JPS6110219A - Separated type foil wound transformer - Google Patents

Abstract

PURPOSE:To prevent the short circuit or the explosion due to leakage of refrigerant, by providing an optical sensor for detecting the light reflected from the surface of the refrigerant in a part where the refrigerant stagnates such as a condenser for cooling the vaporized refrigerant or a refrigerant tank. CONSTITUTION:When refrigerant leaks at a winding or the like inside or outside a transformer due to any defective connection in the cooling system, the supply of the refrigerant 15 to a condenser 8 is reduced whereby the level of the liquefied refrigerant 15' starts to decrease. Since the position where light is reflected is displaced in accordance with such decrease of the level, the area in which light-receiving element 16b absorbs the reflected light becomes smaller. If the leakage continues and level of the refrigerant 15' is decreased over a certain level, the light receiving element 16b becomes unable to absorb any light. Consequently, a power-supply breaker 17 is actuated so that a power supply 18 for the transformer is stopped. Thus further increase in temperature or pressure is inhibited.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a foil-wound transformer using a foil-like winding made by overlapping and wrapping a metal sheet such as copper or aluminum foil and an insulating sheet. In particular, the present invention relates to a separate foil-wound transformer in which the foil winding is cooled by circulating a refrigerant in a cooling duct inserted into the foil winding.

[Technical Background of the Invention 1 Foil-wound transformer wire has the characteristics that the winding has a good space, is compact, and can be made into a m-sized eave. It has already been put into practical use in small capacity transformers with relatively low voltages of several KV and several hundred KVA.

In recent years, in view of its excellent advantages, research has been conducted to expand its application to higher voltage, 275KV, 300M V△ class transformers, which are the most human-friendly, but the biggest key is how to improve the cooling capacity and The question is whether the winding can have insulation ability, and how well it can withstand radial mechanical force in the event of a short circuit accident! It depends on what you get. Although such an elevated press-fit capacity transformer has not yet been put into practical use, as shown in Figure 1, a cooling duct is built into the winding, and a refrigerant with excellent insulation properties is fed into this cooling duct. A heat pipe-type foil-wound transformer, which cools the heat generated from winding loss by using the latent heat of vaporization of a refrigerant, is promising.

That is, in this foil-wound transformer, a low-voltage winding 4 and a high-voltage winding 5, each made of a metal sheet 2 and an insulating sheet 3 wound over each other, are wound around a leg 1 of an iron core. A hollow cooling duct 6 is built-in.

In the thin gap in the hollow part of the cold N1 duct 6, fluorocarbon R-
A refrigerant such as 113 or Fluorinert FC75 is sealed, and is circulated by a pump 7, and the heat generated within the winding is removed by the latent heat of evaporation of the refrigerant, and the vapor is sent to a cooling water pipe 9 in a condenser 8.
It is designed to be cooled and condensed. A cooling system is constructed in which the liquefied refrigerant is stored in a refrigerant tank 10 and further fed into the windings by a pump 7.

The liquid guide pipe 11 constituting the cooling system is made of metal such as stainless steel, and the liquid guide pipe 11 and the cooling duct 6 are connected via an insulating pipe 12 made of Teflon resin or the like. The liquid guide pipe 11 is also connected to the ground potential of the tank 13 and the like. On the other hand, since the cooling duct 6 is built into the winding, it is electrically connected to the same potential as the adjacent winding. Furthermore, the insulation of each part of the winding is provided by the tank 13.
This is ensured by an insulating gas such as SF6 gas sealed inside.

The conventional foil-wound transformer described above is generally called a separate foil-wound transformer because the cooling system in which the refrigerant circulates and the insulating gas of the winding are completely separated. This type of foil-wound transformer utilizes the latent heat of vaporization of the refrigerant, so it can be expected to have excellent cooling properties, making it promising for large-capacity, high-voltage transformers.

[Problems in the background art] By the way, even in such a separate foil-wound transformer, during long-term operation, the solid insulator used inside is susceptible to electrical, thermal, and mechanical stress. As a result, it is inevitable that the insulation performance will deteriorate over time, and that external vibrations or electromagnetic mechanical forces generated in the windings will cause the windings and cooling ducts to become misaligned and fall off. This may cause a problem in the connecting portion of the cooling system of the transformer.

In that case, Freon 113, which is a cooling medium, leaks from inside the cooling system to the inside of the transformer insulated with 5F-6 gas or the like or to the outside of the transformer. As this type of refrigerant leakage progresses,
Transfer of refrigerant from the cooling duct to the condenser becomes impossible,
Refrigerant circulation within the cooling system is no longer possible.

As a result, the cooling of the winding becomes insufficient, the winding temperature rises, the refrigerant pressure inside the cooling duct increases, the refrigerant leaks rapidly, and this leads to insulation deterioration, which can lead to short circuits, explosions, etc. There was a risk of it happening.

[Object of the Invention] The present invention was proposed in order to solve the problems of the prior art as described above, and its purpose is to provide a highly reliable separate type that prevents short circuits or explosions caused by refrigerant leakage. The purpose of the present invention is to provide a foil-wound transformer.

