| 摘要 |
PROBLEM TO BE SOLVED: To raise productivity with the lowering of a film forming temperature by providing a protection film at the sides of an element resistant to lightning, the protection film being made of polymer materials having an oil permeability of not more than a specific value when dipped in insulating oil having a given temperature for a given time. SOLUTION: With respect to a protection film at the sides of an element of a serge arrester resistant to lightning, aluminum foils are separated after application of various kinds of polymer materials on the aluminum foils, followed by curing, and thus isolation films made of these polymer materials, respectively, are produced. After dipping the individual isolation films in high voltage insulating oil of given temperature for 240 hours, oil content permeated in the isolation films is calculated as: oil permeability (mg/cm2)/isolation film surface area (cm2). After obtaining variations of oil permeability (mg/cm2) according to insulating oil temperatures by dipping the isolation films of the various kinds of polymer materials for 240 hours in the insulating oil of varied temperature, a serge arrester having a protection film formed by coating a modified acrylic silicone resin having an oil permeability of not more than 5 mg/cm2, was left in the insulation oil. 1,000 hours after, the electric characteristics did not lower. Accordingly, it becomes possible to lower the film forming temperature.
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