Effects of the Environmental Factors on Electrical Properties of High Voltage Cable Buffer Layer

The buffer layer is an important structure of cable, and its performances have a notable impact on the reliability of cable. In recent years, some problems especially faults in buffer layer have occurred frequently. However, the failure mechanism of buffer layer is unclear, which makes it difficult to prevent this accident. In this paper, the electrical properties of buffer layer were investigated under different environment. Moreover, in order to explore the cause of fault, the radial model of cable was established to compute the electrical field distribution in cable buffer layer. The results show that the electrical properties of the buffer layer will change under the variety of temperature, humidity and pressure in buffer layer. In the simulation analysis, it notes that the maximum electrical field intensity in buffer layer increases with the decline of its conductivity. Furthermore, when the maximum electrical field intensity exceeds air breakdown field, the discharge will occur and consequently lead to failure.