JP2019062143A - Oil-filled transformer - Google Patents

Abstract

An object of the present invention is to improve the long-term reliability of an oil filled transformer using an ester oil as an insulating oil by reducing the oxidative deterioration of the ester oil. An oil-filled transformer including an iron core-winding assembly, a tank containing the iron core-winding assembly and having an insulating cooling medium in contact with an air layer, and a lid portion provided on the tank upper portion. The insulating cooling medium is an ester oil, and a sheet carrying an antioxidant is immersed in the ester oil. [Selected figure] Figure 1

Description

  The present invention relates to an oil-filled transformer.

  Conventionally, mineral oil has been widely used as insulating oil for transformers using insulating oil. Rapeseed oil, soybean oil, which is an ester compound produced from fatty acid and glycerin, a trihydric alcohol, which is highly biodegradable as an insulating oil for transformers in place of mineral oil in recent years due to growing interest in environmental issues And the like, or ester oils such as synthetic ester oils synthesized from fatty acids and monohydric or polyhydric alcohols.

  In addition, it has also been studied to operate the transformer at high temperature using a vegetable oil having a higher flash point and a higher combustion point than the mineral oil, or an ester oil produced from a plant-derived material or a synthetic ester oil.

  In large-capacity transformers that use insulating oil, generally, a sealed tank is used, and deaerated insulating oil or insulating oil saturated with an inert gas is used. On the other hand, in medium and small capacity transformers, insulating oil is often used in the state of being in contact with air.

  For this reason, since an insulating oil is easily oxidized and deteriorated by use over time, an antioxidant is usually added to the insulating oil.

  The addition of an antioxidant to a vegetable oil is disclosed in JP-A-2000-502493 (Patent Document 1).

Japanese Patent Publication No. 2000-502493

  The ester oil is more susceptible to oxidative degradation if it is used in contact with air compared to the case of using a sealed tank and using a deesterified ester oil or an ester oil saturated with an inert gas .

  In addition, when the transformer is operated at a high temperature using vegetable oil produced with a high flash point or combustion point compared to mineral oil, or an ester oil produced from a plant-derived material, or a synthetic ester oil, the higher the operating temperature, the more oxidative degradation occurs. To accelerate. Moreover, it is considered that adding a large amount of antioxidant to transformer oil affects the characteristics of the oil, the amount of addition is specified in the standard, and the patent that it is practically difficult to add more than the specified amount. Document 1 is not considered.

  An object of the present invention is to improve the reliability of an oil-filled transformer using an ester oil as an insulating oil by reducing the oxidative deterioration of the ester oil.

If an example of the "oil-filled transformer" of the present invention for solving the above-mentioned subject is mentioned,
What is claimed is: 1. An oil-filled transformer comprising: an iron core-winding assembly; a tank containing the iron core-winding assembly and having an insulating cooling medium in contact with the air layer; The insulating cooling medium is an ester oil, and a sheet carrying an antioxidant is immersed in the ester oil.

Also, to give another example of the oil-filled transformer of the present invention,
A transformer comprising: an iron core-winding assembly; a tank containing the iron core-winding assembly and having an insulating cooling medium in contact with an air layer; and a lid portion provided on the tank upper portion, The insulating cooling medium is an ester oil, and a paint containing an antioxidant is applied to the inner wall of the tank.

  ADVANTAGE OF THE INVENTION According to this invention, the oxidation degradation of the ester oil of a transformer can be reduced by immersing the sheet | seat which carry | supported antioxidant in the ester oil in a transformer tank. And since a large amount of antioxidants can be installed rather than adding to ester oil directly, the effect of oxidation degradation reduction is large, and the operating temperature of a transformer can be made high.

FIG. 2 is a schematic cross-sectional view showing the concept of the oil-impregnated transformer of Example 1; FIG. 8 is a schematic view showing a configuration of an oil-filled transformer of Example 3. FIG. 14 is a schematic view showing a configuration of an oil-filled transformer of Example 4.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings for describing the embodiments, the same components are denoted by the same names and symbols as much as possible, and the repetitive description thereof will be omitted.

