JPH0313730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a foil-wound transformer in which a cooling duct is built into a coil formed by overlappingly wound a foil-wound conductor and an insulating sheet.

[Background technology of the invention]

Foil-wound transformers have a good space factor for the wrapped conductors, so they can be smaller and lighter than transformers using linear conductors, but they are also smaller and lighter than transformers that use wire conductors. In order to apply it to the coil, it is necessary to improve the cooling capacity of the coil and provide the coil with high insulation capacity.For example, a cooling duct is built into the coil of a foil-wound transformer, and refrigerant is fed into this cooling duct to reduce the heat generated from the conductor. It is designed to directly cool the heat generated by the system.

As shown in FIG. 1, a conventional foil-wound transformer of this type has a coil body formed by overlapping a foil conductor 2 and an insulating sheet 3 on the outside of an iron core 1, and a low-voltage coil 4 and a high-voltage coil 5. To wind. An annular cooling duct 6 is built in each of these coils. This cooling duct is formed with a thin space through which a refrigerant 7 such as fluorocarbon can flow. This refrigerant 7 is circulated by a pump 8 to remove heat generated within the foil-wound coil, and the refrigerant whose temperature has risen is cooled by cooling water 10 of a cooler 9. This cooled refrigerant further flows through a refrigerant circulation circuit where it is sent into the cooling duct by a pump 8. A plurality of cooling ducts are provided within the coil, and each cooling duct is connected to the liquid collection pipe 11 so that the refrigerant can flow in and out in a concentrated manner on the inflow or outflow side thereof. This liquid collecting pipe 11
is made of metal such as stainless steel,
In order to maintain insulation from the cooling duct, the inlet and outlet passages of each cooling duct are connected with an insulating pipe 12.
Together with the tank 13 and the like, it is at ground potential.
The potential of the cooling duct is electrically coupled to approximately the same potential as the foil-wound conductor because it is wound within the coil. The entire coil is insulated by an insulating medium 14 such as insulating oil or SF ₆ gas sealed in a tank.

Note that in FIG. 1, the lead wire from the conductor and the pushing to draw it out to the outside of the tank are omitted. In addition, this type of foil-wound transformer is called a separator-type foil-wound transformer because the circulation circuit through which the refrigerant for cooling flows and the insulating medium 14 for insulation are completely separated. I'll decide.

This separator-type foil-wound transformer can be expected to have excellent cooling characteristics and is therefore promising for large-capacity transformers.
However, in the conventional separator type foil-wound transformer shown in FIG. 1, there is no device for matching the pressure of the refrigerant 7 in the refrigerant flow path and the pressure of the insulator 14 in the tank. If a pressure difference occurs and the pressure of the insulating medium is higher than that of the refrigerant, the insulating medium may mix into the refrigerant from the connection between the insulating pipe 12 and the liquid collecting pipe 11, or vice versa. There is a high probability that an accident will occur, such as a pipe becoming detached and refrigerant leaking into the tank.
This turned out to be a major drawback.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and its purpose is to prevent the refrigerant and the insulator from mixing by constantly maintaining the pressures of the refrigerant and the insulating medium in the tank almost equal. prevent accidents,
The object of the present invention is to easily provide a foil-wound transformer that is highly safe.

[Summary of the invention]

In other words, the present invention provides a pressure control device to control the pressure of the refrigerant and insulating medium during the operation of the transformer.
The purpose is to achieve the above-mentioned purpose by keeping the distance almost the same regardless of the pause.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 2 is a diagram showing a schematic configuration of a foil-wound transformer according to the present invention. Note that the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted. This embodiment differs from the conventional example in that the refrigerant 7 and the insulating medium 14
This is because a movable wall 16 is installed using a bellows 15 at the border. With this configuration, the pressure of the refrigerant 7 in the pressure application section at one end of the bellows 15 can pressurize the insulating medium 14 filling the pressure application section at the other end of the bellows 15 via the movable wall 16.
On the other hand, the insulating medium 1 fills the pressure section at the other end.
The refrigerant 7 can be pressurized at a pressure of 4, and the pressure of the refrigerant 7 and the pressure of the insulating medium 14 are always kept equal. According to the present invention, by constantly maintaining the same pressure between the refrigerant and the insulating medium, accidents such as mixing of the refrigerant and the insulating medium can be prevented, and a highly safe foil-wound transformer can be easily manufactured. Furthermore, if a movable wall is partially provided using a bellows, a simple structure can be achieved. Note that there are no particular restrictions on the shape of the movable wall portion, etc.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic structure of a conventional foil-wound transformer, and FIG. 2 is a diagram showing a schematic structure of a foil-wound transformer according to the present invention. 7... Refrigerant, 14... Insulating medium, 15... Bellows,
16...Movable wall.

Claims (1)

[Scope of Claims] 1. A foil-wrapped transformer body in which a transformer body is constructed by building a cooling duct in which a refrigerant flows inside a coil in which a foil-wrapped conductor and an insulating sheet are wound in layers, and the transformer body is installed in a tank filled with an insulating medium. 1. A foil-wound transformer, characterized in that the transformer is equipped with a pressure control device that keeps the pressures of the refrigerant and the insulating medium substantially equal at all times. 2. The pressure control device is connected to the first
2. The foil-wound transformer according to claim 1, wherein the foil-wound transformer comprises a pressure applying section and a second pressure applying section that controls the pressure of the refrigerant using the pressure of the insulating medium. 3. The foil-wound transformer according to claim 2, wherein the first pressure applying section and the second pressure applying section are constituted by bellows having movable walls.