JPS5893312A - Transformer - Google Patents

Abstract

PURPOSE:To cool transformer-turns by an insulating medium enclosed in the tank by a method wherein a gap for distributing an insulating medium opened to the upper and lower ends of the winding is provided in the halfway portion of the winding between cooling ducts of a separate type foil wound transformer. CONSTITUTION:A transformer equipped with foil windings 4, 5 formed by winding a metal sheet 2 and an insulating sheet 3 on top of each other and supplied with self-contained cooling ducts 6 for distributing a cooling medium to the windings 4, 5 within a plurality of layers is contained in a tank 12. In that case, gaps 16 for distributing the cooling medium opened to the upper and lower ends of the windings 4, 5 are provided in the halfway portion of the windings 4, 5 btween the ducts 6. The gaps 16 are also provided in the intermediate portion between the cooling duct 6 of the winding 4 and a main iron core leg 1 and also the portion between the duct 6 and an insulating barrier 9. The insulating medium such as insulating oil or SF6 gas enclosed in the tank 12 containing the transformer proper is made to flow in each of the gaps 16, 16 because of a natural convection current. Due to this reason, the windings are cooled.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to an insulating transformer body that has a foil winding formed by overlapping metal sheets and insulating sheets and has a built-in cooling duct through which a refrigerant is passed through the winding. It relates to a transformer housed in a tank containing a medium.

Technical Background of the Invention A foil-wound transformer with six windings has a good space factor, is compact and
Because it has the feature of realizing i-quantization, several kV, several tens of
Small-capacity transformers with relatively low voltages of about 0 kV have already been put into practical use, and are currently on the market.

Recently, taking advantage of its excellent advantages, research has been conducted to expand its application to high-voltage, large-capacity transformers, such as TF275kV and 300MVA transformers. It all depends on whether the ability can be imparted to the winding. High-voltage, large-capacity transformers like this one have not been put to practical use, but the cooling method for this foil-wound transformer is to have a cooling duct built into the windings to send a refrigerant with excellent insulation properties. A type of heat sink is being considered that cools the heat generated from winding loss in a straight line.

Figure 1 shows what has been conventionally considered as a foil-wound transformer with such a cooling system. A high voltage winding is wound on the outside of the high voltage winding 4 via an insulating purrier 9. These windings *4.5 are made by overlapping the metal sheet 2 and the insulating sheet 1 to form a nine foil winding. 6 Hiro foil-wound winding 4
It is a cooling duct made of metal such as stainless steel built into each suitable place within ゜5, and this cooling! The coils 6 are wound together in the winding. A refrigerant such as Freon R-113 or FCl2 is passed through the cooling duct 6, and in the process of passing through the cooling duct 6, the refrigerant converts heat in the windings into the latent heat of evaporation of the refrigerant. Cool the windings.

This refrigerant is cooled and condensed by water cooling in the condenser 8, and the liquefied refrigerant is stored in a refrigerant tank 14 and sent 9 into the windings by a four-way pump 7. That is, the refrigerant circulation circuit and the transformer are separated. Also,
The liquid guide pipe 10 that guides the refrigerant is made of metal such as stainless steel, and an insulated pipe 1 is used to connect it to the cooling duct.
1 is used. In addition, the waveguide 10 is electrically connected to the ground potential of a tank 12 that houses the transformer body, and the cooling duct is electrically connected to the same potential as the adjacent metal sheet because it is wound inside the winding. are connected to each other.

In addition, it is insulated with an insulating medium such as SF4 gas.

In this cooling type transformer, the circulation circuit through which the refrigerant for cooling flows and the insulating medium for insulation are completely separated. For this reason, this type of foil-wound transformer is particularly called a separate foil-wound transformer.

Transformers using this cooling method utilize the latent heat of vaporization of the refrigerant, so they can be expected to have excellent cooling characteristics, making them promising for large-capacity transformers.

Problems with the Background Art By the way, in the above-mentioned foil-wound transformer, each winding layer of the metal sheet 2 is insulated by the insulating sheet 3, so in order to improve the reliability of the insulation, the insulating sheet 3 should be made as thick as possible. However, increasing the thickness of the insulation sheet will lead to a deterioration of the cooling efficiency of the windings.

That is, the heat generated within the windings 4 and 5 is transferred to the cooling duct 6 by thermal conduction through the metal sheet 2 and the insulating sheet 3, and is further carried to the outside by the refrigerant passing through the cooling duct 6. The thermal conductivity of the sheet 3 is very poor compared to metal, and the thicker the insulation sheet 3, the more the insulation sheet s
The large temperature gradient within the windings results in large temperature differences between the intermediate portions of the windings between the cooling ducts and the portions close to the cooling ducts. - An example is a metal sheet with a thickness of 0.3111 and a metal sheet with a thickness of 0.025.
In the foil winding made by winding two insulating sheets of No. 111 in one twist, the current density of the metal sheet is t-145V-,
When the distance between the cooling ducts is set to aoss, the temperature difference is about 35°C. This large temperature difference between the middle part of the windings between the cooling ducts and the part near the cooling duct means that the middle part of the winding layers between the cooling ducts is not efficiently cooled. It shows.

