Compact Covered Distribution Lines Supported by Triangle Spacers: Spacer Design

Covered conductors and compact configuration with triangle spacers for 10-kV distribution lines have brought many advantages and benefits in China. In the past, the polymeric spacers cast with polycarbonate material had been designed and applied to make the distribution line compact. The reason that breakage faults occurred on compact distribution lines with polymeric spacer is because the polymeric spacers have bad pollution flashover performance, and the polycarbonate material used is not suitable for outdoor insulation. The pollution experiment of the covered distribution line supported by triangle spacers shows the flaw in the insulation layer is the key reason to generate flashover in a humid environment, which would be formed in the insulation layer of the covered conductor under sun radiation or under lightning effect. A new kind of triangle composite spacer, which is suitable for heavy pollution area, is designed to prevent breakage faults of covered conductors caused by leakage current. From the experimental results, the corona initial voltage and the flashover voltage of 10-kV covered distribution line fixed with composite spacers increased an average of 41.9% and 60.3%, respectively, comparing with the tested data of covered conductor fixed with polymeric spacers. The developed composite spacers can highly improve the pollution performance of 10-kV covered distribution lines. The field applications show the composite spacers are effective, and can prevent conductor breakage faults caused by leakage current.