Electrical insulating oil
AssigneeNippon Oil Co., Ltd.
InventorsMidori Masunaga, Yoshiki Kohno, Kohji Hayashi
Life of this patent
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Abstract
An electrical insulating oil having excellent oxidation stability, thermal stability, corona resistance, corrosion resistance and, if desired, a particularly low pour point, which consists essentially of a blend of a refined oil (I) derived from a paraffin or mixed base crude oil, a refined oil (II) prepared from a lubricating oil fraction of a mineral oil, at least one arylalkane (III) such as an alkylbenzene, and, if desired, an essentially amorphous ethylene-propylene copolymer (IV).
Claims17
An electrical insulating oil consisting essentially of
- (A) 5 - 90% by weight of a refined oil (I) containing not more than 0.25 wt.% of sulphur, the refined oil (I) being prepared by the steps of:
- refining with a solvent capable of selectively dissolving aromatic compounds a distillate containing at least 80 wt.% of a fraction having a boiling range of 230.degree. - 430.degree. C at atmospheric pressure obtained by the distillation of a paraffin or mixed base crude oil at atmospheric pressure or the distillation at a reduced pressure of a bottom oil obtained by the distillation of the crude oil at atmospheric pressure thereby to obtain a raffinate from said distillate,
- hydrofining the raffinate so obtained, and
- dewaxing the thus hydrofined raffinate with a solvent, (B) 1 - 20% by weight of a refined oil (II) prepared by treating at least with a solid absorbent a lubricating oil fraction containing at least 80 wt.% of a mineral oil having a boiling range of 230.degree. - 460.degree. C at atmospheric pressure obtained from a crude oil and (C) 5 - 90% by weight of at least one arylalkane (III), the three components (I) - (III) being mixed together in such amounts that the mixture has a total sulphur content of not more than 0.35 wt.%, thereby to obtain the electrical insulating oil having excellent oxidation stability, thermal stability, corona resistance and corrosion resistance.
An electrical insulating oil consisting essentially of (A) 5 - 90% by weight of a refined oil (I) containing not more than 0.25 wt.% of sulphur, the refined oil (I) being prepared by the steps of:
- refining with a solvent capable of selectively dissolving aromatic compounds a distillate containing at least 80 wt.% of a fraction having a boiling range of 230.degree. - 430.degree. C at atmospheric pressure obtained by the distillation of a paraffin of mixed base crude oil at atmospheric pressure or the distillation at a reduced pressure of a bottom oil obtained by the distillation of the crude oil at atmospheric pressure thereby to obtain a raffinate from said distillate,
- hydrofining the raffinate so obtained, and
- dewaxing the thus hydrofined raffinate with a solvent, (B) 1 - 20% by weight of a refined oil (II) prepared by treating at least with a solid absorbent a lubricating oil fraction containing at least 80 wt.% of a mineral oil having a boiling range of 230.degree. - 460.degree. C at atmospheric pressure obtained from a crude oil, (C) 5 - 90% by weight of at least one arylalkane (III), the three components (I) - (III) being mixed together in such amounts that the mixture has a total sulphur content of not more than 0.35 wt.%, to obtain an electrical insulating oil as a base oil, and (D) 0.001 - 1.0 part by weight per 100 parts by weight of said base oil, of an essentially amorphous ethylene-propylene copolymer (IV) having an average molecular weight of 10,000 - 200,000 and a propylene content of 10 - 70 mol%, thereby to obtain the electrical insulating oil having excellent oxidation stability, thermal stability, corona resistance, corrosion resistance and low-temperature properties.
Dependencies are inferred from the claim text.