Electrical insulating oil having high oxidation stability and method for production thereof
AssigneeNippon Mining Co., Ltd.
InventorsAtsushi Matsunaga, Sampo Kusayanagi, Masamitu Takano, Yutaka Kato
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Abstract
An electrical insulating oil, comprising: a base oil selected from the group consisting of a mineral oil, an alkylbenzene, and a mixture of a mineral oil and an alkylbenzene; a non-basic nitrogen content in an amount of 16 ppm or more; and a basic nitrogen content in an amount of 6% or less based on the weight of the non-basic nitrogen content.
Claims9
An oxidation stability-improving agent for an electrial insulating oil comprising a concentrate separated from mineral oil and containing as main components:
- non-basic nitrogen compounds and sulfide-type sulfur compounds, and substantially not containing basic nitrogen compounds.
A method for improving the oxygen stability of an electrical insulating oil, comprising adding
- (a) an oxygen stability-improving agent for an electrical insulating oil comprising a concentrate separated from a mineral oil and containing as main components:
- non-basic nitrogen compounds and sulfide-type sulfur compounds, and substantially not containing basic nitrogen compounds;
- to
- (b) a member selected from the group consisting of a refined mineral oil having a viscosity of 4 to 30 cSt at 40.degree. C., an alkylbenzene, and a mixed oil of a refined mineral oil having a viscosity of 4 to 30 cSt at 40.degree. C. and an alkylbenzene, to thereby increase the non-basic nitrogen content and the sulfide-type sulfur content in the resulting oil and thus maintain (i) the non-basic nitrogen content in the resulting oil at 16 to 260 ppm, (ii) the sulfide-type sulfur content in the resulting oil at 50 to 2,000 ppm, and (iii) the basic nitrogen content in the resulting oil at 6% or less based on the non-basic nitrogen content.
Dependencies are inferred from the claim text.