JPS59197115A - Stationary induction electric apparatus - Google Patents

Abstract

PURPOSE:To prevent the generation of eddy currents on the passage of leakage flux, and to remove the partial heating of an electrostatic shielding by constituting the electrostatic shielding by a semiconductor material having resistivity of some extent. CONSTITUTION:A lead pipe 61 and an insulating pipe 9 are connected by a clamp 62, and an annular electrostatic shielding 64 is mounted at a connecting position of the insulating pipe 9 with the lead pipe 61. The electrostatic shielding 64 is constituted by a conductive rubber of approximately 10<-4>-10<6>mOMEGA resistivity as one of semiconductor materials. Accordingly, since the electrostatic shielding 64 is manufactured by the conductive rubber as a semiconductor, eddy currents are difficult to be generated by the electric resistance of the rubber even when leakage flux passes in the electrostatic shielding, and the partial heating of the electrostatic shielding can be suppressed.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention has a foil-like winding in which a metal sheet and an insulating sheet 1 to 1 are wound in layers, and a cooling duct is built into the winding. Concerning stationary induction electrical equipment.

[Technical Background of the Invention] Stationary induction electrical equipment having a foil winding, such as a foil-wound transformer, has a good space factor and is therefore characterized by its ability to be made smaller and lighter. It has already been put to practical use in small capacity transformers with relatively low voltages of several KV and several hundred KVA.

Recently, in view of its excellent advantages, research has been conducted to expand its application to higher voltage and larger capacity transformers, such as 275KV and 300MVA, but the biggest problem in practical application is:
The question is how to improve cooling capacity and provide high insulation capacity to the windings. As described above, there are various problems in the practical application of high-voltage input capacity transformers using foil-wound windings, but as foil-wound transformers that are already known and have been studied,
There is a heat pipe type in which a cooling duct is built into the winding, and a refrigerant with good evaporation properties is pumped into this duct, and the heat generated by winding loss is not directly cooled.

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

A metal sheet 2 is wound many times around the outer periphery of the leg portion 1 of the iron core via an insulating sheath 1-3 to form a low-voltage winding 4 and a high-voltage winding 5. Between these low and high voltage windings 4 and 5,
A hollow metal cooling duct 6 is built-in. The cooling ducts 1 to 6 have a cylindrical shape or a divided cylindrical shape along the winding direction of the winding wire, and have a hollow space filled with Freon R-113 or Norolinert FC75. cold! 7 is included. This refrigerant 7 is supplied to the liquid conduit 10 by a pump 8 of a cooling device installed outside the transformer.
The refrigerant is circulated through the cooling duct 1-6 via the insulating vibe 9, and the heat generated in the windings is removed by the latent heat of evaporation of the refrigerant, after which it is led to the cooling device 11 again via the insulating vibe 9 and the liquid guide pipe 10. In the condenser 11 of the cooling device, the water cooling pipe 1
2, it is cooled and condensed again. The condensed and liquefied refrigerant 7 is stored in a refrigerant tank 13, and is sent again to the cooling duct 6 within the windings by the pump 8.

In this way, the main body of the foil-wound transformer provided with the cold W7 circulation circuit is coated with an insulating medium 14 such as insulating oil or SF6 gas.
It is also housed in the tank 15. In this case, the liquid guide pipe 10 made of metal such as stainless steel is connected to the ground potential of the tank 15, etc., and the cooling duct 6 is installed between the windings 4 and 5, so that it is at the same potential as the adjacent winding. electrically connected to a potential.

The transformer with the structure described above is particularly called a separate foil-wound transformer because the refrigerant for cooling and the insulating medium 14 for insulation are completely separated. .

[Problems with the background technology] Since the transformer of this method uses the latent heat of vaporization of the refrigerant,
Since erosion Iζ cooling characteristics can be expected, it is promising for large capacity transformers.

However, the conventional separate foil-wound transformer as shown in FIG. 1 has the following problems.

