Electrical insulating oil composition.

摘要

An electrical insulating oil composition which is excellent in low temperature characteristics and suitable for use in impregnating capacitors, and comprises (a) m-ethylbiphenyl, (b) p-ethylbiphenyl, (c) m-isopropylbiphenyl and (d) p-isopropylbiphenyl, and is characterized in that the total amount of the ethylbiphenyls is not less than 40% by weight and the proportion of solid phase in the composition at a temperature of -40 DEG C is not more than 45% by weight, the solid quantity of each component being calculated according to the following equation of solid-liquid equilibrium: <MATH> wherein Xi is the equilibrium mole fraction of a component i in the liquid phase of the composition, DELTA H @ is the heat of fusion (cal.mol<-><1>) of the component i, T @ is the melting point (K) of the component i, T is the temperature (K) of the system, and R is the gas constant (cal.mol<-><1>.K<-><1>).