JPS5933813A - Foil-wound transformer - Google Patents

Abstract

PURPOSE:To make it possible to maintain an excellent cooling effieiency, by a method wherein in the surfaces surrounding a gap produced by an end part of the cooling duct, a metal foil and an insulating sheet, the surface part constituted by the insulating sheet is coated with an electrically conductive substance, such as an electrically conductive paint, thereby to place all the surfaces surrounding the gap at the same potential. CONSTITUTION:A gap 15 is formed by an end part of a cooling duct 9 filled with a refrigerant 16, a metal sheet 7 and an insulating sheet 8. If one contact surface 21 forming the gap 15 is constituted by the insulating sheet 8, the other contact surface 22 is constituted by the metal sheet 7. The surface of the insulating sheet 8 is covered with an electrically conductive substance 23 with a resistivity not higher than 10<5>OMEGAcm. As this electrically conductive substance 23, a metal foil, semiconductive paper or electrically conductive paint is employed. Even if the gap 15 is produced at the end part of the cooling duct 9, all the contact surfaces 21, 22 and the cooling duct 9 surrounding the gap 15 are substantially equal in potential to each other, since all the contact surfaces 21, 22 and the cooling duct 9 are connected by an electrically conductive substance with a resistivity not higher than 10<5>OMEGAcm. Further, since heat can be transmitted in the circumferential direction, it is possible to prevent the lowering of the cooling efficiency due to the existence of the gap 15.

Description

[Detailed description of the invention] [Technical field of the present invention] The present invention uses a winding made of metal foil and an insulating sheath 1 wrapped in layers, and furthermore, a cooling dan 1 is built into the winding. Regarding foil-wound transformers.

[Technical Blueprint of the Invention 1 A foil-wound transformer using a front winding formed by overlapping metal γj and an insulating sheet has a good space factor, so it has the feature of being able to be made smaller and lighter. It has already been put to practical use in small capacity transformers with relatively low voltages of several kilovolts or hundreds of kilovolts. .

Recently, in view of its excellent advantages, research has been conducted to expand its application to high-voltage, large-capacity, 275KV, 300MV delta transformers, for example, but the biggest problem in practical application is:
The key point is how to increase the cooling capacity of the windings and give them a high insulation capacity. As described above, there are various problems in the practical application of high-voltage, large-capacity suspension transformers using foil windings. Cold 7JI inside the line
Avoiding built-in ducts, a refrigerant with excellent insulation properties of 111 is circulated through the pump, resulting in loss from windings.
There is a type that pipes the heat directly to the cold J1, so to speak, to the heat 1.

Figure 1 shows the IM structure of this heat pipe type foil-wound transformer.

First, an iron core 2 is provided inside a tank 1 filled with an insulating medium such as insulating oil or an insulating gas such as SF6 gas. An insulating cylinder 3 is provided on the outside of the main leg 2a of this iron core 2.
A low voltage winding 1 is wound through the low voltage winding 4, and a high voltage winding 5 is wound around the outside of the low voltage winding 4 through an insulating burr 176. These low-voltage winding 4 and high-voltage winding 5 are made of metal foil 7 made of aluminum or the like, resin film, etc. 1. It is constituted by a foil-wound wire formed by overlapping and winding insulating sheets 8 made of s+.

A cooling duct 1-0 extending in the axial direction of the winding 4 and the high voltage winding FA5 is wound around and built into the low voltage winding 4 and the high voltage winding FA5.
− I am. The inside of this cooling dow 1-0 is hollow so that refrigerants such as No1]n 113 and Norolino-1 to 1-c75 can pass through it.
The heat generated by the winding 1.5 is taken away as the latent heat of evaporation of the refrigerant, and the winding 4,
Cool and cover. This refrigerant is cooled and condensed by a water-cooled JJI in a condenser 1o installed outside the tank 1. After the liquefied refrigerant is stored in the refrigerant tank 11, it is pumped by a pump 12 into a liquid conduit 13 and an insulated pipe. 14), [into one duct 1 to 9].

Note that the metal liquid guide pipes 13 are arranged at both ends of the windings 1 and 5, and connections 1'' 9a are formed at both ends of the cooling ducts 1 to 9, and the liquid guide pipes 13 are connected to the cooling ducts 1 to 9. The connection ports 9a and the like of 9 are connected via an insulating pipe 14.

[Problems with cost technology] By the way, the arrangement of the cooling duct 9 used in the conventional foil-wound transformer as shown in FIG. 1 is as shown in the sectional view of FIG. 2. That is, the shape of the cooling ducts 1 to 9 is set so that the length of the arc is smaller than 180° in terms of circumferential angle from the viewpoint of attachment to the windings and manufacturing. 11[1taku1~9-1.9-2
... are shifted from each other in the circumferential direction, and a plurality of sheets are inserted in the radial direction. Generally, the thickness of the metal foil 7 is several hundred micrometers or less, and the thickness of the insulation sheet h8 is often several tens of meters or less, while the thickness of the cooling duct 1-0 is approximately 2 to 5 mm. Therefore, a gap 15 as shown in FIG. 3 is created around the end of each cooling tact 9. That is, refrigerant 1
A curved triangular gap 1 is formed between the ends of the cooling ducts 1 to 9, each having an IK 6, and the metal foil 7 and the insulating sheet 8.
5 occurs.

