Space charge formation at interface between polyethylene and other polymeric materials

Space charge formation at interfaces between polyethylene and other polymeric materials were observed using a PEA method. Many polymeric materials are proposed to be used as the pre-molded joint for XLPE insulated cables. However, there are few investigations of space charge accumulation at the interface between different polymeric materials. When the space charge is formed at the interface in joint, electric field may be distorted with the consequence that the unexpected accident happens. In this experiment, space charge formation at interface between two layers are measured using the PEA system. Several combinations of different polymers, which are XLPE, silicone-rubber, EP-rubber and epoxy resin, were investigated. From the results of measurement, two kinds of charge formation were observed. One of them is quick formation that is observed immediately after voltage application. Another is slow formation following the former one. Former one seems to be related to the difference of permittivities of two materials. Later one seems to be related to charge injection from electrodes.