The impulse voltage flashover of dielectric spacers in a helium-insulated superconducting cable model
✍ Scribed by R.J. Meats
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 433 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0011-2275
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✦ Synopsis
Prototypes of a helium-insulated superconducting cables, with conductors and dielectric of realistic geometry and construction, have been subjected to impulse voltage tests in a superconducting cable test facility. Five metre lengths of a co-axial pair of tubular conductors, separated by insulating spokes, were evaluated in helium at 5.5 K and 4 bar pressure. A pressure vessel was designed and built for this purpose and was accommodated in a horizontal cryostat, 8 m in length and 305 mm bore. Cooldown of the cable was achieved by a flow of cold helium circulated from an external refrigerator.
Previous work had shown that dielectric spacers made from either polypropylene or a filled epoxy resin (Stycast 2850 FT) might perform well. First flashover voltages were 96 k Vp for polypropylene spacers and 94 k Vp for Stycast spacers. Flashover took place across spacers in the lower region of the cable," it is suggested that particulate contamination governed flashover. Polypropylene spacers deformed during test, but Stycast spacers only broke up at flashover sites and are preferred.