  The cross-sectional schematic which shows the concept of the oil-impregnated transformer of Example 1 of this invention in FIG. 1 is shown. The configuration of the oil-filled transformer includes a tank 1, an iron core 2 disposed inside the tank 1, a primary winding 3 and a secondary winding 4 mounted on the iron core 2, and a lid provided at the top of the tank It has five. The iron core 2 and the primary winding 3 and the secondary winding 4 constitute an iron core-winding assembly.

  Inside the tank 1, an ester oil 6 which is an insulating cooling medium for insulating and cooling the iron core 2 and the primary winding 3 and the secondary winding 4, and air existing above the ester oil 6 7 and is housed.

  The ester oil 6 which is an insulating cooling medium accommodated inside the tank 1 is a compound having an ester bond, which is represented by a chemical structural formula such as the following chemical formula 1, chemical formula 2 or chemical formula 3. These may be used alone or in combination. Moreover, it is also possible to add additives, such as an antioxidant and a hydrolysis inhibitor.

  Chemical formula 1 is a general chemical structural formula of vegetable oil, and is a compound in which glycerin and a fatty acid are ester-bonded.

  Chemical formulas 2 to 5 are representative chemical structural formulas of synthetic ester oils, and are compounds in which a polyhydric alcohol and a fatty acid are ester-bonded. Although polyvalent alcohol described the case of pentaerythritol, trimethylolpropane, neopentyl glycol, and dipentaerythritol, respectively, polyalkylene glycol etc. are used as polyvalent alcohol.

Chemical Formula 6 is a compound in which a monohydric alcohol and a fatty acid are ester-bonded.

  In the oil-impregnated transformer of the first embodiment, in order to reduce the oxidative deterioration of the ester oil 6 which is an insulating cooling medium, the sheet 8 supporting the antioxidant in the ester oil is immersed. Although sealed with a lid 5 at the top of the tank, the ester oil 6 is in contact with the air 7 present above. For this reason, it is thought that air dissolves in ester oil and the ester oil is oxidatively degraded. In order to reduce oxidative degradation, an antioxidant may be added directly to the ester oil, but the oxidation degradation reaction of the ester oil is reduced by immersing the sheet 8 carrying the antioxidant in the ester oil. It is possible to further enhance the effect.

  When the transformer is operated at a high temperature using vegetable oil with a high flash point and a high combustion point compared to mineral oil, or ester oil produced from plant-derived materials, or synthetic ester oil, the oxidative degradation accelerates as the operating temperature increases. . Moreover, it is considered that adding a large amount of antioxidant to transformer oil affects the characteristics of the oil, and the amount of addition is specified in the standard, and it is substantially difficult to add it beyond the stipulated amount. By immersing the sheet 8 carrying the antioxidant in ester oil, the effect of reducing the oxidative degradation reaction can be enhanced compared to the case where the antioxidant is directly added to the ester oil.

  As a material of the sheet | seat which carry | supports antioxidant, inorganic insulators, such as glass cloth and a ceramic sheet, can be preferably used other than organic insulators, such as paper, cloth, and a plastic film. By using a fibrous material such as paper, cloth, non-woven fabric, or glass cloth, the surface area, that is, the contact area with the ester oil can be increased, and the antioxidant effect can be further enhanced. Further, the surface area per unit volume can be increased by stacking thin sheets, folding them, rolling them, etc. It is also possible to use an inorganic or organic powder or fiber carrying an antioxidant as a composite material disposed on the surface of a plastic film.

  As a method of supporting the antioxidant on the sheet, a dip method can be preferably used. By dipping a fibrous material such as paper, cloth, non-woven fabric, or glass cloth into a solution prepared by dissolving a predetermined amount of an antioxidant in a solvent and then pulling it out of the solution, a certain amount of the antioxidant is added to these sheets. Can be adsorbed and carried. It is also possible to spray apply a solution of an antioxidant. The sheet material can be continuously immersed in the solution of the antioxidant for a certain period of time and then pulled up, or mass-produced by spraying a solution of the antioxidant for a certain period of time. In the case of supporting on a sheet of non-woven fabric, plastic film or the like, it is also possible to use pellets of raw material compounded with an antioxidant.

