JP2013235923A - Electrostatic plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency of a transformer by reducing an eddy current loss.SOLUTION: The electrostatic plate comprises: an insulation substrate having an annular shape similar to a shape of an opposed face of a coil; a conductive section 120 provided on a surface of the insulation substrate; and an insulation section 10 for making the conductive section 120 discontinuous in a circumferential direction on the surface of the insulation substrate. Also, it comprises: a short-circuit plate 130 arranged on the conductive section 120; and first insulation papers 150 wound around the insulation substrate from above of the conductive section 120 to cover the insulation section 10. Furthermore, it comprises: belt-like metal foils 160 wound around the insulation substrate from above of the first insulation papers 150, and connected to the short-circuit plate 130 on one end; and belt-like second insulation papers 170 wound around the insulation substrate from above of the first insulation papers 150 so that it is overlaid on the metal foils 160 while it is displaced from the metal foils in a width direction of the metal foils 160, and making the wound metal foils 160 discontinuous in the circumferential direction of the insulation substrate.

Description

  The present invention relates to an electrostatic plate, and more particularly, to an electrostatic plate used for suppressing potential vibration of a winding of a transformer.

  The transformer has the same planar shape as the winding for the purpose of equalizing the electric field in order to suppress the occurrence of potential oscillation of the winding of the transformer and local high electric field when a lightning surge enters. An electrostatic plate, which is a plate electrode, is installed in the winding group.

  Japanese Laid-Open Utility Model Publication No. 61-151318 (Patent Document 1) is a prior art document that discloses a high-voltage transformer having a shield plate for preventing intrusion having a configuration similar to that of an electrostatic plate. In the high-voltage transformer described in Patent Document 1, the shield plate includes an annular plate member having a gap, a shield piece that is integrally extended and formed on the annular plate member, and covers the gap by being bent, and between the gap and the shield piece. And an insulating member interposed therebetween.

Japanese Utility Model Publication No. 61-151318

  When a current flows through the winding, magnetic flux generated around the winding enters the electrostatic plate located opposite the winding. When the shield piece is bent and the gap is covered like the shield plate, an eddy current is generated around the entire surface of the shield piece by the magnetic flux entering the shield piece. In this case, the eddy current loss increases and the efficiency of the transformer decreases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic plate that can reduce eddy current loss and improve the efficiency of a transformer.

  The electrostatic plate based on this invention is an electrostatic plate arrange | positioned so that it may oppose adjacent to the coil | winding of a transformer. The electrostatic plate has an insulating substrate having an annular shape equivalent to the shape of the opposing surface of the winding, a conductive portion provided on the surface of the insulating substrate, and a circulating current flows in the circumferential direction of the insulating substrate. In order to avoid this, an insulating portion is provided that makes the conductive portion discontinuous in the circumferential direction on the surface of the insulating substrate. The electrostatic plate includes a short-circuit plate disposed on the conductive portion and first insulating paper wound around the insulating substrate from above the conductive portion so as to cover the insulating portion. Further, the electrostatic plate is wound on the insulating substrate from the top of the first insulating paper, and the strip-shaped metal foil whose one end is connected to the short-circuit plate is overlapped with the metal foil and the metal foil in the width direction. A belt-shaped second insulating paper is provided which is wound around the insulating substrate from above the first insulating paper and makes the wound metal foils discontinuous in the circumferential direction of the insulating substrate.

  According to the present invention, it is possible to reduce the eddy current loss and improve the efficiency of the transformer.

It is a top view which shows the structure of the electrostatic plate which concerns on one Embodiment of this invention. It is sectional drawing seen from the II-II line arrow direction of FIG. It is a top view which shows the structure of the electrostatic plate before 1st insulating paper is wound. It is a top view which shows the structure of the electrostatic plate of the state in which the 1st insulating paper was wound. It is a top view which shows the state which piles up metal foil and 2nd insulating paper on the 1st insulating paper, and is wound around the insulating board | substrate. It is sectional drawing which shows the metal foil pinched | interposed into the 3rd insulating paper.

  Hereinafter, an electrostatic plate according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

  FIG. 1 is a plan view showing a configuration of an electrostatic plate according to an embodiment of the present invention. FIG. 2 is a cross-sectional view as seen from the direction of arrows II-II in FIG. FIG. 3 is a plan view showing a configuration of the electrostatic plate before the first insulating paper is wound. FIG. 4 is a plan view showing the configuration of the electrostatic plate in a state where the first insulating paper is wound. FIG. 5 is a plan view showing a state in which the metal foil and the second insulating paper are overlapped on the first insulating paper and wound around the insulating substrate.

  The electrostatic plate which concerns on this embodiment is an electrostatic plate arrange | positioned so that it may oppose adjacent to the coil | winding of a transformer. Specifically, the electrostatic plate is disposed so as to face and oppose the winding located at the end or the winding connected to the current drawing tap in the winding group in the transformer. .

  As shown in FIGS. 1-5, the electrostatic plate 100 has the insulating board | substrate 110 which has the cyclic | annular shape equivalent to the shape of the surface where a coil | winding opposes. In the present embodiment, a press board is used as the material of the insulating substrate 110. However, the material of the insulating substrate 110 is not limited to a press board, and may be an insulating resin such as polypropylene.

  A conductive part is provided on the surface of the insulating substrate 110 by applying a conductive paint. In the present embodiment, the conductive portion 120 is provided on both the front and back surfaces of the insulating substrate 110. However, the conductive paint is not applied to a part of the insulating substrate 110, so that the conductive portion 120 is not continuous in the circumferential direction of the insulating substrate 110. A portion where the conductive paint is not applied is the insulating portion 10.

  The insulating unit 10 has a function of making the conductive unit 120 discontinuous in the circumferential direction on the surface of the insulating substrate 110 and preventing a circulating current from flowing in the circumferential direction of the insulating substrate 110.

  In order to suppress the potential oscillation generated in the winding when the lightning surge enters by the electrostatic plate 100, the potential of the electrostatic plate 100 and the potential of the winding adjacent to the electrostatic plate 100 when the lightning surge enters. Need to be at the same potential.

  As the electrical resistivity of the conductive portion 120 increases, the potential followability of the electrostatic plate 100 decreases. If the potential followability of the electrostatic plate 100 is low, the function of the electrostatic plate 100 that suppresses potential vibration may not be sufficiently exhibited.

  Therefore, the surface resistivity of the conductive part 120 is preferably in the range of 10Ω / □ or more and 1000Ω / □ or less. More preferably, the surface resistivity of the conductive portion 120 is in the range of 10Ω / □ to 50Ω / □. The surface resistivity (Ω / □) is an eigenvalue that does not depend on the measurement method, and the surface resistivity is a value after drying the conductive paint.

  As the conductive paint, a paint having a low viscosity so that the surface resistivity can be obtained and can be uniformly applied to the insulating substrate 110 is preferable. The viscosity of the conductive paint is preferably in the range of 1 Pa · s to 100 Pa · s at room temperature.

  In the conductive paint, it is preferable to contain spherulitic carbon, a resin varnish, and a curing agent as materials. Further, the conductive paint may contain a known additive.

  The average particle size of the spherulitic carbon is preferably in the range of 5 μm to 50 μm. By including the spherulitic carbon having this average particle diameter in the conductive paint, the increase in the viscosity of the conductive paint due to the addition of a conductive substance such as carbon is suppressed, and the surface resistivity of the conductive portion 120 is lowered. be able to. In addition, said average particle diameter is the value calculated | required from the maximum value of the scattering angle in the scattering image measured by the orthogonal Nicol method using the light-scattering measuring apparatus.

  The content of spherulitic carbon in the conductive coating is preferably in the range of 50% by mass to 70% by mass. By making the content rate of the spherulitic carbon in the conductive paint within the above range, the viscosity of the conductive paint and the surface resistivity of the conductive portion 120 can be improved in a balanced manner.

  Specifically, for example, as a main component of the conductive paint, 60% by mass to 65% by mass of spherulitic carbon, 20% by mass to 25% by mass of a polyester resin varnish, and 5% by mass to 10% by mass. % Xylene, 5% by mass or more and 10% by mass or less ethylbenzene and 1% by mass or more and 5% by mass or less acetic acid-n-butyl acetate are adjusted so as to be 100% by mass in total. A conductive paint can be prepared by mixing a 100% by mass polyisocyanate solution as a curing agent with these main components so that the volume ratio is 4: 1.

  The conductive paint can be diluted with an organic solvent such as thinner when applied. When diluted and used, the carbon content in the diluted conductive paint is preferably in the range of 12% by mass to 13% by mass. The viscosity of the diluted conductive paint is preferably in the range of 0.4 Pa · s to 40 Pa · s at room temperature.

  Specifically, for example, as a diluent, 20% by mass to 30% by mass isobutyl acetate, 5% by mass to 10% by mass aromatic hydrocarbon mixed solvent, and 40% by mass to 50% by mass. Xylene and 10% by mass or more and 20% by mass or less of propylene glycol monomethyl ether acetate are adjusted so as to be 100% by mass in total. The dilution rate is about 25%.

  The content of spherulitic carbon in the conductive part 120 formed by drying the conductive paint diluted and applied as described above is preferably in the range of 60% by mass to 70% by mass. More preferably, the content of spherulitic carbon is about 65% by mass. In this case, good surface resistivity can be obtained in the conductive portion 120.

  The short-circuit plate 130 is disposed on the conductive part 120 formed as described above. The short-circuit plate 130 is provided along the edge of the electrostatic plate 100 and is connected to the line end portion 140. As a result, the potentials of the conductive portion 120 and the short-circuit plate 130 are fixed to the potential of the line end portion 140. The short-circuit plate 130 is made of a metal foil or the like and is fastened and fixed while being in contact with the conductive portion 120. The electrical resistivity of the short-circuit plate 130 is considerably lower than the electrical resistivity of the conductive part 120.

  As shown in FIG. 3, in the electrostatic plate 100 according to the present embodiment, the insulating portion 10 is formed at a position substantially opposite to the line end portion 140 in the circumferential direction of the insulating substrate 110.

  In the present embodiment, a part of the short-circuit plate 130 is continuously arranged from the line end portion 140 to the insulating portion 10 in one direction in the circumferential direction of the insulating substrate 110. The remaining portion of the short-circuit plate 130 is continuously arranged from the line end portion 140 to the insulating portion 10 in the other direction opposite to the one direction. And a part of short circuit board 130 and the remainder are arranged substantially symmetrically.

  According to the above configuration, since the surge impedance is substantially equal between a part of the short-circuit plate 130 and the remaining portion of the short-circuit plate 130 between the line end 140 and the insulating portion 10, the line end 140 is steep. Even when a surge enters, the voltage generated at both ends of the insulating portion 10 can be reduced.

  The electrostatic plate 100 is used by being immersed in insulating oil in the transformer. The electric field tends to concentrate on the corners of the end portions of the conductive portions 120 that sandwich the insulating portion 10 shown in FIG.

  Therefore, in the electrostatic plate 100 according to the present embodiment, in order to prevent the electric field from concentrating on the corner portion of the end portion of the conductive portion 120, as shown in FIG. A first insulating paper 150 is wound on the insulating substrate 110 from above 120.

  In the present embodiment, the first insulating paper 150 is provided with a cut portion 151 for preventing the first insulating paper 150 from riding on the short-circuit plate 130. The first insulating paper 150 is kraft paper. However, the material of the first insulating paper 150 is not limited to kraft paper, and may be other insulating paper.

  In the electrostatic plate 100, as shown in FIG. 5, a strip-shaped metal foil 160 is spirally wound around the insulating substrate 110 from the first insulating paper 150. As shown in FIG. 2, one end of the metal foil 160 is connected to the end of the short-circuit plate 130 by solder 180. The metal foil 160 is fixed to the potential of the line end 140 by being connected to the short-circuit plate 130.

  The metal foil 160 and the second insulating paper 170 are wound around the insulating substrate 110 together in a state of being slightly shifted and overlapped with each other in the width direction. The connection between the metal foil 160 and the short-circuit plate 130 by the solder 180 may be performed before or after the short-circuit plate 130 is provided on the conductive portion 120.

  In this embodiment, the metal foil 160 contains nickel silver. Nickel silver is excellent in flexibility, bending workability and corrosion resistance, and has good adhesion to the solder 180. Therefore, the nickel silver can be easily wound around the insulating substrate 110 and easily connected to the short-circuit plate 130, and is suitable as a material for the metal foil 160. . However, the main material of the metal foil 160 is not limited to nickel silver but may be other metals.

  Further, a strip-shaped second insulating paper 170 is spirally wound around the insulating substrate 110 from above the first insulating paper 150 so that the metal foil 160 and the metal foil 160 overlap in the width direction. The second insulating paper 170 makes the wound metal foils 160 discontinuous in the circumferential direction of the insulating substrate 110.

  In the present embodiment, the second insulating paper 170 is crepe paper. Since the crepe paper has elasticity, it can be easily wound around the insulating substrate 110 and is suitable as a material for the second insulating paper 170. However, the material of the second insulating paper 170 is not limited to crepe paper, and other insulating paper may be used.

  As described above, by winding the first insulating paper 150, the metal foil 160, and the second insulating paper 170 around the insulating substrate 110, the electric field generated at the corner of the end portion of the conductive portion 120 is changed to the thickness of the first insulating paper 150. Can act in the direction. Since the first insulating paper 150 exhibits high insulation performance with respect to the electric field acting in the thickness direction, the insulation performance of the insulating portion 10 of the electrostatic plate 100 can be significantly improved.

  Further, since the wound metal foils 160 are discontinuous in the circumferential direction of the insulating substrate 110, the orbit of the eddy current generated by the magnetic flux generated around the windings entering the metal foil 160. Can be reduced to reduce eddy current loss. As a result, the efficiency of the transformer including the electrostatic plate 100 can be improved.

  In the present embodiment, the electrostatic plate 100 includes the third insulating paper 190 that sandwiches the end portion of the metal foil 160 located on the outermost side in the circumferential direction of the insulating substrate 110 among the wound metal foil 160. It has more.

  FIG. 6 is a cross-sectional view showing a metal foil sandwiched between third insulating papers. In FIG. 6, only the metal foil 160, the second insulating paper 170, and the third insulating paper 190 are illustrated.

  Since the end portion of the outermost metal foil 160 not sandwiched between the second insulating papers 170 becomes an edge portion and the electric field tends to concentrate, as shown in FIG. By sandwiching the end portion with the third insulating paper 190, the concentration of the electric field can be reduced. As a result, the insulating performance in the vicinity of the insulating portion 10 of the electrostatic plate 100 can be further improved. In the present embodiment, the third insulating paper 190 is craft paper bent into a V shape. However, the material of the third insulating paper 190 is not limited to kraft paper, and may be other insulating paper.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It does not become a basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Further, all modifications within the meaning and scope equivalent to the scope of the claims are included.

  DESCRIPTION OF SYMBOLS 10 Insulating part, 100 Electrostatic board, 110 Insulating substrate, 120 Conductive part, 130 Short circuit board, 140 Line end part, 150 1st insulating paper, 151 Notch | cutting part, 160 Metal foil, 170 2nd insulating paper, 180 Solder 190 Third insulating paper.

Claims (4)

An electrostatic plate disposed adjacent to and facing the winding of the transformer,
An insulating substrate having an annular shape equivalent to the shape of the opposing surface of the winding;
A conductive portion provided on the surface of the insulating substrate;
In order to prevent circulating current from flowing in the circumferential direction of the insulating substrate, an insulating portion that makes the conductive portion discontinuous in the circumferential direction on the surface of the insulating substrate;
A short-circuit plate disposed on the conductive portion;
A first insulating paper wound on the insulating substrate from above the conductive portion so as to cover the insulating portion;
A strip-shaped metal foil wound around the insulating substrate from above the first insulating paper and having one end connected to the short-circuit plate;
The metal foil is wound around the insulating substrate from above the first insulating paper so as to overlap and overlap in the width direction of the metal foil, and the wound metal foils are wound in the circumferential direction of the insulating substrate. An electrostatic plate comprising a discontinuous strip-shaped second insulating paper.   2. The electrostatic plate according to claim 1, further comprising a third insulating paper sandwiching an end portion of the metal foil positioned on the outermost side in the circumferential direction of the insulating substrate among the wound metal foil.   The electrostatic plate according to claim 1, wherein the metal foil includes nickel silver.   The electrostatic plate according to claim 1, wherein the second insulating paper is crepe paper.

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