JP2018160484A - Stationary inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transformer having high insulation reliability by a winding structure which relaxes electric field concentration in a wedge-shaped gap formed around a transformer winding and secures cooling of the winding. Is. According to the present invention, an iron core leg 1 and a winding 2 formed by concentrically winding a conductor coated with an insulating paper 21 around the iron core leg, the iron core leg, and the winding. In a static inducer housed in a tank together with a gas or liquid as an insulating and cooling medium, a high-dielectric material-containing member 25 having at least a higher specific dielectric constant than the insulating paper is provided between the adjacent conductors in the winding. It is characterized by that. [Selection diagram] Fig. 7

Description

  The present invention relates to an electric field relaxation structure in a wedge-shaped gap formed around a winding conductor of a static inductor.

  Due to the recent increase in power demand, transformers tend to increase in voltage and capacity. On the other hand, due to population concentration in urban areas, there is an increasing need for transformer miniaturization. One way to reduce the size of the transformer is to shorten the insulation distance. In order to shorten the insulation distance, studies have been made on the contrivance of the insulation structure and the enhancement of the functionality of the insulation material.

  In an insulating structure inside a transformer that uses liquid or gas as an insulation and a liquid medium, generally, a wedge-shaped air gap formed in a contact portion of a solid insulator becomes a weak point in insulation. This is because, in the wedge-shaped gap, the electric field is concentrated on a liquid or gas having a relative dielectric constant smaller than that of the solid insulator.

  In addition, it is a well-known fact that the insulating oil used in the oil-filled transformer is refined, and that dust prevention and foreign matter management are performed at the stage of manufacturing the transformer. However, it is inevitable that fine solid particles are mixed in the oil.

  In the wedge-shaped void, the flow of oil is stagnant compared to the surroundings, so that foreign matter mixed in the insulating oil is likely to stay and settle. Therefore, dielectric breakdown in the transformer often occurs starting from a wedge-shaped gap.

  Patent Document 1 describes a transformer in which a part of an insulator is made of an elastic body and a wedge-shaped gap is embedded to reduce electric field concentration. Patent Document 2 describes a transformer in which a non-linear resistance material is applied or impregnated in a winding coating to reduce electric field concentration in a wedge-shaped gap.

JP-A-6-267661 JP 2013-254771 A

  In Patent Document 1, electric field concentration is alleviated by forming a part of an insulator with an elastic body and embedding a wedge-shaped gap. However, in such a structure, since the whole winding is covered with an elastic body, there is a possibility that the winding cannot be cooled sufficiently. Further, depending on the winding structure, the elastic body may not completely fill the wedge-shaped gap, and may form a further weak point on insulation.

  In Patent Document 2, non-linear resistance material is applied to or impregnated in the winding coating to reduce electric field concentration in the wedge-shaped gap. However, since the non-linear resistance material having an epoxy resin as a base material is applied or impregnated over the entire winding coating, cooling of the winding is hindered. As a result, the temperature around the winding increases, and the deterioration of the insulator is promoted. In addition, in addition to the conventional winding work, an epoxy resin coating or impregnation and curing process is added, which increases the number of work steps and time.

  The present invention has been made in view of the above points, and an object thereof is to alleviate electric field concentration in a wedge-shaped gap formed inside a transformer and to ensure cooling of a winding. Thus, the insulation reliability of the transformer is improved.

  In order to achieve the above object, the present invention provides an iron core leg, a winding formed by concentrically winding a conductor coated with insulating paper on the iron core leg, the iron core leg, and the winding. A high-inductance material-containing member having a dielectric constant higher than that of the insulating paper between the conductors adjacent to each other in the winding in a static inductor housed in a tank together with a gas or a liquid that is an insulating and cooling medium. It is provided.

  According to the transformer of the present invention, the electric field concentration in the wedge-shaped gap formed around the transformer winding can be alleviated, and the dielectric breakdown starting from the wedge-shaped gap can be suppressed. Further, long-term insulation reliability can be ensured by ensuring cooling of the winding and suppressing thermal deterioration of the insulator around the winding.

