| abstract |
PROBLEM TO BE SOLVED: To provide an electrical insulating oil which is excellent in biodegradability, has a low viscosity at a low temperature, shows little deterioration in insulation performance even if some moisture is mixed, and has sufficient electrical characteristics. SOLUTION: An alcohol of neopentyl glycol and trimethylolpropane and / or pentaerythritol, and two or more carboxylic acids selected from pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid and decanoic acid. An electrically insulating oil having a kinematic viscosity at 0 ° C. of 10 to 250 mm 2 / s, a dielectric breakdown voltage of 50 KV or higher, a biodegradability of 60% or higher, and a pour point of −35 ° C. or lower. [Selection figure] None |