled by immersing in water after removing the by-products, and the water in the other type (Type B) of samples is controlled by the water from the decomposition of cumyl-alcohol by heating. We measured the space charge formation by the pulsed electro-acoustic (PEA) method. A large difference was observed between Type A and Type B. In Type A samples (containing only water) the space charge distribution changes from homogeneous to heterogeneous as the water content increases, whereas in Type B (containing water and by-products) all samples exhibit heterogeneous space charge distribution. However, merely the effect of water for both types was almost the same, including peculiar space charge behavior near the water solubility limit.