JPH02126613A - Foil wound transformer - Google Patents

Abstract

PURPOSE:To reduce the pressure loss of an insulating pipe and lessen the loss of accessories after decreasing the head of the pump by causing an insulating pipe which is connected to an end part of a cooling panel to have a smooth inner face and an end or both ends of it to be equipped with an insulating tube consisting of a corrugated tube. CONSTITUTION:The construction of an insulating pipe 11 is made with an insulating tube 11a having a large wall thickness in which its inner face is smooth and one end side of the above insulating tube or both ends of it is equipped with a corrugated tube 11b having a thin wall thickness. Connection to a cooling duct is performed in such a way that a flange fitting 17 which is bonded to an end part of the pipe 11 is clamped to a nozzle 16 of a cooling duct end part with a nut 18. As the pipe 11 is composed of the insulating tube 11a and the corrugated tube 11b, a required strength for outside pressure is fully secured. Since a part of the pipe 11 is made by the corrugated tube, it holds flexibility and then it is mounted and assembled easily. The inner part of the insulating tube 11a having the thick wall thickness which occupies about 90% of the total length of the insulating pipe is so smooth that its friction factor of the inner part of the pipe becomes about 1/10 in comparison with a case where the tube is constructed only by the corrugated tube and even a pressure loss becomes about 1/10.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a foil-wound transformer in which a cooling panel is built into a foil-like winding formed by overlapping and winding a metal sheet and an insulating sheet. Concerning vessels.

(Prior art) A foil-wound transformer, in which a metal sheet and an insulating sheet are layered and wound around a core leg to form a foil winding, has a good space factor for the single winding source, so It has the characteristics of being smaller and lighter than transformers using conductors.

However, in order to realize higher-voltage, larger-capacity transformers, it is essential to further improve the cooling ability of the windings and provide the windings with high insulation ability. It has been considered to incorporate a cooling panel in which a refrigerant flows within the wire so that the heat generated from the winding can be directly cooled. This type of transformer is known from US Pat. No. 4,039,990.

This conventionally proposed foil-wound transformer, for example,
As shown in the figure, a metal sheet 2 and an insulating sheet 3 are layered and wound around a core leg 1 to form a winding. This winding consists of an inner winding 4 and an outer winding 5, and an annular cooling panel 6 is built into each of these windings.

The cooling panel 6 is made up of two metal plates stacked one on top of the other with a narrow gap for the coolant to flow, and the periphery of the two metal plates is sealed by welding or the like. Cooling is performed by constantly flowing a refrigerant such as Freon R-113 or Fluorinert FC-75 into the gap between the cooling panels 6 using a pump 7 and allowing the refrigerant to remove the heat generated within the foil-wound windings. The refrigerant that has absorbed the heat is sent out to the outside of the winding from the outlet nozzle, cooled in a cooler 9 provided outside the tank 8, and sent into the cooling panel 6 again. Note that the refrigerant is once collected in a liquid collection pipe 10 before being sent to the cooling panel 6, but since this liquid collection pipe 10 maintains the same ground potential as the tank 8, etc., it has the same potential as the metal sheet 2. The connection to the cooling panel 6 having a cooling panel 6 is made through an insulating pipe 11. The cooling panel 6 is in contact with the metal sheet 2 or the insulating sheet 3 in order to cool the metal sheet 2 by thermal conduction, and since the cooling panel 6 is wrapped in the winding, the cooling panel 6 is also in contact with the metal sheet 2 or the insulating sheet 3. Almost the same voltage is applied, and insulation between the metal sheet 2 and the cooling panel 6 and the outside is achieved by an insulating gas such as sulfur hexafluoride (SF) sealed in the tank 8.

The foil-wound transformer described above is called a separate foil-wound transformer because the circulation circuit through which the refrigerant for cooling flows and the insulating gas are completely separated. Compared to transformers that use

(Problems to be Solved by the Invention) However, the conventional foil-wound transformer described above has the following problems. That is, as shown in FIG. 3, one of the insulated pipes 11 is connected to the cooling panel 6 at the upper and lower end surfaces of the winding 4.5, and the other is connected to the liquid collection pipe 10 arranged at a sufficient insulation distance from the winding. However, on the upper and lower end surfaces of the windings 4 and 5, there are also lead-out leads of the windings 4 and 5, support insulators for the windings, etc., so consider insulation from these and insulate the cooling panel. In order to decide the arrangement of the connection part of the pipe 11 and pull out the insulated pipe 11, the insulated pipe 11 needs to have flexibility.
Although insulating corrugated pipes are used as in Publication No. 2800, corrugated pipes have a disadvantage in that their internal fluid resistance is greater than that of smooth pipes, leading to an increase in pressure drop in the refrigerant circulation system and an increase in auxiliary machine losses. Ta.

For example, let us compare the fluid resistance of a smooth Teflon tube with an inner diameter of φ15 and a Teflon corrugated tube of the same diameter as shown in FIG. The calculation method is based on "Fluid Resistance of Pipes and Ducts", Japan Society of Mechanical Engineers, P. 30-P. 33.

