Very low frequency breakdown properties of electrical insulation materials at cryogenic temperatures

I. Sauers, E. Tuncer, G. Polizos, D. R. James, A. R. Ellis, M. O. Pace

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

For long cables or equipment with large capacitance it is not always possible to conduct high voltage withstand tests at 60 Hz due to limitations in charging currents of the power supply. Very low frequency (typically at a frequency of 0.1 Hz) has been used for conventional cables as a way of getting around the charging current limitation. For superconducting grid applications the same issues apply. However there is very little data at cryogenic temperatures on how materials perform at low frequency compared to 60 Hz and whether higher voltages should be applied when performing a high voltage acceptability test. Various materials including G10 (fiberglass reinforced plastic or FRP), Cryoflex™ (a tape insulation used in some high temperature superconducting cables), kapton (commonly used polyimide), polycarbonate, and polyetherimide, and in liquid nitrogen alone have been tested using a step method for frequencies of 60 Hz, 0.1 Hz, and dc. The dwell time at each step was chosen so that the aging factor would be the same in both the 60 Hz and 0.1 Hz tests. The data indicated that, while there is a small frequency dependence for liquid nitrogen, there are significant differences for the solid materials studied. Breakdown data for these materials and for model cables will be shown and discussed.

Original languageEnglish
Title of host publicationAdvances in Cryogenic Engineering - Transactions of the International Cryogenic Materials Conference, ICMC, Vol. 56
Pages68-74
Number of pages7
DOIs
StatePublished - 2010
Event2009 Cryogenic Engineering and International Cryogenic Materials Conferences, CEC-ICMC 2009 - Tucson, AZ, United States
Duration: Jun 28 2009Jul 2 2009

Publication series

NameAIP Conference Proceedings
Volume1219
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Conference

Conference2009 Cryogenic Engineering and International Cryogenic Materials Conferences, CEC-ICMC 2009
Country/TerritoryUnited States
CityTucson, AZ
Period06/28/0907/2/09

Keywords

  • Cryogenic dielectric
  • Dc
  • High voltage breakdown
  • Liquid nitrogen
  • VLF
  • Very low frequency

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