ELECTRICAL INSULATING OIL COMPOSITION

摘要

Provided, as an electrical insulating oil composition which has improved dielectric breakdown voltage and excellent insulation performance, while being extremely insusceptible to deposition of crystals particularly at -50°C, is an electrical insulating oil composition which is characterized by containing: 1-phenyl-1-xylylethane and/or 1-phenyl-1-ethylphenylethane in an amount of 30-70% by mass in total; methylnaphthalene and/or dimethylnaphthalene in an amount of 1-30% by mass in total; and a fused or unfused bicyclic and/or tricyclic aromatic compound other than the above-mentioned compounds in an amount of 29-69% by mass, said aromatic compound having a boiling point of from 220°C to 350°C (inclusive).