CA2018118C - Electrical insulating fluid - Google Patents
Electrical insulating fluidInfo
- Publication number
- CA2018118C CA2018118C CA 2018118 CA2018118A CA2018118C CA 2018118 C CA2018118 C CA 2018118C CA 2018118 CA2018118 CA 2018118 CA 2018118 A CA2018118 A CA 2018118A CA 2018118 C CA2018118 C CA 2018118C
- Authority
- CA
- Canada
- Prior art keywords
- weight
- electrical insulating
- insulating fluid
- fire point
- pentaerythritol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Organic Insulating Materials (AREA)
Abstract
The electrical insulating fluid, which has a high fire point, a relatively low viscosity and is less costly than conventional saturated hydrocarbon oils, includes about 20 to about 90 weight % of a saturated aliphatic or aromatic hydrocarbon oil having an average molecular weight greater than 400 and a fire point great than 300°C, about 10 to about 80 weight % of an ester oil of pentaerythritol having a fire point greater than 300°C and 0 to about 2 weight % of an antioxidant.
Description
2(~18118 ELECTRICAL INSULATING FLUID
This invention relates to electical insulating fluids used in electrical equipment to exclude gases from the insulating portion, thereby providing higher voltage capacity.
05 Refined petroleum oils have been used as electrical insulating fluids and electrical equipment such as transformers, circuit breakers, capacitors, and the like. U.S. Patent Nos. 4,082,866 and 4,284,522 describe saturated hydrocarbon oils which have both a high dielectric capacity and a high enough fire point to make them suitable as an electrical insulating fluid. One of the principal shortcomings to the use of such oils as electric insulating fluid is that they have a relatively high viscosity.
U.S. Patent No. 3,894,959 discloses the use of esters of pentaerythritol and other polyhydric alcohols as electrical insulating fluid. Such fluids have a high fire point and a viscosity lower than that of petroleum-based oils. However, their cost is relatively high in comparison to petroleum-based oils 2~8118 which is a principal drawback to their use in power transformers.
Other compositions for electrical insulating fluids are disclosed in U.S. Patent Nos.
05 4,276,184, 4,521,826 and 4,679,119.
A principal object of the invention is to provide an electrical insulating fluid which, although less expensive than pentaerythritol ester oils, has a high fire point and a viscosity lower than conventional hydrocarbon oils to thereby enhance the heat transfer characteristics.
Another object of the invention is to provide such an electrical insulating fluid having improved low-temperature properties.
Other objects, aspects and advantages of the invention will become apparent to those skilled in the art upon reviewing the following detailed description and the appended claims.
The electrical insulating fluid provided by the invention includes about 20 to about 90 weight % of a saturated hydrocarbon oil having an average molecular weight greater than 400 and a fire point greater than 300~C, about 10 to about 80 weight % of~an ester oil of pentaerythritol having a fire point greater than 300~C and 0 to about 2.0 weight %
of an antioxidant.
2~8~18 As used herein, the term "fire point"
means the fire point determined by ASTM D92.
Suitable hydrocarbon oils include conventional straight and branched chain saturated 05 aliphatic and aromatic hydrocarbon oils, such as those disclosed in U.S. Patent No. 4,082,866, having an average molecular weight greater than 400 and a fire point greater than 300~C and conventional blends of natural and synthetic saturated aliphatic hydrocarbons, such as those disclosed in U.S. Patent No. 4,284,522, having the same molecular weight and fire point. Hydrocarbon oils having an average molecular weight of about 500 to 700 are preferred and saturated aliphatic and naphthenic hydrocarbon oils are the preferred types.
If desired, a blend of saturated aliphatic and aromatic hydrocarbon oils, a blend of natural and synthetic saturated hydrocarbon oils and/or a misture of these two blends can be used as the hydrocarbon oil component.
The amoubt of saturated hydrocarbon oil used is about 20 to about 90, preferably about 60 to about 80 weight ~~, based on the total weight of the electrical insulating fluid.
