JP7171514B2 - electrical equipment - Google Patents

Description

The present invention relates to electrical equipment.

An oil-filled transformer, which is one type of electrical equipment containing an insulating cooling medium, generally includes an iron core, a coil made of an electric wire attached to the iron core and wrapped with insulating paper, and a coil in the insulating cooling medium in a tank. Windings with insulation for insulation and for configuring cooling passages for the insulating cooling medium are immersed. Conventionally, mineral oil, which has excellent insulating properties, has been widely used as an insulating cooling medium for oil-filled transformers. In recent years, biodegradable vegetable oil has been applied as an insulating cooling medium instead of mineral oil.

Vegetable oil is a compound in which fatty acid and glycerin are ester-bonded, and reacts with water to decompose (hydrolyze) into fatty acid and glycerin. In addition, the fatty acids produced may accelerate the hydrolysis of vegetable oils by catalytic action. Fatty acids include saturated fatty acids in which all the bonds between carbon atoms in the hydrocarbon chain are single bonds, and unsaturated fatty acids in which the carbon bonds in the hydrocarbon chain are unsaturated (double bonds). Bonds may oxidize or polymerize over time.

On the other hand, in the windings of oil-immersed transformers, a large amount of mineral oil and paper made of high-quality wood pulp are used as insulating materials. For example, kraft paper or crepe paper is used as the insulating coating for winding lead wires, various spacers to secure cooling oil passages in the winding, insulators that make up the main insulation, and windings to support the winding. Pressboards made by strongly compressing paper have been used as materials for support insulators arranged above and below wires, insulating cylinders and spacers constituting lead wire barriers, arms for supporting lead wires, and the like.

Ether bonds in cellulose, the main component of insulating paper, are hydrolyzed in the presence of water. In addition, fatty acids produced by the hydrolysis of vegetable oils may accelerate the hydrolysis of kraft paper through catalytic action. When the main chain of cellulose is cut by the hydrolysis reaction, the degree of polymerization of the cellulose molecules is lowered, so it is considered that the tensile strength of the insulating paper is also lowered.

Oil-immersed transformers, which are important components of power distribution, are required to be highly reliable. However, the aging deterioration of insulating materials such as vegetable oil and insulating paper mentioned above is a factor in the aging deterioration of transformers. , is considered to influence the life of the transformer.

The following patent document 1 and patent document 2 are known as techniques for suppressing aged deterioration of transformers. Patent Literature 1 discloses a method for removing moisture from insulating oil by detachably attaching an adsorbent case via a polymer film material on a piping system that circulates insulating oil. Patent Literature 2 discloses adding antioxidants to vegetable oils.

JP 2007-221047 A Japanese Patent Publication No. 2000-502493

As a method for suppressing hydrolysis of vegetable oil as an insulating cooling medium in an oil-filled transformer tank or insulating paper as an insulating material, removing water in vegetable oil can be mentioned as described in Patent Document 1 described above. It is possible to remove the water in the insulating cooling medium by placing an adsorbent such as zeolite or silica that adsorbs water well in the insulating cooling medium. However, since these adsorbents also adsorb compounds other than water, when the adsorbent is placed directly in the insulating cooling medium, it is difficult to sufficiently remove the water in the insulating cooling medium. .

On the other hand, as a method of suppressing the oxidation of the vegetable oil of the insulating cooling medium, there is a method of adding an antioxidant to the vegetable oil, as in Patent Document 2 mentioned above. This is because the added antioxidant captures the radicals generated by the reaction between the vegetable oil and oxygen, thereby suppressing the oxidation due to the chain reaction of the radicals. However, it is not possible to reduce fatty acids contained in vegetable oils or to reduce double bonds contained in unsaturated fatty acid structures.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrical device that suppresses aged deterioration of an insulating material (insulating oil or insulating paper).

An electrical device comprising an insulating oil containing absolute vegetable oil and a boron compound represented by Formula 1 below.

