JP3846176B2 - Water cooling bushing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to bushings to perform the cooling by water.
[0002]
[Prior art]
Bushings used in electrical equipment such as transformers and rotating electrical machines are cooled by passing a refrigerant such as gas or oil through the bushing to cool the heat generated by the electrical resistance of the conductor. .
[0003]
2. Description of the Related Art Conventionally, in cooling of a bushing of a rotating electric machine, a number of gas cooling systems are used in which a cooling gas filled in the machine is also introduced into the bushing and circulated for cooling. An example of this type of gas cooling bushing is disclosed in Japanese Patent Application Laid-Open No. 58-206012. In this case, since the same cooling gas is filled inside and outside the bushing, the sealing condition between the ventilation tube and the hollow conductor is relatively loose, and sealing is performed by an O-ring.
[0004]
On the other hand, with the recent increase in capacity of rotating electrical machines, the current flowing through the hollow conductor of the bushing has also increased, and there have been examples in which the amount of generated heat exceeds the limit that can be cooled by gas. In such a case, a water-cooled bushing may be employed in which cooling water used for cooling the rotating electrical machine stator winding is guided and circulated in the bushing instead of the gas to be cooled.
[0005]
[Problems to be solved by the invention]
When the water-cooled bushing is employed, the bushing is filled with a cooling gas, and the cooling water flows inside the bushing. Therefore, the bushing sealing structure is very important. If this is insufficient, leakage of cooling water into the rotating electrical machine or conversely leakage of cooling gas into the bushing occurs. In either case, the cooling efficiency of the bushing deteriorates, which may result in serious damage to the rotating electrical machine.
[0006]
As described above, in the gas cooling bushing, an O-ring can be used for sealing between the ventilation pipe and the hollow conductor. Sealing with an O-ring is a simple method, and can be a very effective sealing means even in a water-cooled bushing if it is a site where maintenance and inspection are easy to perform. However, if water leaks from the O-ring part in the rotating electrical machine, the relevant part cannot be accessed directly while the rotating electrical machine is operating, so the rotating electrical machine is stopped only for O-ring replacement work. In addition, it is necessary to perform time-consuming and labor-intensive work such as replacing all the cooling gas with air. Rotating electrical machines that pass large currents that require water-cooled bushings require high reliability that can withstand long-term continuous operation. It is necessary to apply a sealing method that is more reliable than the O-ring for sealing between the wire and the hollow conductor.
[0007]
The present invention has been made in view of the above problems, its object is to provide a water cooling bushings to reduce the possibility of water leakage.
[0008]
[Means for Solving the Problems]
The present invention includes an insulating pipe, a copper hollow conductor that exchanges electricity with an external device housed in the insulating pipe, and a stainless steel water pipe that passes through the hollow conductor, and the hollow conductor In the water-cooled bushing for cooling by flowing cooling water into the water pipe , a copper connection member is provided between the water pipe and the hollow conductor, and the copper connection member, the hollow conductor, and the water pipe are respectively provided. The above-mentioned object is achieved by forming by brazing .
[0010]
In other words, the water-cooled bushing configured as described above has a structure in which the entire connecting portion including the water pipe, the hollow conductor, and the connecting member has a very high sealing performance, so that the possibility of water leakage can be reduced.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail based on the illustrated embodiments. FIG. 1 is a sectional view showing an embodiment of the water-cooled bushing of the present invention. The water-cooled bushing in the figure is provided with an insulating tube 1, a hollow conductor 2, and a water pipe 3 provided therein. In FIG. 1, the flow 4 of cooling water descends the inner surface of the water pipe as indicated by an arrow, and rises in the space constituted by the outer surface of the water pipe and the inner surface of the conductor. At this time, the heat generated by the electrical resistance of the conductor is taken away and cooling is performed. Further, the cooling water is drained to the rotating electric machine outlet side. The flow of cooling water can be in the opposite direction.
[0012]
In this embodiment, the water pipe and the hollow conductor are connected by welding or brazing. Therefore, unlike a sealing structure such as an O-ring, the structure is fundamentally highly sealed. Also, there is very little worry about deterioration over time. Therefore, it is very excellent as a connection method for a part that is in a rotating electrical machine such as the part and is difficult to perform maintenance and inspection easily.
[0013]
In general, since the hollow conductor is made of copper having a low electrical resistance, when the water pipe is copper, the copper is welded or brazed to each other, and a relatively widely used technique can be applied. Is advantageous. As another example, when the water pipe is made of stainless steel, it is brazed between stainless steel and copper, and technically, a higher level is required compared to the case of copper, but it is made of stainless steel. There is no worry about corrosion due to cooling water in the water pipe, and it is also superior in mechanical strength compared to copper, so there is a possibility that the water cooling bushing can be downsized. If the problem of connection technology can be solved, the water cooling bushing As an excellent one.
[0014]
FIG. 2 shows another embodiment of the present invention. In this embodiment, a connecting member 5 is provided between the water conduit 3 and the hollow conductor 2. As described above, advanced techniques are required for brazing copper and dissimilar metals, particularly stainless steel. One reason for this is that a joining operation at a higher temperature is required as compared with the joining of copper. When trying to braze the hollow conductor directly to the water pipe, heat escapes to the side of the hollow conductor, which has a large heat transfer compared to the water pipe, and it is difficult to heat the brazed surface efficiently and evenly. Become. Therefore, a part where the flow of the solder is insufficient is generated on the brazing surface, and as a result, there is a possibility that water leaks from the part.
[0015]
However, when the connection member 5 is provided between both as in this embodiment, the connection member 5 is selected by considering the material and shape of the connection member 5 in consideration of the compatibility of the connection with the water pipe and the hollow conductor, heat transfer, etc. The reliability of the part can be improved.
[0016]
As an example, a case where the connecting member is made of the same copper as the hollow conductor will be described as an example. First, brazing of stainless steel water pipes and copper connection members is performed, but by optimizing the shape of the connection members in consideration of heat transfer, the temperature required for high-temperature brazing is achieved evenly and efficiently. And as a result, a very good bonding state can be obtained. After that, the connecting member and the hollow conductor are brazed as usual. However, the brazing of copper at this time is a lower temperature than the brazing of stainless steel and copper, so there is no effect on the high temperature brazing surface. Can be connected without giving. When a connecting member is provided as in this embodiment, the number of brazing operations is increased by one, but the workability of brazing between stainless steel and copper, which has been difficult, is remarkably improved, and the reliability of the joint is also extremely high. The possibility of water leakage can be reduced.
[0017]
【The invention's effect】
Since the present invention is configured as described above, it is possible to improve the sealing performance between the water pipe and the hollow conductor and the reliability thereof, and to provide a water-cooled bushing that reduces the possibility of water leakage and a manufacturing method thereof. Obtainable.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a water-cooled bushing according to the present invention.
FIG. 2 is a cross-sectional view showing another embodiment of the water-cooled bushing of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulation tube, 2 ... Hollow conductor, 3 ... Water flow pipe, 4 ... Flow of cooling water, 5 ... Connection member.

Claims (1)

An insulating tube; a copper hollow conductor that exchanges electricity with an external device housed in the insulating tube; and a stainless steel water conduit that penetrates the hollow conductor; the hollow conductor and the water conduit In a water-cooled bushing for cooling by flowing cooling water into a pipe , a copper connection member is provided between the water pipe and the hollow conductor, and the copper connection member, the hollow conductor and the water pipe are brazed and joined, respectively. A water-cooled bushing characterized by being formed .

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