Compositions – Fluent dielectric – O-containing
Reexamination Certificate
1999-05-28
2001-08-14
Ogden, Necholus (Department: 1751)
Compositions
Fluent dielectric
O-containing
C252S073000, C252S075000, C252S079000, C252S578000, C508S365000, C508S382000, C508S491000, C508S488000
Reexamination Certificate
active
06274067
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a high oleic oil composition useful as an electrical insulation fluid, to electrical insulation fluid compositions and electrical apparatuses which comprise the same. The high oleic oil compositions of the invention have electrical properties which make them well suited as insulation fluids in electrical components.
BACKGROUND OF THE INVENTION
The electrical industry uses a variety of insulating fluids which are easily available and cost effective. Examples are mineral oil, silicone fluid, and synthetic hydrocarbon oils used in transformers, power cables and capacitors. Examples of such fluids include those described in U.S. Pat. No. 4,082,866 issued Apr. 4, 1978 to Link, U.S. Pat. No. 4,206,066 issued Jun. 3, 1980 to Rinehart, U.S. Pat. No. 4,621,302 issued Nov. 4, 1986 to Sato et al., U.S. Pat. No. 5,017,733 issued May 21, 1991 to Sato et al. U.S. Pat. No. 5,250,750 issued Oct. 5, 1993 to Shubkin et al., and U.S. Pat. No. 5,336,847 issued Aug. 9, 1994 to Nakagami, which are each incorporated herein by reference.
Many of these fluids are not considered to be biodegradable in a reasonable time frame. Some have electrical properties which render them less than optimal. In recent years regulatory agencies have become increasingly concerned about oil spills which can contaminate the ground soil and other areas. A biodegradable oil would be desirable for electrical apparatus such as transformers used in populated areas and shopping centers.
Vegetable oils are fully biodegradable, but the oils presently available in the market are not electrical grade. A few vegetable oils such as rapeseed oil and castor oil have been used in limited quantities, mostly in capacitors, but these are not oleic esters.
There is a need for a fully biodegradable electrical fluid. There is a need for electrical apparatuses which comprise such an oil. There is a need for a method of processing vegetable oil to electrical grade.
SUMMARY OF THE INVENTION
The present invention relates to high oleic acid triglyceride compositions that comprise fatty acid components of at least 75% oleic acid, less than 10% diunsaturated fatty acid component; less than 3% triunsaturated fatty acid component; and less than 8% saturated fatty acid component; and wherein said composition is further characterized by the properties of a dielectric strength of at least 35 KV/100 mil (2.5 mm) gap, a dissipation factor of less than 0.05% at 25° C., acidity of less than 0.03 mg KOH/g, electrical conductivity of less than 1 pS/m at 25° C., a flash point of at least 250° C. and a pour point of at least −15° C.
The present invention relates to an electrical insulation fluid comprising at least 75% of a high oleic acid triglyceride composition that comprise fatty acid components of at least 75% oleic acid, less than 10% diunsaturated fatty acid component; less than 3% triunsaturated fatty acid component; and less than 8% saturated fatty acid component; and wherein said composition is further characterized by the properties of a dielectric strength of at least 35 KV/100 mil gap, a dissipation factor of less than 0.05% at 25° C., acidity of less than 0.03 mg KOH/g, electrical conductivity of less than 1 pS/m at 25° C., a flash point of at least 250° C. and a pour point of at least −15° C., and one or more additive selected from the group of an antioxidant additive, a pour point depressant additive and a copper deactivator.
In some preferred embodiments the electrical insulation fluid comprises a pour point depressant additive, which in some embodiments is polymethacrylate.
In some preferred embodiments the electrical insulation fluid comprises a combination of antioxidant additives . In some preferred embodiments, the electrical insulation fluid comprises a combination of IRGANOX L-57 antioxidant and IRGANOX L-109 antioxidant.