In Formula 1, Z ₁ and Z ₂ are each independently an alkyl group (R ₁ ) or an alkoxy group (OR ₁ ), and R ₁ is an alkyl group, cycloalkyl group, aralkyl group or aryl group.

In addition, a second aspect of the present invention for achieving the above object has an insulating oil containing a vegetable oil and a support that is disposed in the vegetable oil and contains the boron compound represented by Formula 1 described above. An electrical device characterized by:

More specific configurations of the invention are described in the claims.

ADVANTAGE OF THE INVENTION According to this invention, the electrical equipment which suppresses the aged deterioration of an insulating material can be provided.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS The cross-sectional schematic diagram which shows one Embodiment of the oil-filled transformer of this invention.

Hereinafter, the electrical equipment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the electrical equipment of the present invention. In this embodiment, an oil-immersed transformer (hereinafter also simply referred to as a "transformer") will be described as an example of an electrical device. As shown in FIG. 1, the oil-filled transformer 100 includes an iron core 2, windings (inner winding 3 and outer winding 4) attached to the iron core 2, insulating oil 6 filled in a tank 1, have The insulating oil 6 cools the iron core 2, the inner winding 3 and the outer winding 4 provided inside the tank 1 so as to remove Joule heat generated from the iron core 2, the inner winding 3 and the outer winding 4. is functioning

Transformer 100 shown in FIG. 1 includes cooler 8 for cooling insulating oil 6 . Cooling pipes 9a and 9b are provided between the tank 1 and the cooler 8, and the insulating oil 6 contained in the tank 1 passes through the cooling pipe 9a provided in the upper part of the tank 1 and flows into the tank. 1 to the inside of the cooler 8 in the direction indicated by the arrow. The insulating oil cooled by the cooler 8 is sent into the tank 1 again from the cooler 8 through the cooling pipe 9b provided at the bottom of the tank 1 .

The iron core 2 is fastened and held by fasteners 10a and 10b attached to its upper and lower parts, respectively.

The inner winding 3 and the outer winding 4 are accommodated in an insulating cylinder 5, and insulators 11 and 12 are respectively installed on the upper part thereof, and insulators 13 and 14 are respectively installed on the lower part thereof. A cooling oil introduction portion 15 for cooling the iron core 2 is formed on the center side of the iron core 2 . Nitrogen gas 7 is enclosed in the upper portion of the tank 1 .

Next, the configuration of the insulating oil 6 will be described in detail. The insulating oil 6 contains vegetable oil and the boron compound represented by Formula 1 described above. In addition, in this specification, a "boron compound" shall mean the boron compound shown by Formula 1 mentioned above. This boron compound has the effect of suppressing deterioration of vegetable oil.

The vegetable oil is not particularly limited, but for example, rapeseed oil and soybean oil, which are ester compounds produced from fatty acids and trihydric alcohol glycerin, can be used.

Vegetable oil is hydrolyzed in tank 1 to produce glycerin and fatty acids, as shown in Equation A below.

The fatty acid produced by the reaction of formula A has an action of promoting the hydrolysis of vegetable oil (fatty acid catalytic action). Furthermore, fatty acids include saturated fatty acids in which all the carbon-carbon bonds in the hydrocarbon chain are single bonds, and unsaturated fatty acids with unsaturated carbon bonds (double bonds). The double bond of this unsaturated fatty acid may be oxidized or polymerized due to deterioration over time, and as a result, there is a possibility that the function as an insulating oil (insulating performance and cooling performance) may be deteriorated.

Therefore, in the present invention, the deterioration of the insulating oil is suppressed by reacting the fatty acid with the boron compound of formula 1 described above. Specifically, the carboxyl group of the fatty acid and the boron compound of Formula 1 above react with the double bond in the unsaturated fatty acid structure. An example of the reaction when dialkylborane (Z ₁ =R ₁ , Z ₂ =R ₂ ) is used as the boron compound of Formula 1 is shown in Formula B below.

