VERY LOW FREQUENCY BREAKDOWN PROPERTIES OF ELECTRICAL INSULATION MATERIALS AT CRYOGENIC TEMPERATURES

Conference · Tue Jun 01 00:00:00 EDT 2010

DOI:https://doi.org/10.1063/1.3402335· OSTI ID:1052236

Sauers, Isidor ^[1]; Tuncer, Enis ^[1]; Polyzos, Georgios  ^[1]; James, David Randy ^[1]; Ellis, Alvin R. ^[1]; Pace, Marshall ^[1]

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1. ORNL

For long cables or equipment with large capacitance it is not always possible to conduct high voltage withstand at 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.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1052236
• Resource Relation: Conference: Joint Cryogenic Engineering Conference/International Cryogenic Materials Conference - Tucson, Alabama, United States of America - 6/28/2009 12:00:00 AM-7/2/2009 12:00:00 AM
• Country of Publication: United States
• Language: English

Related Subjects

Very low frequency
VLF
high voltage breakdown
dc
liquid nitrogen
cryogenic dielectric