[Summary of the Invention] The Hibarate type foil-wound transformer of the present invention has a refrigerant retention part such as a condenser or a refrigerant tank that cools vaporized refrigerant, a light emitting part, the back of the light from the light emitting part, and a refrigerant. By installing an optical sensor equipped with a light receiving part that detects the reflected light on the liquid surface, and by connecting a transformer power cutoff device or alarm device to this optical sensor, the refrigerant can be detected in case of refrigerant leakage. An optical sensor detects a drop in the liquid level of the cooling system and shuts off the transformer power supply or issues an alarm, thereby preventing a rise in winding temperature and pressure-induced illness inside the cooling system.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be specifically described based on FIG. 2.

In FIG. 2, a refrigerant 15 vaporized within a transformer is introduced into a closed container type condenser 8 via a liquid guide pipe 11. A cooling water pipe 9 inserted from the outside of the condenser 8 is located in this vaporized refrigerant 15 portion. Condenser 8
At the bottom of the cooling water pipe 9, a refrigerant 15 is condensed and liquefied.
' is stored, and this liquefied refrigerant 15- is sent into the refrigerant tank 10 through a liquid guide pipe 11- provided at the bottom of the condenser 8.

At the top of the condenser 8, an optical sensor consisting of a light emitting section 16a made of a light emitting diode or the like and a light receiving section 16b is provided. These light-emitting part 16a and light-receiving part 16b are arranged so that when the transformer is in steady operation, light having a certain area from the light-emitting part 16a is reflected on the surface of the refrigerant 15' and absorbed by the light-receiving part 16b. It is located in Further, the light emitting part 16a is connected to the transformer tube [18], and the light receiving part 16b is connected to a power cutoff device 17 that cuts off the transformer power supply 18.

In the transformer of this embodiment having such a configuration, if refrigerant leaks due to poor connection of the cooling system inside or outside the transformer, the amount of refrigerant 15 supplied to the condenser 8 will decrease. , the liquid level of the liquefied refrigerant 15- begins to fall. As the liquid level decreases, the light reflection position moves, so the absorption area of the reflected light in the light receiving part 16b becomes smaller, and the leakage progresses further, causing the cold*15= liquid level to drop below a certain level. Then, the light receiving section 16b becomes unable to absorb light. As a result, the power supply device 17 is activated and the transformer power supply 18 is stopped, thereby preventing any further rise in temperature or pressure.

As described above, according to this embodiment, the temperature and pressure increases caused by leakage of refrigerant due to poor connections inside and outside the transformer can be minimized, and short circuits and explosion accidents of the transformer can be prevented. However, the present invention is not limited to this embodiment. For example, by changing the position of the light emitting part or the light receiving part, when the liquid level of the refrigerant 15- falls, the light receiving part 16
b may detect light from the light emitting section 16a and activate the power cutoff device 17. Furthermore, instead of directly cutting off the power, an alarm may be generated and the transformer power may be manually cut off.

Further, in the illustrated embodiment, the optical sensors 16a and 16b are installed in the condenser 8, but the same effect can be obtained by installing the sensors in a refrigerant retention area such as the refrigerant tank 10.

[Effects of the Invention] As described above, according to the present invention, a simple configuration in which an optical sensor for detecting the refrigerant liquid level is provided in a refrigerant retention part such as a condenser or a refrigerant tank provided outside the tank allows operation to be performed. Even if refrigerant sometimes leaks due to poor connection in the cooling system, increases in the temperature of the windings and the pressure of the refrigerant can be minimized, making it possible to prevent short circuits or explosions.

As a result, it is possible to provide a separate foil-wound transformer that is highly reliable even during long-term operation.

In particular, the present invention has the advantage that the liquid level of the refrigerant can be detected without using a float or the like, and the overall structure of the apparatus is simple and highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of a separate foil-wound transformer, and FIG. 2 is a sectional view of a condenser portion in an embodiment of the foil-wound transformer of the present invention. DESCRIPTION OF SYMBOLS 1... Leg of iron core, 2... Metal sheet, 3... Insulating sheet, 4... Low L1 winding, 5... High voltage winding, 6
...Cooling duct 1-17...Pump, 8...Condenser, 9...Cooling water pipe, 10...Refrigerant tank, 11...
・Liquid conduit, 12... Insulated vibe, 13... Tank,
15.15'... Refrigerant, 16... Displacement sensor, 16
a... Light emitting part of optical sensor, 16b... Light receiving part of optical sensor, 17... Power cutoff device, 18... Transformer power supply. 7317 Agent Patent Attorney Kensuke Chichi (1 other person) Figure 1 Figure 2, r18 9A-

Claims (1)

[Claims] (1) A metal sheet and an insulating sheet are overlapped and wound around the legs of an iron core to form a foil winding, and this foil winding is stored together with an insulating medium in a transformer tank. A separate foil-wound transformer in which a hollow cooling duct is inserted inside the winding, and a refrigerant cooled by a condenser provided outside the tank is circulated in the cooling duct in a state separated from the insulating medium, An optical sensor including a light emitting part and a light receiving part that detects light reflected from the refrigerant liquid surface out of the light from the light emitting part is provided in the refrigerant retention part such as the condenser, and this optical sensor is transformed into a A separate foil-wound transformer characterized in that it is connected to a power supply cutoff device or an alarm device for power cutoff.