VERY LOW FREQUENCY BREAKDOWN PROPERTIES OF ELECTRICAL INSULATION MATERIALS AT CRYOGENIC TEMPERATURES
- Applied Superconductivity Group, Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
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.
- OSTI ID:
- 21371747
- Journal Information:
- AIP Conference Proceedings, Vol. 1219, Issue 1; Conference: International cryogenic materials conference (ICMC) on advances in cryogenic engineering materials, Tucson, AZ (United States), 28 Jun - 2 Jul 2009; Other Information: DOI: 10.1063/1.3402335; (c) 2010 American Institute of Physics; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AGING
CAPACITANCE
CRYOGENICS
DIELECTRIC MATERIALS
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
ELECTRICAL FAULTS
ELECTRICAL INSULATION
FIBERGLASS
FREQUENCY DEPENDENCE
POLYCARBONATES
REINFORCED PLASTICS
SUPERCONDUCTING CABLES
TEMPERATURE RANGE 0065-0273 K
CABLES
CARBON COMPOUNDS
CARBONATES
COMPOSITE MATERIALS
CONDUCTOR DEVICES
CURRENTS
ELECTRIC CABLES
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
EQUIPMENT
MATERIALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXYGEN COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHYSICAL PROPERTIES
PLASTICS
POLYMERS
REINFORCED MATERIALS
SYNTHETIC MATERIALS
TEMPERATURE RANGE