The carboxyl group in the fatty acid produced by the hydrolysis of vegetable oil and the dialkylborane compound react with the double bond in the structure of the unsaturated fatty acid to ) is reduced. As a result, oxidation or polymerization of double bonds in vegetable oil can be suppressed.

The present invention suppresses the hydrolysis reaction of ester bonds in vegetable oil and ether bonds in cellulose, which is the main component of insulating paper, by reducing fatty acids contained in vegetable oil as a result of the reaction shown in formula B above. In addition, by reducing the amount of double bonds in the unsaturated fatty acid structure, the oxidation reaction is suppressed. The reaction mechanism is different. The suppression of oxidation by antioxidants suppresses the reaction between vegetable oil and oxygen, but does not suppress the catalytic action of fatty acids or reduce the double bonds in unsaturated fatty acids.

In the oil-filled transformer of the present invention, the boron compound contained in the insulating oil reduces double bonds and carboxyl groups (acids) in the unsaturated fatty acid, thereby suppressing aging deterioration of the insulating material.

Other deterioration inhibitors (for example, antioxidants, hydrolysis inhibitors, moisture absorbers, etc.) may be added to the insulating oil as long as they do not interfere with the reaction of the boron compound described above.

As the boron compound having the chemical structure shown in Formula 1 above, for example, a dialkylborane compound having the chemical structure shown in Formula 2 below can be used.

In Formula 2, R ₁ and R ₂ are independent of each other and may be different or the same. R ₁ may be an alkyl group or a substituent derived from an alkyl group such as a cycloalkyl group, an aralkyl group or an aryl group. Also, a plurality of these substituents may be included. Furthermore, R ₁ may be a compound having a cyclic structure. Specific examples of dialkylborane compounds include 9-BBN (9-borabicyclononane) and isopinocampheylborane. These boron compounds may be dimers or amine complexes.

Further, as the boron compound, a dialkoxyborane compound having a chemical structure shown in Formula 3 below can be used.

Specific examples of dialkoxyborane compounds include pinacolborane and catecholborane.

Further, alkylalkoxyborane represented by the following formula 4 can be used as the boron compound.

As the boron compound in the insulating oil, at least one compound having the chemical structure represented by Formulas 2 to 4 may be used, and a plurality of compounds may be used in combination. Among the boron compounds represented by formulas 2 to 4, the dialkylborane represented by formula 2 is most preferred because of its high reactivity.

As prior art, Japanese Patent Laid-Open No. 5-186788 discloses fluid automatic transmissions and wet brakes for automatic transmissions and wet brakes containing vegetable oil as a base oil and boric acid (B(OH) ₃ ) as an additive. A fluid for use is disclosed. However, the reaction of Formula B above does not occur with boric acid, because it is a reaction that does not occur unless the boron compound has hydrogen.

The boron compound mentioned above may be added directly to the vegetable oil, or may be placed in the tank 1 as a solid. Specifically, the retainer containing the boron compound described above may be arranged in the tank 1 .

The material for the support containing the boron compound is not particularly limited as long as it is difficult to dissolve in the vegetable oil, but inorganic or organic powders, sheets, fibers and the like can be used. More specifically, in addition to organic insulators such as paper, cloth, and plastic film, inorganic insulators such as glass cloth and ceramic sheets can be used as the holder.

By using a fibrous material such as paper, cloth, non-woven fabric, and glass cloth as the support, the surface area, that is, the contact area with the ester oil can be increased, and the chemical reaction shown in the above formula B can be performed. The effect of reducing aging deterioration of insulating oil can be enhanced.

Also, by stacking, folding, or rolling thin sheets, the surface area per unit volume can be increased. Furthermore, for example, it is possible to form a composite material in which inorganic or organic powders or fibers holding a boron compound having the chemical structure shown in Formula 1 are placed on the surface of a plastic film.