In some preferred embodiments the electrical insulation fluid comprises a copper deactivator. In some preferred embodiments, the copper deactivator is IRGAMET-30 metal deactivator.
In some preferred embodiments that antioxidant additives and copper deactivators make up about 0.2-2.0% of electrical insulation fluid. It is preferred that the additives comprise a combination of IRGANOX L-57 antioxidant, IRGANOX L-109 antioxidant and IRGAMET-30 metal deactivator. It is preferred that the combination is provided at a ratio of about 1 part IRGANOX L-57 antioxidant to 2-4 parts IRGANOX L-109 antioxidant to about 1 part IRGAMET-30 metal deactivator.
In some preferred embodiments, the electrical insulation fluid comprises at least 94% of the high oleic acid triglyceride composition. In some preferred embodiments, the electrical insulation fluid comprises fatty acid components of: at least 75% oleic acid, less than 10% linoleic acid, less than 3% linolenic acid, less than 4% stearic acid, and less than 4% palmitic acid. In some preferred embodiments the electrical insulation fluid is characterized by the properties of: a dielectric strength of at least 40 KV/100 mil gap, a dissipation factor of less than 0.02% t 25° C., acidity of less than 0.02 mg KOH/g, electrical conductivity of less than 0.25 pS/M at 25° C., a flash point of at least 300° C., and a pour point of at least −20° C., and in some embodiments, at least −40° C. In some preferred embodiments the electrical insulation fluid comprises 0.5-1.0%, in some embodiments 0.5%, of the combination of IRGANOX L-57 antioxidant, IRGANOX L-109 antioxidant and IRGAMET-30 metal deactivator. In some preferred embodiments the combination of IRGANOX L-57 antioxidant, IRGANOX L-109 antioxidant and IRGAMET-30 metal deactivator has a ratio of about 1 part IRGANOX L-57 antioxidant to about 3 parts IRGANOX L-109 antioxidant to about 1 part IRGAMET-30 metal deactivator.
The present invention relates to electrical apparatuses comprising the electrical insulation fluid.
The present invention relates to the use of electrical insulation fluid to provide insulation in electrical apparatuses.
The present invention relates to a process for preparing the high oleic acid triglyceride composition comprising the steps of combining refined, bleached and deodorized high oleic acid triglyceride with clay to form a mixture and filtering the mixture to remove the clay.
DETAILED DESCRIPTION OF THE INVENTION
This present invention provides a novel application for high oleic vegetable oils as electrical insulation fluids. Vegetable oils usually have a high percent of triglyceride esters of saturated and unsaturated organic acids. When the acid is saturated, the triglyceride is either a semi-solid or a liquid with high freezing point. Unsaturated acids produce oils with low freezing points. However, monounsaturated acids are preferred over diunsaturated and triunsaturated acids because the latter tend to dry fast in air due to cross-linking with oxygen. Increasing the amount of diunsaturates and triunsaturates makes the oil more vulnerable to oxidation; increasing the saturates raises the pour point. Ideally, the higher the monosaturate content, the better the oil as an electrical fluid.
Oleic acid is a monounsaturated acid found as triglyceride ester in many natural oils such as sunflower, olive oil and safflower in relatively high proportions (above 60%). High oleic acid content is usually above 75% of the total acid content. Oleic acid content above 80% is achieved by genetic manipulation and breeding. Two oils that are currently available in the United States with high oleic acid content and low saturates are sunflower oil and canola oil. These oils are of value in producing high quality lubricating oils but have not been used in the production of electrical insulation fluids.
High oleic oils may be derived from plant seeds such as sunflower and canola which have been genetically modified to yield high oleic content. The pure oils are triglycerides of certain fatty acids with a carbon chain ranging from 16 to 22 carbon atoms. If the carbon chain has no double bonds, it is a saturated oil, and is designated Cn:0 where n is the number of
Claiborne C. Clair
Oommen Thottathil V.
ABB Power T&D Company Inc.
Hamlin D. G.
Ogden Necholus
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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