Evaluation of polymer films for electrical insulation

Technical Report · Mon Apr 01 04:00:00 EST 1985

OSTI ID:5740290

McCoy, Jr, H E

Polymer films of several kinds were studied for use as electrical insulators. The studies were initiated in support of the development of gas transformers, in which SF/sub 6/ gas is used as the dielectric material and polymer films might be used as insulators. The polymers studied were polyethylene terephthalate, polycarbonate, polyethersulfone, polyparabanic acid, and polyimide. Samples were exposed to SF/sub 6/ at 0.4 MPa (4 atm) pressure and at 70, 100, 135, and 160/sup 0/C for times to 23,000 h. Changes in properties during aging were monitored by periodically removing samples and performing visual, tensile, electrical breakdown, density, and microstructural tests. Tests on two lots of polyethylene terephthalate showed that strength increased and ductility decreased with increasing crystallinity. Tests were initiated on polyetherimide and polysulfone as well as some additional lots of the initial five polymers selected for evaluation. Tensile tests at elevated temperatures were used as one method to determine the maximum use temperatures. General creep characteristics as well as specific creep data were determined for six polymers. Differential thermal expansion distorted the polymer in a bonded polymer-metal composite, and a test was developed for evaluating this form of thermal strain fatigue failure. Some heating tests were run on a prototypic gas transformer coil wound of aluminum and two interlayers of polyethylene terephthalate. The largest problems noted in these tests were associated with thermal expansion mismatches between the structural components of the coil.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5740290
• Report Number(s): ORNL-6134; ON: DE85013532
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360400* -- Polymers & Plastics-- (-1987)
42 ENGINEERING
420800 -- Engineering-- Electronic Circuits & Devices-- (-1989)
AGING
CARBON COMPOUNDS
CARBONATES
COMPARATIVE EVALUATIONS
CREEP
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATION
ELECTRICAL INSULATORS
EQUIPMENT
ESTERS
EXPANSION
FILMS
FLUORIDES
FLUORINE COMPOUNDS
GAS-INSULATED TRANSFORMERS
HALIDES
HALOGEN COMPOUNDS
MECHANICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXYGEN COMPOUNDS
POLYCARBONATES
POLYESTERS
POLYMERS
SULFUR COMPOUNDS
SULFUR FLUORIDES
THERMAL EXPANSION
TRANSFORMERS