Electrical performance of 330-kV composite insulators with different shed configurations under icing conditions

Composite insulators have been widely used in the electric power utilities worldwide because of their excellent anti-contamination performance. However, because of their compact shed configurations, the electrical performance of fully ice-bridged composite insulators is inferior to that of the porcelain and glass insulators at the same voltage level. As shown in previous studies, shed configuration influences the electrical performance of iced composite insulators. In order to improve the electrical performance of composite insulators under icing conditions, five types of 330-kV composite insulators with different number of big sheds were used to compare their V50 withstand voltage performances. The experiments were carried out in the multifunction climate chamber in Chongqing University. The test results show that the V50 withstand voltage can be increased by adding big sheds. To obtain the best performance, the shed spacing of big sheds should be long enough to avoid icicle bridging. The test results also show that there is no guarantee that the electrical performance of composite insulators can be increased when the corona rings are present under heavy icing condition. When corona rings are needed, their dimension and that of the shed configuration should be designed with care.