New electrical insulating oil composition

摘要

A new electrical insulating oil composition having improved low temperature characteristics which composition comprises a mixture of 40% by weight or more of benzyltoluene and the remainder of alkyl substituted diphenylmethane having 15 to 17 carbon atoms which is represented by the following general formula: wherein R1 and R2 are C1 to C4 alkyl groups and the total number of carbon atoms in R1 and R2 is 1 to 4, except that R1 and R2 are simultaneously methyl groups: and the proportion of the total quantity of solid phase calculated according to the following general solid-liquid equilibrium equation is 45% by weight or less relative to the total quantity of said composition at -40 DEG C: wherein Xi is the equilibrium mole fraction of a component i, in the liquid phase, DELTA H @ is the heat of fusion (cal.mol<-><1>), T @ is the melting point (K), T is the temperature (K) system, and R is the gas constant (cal.mol<-><1>.K<-><1>).