Determining electric field distribution in high voltage cable in presence of cavity

Power cables as one of main components of power networks, play an important role in electric power transmission between different zones. In cable insulation system, due to the presence of pollution such air voids, water voids, and also occurrence of water treeing phenomena, local field increase. As a resulting, enhancing electric field can cause local breakdown in cable insulation. The presence of water within the insulation materials can only lead to forming water trees if a sufficient electric field exists. One of the major problems, which shorten the life of high voltage cables, is the presence of water inside the insulation material of the cables. In this paper, the Finite Element Method is used to computing and evaluating of the electric field in the power cables by considering to existence of water particles and air voids inside the polyethylene insulation. For this propose, the field computation program Maxwell has been used for the modeling. These results indicate that the stress is influenced by the void permittivity, shape of voids and also void position.