Environmental friendly thermoplastic cable has become a hotspot in cable industry. Taking 35kV polypropylene cable as the research object, the installation process of prefabricated joint and molded joint was compared, and the dielectric properties of polypropylene cable insulation material and silicone rubber insulation material were tested at different temperatures and frequencies. The test results were substituted into the simulation software for electrothermal coupling simulation, and the electric field distribution was obtained. The results show that the installation hidden trouble of polypropylene molded joint is lower than prefabricated joint. In the case of the prefabricated joint, the electric field is concentrated on the polypropylene insulation side of the cable because the permittivity of polypropylene is lower than that of silicone rubber, and the electric field is concentrated at the root of the stress cone and the end of the shielded pipe. In another case of the molded joint without stress cone and movable interface, the equipotential line distribution is more uniform and basically consistent with the cable. Combining installation process, material properties and electric field distribution, it can be concluded that the performance of polypropylene molded joint is better.
 

polypropylene cable;prefabricated joint;molded joint;installation process;dielectric performance test;electrothermal coupling simulation