However, when such a gap 15 occurs in a foil-wound transformer, the dielectric constant of that part decreases? There were drawbacks such as concentration of the R field and insufficient insulation effect of the insulating gas. Furthermore, in a foil-wound transformer where the heat generated in the winding 4.5 is transferred to the refrigerant 16 in the cooling duct I-〇, if such a gap 15 occurs, the heat in that part will be reduced. There were also disadvantages in that the S conductivity decreased considerably, the cooling efficiency decreased, and the temperature distribution within the winding became non-uniform.

In order to overcome these drawbacks, it is conceivable to process the ends of the ducts 1 to 9 into triangular shapes to fill the gaps 15, but this would not cause any difficulties in the manufacturing process. The electric field tends to concentrate at the sharpened end, which is not desirable.

[Object of the Invention] The present invention has been proposed to eliminate the drawbacks of the conventional foil-wound transformer as described above.
An object of the present invention is to provide a foil-wound transformer with high insulation performance and high cooling effect despite the existence of a gap between one end and the winding.

[Summary of the Invention] The foil-wound transformer of the present invention has a surface that surrounds the gap formed between the end of the cooling duct l- and the metal foil and the insulating sheet.
The part consisting of the insulating sheet is conductive and is the best! ! By coating with an electrically conductive material, the surfaces surrounding the gap are at the same potential, preventing a drop in dielectric strength. Also, by utilizing the good thermal conductivity of the electrically conductive material, excellent cooling efficiency can be maintained. -6- (゛There is.)

[Embodiment of the Invention] An embodiment of the present invention will be specifically described below with reference to FIG.

(K-The previous foil volume ri',!! As in the case of A, a gap 15 is formed between the end of the cooling duct containing the refrigerant 16 and the metal sheet 7 and the insulating sheet 1-0. In this case, one contact surface 21 forming the gap 15
is the insulating sheet 8, the other contact surface 22 (, 1, metal sheets 1 to 7) is formed. The surface of -8 is covered with a conductive substance 23 having a resistivity of 105 ΩCm or less 5. As this conductive substance 23, metal foil, semiconductive paper, i# conductive paint, etc. can be adopted.

In this embodiment having such a configuration, the cooling duct 1
Even if a gap 15 occurs at the end of ~9, the contact surface 21.22 surrounding the gap 15 and the dimension of 9 to the cooling duct 1 will have a resistivity of 1
This means that they are connected to each other by a conductive material of 0.05 ΩCm or less, and the potentials are approximately the same -7-, so that no electrical stress is applied to the gap 15 and the dielectric strength does not decrease.

In addition, conductive materials with a resistivity of 105 Ωcm or less generally have good thermal conductivity, so the heat generated within the winding is transferred to the gap 15.
Even if heat cannot be transmitted in the radial direction due to an obstruction, the conductive material can quickly transmit heat in the circumferential direction, so that a decrease in cooling efficiency due to the gap 15 can be prevented.

Furthermore, since no electrical stress is applied to the gap 15, the shape of the end of the cooling duct 9 can be the same as before, and there is no need for special processing, which simplifies the manufacturing process.

Note that the present invention is not limited to the thickness of the cooling duct 9 or the arc angle in the circumferential direction, and can be applied to any cooling duct 1 that has a gap at its end.

Furthermore, it does not depend on the flow direction of the coolant in the cooling duct or the arrangement direction of the windings themselves.

[Effects of the Invention] As described above, according to the present invention, excellent insulation performance is achieved despite the presence of gaps at the circumferential ends of the cooling duct. It is possible to provide a 06-turn transformer with 11-high performance that prevents a decline in cooling efficiency.

[Brief explanation of the drawing]

Figure 1 shows the conventional 9! FIG. 2 is a cross-sectional view showing the structure of a J-wound transformer, FIG. 3 is an enlarged view of the end of the cooling duct, and FIG. 4 is an embodiment of the foil-wound transformer of the present invention. (This is an enlarged view of the end of the cooling duct. 1...Tank, 2...Iron core, 2a...Main legs of the iron core, 3...Insulation tube, 4...Low voltage winding, 5 ...High voltage winding, 6...Insulated Paris hair 7.7...Metal foil, 8...
Insulation seam 1~. 9...Cooling duct 1~. 10... Condenser, 11... Refrigerant tank, 12... Pump, 13...
...Liquid conduit, 14...Insulated pipe, 15...Gap,
16... Refrigerant, 21.22... Contact surface, 23...
conductive material. 1317 Representative Patent Attorney Kensuke Norichika (1 idiot) -9- Figure 1 Figure 3\ Figure 4

Claims (4)

[Claims] (1) A foil winding made by overlapping metal foil and insulation sheath 1 is wound around the legs of the iron core, and a cooling duct 1 curved into an arc is built into this winding. This constitutes the contents of a transformer, and the contents of this transformer are housed in a tank filled with an insulating medium, and cooling units 1 to 1 exposed to the outside of the tank are connected to the cooling rod. A foil-wrapped transformer in which a cooled refrigerant is circulated separately from the insulating medium between the duct 1 and the cooling unit 1. 1. A foil-wound transformer characterized in that a portion of the surface surrounding the gap formed by the heel, which consists of the insulation sheets 1 to 1, is coated with a conductive material having a resistivity of 105 ΩCm or less. (2) When the conductive substance is conductive coating II+ [the foil-wound transformer according to claim 1]; (3) A patent claim in which the s-electronic substance is semiconductive paper.
1- Foil-wound transformer 3 according to item 1, (4) Claim 1 in which the conductive substance is metal foil
Foil-wound transformer as described in section.