Electrical insulating oil having high oxidation stability and method for production thereof.

摘要

An electrical insulating oil comprises a mineral oil and/or an alkylbenzene having a non-basic nitrogen content in an amount of 16 ppm or more, and a basic nitrogen content in an amount of not more than 6% of the non-basic nitrogen content. Preferably the sulfide S content is at least 50 ppm.

The mineral oil can be distilled from a crude oil, as a fraction of viscosity 4 to 30 cSt at 40°C, and refined. An alkylbenzene is mono-, di or trialkyl with a side chain alkyl * 9C, of viscosity 5 to 30 cSt and can be a by-product of synthesis of alkylbenzene for a detergent.

The insulating oil is produced by mixing mineral oils of different refinery fractions, obtained from crude oil, optionally admixing alkylbenzene, and treating the mixture with clay to remove basic nitrogen compounds; or by adding a non-basic N compound concentrate to a refined mineral oil of low N content.