The method for producing a support containing a boron compound is not particularly limited, but it can be produced, for example, by coating a support with a paint in which a boron compound is dissolved or dispersed, or by immersing the support in a paint. Japanese Patent Application Laid-Open No. 2019-62143 discloses a sheet containing an antioxidant, and a support containing a boron compound can be produced in a similar manner. Alternatively, a material in which a boron compound and a support are chemically bonded may be used.

As a place to arrange the holding body, it can be arranged inside the tank 1, the cooler 8, or the cooling pipes 9a, 9b. Among these, it is preferable to dispose inside the cooling pipe 9b at the bottom of the tank. It is believed that the hydrolysis reaction of the vegetable oil of Formula A is more likely to occur at the top of the tank where the temperature is higher. In contrast, the reaction of formula B occurs even under mild conditions such as room temperature. For this reason, after the temperature of the fatty acid produced by hydrolysis is lowered in the cooler, before returning to the inside of the tank 1 again through the cooling pipe 9b, the reaction of the above formula B causes the two in the unsaturated fatty acid It is preferred to reduce the double bond and the carboxyl group (carboxylic acid) of the fatty acid.

The support containing the boron compound having the chemical structure shown in Formula 1 can also be replaced periodically. Also, if the boron compound is added directly to the vegetable oil, it can be replenished periodically.

As described above, according to the present invention, it was shown that it is possible to provide an oil-filled transformer that suppresses aged deterioration of the insulating material that constitutes the oil-filled transformer.

In addition, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the described configurations. Moreover, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

In the above-described embodiments, an oil-filled transformer is used as an electrical device, but the insulating oil that constitutes the electrical device of the present invention is not limited to the oil-filled transformer, and other electrical devices containing vegetable oil, such as capacitors, etc. It can also be applied to other electrical equipment. Moreover, the insulating oil constituting the electric device of the present invention described above may contain oils other than vegetable oils, such as synthetic ester oils and mineral oils. Furthermore, the insulating oil constituting the electrical equipment of the present invention described above can also be used for applications other than electrical equipment, such as lubricating oil, hydraulic oil, heat transfer fluid, and cooling oil.

DESCRIPTION OF SYMBOLS 1... Tank, 2... Iron core, 3... Inner coil, 4... Outer coil, 5... Insulating tube, 6... Insulating oil, 7... Nitrogen gas, 8... Cooler, 9a, 9b... Cooling pipe, 10a, 10b ... Fasteners, 11, 12, 13, 14 ... Insulators, 15 ... Oil introduction part, 100 ... Oil-filled transformer.

Claims (5)

An electrical device comprising insulating oil containing vegetable oil and a boron compound represented by Formula 1 below.

In Formula 1, Z ₁ and Z ₂ are each independently an alkyl group (R ₁ ) or an alkoxy group (OR ₁ ), and said R ₁ is an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group. . 1. An electrical device comprising an insulating oil containing a vegetable oil and a support disposed in the vegetable oil and containing a boron compound represented by the following formula 1.

In Formula 1, Z ₁ and Z ₂ are each independently an alkyl group (R ₁ ) or an alkoxy group (OR ₁ ), and said R ₁ is an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group. . The electric device includes an iron core, a winding attached to the iron core, a tank for accommodating the iron core and the winding, the insulating oil filled in the tank, and a cooling oil for cooling the insulating oil. an oil-filled transformer having a cooler of
3. The container according to claim 2, wherein a holder containing the boron compound represented by the formula 1 is arranged inside the tank, the cooler, or a pipe connecting the tank and the cooler. electrical equipment. 4. The electrical equipment according to claim 2, wherein said boron compound is contained in a holder made of inorganic compound or organic compound powder, sheet or fiber. 5. The electrical equipment according to claim 1, wherein said boron compound is dialkylborane, dialkoxyborane or alkylalkoxyborane.

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