It is the schematic which shows the structure of an oil-filled transformer. It is the figure which represented typically the connection of the coil | winding in the oil-filled transformer of FIG. It is the figure which showed typically the cross section of the high voltage | pressure winding shown in FIG. It is the figure which showed a part of A-A 'cross section in FIG. FIG. 5 is an enlarged perspective view of a wedge-shaped gap formed between adjacent winding conductors in FIG. 4. It is the figure which expanded the wedge between turns of FIG. 1 is an axial sectional view of a high-voltage winding employed in Example 1. FIG. 1 is a perspective view showing a configuration of a high dielectric material-containing member employed in Example 1. FIG. FIG. 8 is an enlarged perspective view of a wedge-shaped gap formed between adjacent winding conductors in FIG. 7. It is the figure which expanded the wedge between turns in FIG. It is the figure which showed typically the radial direction cross section of the high voltage | pressure winding in Example 2. FIG. It is the figure which showed a part of axial cross section of the coil shown in FIG. It is the perspective view which showed the structure of the high dielectric material containing member 25 comprised by apply | coating or impregnating the high dielectric material in Example 2 around the electrostatic shield.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram showing a configuration of an oil-filled transformer which is an example of a static induction electric machine. In the figure, an iron core 1 and a winding 2 are housed in a tank 3 in which an insulating medium 4 (for example, insulating oil) as an insulating and cooling medium is enclosed.

  FIG. 2 is a diagram schematically showing the connection of the winding 2 in the oil-filled transformer of FIG. In the figure, a low-voltage winding 6 and a high-voltage winding 7 are arranged concentrically around an iron core leg 5. Here, there is a high voltage winding line end 8 of the high voltage winding 7 and a low voltage winding line end 11 of the low voltage winding 6. The high-voltage winding 7 has a structure that is divided into upper and lower portions, and the upper and lower high-voltage windings 7 are connected to a neutral point terminal 9 by a high-voltage winding connection line 10.

  FIG. 3 is a diagram schematically showing a cross section of the high-voltage winding 7 shown in FIG. 2, and shows a cross section perpendicular to the winding axis direction. As shown in the figure, an inner diameter side insulating cylinder 12 having a predetermined axial length and an inner diameter side vertical insulator having a length equivalent to the inner diameter side insulating cylinder 12 and arranged in the circumferential direction. And a spacing piece 14. On the outer periphery of the inner diameter side insulating cylinder 12, the high voltage winding 7 covered with an insulating material is wound a predetermined number of times concentrically around an iron core leg (not shown) to form a disk coil 17. On the outer diameter side of the disk coil 17, an outer diameter side vertical insulator spacing piece 15 is disposed at a position corresponding to the inner diameter side vertical insulator spacing piece 14, and further on the outer diameter side, the outer diameter side insulating cylinder 13 is disposed. Is arranged. Here, on the circumference of the disc coil 17, the disc coil is sandwiched between the horizontal insulator spacing pieces 16 at positions held by the inner diameter side vertical insulator spacing pieces 14 and the outer diameter side vertical insulator spacing pieces 15. A disk winding is constituted by laminating a plurality of 17 in the axial direction. As other winding shapes, a helical winding, a cylindrical winding, and the like are conceivable.

  FIG. 4 is a diagram showing a part of the A-A ′ cross section in FIG. 3, which is one cross section in the winding axis direction. In this figure, the same parts as those in FIG. The high-voltage winding 7 includes a winding conductor 20 and an insulating coating 21 provided around the winding conductor 20. Usually, in an oil-filled transformer, an insulating paper is used as the insulating coating 21 in consideration of cooling of the winding conductor 20. A wedge-shaped gap 22 is formed between adjacent winding conductors 20.

  FIG. 5 is an enlarged perspective view of the wedge-shaped gap 22 formed between the adjacent winding conductors 20 in FIG. In this figure, the same parts as those in FIG. Here, the wedge-shaped gap formed between adjacent winding conductors 20 is an inter-turn wedge 23, and the wedge-shaped gap formed between the winding conductor 20 and the horizontal insulator spacing piece 16 is a coil. It is a wedge 24.

  FIG. 6 is an enlarged view of the inter-turn wedge 23 of FIG. 5, and shows the winding conductor 20 and the equipotential line 30 formed around the inter-turn wedge 23. Usually, insulating paper (relative permittivity of 3.5 in mineral oil) is used for the insulating coating 21, and mineral oil (relative permittivity of 2.2) is used for the surrounding insulating medium 4. As the insulating coating 21, craft paper or aramid paper, which is insulating paper, and other insulating materials such as enamel, varnish, and insulating film can be used. In addition to the mineral oil, silicone oil and SF6 gas can be used as the insulating medium 4. In the vicinity of the inter-turn wedge 23, the equipotential lines 30 are dense because the insulating medium 4 having a relative dielectric constant smaller than that of the solid insulator used for the insulating coating 21 is used. That is, the electric field concentrates in the wedge 23 between turns, and the high electric field portion 31 is formed.

