Characteristic analysis of solid materials for electrical insulation of HTS magnets

Duck Kweon Bae, Jong Man Joung, Seung Myeong Baek, Chan Joo Lee, Sang Jin Lee, Tae Kuk Ko, Sang Hyun Kim

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Following the successful development of practical high temperature superconducting (HTS) wires, there have been renewed activities in developing superconducting power equipment. HTS equipment has to be operated in a coolant such as liquid nitrogen (LN2), or cooled by conduction-cooling method such as using Gifford-McMahon (G-M) cryocooler to maintain the temperature below critical level. In this paper, the dielectric strength of some insulating materials, such as polyimide film, epoxy, and Teflon tape in LN2 was measured. The insulation materials for HTS current lead cooled by cryocooler needs to satisfy two opposing requirements: electrical insulation and heat conduction. To meet the two requirements, a thermal link that consists of oxide free copper (OFC) sheets, polyimide films, glass GFRP plates, and interfacing material was fabricated. Polyimide film was used as an electrical insulator for the current lead. Surface flashover voltage of glass fiber reinforced plastic (GFRP), the basic property of designing HTS solenoid coil, was also analyzed. Epoxy is a good insulating material but fragile at cryogenic temperature. The multi-layer insulating method for current lead has been suggested to compensate for this fragile property. It consists of Teflon tape layer and epoxy layer fixed by fiber material. Based on these measurements, conduction-cooled HTS current lead for 1.2 kV class DC reactor type high temperature superconducting fault current limiter (HTSFCL) and 6.6 kV class HTS magnets for same type HTSFCL cooled by sub-cooled LN2 were successfully fabricated and tested.

Original languageEnglish
Pages (from-to)1189-1193
Number of pages5
JournalIEEE Transactions on Applied Superconductivity
Issue number2
Publication statusPublished - 2004 Jun

Bibliographical note

Funding Information:
Manuscript received October 21, 2003. This work was supported by a grant from Center for Applied Superconductivity Technology of the 21st Century Frontier R&D Program funded by the Ministry of Science and Technology, Republic of Korea.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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