That is, in the levered foil-wound transformer, the insulating vibrator 9 is used to connect the metal cooling duct 6, which has the same potential as the winding, and the metal liquid guiding pipe 10, which has the earth potential. As shown in FIG. 2, the cooling duct 6 and the insulating vibrator 9 are connected by inserting the tip i1 of the opening vibro 1 provided at the upper edge of the cooling ducts 1 to 6 into the lower end of the insulating vibrator 9. This is done by However, in this connection, the opening vibro 1
Since there is a large potential difference between
If a metal stopper 62 is used at the connection, the electric field will concentrate using this as a protrusion, causing partial discharge in the insulating medium. It had insulation weaknesses such as

In order to compensate for this weakness, as shown in FIG. 3, an electrostatic shield 63 made of an annular ring made of gold or the like is provided on the top of the metal outlet vibro 1 to prevent the electric field from concentrating on the tip of the outlet vibro 1. A foil-wound transformer configured as follows has been proposed. However, even this type of foil-wound transformer has the following problems.

That is, in the foil-wound winding, a metal sheet 2 is wound around the outer periphery of the leg of the iron core with an insulating sheet 3 interposed therebetween, so a large amount of the magnetic flux flows through the leg of the iron core, but at this time, leakage magnetic flux flows into the winding. It flows inside and in the insulating space between the winding and the yoke core 16. When this leakage magnetic flux passes through the electrostatic shield 63, since the electrostatic shield 63 is made of metal in the conventional foil-wound transformer, a current flows there and causes local heating. This local heating warms the refrigerant passing through the outlet vibro 1,
Because the warmed refrigerant flows through the cooling duct,
There is a risk that the cooling efficiency will decrease and the humidity of the entire transformer will reach an upper limit, which will further warm the refrigerant and cause a vicious cycle in which the cooling efficiency will decrease. And the blade to prevent this
In order to increase the number of cooling ducts built into the windings, a large and powerful cooling device is required, which makes it difficult to downsize the transformer.

[Object of the Invention] The present invention was proposed in view of the above-mentioned shortcomings of the prior art, and it provides a miniaturized large-capacity foil wrapping that prevents local heating of the electrostatic shield and improves the cooling efficiency of the refrigerant. The purpose is to provide transformers.

[Summary of the Invention] The foil-wound transformer of the present invention has an electrostatic shield provided at the top of a metal outlet pipe made of a semiconductor material having a certain degree of resistivity. This resistor prevents the generation of eddy current during leakage magnetic flux and eliminates local heating of the electrostatic shield.

[Embodiments of the invention] A first embodiment of the present invention will be explained with reference to FIG.

The same parts as those of the conventional foil-wound transformer shown in FIGS. 1 to 3 are given the same reference numerals, and the description thereof will be omitted.

In the foil-wound transformer of this embodiment, the lead vibro 1 and the insulating pipe 9 are connected by a stopper 62, and the connection point with the insulating pipe on the lead vibro 1 is as follows.
An annular electrostatic shield 64 is provided. This electrostatic shield 64 is made of a semiconductor material with a resistivity of 10
It is made of conductive rubber of about -4 to 106 mΩ. The electrostatic shield 64 is separate from the leading vibro 1 and is formed in a half-shape so as to surround the leading vibro 1 from both sides. The electrostatic shield 64 and the outlet vibro 1 are connected to each other by attaching the half-shaped electrostatic shield 6 to the flange 61a provided on the upper part of the outlet vibro 1.
This is done by attaching the connecting flange portion 65 to 4 using bolts or the like.

