Mechanism on breakdown phenomenon of cable joint with impurities

The electric-field intensity around the cable joint is computed based on the finite element method when the power cable is loaded on the 110 kV constant voltage source. If there are impurities in the cable joint, the impurities would cause the local electrical field distorted and the electric-field intensity increasing sharp. The insulation materials are breakdown when the local electrical field is distorted for the intensity exceeding the dielectric strength possibly. To analyze the mechanism on breakdown phenomenon mathematical models are established according to cable joint with impurities, and the distribution of the electric-field intensity on the models is computed when loaded on the 110 kV constant voltage source. In the test, cable joint with impurities run on different constant voltage source. The result shows the discharge path in the cable joint with impurities.