  FIG. 7 is a sectional view in the axial direction of the high-voltage winding employed in the first embodiment, and corresponds to one section of A-A ′ in FIG. 3. In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted. In the winding structure in the present embodiment, for example, a high dielectric material-containing member 25 is wound together with the winding conductor 20.

  FIG. 8 is a perspective view showing the configuration of the high dielectric material-containing member 25 employed in the first embodiment. For example, the high dielectric material 26 is applied or impregnated around the insulating member 27 such as a press board. It is also conceivable that a film sheet containing a high dielectric material is wound around the insulating member 27. Here, the high dielectric material 26 is a material having a dielectric constant higher than that of at least the solid insulator used for the insulating coating 21. As the high dielectric material 26, for example, high dielectric material particles such as zinc oxide, barium oxide, barium titanate, titanium dioxide, silicon carbide or alumina, or a mixture thereof is mixed with a base material. As the base material, for example, an epoxy resin can be considered in consideration of application or impregnation to the insulating member 27. The characteristics of the high dielectric material 26 can be adjusted by adjusting the mixing ratio of the high dielectric material particles to the epoxy resin. In order to prevent the high dielectric material 26 from being peeled off from the insulating member 27 and mixed into the transformer as a foreign substance, an insulating coating 21 is applied around the insulating member 27 and the high dielectric material 26.

  FIG. 9 is an enlarged perspective view of the wedge-shaped gap 22 formed between the adjacent winding conductors 20 in FIG. In this figure, the same parts as those in FIG. A high dielectric material-containing member 25 is inserted between the winding conductors 20.

  FIG. 10 is an enlarged view of the inter-turn wedge 23 in FIG. 9, and shows the adjacent winding conductors 20 and equipotential lines 30 formed around the inter-turn wedge 23. By inserting the high dielectric material-containing member 25 between the winding conductors 20, the equipotential lines around the wedge 23 between turns become sparse. That is, the electric field around the wedge 23 between turns is relaxed. By adopting the present embodiment, the electric field concentration around the wedge-shaped gap 22 formed between the winding conductors 20 can be reduced as compared with the structure of FIG. 6 that does not use the high dielectric material-containing member 25.

  Insulators such as the insulating coating 21 and the insulating medium 4 of the winding conductor 20 are deteriorated by heat. In this embodiment as shown in FIG. 7, the surface area where the winding conductor 20 is in contact with the insulating medium 4 is hardly changed from the conventional transformer structure shown in FIG. A certain degree of cooling of the winding conductor 20 can be ensured. Therefore, in this embodiment, the temperature distribution inside the transformer is about the same as the conventional one, and the deterioration of the insulator is about the conventional one.

  As described above, according to the first embodiment, since the electric field concentration of the wedge-shaped gap 22 formed between the winding conductors 20 is alleviated, the dielectric breakdown starting from the wedge-shaped gap 22 can be suppressed. it can. In addition, in the structure of the present embodiment, it is possible to ensure the same cooling performance as the conventional structure, so that it is possible to suppress deterioration of the insulator due to heat and to provide a device with high insulation reliability. Can do.

  FIG. 11 is a diagram schematically showing a radial section of the high-voltage winding 7 in the second embodiment, and shows a section perpendicular to the winding axis direction. In the figure, an inner diameter side insulating cylinder 12 having a predetermined axial length, and a plurality of inner diameter side vertical insulator spacing pieces 14 having a length equivalent to the inner diameter side insulating cylinder 12 and arranged in the circumferential direction thereof. It has. On the outer periphery of the inner diameter side insulating cylinder 12, the high voltage winding 7 covered with an insulating material and the electrostatic shield 40 for improving the impact voltage characteristics are concentrically formed a predetermined number of times around an iron core leg (not shown). The disk coil 17 is formed by winding. On the outer diameter side of the disk coil 17, an outer diameter side vertical insulator spacing piece 15 is disposed at a position corresponding to the inner diameter side vertical insulator spacing piece 14, and further on the outer diameter side, the outer diameter side insulating cylinder 13 is disposed. Is arranged. Here, on the circumference of the disc coil 17, the disc coil is sandwiched between the horizontal insulator spacing pieces 16 at positions held by the inner diameter side vertical insulator spacing pieces 14 and the outer diameter side vertical insulator spacing pieces 15. A disk winding is constituted by laminating a plurality of 17 in the axial direction.