~ Suitable ester oils of pentaerythritol include conventional ones such as those disclosed in 2 ~ ~8~1 8 U.S. Patent No. 3,894,959. As used herein, the term ~pentaerythritol~ includes pentaerythritol and polypentaerythritols, such as diepentaerythritol, tripentaerythritol, tetrapentaerythritol, 05 pentapentaerythritol, heptapentaerythritol and octapentaerythritol. The amount of ester oil of pentaerythritol used is about lO to about 80, preferably about 20 to about 40 weight %, based on the total weight of the electrical insulating fluid.
A small amount of a conventional antioxidant preferably is included to improve resistance to oxidation during use. Suitable antioxidants include hindered phenols, such as 2, 6-di-tert-butylphenol, 2, 4, 6-tri-tert-butylphenol, and ortho-tert-phenol. When used, the amount of the antioxidant can be up to about 2 weight % and preferably is about 0.2 to about 0.3 weight ~, based on the total weight of the electrical insulating fluid.
The electrical insulating fluid is ; prepared by blending the saturated hydrocarbon oil and the pentaerythritol ester oil, filtering the resulting blend through a suitable adsorbent medium, such as Fuller's earth, to remove impurities and thereby improve the dielectric strength and lower the dissipation factor and then adding an antioxidant, if used.
The electrical insulating fluid of the invention has a high fire point (above 300~C), has a 2~18~18 viscosity which is lower than that of conventional hydrocarbon oils and is less expensive than conventional pentaerythritol ester oils. The lower viscosity enhances the heat transfer 05 characteristics. The low temperature flow properties of the electrical insulating fluid are improved over those of Gonventional hydrocarbon oils which reduces the need for flow modifying additives to inhibit wax crystal formation at lower temperatures.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of the invention and, without departing from the spirit and scope thereof, make various changes and modifications to adapt it to various usages.
This invention relates to electical insulating fluids used in electrical equipment to exclude gases from the insulating portion, thereby providing higher voltage capacity.
05 Refined petroleum oils have been used as electrical insulating fluids and electrical equipment such as transformers, circuit breakers, capacitors, and the like. U.S. Patent Nos. 4,082,866 and 4,284,522 describe saturated hydrocarbon oils which have both a high dielectric capacity and a high enough fire point to make them suitable as an electrical insulating fluid. One of the principal shortcomings to the use of such oils as electric insulating fluid is that they have a relatively high viscosity.
U.S. Patent No. 3,894,959 discloses the use of esters of pentaerythritol and other polyhydric alcohols as electrical insulating fluid. Such fluids have a high fire point and a viscosity lower than that of petroleum-based oils. However, their cost is relatively high in comparison to petroleum-based oils 2~8118 which is a principal drawback to their use in power transformers.
Other compositions for electrical insulating fluids are disclosed in U.S. Patent Nos.
05 4,276,184, 4,521,826 and 4,679,119.
A principal object of the invention is to provide an electrical insulating fluid which, although less expensive than pentaerythritol ester oils, has a high fire point and a viscosity lower than conventional hydrocarbon oils to thereby enhance the heat transfer characteristics.
Another object of the invention is to provide such an electrical insulating fluid having improved low-temperature properties.
Other objects, aspects and advantages of the invention will become apparent to those skilled in the art upon reviewing the following detailed description and the appended claims.
The electrical insulating fluid provided by the invention includes about 20 to about 90 weight % of a saturated hydrocarbon oil having an average molecular weight greater than 400 and a fire point greater than 300~C, about 10 to about 80 weight % of~an ester oil of pentaerythritol having a fire point greater than 300~C and 0 to about 2.0 weight %
of an antioxidant.
2~8~18 As used herein, the term "fire point"
means the fire point determined by ASTM D92.
Suitable hydrocarbon oils include conventional straight and branched chain saturated 05 aliphatic and aromatic hydrocarbon oils, such as those disclosed in U.S. Patent No. 4,082,866, having an average molecular weight greater than 400 and a fire point greater than 300~C and conventional blends of natural and synthetic saturated aliphatic hydrocarbons, such as those disclosed in U.S. Patent No. 4,284,522, having the same molecular weight and fire point. Hydrocarbon oils having an average molecular weight of about 500 to 700 are preferred and saturated aliphatic and naphthenic hydrocarbon oils are the preferred types.