Conventionally, as a method to reduce the above temperature difference, a method has been considered to increase the number of cooling ducts built into one unit and narrow the distance between the cooling ducts, but this method includes the following: In other words, as shown in FIG. 1, the lower and upper ends of the cooling duct 6 are designed to divide the refrigerant supplied from the lower insulation/arm hole 11 to the entire circumference of the duct. , liquid guiding paths 15 and 15 are respectively provided for collecting the refrigerant passing through the duct 6 and guiding it to the upper insulating pipe 11. In order to flow the refrigerant in an amount commensurate with the flow rate inside the cooling duct 6, the liquid guide @15 has an arm-like shape with a diameter larger than the thickness of the cooling duct 6. The diameter is -cxo-L2o, while the thickness of the cooling jacket 6 is 2.5 to 5 mm. For this reason, when the distance between the cooling ducts 6.6 is narrowed, the distance between the liquid guide paths 15.15 of each cooling duct 6.6 becomes extremely small9, making it difficult to insulate the cooling ducts 6.6 from each other. Become. Moreover, increasing the number of cooling ducts 6, -6 means that the liquid guiding path 15 of each cooling duct 6.6.
The number of insulators 11 connecting the cooling duct 6.6 and the liquid guiding pipe 10 will also increase.
It becomes difficult to insulate between the insulation pipe J l'
, There is also the problem that the routing of 11 becomes complicated.

Purpose of the Invention The present invention has been made in view of the above-mentioned circumstances, and its purpose is to reduce the number of cooling ducts without increasing the number of cooling ducts built into the first foil winding. It is an object of the present invention to provide a large voltage transformer that can efficiently cool windings.

SUMMARY OF THE INVENTION That is, the transformer of the present invention includes an insulating medium circulation gap that is open to the upper and lower ends of the windings in the middle part of the windings between the cooling ducts, and that the windings are also protected by the insulating medium sealed in the tank. It was also made to cool down.

Examples of the invention Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Foil-wound windings on the low-voltage side and the high-voltage side are made by overlapping the metal sheet 2 and the insulating sheet 3, and 6 is a cooling duct built into the winding 4゜6, and this cooling duct 6 is on the low-pressure side. They are provided in one layer in the winding 4 and in multiple layers in the high voltage side winding 5. 1σ is an insulating medium circulation gap formed at the intermediate part between the high voltage side wires 5 and open to one end of the winding, and this gap @1r; It is set up nine times. This insulation medium distribution.

The gap 16 is formed by winding the metal sheet 2 and the insulating sheet 3 by the number of turns wound between the cooling duct 6.6, and a plurality of insulating protrusions 1B and 1g on the outer surface thereof. It is formed by wrapping the insulating sheets 17 pasted at equal intervals only once, and then successively wrapping the metal sheet 2 and the insulating sheet s on the outside. 114 between the cooling duct 6 and the core main leg 1, and the cooling duct 6 and the insulating purrier 9
It is also formed in the middle part between. Each insulating medium flow gap 16.16 is a trap so that an insulating medium such as insulating oil, gas, or the like, which is sealed in the tank 12 housing the transformer body, flows by natural convection. Components in the drawings that are the same as those shown in FIG. 1 are given the same reference numerals in the drawings, and their explanations will be omitted.

In this transformer, in addition to the cooling of the windings 4 and 5 performed by passing a refrigerant through the cooling duct 6, the inside of the insulating medium flow gap 16.
The windings 4 and 5 are also cooled by the flow of the insulating medium therein.

Since the cooling effect of this insulating medium is smaller than the cooling effect of the cooling duct 6, the temperature gradient in the winding radial direction in the winding portion near the insulating medium flow connection apr is lower than the temperature gradient in the vicinity of the cooling duct 6. is large, so the temperature distribution of the windings between the cooling ducts 6°6 becomes as shown in Fig. 4(b), but what if HJg between the insulating medium channels is not provided? The cooling efficiency of the winding is considerably improved compared to the case where the temperature distribution becomes uneven as shown in Fig. #I4 (a).

Effects of the Invention Since the transformer of the present invention has the above configuration,
The winding can be efficiently cooled with a small number of cooling ducts without increasing the number of cooling ducts built into the foil winding.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional transformer, Fig. #I2 is a sectional view showing an embodiment of the present invention, Fig. 3 is an enlarged perspective view of a part of the winding, and Fig. 4 (, ), (b ) L is a diagram showing the winding temperature distribution between the cooling ducts when no insulating fluid flow gap is provided and when it is provided. 2... Metal sheet, 3... Insulating sheet, 4.5...
・Winding, 6... Cooling shutoff, 12... Tank, 16
.... Insulating media flow gap. Applicant's agent Patent attorney Takehiko Suzue 11 Figure 8 11 10 Spear 2 Figure 11 1υ

Claims (1)

[Claims] The transformer body is equipped with foil-wound windings made by layering metal sheets and insulating sheets, and a cooling medium is passed through the windings. A transformer characterized in that an insulating medium circulation gap that is open to the upper and lower ends of the windings is provided in the middle part of the windings between the cooling ducts.