  FIG. 12 is a view showing a part of the axial cross section of the coil shown in FIG. 11, and particularly an enlarged view of the periphery of the high-voltage winding line end 8. In the figure, there are a high-voltage winding line end 8 and a winding conductor 20, and an insulating coating 21 which is a coating of the winding conductor 20 is provided around the winding conductor 20. When an abnormal voltage enters from the high voltage winding line end 8, the potential distribution in the winding vibrates, and the gradient of the potential becomes transiently large at the high voltage winding line end 8. As a result, a high electric field is generated in the portion. In order to suppress this, the electrostatic shield 40 is inserted between the winding conductors 20.

  FIG. 13 is a perspective view showing a configuration of a high dielectric material-containing member 25 formed by applying or impregnating the periphery of an electrostatic shield with a high dielectric material in the second embodiment. The high dielectric material-containing member 25 is formed by applying or impregnating a material having a relative dielectric constant higher than that of at least the solid insulator used for the insulating coating 21 of the winding conductor 20 around the electrostatic shield 40. It is also conceivable that a film sheet including the high dielectric material 26 is wound around the electrostatic shield 40. As the high dielectric material 26, for example, high dielectric material particles such as zinc oxide, barium oxide, barium titanate, titanium dioxide, silicon carbide or alumina, or a mixture thereof is mixed with a base material. As the base material, for example, an epoxy resin can be considered in consideration of application or impregnation to the electrostatic shield 40. The high dielectric material 26 produced by this method can adjust the characteristics of the high dielectric material 26 by adjusting the mixing ratio of the high dielectric material particles to the epoxy resin. In order to prevent the high dielectric material 26 from being peeled off from the electrostatic shield 40 and entering the transformer as foreign matter, an insulating coating 21 is applied around the electrostatic shield 40 and the high dielectric material 26.

  By adopting this configuration, the electric field concentration in the wedge-shaped gap 22 formed between the winding conductors 20 shown in FIG. 12 can be reduced. In addition, since the structure of the present embodiment can ensure the same cooling performance as that of the conventional structure, it is possible to suppress deterioration of the insulator due to heat. Furthermore, since the electrostatic capacity between turns can be increased by applying the high dielectric material 26 to the electrostatic shield 40, the effect of smoothing the potential distribution at the time of abnormal voltage intrusion can be obtained more than the conventional structure. . From the above, by adopting this embodiment, it is possible to provide a device with high insulation reliability.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. The above-described embodiments are illustrative of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Iron core 2 ... Winding 3 ... Tank 4 ... Insulation medium 5 ... Iron core leg 6 ... Low voltage winding 7 ... High voltage winding 8 ... High voltage winding line end 9 ... Neutral point terminal 10 ... High voltage winding connection line 11 ... Low voltage winding line end 12 ... inner diameter side insulating cylinder 13 ... outer diameter side insulating cylinder 14 ... inner diameter side vertical insulator spacing piece 15 ... outer diameter side vertical insulating spacing piece 16 ... horizontal insulator spacing piece 17 ... disc coil 20 ... Winding conductor 21 ... Insulation coating 22 ... Wedge-shaped gap 23 ... Wedge between turns 24 ... Wedge between coils 25 ... High dielectric material containing member 26 ... High dielectric material 27 ... Insulating member 30 ... Equipotential line 31 ... High electric field part 40 ... Electrostatic shield

Claims (5)

Iron core legs,
A winding formed by concentrically winding a conductor coated with insulating paper on the iron core leg;
In the stationary inductor housed in the tank together with the iron core leg, the winding, and the gas or liquid which is an insulating and cooling medium,
A stationary inductor having a high dielectric material-containing member having at least a relative dielectric constant higher than that of the insulating paper between the conductors adjacent to each other in the winding. The static inductor according to claim 1, wherein
The high dielectric material-containing member is formed by applying or impregnating a member made of an insulator with a high dielectric material having a dielectric constant higher than that of the insulating paper. The stationary inductor according to claim 2,
The high dielectric material-containing member is formed by coating or impregnating a member made of an insulating material with a high dielectric material having a relative dielectric constant higher than that of the insulating paper, and further covering with an insulating material. Stationary inductor. The static inductor according to claim 1, wherein
The high-dielectric material-containing member is coated or impregnated with a high-dielectric material having a relative dielectric constant higher than that of the insulating paper on an electrostatic shield winding that is wound together with the winding to improve shock resistance characteristics. A stationary inductor characterized by being a member. The stationary inductor according to claim 4,
A static induction device characterized in that a member obtained by applying or impregnating a high dielectric material having a dielectric constant higher than that of insulating paper to the electrostatic shield is further covered with an insulating material.

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