Dielectrophoresis Phenomenon on Stress Relief Cone Deposit for XLPE Cable Termination

摘要

Stress relief cone is used in prefabricated XLPE cable termination. Some cases have been reported that white deposit has generated inside due to long-term operation and lead to a dielectric breakdown, but the process has not been elucidated yet. This research focused on presenting a study of the white deposit aggregation state based on dielectrophoresis phenomenon. Simulation of the actual stress relief cone was conducted to calculate dielectrophoresis force and velocity. Next, an electrode which imitated the actual condition at the interfaces was made to reproduce the aggregation state of the white deposit and observed its partial discharges characteristics. As an artificial deposit, the mixing material between barium titanate and silicone oil was used. As a result, the dielectrophoresis force and velocity that worked at the hundreds nanometer size of the white deposit were at atto.Newton and piko.meter/seconds. The poor interface smoothness made the deposit stop moving. The partial discharges repetition rate during the dielectrophoresis phenomenon was very low, and positive partial discharge dominantly occurred at the peak of the positive cycle. However, partial discharges activities were decreasing over time. The higher the viscosity, the slower the deposit movements and the fewer the partial discharges activities.