  When the lid 5 at the top of the tank is opened, the sheet 8 can be checked from the opening, and the sheet 8 can be disposed at a position where it can be removed. By replacing the sheet, it is possible to improve the long-term reliability of the transformer.

  In the present invention, the term "reliability" is a concept including insulation reliability, safety or stability. Moreover, with insulation reliability, there are a thing with high insulation, it is hard to fall in insulation, etc., for example.

  As an antioxidant, a general phenol type or aromatic amine type compound can be used. For example, in the case of phenols, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-methylphenol and the like can be mentioned. Moreover, you may use the naturally derived antioxidant added to foodstuffs, such as vitamin C (L-ascorbic acid), vitamin E (tocopherol), and catechin. Two or more types of antioxidants may be used in combination. The antioxidant is preferably used in a combination of an antioxidant / sheet which strongly adsorbs on the above-mentioned sheet or the inorganic or organic powder or fiber in the sheet and which is difficult to elute in ester oil. The antioxidant may be chemically bonded to the aforementioned sheet or the inorganic or organic powder or fiber in the sheet.

  Inside the transformer tank, ester oil cools the transformer by convection and circulation. Usually, in the medium and small capacity transformers, cooling fins are provided on the outer wall of the tank for heat dissipation. It is considered that the heat sink of the outer wall of the tank cools the lower ester oil of the transformer core and the heat generated upper part of the coil and flows to the lower side. For this reason, the antioxidant effect can be made higher by arranging the sheet carrying the antioxidant near the inner wall of the tank where there is a flow of ester oil.

  According to this embodiment, it is possible to reduce the oxidative degradation of the ester oil of the transformer by immersing the sheet supporting the antioxidant in the ester oil in the transformer tank. Then, a larger amount of antioxidant can be installed than adding the antioxidant directly to the ester oil, the effect of reducing oxidative degradation is large, and the operating temperature of the transformer can be increased.

  Although the thin sheet of Example 1 can be preferably used to increase the surface area, it can be installed as a structure of various shapes without being limited to the sheet in order to obtain the oxidation preventing effect. The oil-impregnated transformer of the second embodiment carries an antioxidant on a member constituting the transformer. A paint in which an antioxidant is dispersed or dissolved, or a paint in which an inorganic or organic powder or fiber carrying an antioxidant is dispersed can be applied to the inner wall surface of the tank or the surface of the composition. By supporting the antioxidant on the member constituting the transformer, the contact area between the antioxidant and the insulating oil can be increased. Further, the space in the transformer tank can be effectively used, and the cooling by the circulation of the insulating oil in the tank is not hindered, which is preferable from the viewpoint of insulation. Inside the transformer tank, ester oil cools the transformer by convection and circulation. Usually, in the medium and small capacity transformers, cooling fins are provided on the outer wall of the tank for heat dissipation. It is considered that the heat sink of the outer wall of the tank cools the lower ester oil of the transformer core and the heat generated upper part of the coil and flows to the lower side. For this reason, the antioxidant effect can be made higher by applying the antioxidant to the inner wall surface of the tank or the like where there is a flow of ester oil.

  The structure of the oil-impregnated transformer of Example 3 of this invention is shown in FIG. FIG. 2A is a plan sectional view of the inside of the tank 1. Moreover, FIG.2 (b) is the top view seen from the upper part of the modification. In the oil-filled transformer shown in FIG. 2 (a), the sheets 8 carrying the antioxidant are disposed at the four corners of the tank. The arrangement at the four corners of the tank is preferable without interfering with the heat radiation effect of the cooling fins.

  In the modification of FIG. 2B, the sheet 8 is disposed at the corner on the secondary bushing side from the viewpoint of safety and insulation reliability. Since the voltage of the secondary winding is lower than that of the primary winding, insulation reliability and safety can be enhanced by arranging the sheet on the secondary bushing side to which the secondary winding is connected.