In the foil-wound transformer of this embodiment having such a configuration, the electrostatic shield 64 is made of S-conductive rubber, which is a semiconductor, so even if magnetic flux leaks and passes through the electrostatic shield, the rubber Electrical resistance makes it difficult for eddy currents to occur, eliminating local heating of the electrostatic shield. Therefore, heating of the refrigerant due to local heating of the electrostatic shield does not occur. Furthermore, since semiconductors act as good conductors at high voltages, the high potential of the windings is applied to the electrostatic shield 64, and the pipe connections and stops 62 are covered with the electrostatic shield 64. Since no electric field is applied, dielectric breakdown from this part can be prevented. Furthermore, in this embodiment, since the electrostatic shield is made of R-conductive rubber, it is possible to manufacture the electrostatic shield by means such as pressing or casting. By comparison, processing becomes easier and the number of manufacturing steps and 11 operations can be shortened.

Next, in the foil-wound transformer of the second embodiment shown in FIG. It is composed of Semiconductor liquid here! Ji67 is made by tightly shielding the surface of the core material 66 with thin conductive rubber, or by applying a conductive rubber emulsion or other semiconductor paint to the surface of the core material 66 by brushing or spraying. Use.

It goes without saying that this second embodiment also has the same effect as the first embodiment, but when semiconductor paint is used, it is possible to simply apply the paint to the existing electrostatic shield. This makes it extremely easy to manufacture a semiconductor electrostatic shield, and it can also be manufactured in any shape.

Although the above embodiments apply the present invention to a foil-wound transformer, the present invention can be similarly applied to other static induction electrical equipment.

[Effects of the Invention] As described above, according to the present invention, it is possible to prevent the generation of melting current in the electrostatic shield and to prevent heating of the refrigerant due to local heating at the outlet pipe. Efficiency is improved, and since the tip of the outlet pipe is electrically shielded and electric field concentration is alleviated, there is no fear of dielectric breakdown, and high-voltage, large-capacity static induction electrical equipment can be provided. In addition, since the electrostatic shield is easy to manufacture and process, it also has the effect of shortening work time when manufacturing equipment.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of a conventional double-wound transformer, Figure 2 (△) is a perspective view showing the connection between a conventional cooling duct and an insulating vibrator. (8) is △ in Figure 2)
Figure 3 (△) is a cross-sectional view of the conventional foil-wound transformer showing the connection C between the cooling ducts 1 and the insulating pipes.
Figure (B) is '! 53 (△) is a sectional view, FIG. 4 (A> is a perspective view of the first embodiment of the present invention, and FIG. 4 (B) is a cross-sectional view of FIG. 4 (
FIG. 5 is a cross-sectional view showing another embodiment of the present invention. 1... Legs of iron core, 2... Metal seams 1~. 3...
Insulating sheet, 4...Low voltage winding, 5...High voltage winding, 6
...Cooling duct, 7...Refrigerant, 8...Pump, 9
... Insulated pipe, 10 ... Liquid pipe, 11 ... Condenser, 12 ... Water cooling 7, dI pipe, 13 ... Refrigerant tank, 14 ... Insulating medium, 15 ... Transformer vessel tank, 16
...Yoke iron core, 61...L" out vibe, 62.
... Stopper, 63.64 ... Electrostatic shield, 65...
- Connection 7 lange, 66...core material, 67...semiconductor coating. Figure 1 Figure 2 (A) (Snake) Figure 3 (B) Figure 4 (B)

Claims (4)

[Claims] (1) A foil winding is formed by wrapping a metal sheet around the leg of the iron core many times through an insulating sheet, and a metal cooling duct is built in between the foil windings. In stationary induction electrical equipment, in which a metal outlet vibrator installed at A static induction electric device 1 characterized in that a ring-shaped electrostatic shield is provided at the connecting part (Jl). (2) The static induction electric device according to claim 1, wherein the electrostatic shield is made of conductive rubber that is a semiconductor. (3) The electrostatic shield has a semiconductor on its surface.
The stationary induction electric device according to claim 1, wherein the electric rubber is adhered to the stationary induction electric device. (4) The static induction electric device according to claim 1, wherein the electrostatic shield has a surface coated with a semiconductor sake bottle.