For example, the coefficient of fluid friction in a corrugated pipe is: On the other hand, if a smooth Teflon pipe has a surface roughness of 0.0015 and a flow velocity of 2.3 m, then λ = 0.0205, which is 1/10 smaller than that of a corrugated pipe. .

Therefore, with both flow velocities v = 2.3n+/s, the length of the insulated pipe is u = 2 x 90am (total length of insulated pipes on the inlet side and 8 ports for one cooling panel), and the refrigerant is FC-7.
5 (density γ = 1.6855°C), the pressure loss in the insulated pipe is 2 v2 ΔP = λ” −-” in the case of a corrugated pipe. ”0.207X 2XO・9
2・3'd, 2g 15X10-' 2X9
．． 8x1°68" 11.3m water column On the other hand, in a smooth pipe, the pressure loss is 0.0205 ΔP = 11.3X = 1.12m water column 0.207, which can be reduced to 1/10 of that of a corrugated pipe.

Although it is possible to reduce pressure loss by using a smooth tube as described above, since a smooth tube is not flexible, it cannot be used by bending it into various shapes. If a smooth, thin-walled tube is used, it will have some degree of flexibility, but since the pressure of the insulating gas on the outside is applied to this insulated pipe as external pressure, it is impossible to use a thin-walled tube. be.

Furthermore, it is possible to reduce pressure loss by increasing the diameter of the corrugated pipe, but in this case, the radius of curvature of the face increases, and the volume that occupies space also increases, making it difficult to arrange the ends of the winding.

In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a foil-wound transformer that reduces the head of the pump and reduces the loss of auxiliary equipment by reducing the pressure loss of the insulated pipe connected to the cooling duct. It's about getting.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, in the present invention, an insulating pipe having a smooth inner surface and having a corrugated pipe structure at one end or both ends is used as an insulating pipe.

(Function) As a result, the pressure loss within the insulated pipe is significantly reduced compared to when only corrugated pipes are used.

(Example) Examples of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, the insulating pipe 11 has a structure in which one end or both ends of a thick-walled insulating pipe 11a with a smooth inner surface are made into a thin-walled corrugated pipe 11b.

Connection with the cooling duct is carried out by tightening the flange fitting 17 fixed to the end of the insulating pipe 11 into the nozzle 16 at the end of the cooling duct using a nut 18. Although the pressure of the insulating gas is applied as external pressure to the insulating pipe 11 having this structure, since it is constituted by the thick-walled insulating pipe 11a and the corrugated pipe 11b, the required strength against external pressure can be ensured sufficiently. Further, since a part of the insulating pipe 11 is made of a corrugated pipe, it has flexibility and is easy to assemble.

Furthermore, thick-walled insulation pipe 1 occupies about 90% of the total length of the insulation pipe.
Since the inner surface of the pipe 1a is smooth, the coefficient of fluid friction inside the pipe is about 1710 compared to the case where the pipe is composed of only the corrugated pipe 11b, and the pressure loss can also be reduced to about 1710.

FIG. 2 shows a portion of the thick-walled insulating tube 11a shown in FIG. 1, whose inner surface is smooth and whose outer surface conforms to the outer shape of a corrugated tube. Even in such a configuration, the same effects as in FIG. 1 can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, one or both ends of the insulated pipe with a smooth inner surface are made of a corrugated pipe, so that it has the required external pressure strength, is easy to assemble, and is easy to assemble. The fluid pressure loss can be reduced to 1710, and a foil-wound transformer with small auxiliary equipment can be provided.

[Brief explanation of drawings]

Fig. 1 is a half sectional view showing an insulated pipe according to the present invention, Fig. 2 is a half sectional view showing another embodiment of the invention, Fig. 3 is a sectional view showing a separate type transformer, and Fig. 4 is a conventional 61 is a cross-sectional view of the insulated pipe of... Iron core leg 2.
...Metal sheet 3...Insulating sheet 4...Inner winding 5...Outer winding 6...Cooling panel 7...Pump 8...Tank 9...Cooler 10... Liquid collecting pipe 11...Insulating pipe 11a...Smooth inner surface insulating layer 11b...Corrugated pipe 16...Nozzle 17...Flange fitting 18...Natto agent Patent attorney Noriyuki Chika Agent I 1゛Physicalist Daishimaru Ken's drawing diagram

Claims (1)

[Claims] A foil winding made of overlapping metal sheets and insulating sheets is wound around the legs of the iron core, a cooling panel is placed inside the foil winding, and a refrigerant is circulated within the cooling panel to cool the winding. In a foil-wrapped transformer for cooling, an insulating pipe connected to an end of the cooling panel for introducing and removing refrigerant into the cooling panel is an insulating pipe with a smooth inner surface and one or both ends made of corrugated pipe. A foil-wound transformer characterized by a tube.