Experimental research on the surface discharge characteristics for a HTS cable termination

As energy demands increase and environmental concerns heighten, an underground high-temperature superconducting (HTS) cable will provide the necessary alternative to meet power supply needs. Within conventional cable technology, the terminations are important components. HTS cable terminations are required when the insulated shield HTS cables connect with other conductors such as a bus or uninsulated overhead lines. HTS cable terminations must span a temperature range from 77 to 300°K. The termination is insulated with insulating oil or air, cryogenic gaseous nitrogen, and liquid nitrogen. Difficult conditions for high-voltage insulation had to be overcome with HTS cable. Different environments can substantially raise the flashover possibility at a HTS cable termination. This paper will report on experimental investigations of the surface flashover of terminations with various surface lengths and different glass fiber-reinforced plastics thicknesses in air, transformer oil, liquid nitrogen (LN₂), and complex conditions. This paper examined the surface flashover characteristics under ac voltage application for the Oil-LN₂ type using a model electrode containing a particle. The particle initiated flashover voltage versus a termination without a particle. Particle position was also investigated.