  The structure of the oil-impregnated transformer of Example 4 of this invention is shown in FIG. FIG. 3 (a) is a plan sectional view of the inside of the tank 1, and FIG. 3 (b) is a plan view as viewed from above. In the oil-filled transformer shown in FIG. 3, the sheet 8 carrying an antioxidant is disposed at the top of the winding. The upper part is considered to be susceptible to oxidative degradation since the temperature of the ester oil is higher and it is in direct contact with the air 7 present in the upper part. Therefore, in order to enhance the oxidation preventing effect, it can be preferably arranged on the upper part of the winding. Furthermore, as shown in FIG. 3B, the sheet 8 can be preferably disposed on the wall surface of the tank on the secondary bushing side from the viewpoint of safety and insulation reliability.

  The present invention is not limited to the embodiments described above, but includes various modifications. For example, the embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. In addition, with respect to a part of the configuration of each embodiment, it is possible to add, delete, and replace other configurations.

1: Tank 2: Core 3: Primary winding 4: Secondary winding 5: Lid 6: Ester oil 7: Air 8: Sheet carrying an antioxidant 9: Cooling fin 10: Primary bushing 11: Secondary bushing

Claims (14)

What is claimed is: 1. An oil-filled transformer comprising: an iron core-winding assembly; a tank containing the iron core-winding assembly and having an insulating cooling medium in contact with the air layer; ,
The insulating cooling medium is an ester oil,
An oil-impregnated transformer characterized in that a sheet carrying an antioxidant is immersed in the ester oil. In the oil-filled transformer according to claim 1,
An oil-filled transformer characterized in that the ester oil is a vegetable oil, an ester oil produced from a plant-derived raw material or a synthetic ester oil. In the oil-filled transformer according to claim 1,
An oil-impregnated transformer characterized in that the sheet carrying the antioxidant is obtained by immersing the sheet in a solution in which the antioxidant is dissolved. In the oil-filled transformer according to claim 1,
An oil-impregnated transformer characterized in that the sheet carrying the antioxidant is a spray-coated solution of an antioxidant. In the oil-filled transformer according to claim 1,
An oil-filled transformer characterized in that the sheet carrying the antioxidant is a sheet of fibrous material. In the oil-filled transformer according to claim 1,
An oil-impregnated transformer characterized in that the sheet carrying the antioxidant is an inorganic or organic powder or fiber carrying an antioxidant, which is disposed on the surface of a plastic film. In the oil-filled transformer according to claim 1,
An oil-impregnated transformer characterized in that the sheet carrying the anti-oxidant is disposed at a replaceable place from an opening with an open lid at the top of the tank. In the oil-filled transformer according to claim 1,
An oil-filled transformer characterized in that the sheet carrying the antioxidant is disposed at four corners of a tank. In the oil-filled transformer according to claim 1,
An oil-filled transformer characterized in that the sheet carrying the antioxidant is disposed at a corner on the secondary bushing side. In the oil-filled transformer according to claim 1,
An oil-impregnated transformer characterized in that the sheet carrying the antioxidant is disposed at the top of a winding. The oil-filled transformer according to claim 10,
An oil-filled transformer characterized in that the sheet carrying the antioxidant is disposed on a wall surface of a tank on the secondary bushing side. A transformer comprising: an iron core-winding assembly; a tank containing the iron core-winding assembly and having an insulating cooling medium in contact with an air layer; and a lid portion provided on the tank upper portion,
The insulating cooling medium is an ester oil,
An oil filled transformer characterized in that a paint containing an antioxidant is applied to the inner wall of the tank. In the oil-filled transformer according to claim 12,
An oil filled transformer comprising cooling fins on the outer wall of the tank. In a tank having an insulating cooling medium in contact with an air layer, and a transformer provided with a lid on the top of the tank,
The cooling medium is vegetable oil, ester oil produced from plant-derived raw materials, or synthetic ester oil,
A transformer characterized in that a sheet carrying an antioxidant is immersed in the vegetable oil, or an ester oil or synthetic ester oil produced from a plant-derived raw material.

Images