If desired, a blend of saturated aliphatic and aromatic hydrocarbon oils, a blend of natural and synthetic saturated hydrocarbon oils and/or a misture of these two blends can be used as the hydrocarbon oil component.
The amoubt of saturated hydrocarbon oil used is about 20 to about 90, preferably about 60 to about 80 weight ~~, based on the total weight of the electrical insulating fluid.
~ Suitable ester oils of pentaerythritol include conventional ones such as those disclosed in 2 ~ ~8~1 8 U.S. Patent No. 3,894,959. As used herein, the term ~pentaerythritol~ includes pentaerythritol and polypentaerythritols, such as diepentaerythritol, tripentaerythritol, tetrapentaerythritol, 05 pentapentaerythritol, heptapentaerythritol and octapentaerythritol. The amount of ester oil of pentaerythritol used is about lO to about 80, preferably about 20 to about 40 weight %, based on the total weight of the electrical insulating fluid.
A small amount of a conventional antioxidant preferably is included to improve resistance to oxidation during use. Suitable antioxidants include hindered phenols, such as 2, 6-di-tert-butylphenol, 2, 4, 6-tri-tert-butylphenol, and ortho-tert-phenol. When used, the amount of the antioxidant can be up to about 2 weight % and preferably is about 0.2 to about 0.3 weight ~, based on the total weight of the electrical insulating fluid.
The electrical insulating fluid is ; prepared by blending the saturated hydrocarbon oil and the pentaerythritol ester oil, filtering the resulting blend through a suitable adsorbent medium, such as Fuller's earth, to remove impurities and thereby improve the dielectric strength and lower the dissipation factor and then adding an antioxidant, if used.
The electrical insulating fluid of the invention has a high fire point (above 300~C), has a 2~18~18 viscosity which is lower than that of conventional hydrocarbon oils and is less expensive than conventional pentaerythritol ester oils. The lower viscosity enhances the heat transfer 05 characteristics. The low temperature flow properties of the electrical insulating fluid are improved over those of Gonventional hydrocarbon oils which reduces the need for flow modifying additives to inhibit wax crystal formation at lower temperatures.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of the invention and, without departing from the spirit and scope thereof, make various changes and modifications to adapt it to various usages.
Claims (5)
1. An electrical insulating fluid including about 20 to about 90 weight % of a saturated hydrocarbon oil having an average molecular weight greater than 400 and a fire point greater than 300°C;
about 10 to about 80 weight % of an ester oil of pentaerythritol having a fire point greater than 300°C; and 0 to about 2 weight % of an antioxidant.
about 10 to about 80 weight % of an ester oil of pentaerythritol having a fire point greater than 300°C; and 0 to about 2 weight % of an antioxidant.
2. An electrical insulating fluid according to Claim 1 wherein said hydrocarbon oil is a saturated aliphatic hydrocarbon oil.
3. An electrical insulating fluid according to Claim 2 wherein the amount of said hydrocarbon oil is about 60 to about 80 weight %.
4. An electrical insulating fluid according to Claim 3 wherein the amount of said ester oil of pentaerythritol is about 20 to about 40 weight %.
5. An electrical insulating fluid according to Claim 4 wherein the amount of the antioxidant is about 0.2 to about 0.3 weight %.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US36143389A | 1989-06-05 | 1989-06-05 | |
| US361,433 | 1989-06-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2018118A1 CA2018118A1 (en) | 1990-12-05 |
| CA2018118C true CA2018118C (en) | 1999-03-23 |
Family
ID=23422045
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2018118 Expired - Fee Related CA2018118C (en) | 1989-06-05 | 1990-06-01 | Electrical insulating fluid |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2018118C (en) |
-
1990
- 1990-06-01 CA CA 2018118 patent/CA2018118C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2018118A1 (en) | 1990-12-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |