JP2012134285A - Electrostatic board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress voltage applied to an insulation even when a surge intrudes externally into a line end.SOLUTION: An electrostatic board comprises an insulating base having a peripheral shape equivalent to the shape of the facing surface of a line end winding, a metal foil 220 provided on the surface of the insulating base, a line end 250 connected with a part of the metal foil 220 and the line end winding, and an insulation 260 which makes the metal foil 220 discontinuous in the circumferential direction on the surface of the insulating base so that a cyclic current does not flow in the circumferential direction of the insulating base. The insulation 260 is formed at a position on the reverse side of the line end 250 in the circumferential direction.

Description

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

  In order to suppress potential vibration of adjacent windings, conventional transformer electrostatic plates form electrodes by winding a metal foil around an insulating substrate, or by applying a conductive material to an insulating substrate. A surface is formed.

  When forming an electrode by winding a metal foil, in order to suppress eddy current loss due to magnetic flux entering the electrostatic plate, the electrode is configured by winding a strip-shaped metal foil around an insulating substrate. In this case, the impedance of the metal foil is increased, and the potential tracking of the metal foil with respect to the surge voltage is delayed. Therefore, in order to improve the potential followability of the entire electrostatic plate, a short-circuit copper plate is connected around the metal foil. By connecting the short-circuited copper plate to the line end of the adjacent winding, the potential of the electrostatic plate is fixed to the line end potential.

  On the other hand, when an electrode is formed by applying a conductive material, eddy current loss is suppressed because of the high resistance of the conductive material, but the surge of the entire electrostatic plate is suppressed due to the high resistance of the conductive material. As a countermeasure against this, the potential follow-up is slow, and a short-circuit copper plate is provided as a countermeasure to fix the potential of the entire electrostatic plate at the line end potential.

  Since the entire electrostatic plate is placed in the magnetic field created by the windings, if the entire electrostatic plate is short-circuited continuously by metal foil, conductive material or short-circuited copper plate, a large circulation is generated by the magnetic flux entering the electrostatic plate. Current flows and the electrostatic plate is damaged by heat generation. In order to prevent this, the electrostatic plate is provided with an insulating portion in order to prevent a short circuit from being formed on the entire electrostatic plate by a metal foil, a conductive material, or a short-circuited copper plate.

  As a prior document disclosing the electrostatic plate provided with the insulating portion, there is Patent Document 1. In the electrostatic plate described in Patent Document 1, the insulating portion is provided in a portion surrounded by an iron core, which is a position with high work stability.

JP 2010-92915 A

  In general, the above insulating portion generates only a potential corresponding to one turn of the coil due to the magnetic flux entering the electrostatic plate. Therefore, it is sufficient that the insulating portion is formed of a thin insulating layer. There is no significant difference in the voltage applied to the insulating portion depending on the position.

  However, when the insulating portion is provided in the portion surrounded by the iron core as described above, the inventors have an order of magnitude greater than the voltage normally applied to the insulating portion when a steep surge enters the line end from the outside. We have found that high voltages of the order are generated. This is because the distance from the insulation part to the line end is greatly different between one direction in the circumferential direction of the electrostatic plate and the other direction that is opposite to the one direction. This is thought to be due to the difference in surge voltage generated in both directions when entering. As described above, when a high surge voltage is applied to the insulating portion, the generated voltage of the insulating portion becomes high, and the insulating portion may be damaged.

  The present invention has been made in view of the above problems, and provides an electrostatic plate capable of suppressing a voltage applied to an insulating portion even when a surge enters the line end from the outside. Objective.

  The electrostatic plate based on this invention is an electrostatic plate arrange | positioned so that it may oppose adjacent to the line | wire end winding of a transformer. The electrostatic plate includes an insulating base having a circumferential shape equivalent to the shape of the opposing surface of the line end winding, a conductive portion provided on the surface of the insulating base, a part of the conductive portion, and the line end. In order to prevent circulating current from flowing in the circumferential direction of the insulating substrate, the line end connected to the winding, and an insulating portion that makes the conductive portion discontinuous in the circumferential direction on the surface of the insulating substrate . The insulating part is formed at a position opposite to the line end in the circumferential direction.

  According to the present invention, the voltage applied to the insulating portion can be suppressed even when a surge enters the line end from the outside in the electrostatic plate.

It is sectional drawing which shows the structure of the external iron type | mold transformer provided with the electrostatic plate which concerns on Embodiment 1 of this invention. It is a perspective view which shows the external appearance of the metal foil wound around the electrostatic plate which concerns on the same embodiment, and insulating paper. It is sectional drawing which shows the structure of the insulation part of the electrostatic plate which concerns on the same embodiment. It is the figure seen from the IV-IV line arrow direction of the electrostatic plate shown in FIG. It is a top view which shows the positional relationship of the track | line end part and insulation part in the electrostatic plate which concerns on the same embodiment. It is a top view which shows the positional relationship of the track | line end part and insulating part in the electrostatic plate which concerns on Embodiment 2 of this invention.

  Hereinafter, an electrostatic plate according to Embodiment 1 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.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing a configuration of a shell-type transformer including an electrostatic plate according to Embodiment 1 of the present invention. FIG. 2 is a perspective view showing the appearance of the metal foil and insulating paper wound around the electrostatic plate according to the present embodiment. FIG. 3 is a cross-sectional view showing the configuration of the insulating portion of the electrostatic plate according to the present embodiment. 4 is a view of the electrostatic plate shown in FIG. 3 as viewed from the direction of arrows IV-IV.

  As shown in FIG. 1, the outer iron type transformer 1 including the electrostatic plate 200 according to the first embodiment of the present invention includes an iron core 100 on which magnetic steel plates are laminated, and a winding wound around the iron core 100. The electrostatic plate 200 is disposed so as to be opposed to the line end winding. In FIG. 1, the winding does not appear because the winding is disposed on the depth direction side of the electrostatic plate 200.

  As shown in FIGS. 1 to 4, the electrostatic plate 200 includes an insulating substrate 210 having a circumferential shape equivalent to the shape of the surface of the line end winding facing the electrostatic plate 200. A band-shaped insulating paper 230 is wound around the surface of the insulating base 210 in a state where the band-shaped insulating paper 230 is partly shifted and overlapped on a band-shaped metal foil 220 which is a conductive portion. The metal foils 220 are wound and insulated from each other on the main surface of the insulating base 210 so that the metal foils 220 wound adjacently do not come into contact with each other.

  As shown in FIG. 3, the insulating portion 260 is provided at a winding end position before winding about one turn when the metal foil 220 and the insulating paper 230 are wound on the insulating base 210 in the circumferential direction indicated by the arrow 280. It is done. In the insulating part 260, the metal foil 220 and the insulating paper 230 at the other end of winding are wound on the metal foil 220 and the insulating paper 230 at one end on the winding start side via the insulating paper 270 as an insulating member. Thus, the metal foils 220 on the winding start side and the winding end side are insulated by the insulating portion 260. As a result, the metal foil 220 can be discontinuous in the circumferential direction of the insulating substrate 210 on the surface of the insulating substrate 210, so that no circulating current flows in the circumferential direction of the insulating substrate 210.

  A part of the metal foil 220 is connected to a line end portion 250 formed of a conductive wire, and is connected to the line end winding via this. The short-circuit plate 240 has a function of reducing the surge impedance of the metal foil 220 and suppressing the surge voltage generated in the insulating portion when the surge voltage enters. When the short-circuit plate 240 is provided, the surge impedance between the line end portion 250 and the insulating portion 260 is dominated by the surge impedance of the short-circuit plate 240.

  In the present embodiment, the electrostatic plate 200 includes a short-circuit plate 240 disposed on the metal foil 220. The short-circuit plate 240 is provided along the edge of the electrostatic plate 200 and is connected to the line end portion 250. As a result, the potentials of the metal foil 220 and the short-circuit plate 240 are fixed to the potential of the line end 250. The short-circuit plate 240 is made of a metal foil or the like and is fastened and fixed while being in contact with the metal foil 220.

  FIG. 5 is a plan view showing the positional relationship between the line end portion and the insulating portion in the electrostatic plate according to the present embodiment. As shown in FIG. 5, in the electrostatic plate 200 of this embodiment, the insulating portion 260 is formed at a position opposite to the line end portion 250 in the circumferential direction of the insulating base 210.

  In the present embodiment, a part of the short-circuit plate 240 is continuously arranged from the line end portion 250 to the insulating portion 260 in one direction in the circumferential direction of the insulating base 210. The remaining portion of the short-circuit plate 240 is continuously arranged from the line end portion 250 to the insulating portion 260 in another direction opposite to the one direction. And a part of short circuit board 240 and the remainder are arranged almost symmetrically. In FIG. 5, the length of a portion corresponding to a part of the short-circuit plate 240 is indicated by an arrow 290, and the length of a portion corresponding to the remaining portion of the short-circuit plate 240 is indicated by an arrow 291.

  According to the above configuration, the surge impedances of the portion of the short-circuit plate 240 indicated by the arrow 290 and the portion of the short-circuit plate 240 indicated by the arrow 291 between the line end portion 250 and the insulating portion 260 are substantially equal. Even when a steep surge enters the portion 250, the voltage V generated at both ends of the insulating portion 260 can be reduced.

  With the reduced voltage V, the insulation of the insulating paper 270 disposed in the insulating portion 260 is not damaged by the surge voltage. Therefore, even when a surge enters from the line end portion 250, it is possible to prevent the insulating portion 260 from being damaged.

  In addition, although the short circuit board 240 was provided in this embodiment, the short circuit board 240 does not necessarily need to be provided. Even when the short-circuit plate 240 is not provided, the above effect can be obtained by making the surge impedance in the metal foil 220 substantially equal on one side and the other side in the circumferential direction of the insulating substrate 210.

Hereinafter, an electrostatic plate according to Embodiment 2 of the present invention will be described.
(Embodiment 2)
Since the electrostatic plate 300 according to the present embodiment is different only in that the conductive portion is formed by applying a conductive material instead of a metal foil, and the short-circuit plate is provided in the central portion of the electrostatic plate. The description of other configurations will not be repeated.

  FIG. 6 is a plan view showing the positional relationship between the line end portion and the insulating portion in the electrostatic plate according to the second embodiment of the present invention. As shown in FIG. 6, in the electrostatic plate 300 of the present embodiment, the conductive portion 320 is formed by applying a conductive material to the surface of the insulating substrate. The insulating part 360 is provided by not partially applying a conductive material.

  Specifically, as the conductive material, 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 of xylene are used as the main agent. And 5% by mass to 10% by mass of ethylbenzene and 1% by mass to 5% by mass of n-butyl acetate are adjusted so as to be 100% by mass in total, and 100% by mass of polyisocyanate solution is used as a curing agent. May be mixed so that these volume ratios are 4: 1. At the time of application, the conductive paint is, for example, 20% by mass to 30% by mass isobutyl acetate, 5% by mass to 10% by mass aromatic hydrocarbon-based mixed solvent, 40% by mass to 50% by mass xylene, It is diluted to a dilution rate of about 25% using a known diluent such as thinner composed of 10% by mass to 20% by mass of propylene glycol monomethyl ether acetate. The diluted conductive coating is applied and dried by a known method to form a conductive layer.

  A part of the short-circuit plate 340 is continuously arranged from the line end portion 350 to the insulating portion 360 in one direction in the circumferential direction of the insulating base. The remaining portion of the short-circuit plate 340 is continuously arranged from the line end portion 350 to the insulating portion 360 in another direction opposite to the one direction. And a part of short circuit board 340 and the remainder are arranged substantially symmetrically. In FIG. 6, the length of a portion corresponding to a part of the short-circuit plate 340 is indicated by an arrow 390, and the length of a portion corresponding to the remaining portion of the short-circuit plate 340 is indicated by an arrow 391.

  According to the above configuration, the surge impedance is substantially equal between the short-circuit plate 340 at the portion indicated by the arrow 390 and the short-circuit plate 340 at the portion indicated by the arrow 391 between the line end portion 350 and the insulating portion 360. Even when a steep surge enters the portion 350, the voltage V ′ generated at both ends of the insulating portion 360 can be reduced.

  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 1 Outer iron type transformer, 100 Iron core, 200,300 Electrostatic board, 210 Insulating base, 220 Metal foil, 230,270 Insulating paper, 240,340 Short circuit board, 250,350 Line end part, 260,360 Insulating part , 320 conductive part.

Claims (4)

An electrostatic plate disposed adjacent to and opposite to the line end winding of the transformer,
An insulating base having a circumferential shape equivalent to the shape of the opposing surface of the line end winding;
A conductive portion provided on the surface of the insulating substrate;
A line end connected to a part of the conductive part and the line end winding;
In order to prevent circulating current from flowing in the circumferential direction of the insulating substrate, the insulating substrate is provided with an insulating portion that makes the conductive portion discontinuous in the circumferential direction on the surface of the insulating substrate,
The insulating part is an electrostatic plate formed at a position opposite to the line end in the circumferential direction. Further comprising a short-circuit plate disposed on the conductive portion;
In the short-circuit plate, a part is continuously arranged in one direction in the circumferential direction from the line end to the insulating part, and the remaining part is opposite to the one direction from the line end to the insulating part. The electrostatic plate according to claim 1, wherein the electrostatic plate is continuously arranged in the other direction, and the part and the remaining part are arranged substantially symmetrically. The conductive portion is provided by winding a strip-shaped metal foil around the insulating base,
The electrostatic plate according to claim 1, wherein the insulating part is provided by disposing an insulating member between one end and the other end of the strip-shaped metal foil. The conductive portion is provided by applying a conductive material to the insulating base,
The electrostatic plate according to claim 1, wherein the insulating portion is provided by not partially applying the conductive material.

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