JPH0581043B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an oil-immersed transformer, and in particular to uniform cooling of local overheating of tank components caused by the magnetic field of large current leads inside the transformer. The present invention relates to an oil-immersed transformer with an improved cooling structure.

(Prior Art) Generally, as the capacity of a transformer increases, the amount of leakage magnetic flux from the coil or the magnetic field of the large current lead increases. As a result, the amount of magnetic flux entering the transformer tank side wall also increases, increasing losses due to eddy currents,
This causes the problem of overheating of the tank side wall. In addition, in recent years, as the capacity of transformers has become extremely large, not only countermeasures against magnetic flux leakage from the coils but also local overheating of the tank side wall facing the high current lead have become a problem. Since it is one-sided cooling and heat dissipation by oil flow cannot be expected, it has become necessary to take sufficient measures to prevent local overheating. Also,
Measures to prevent overheating of tank top walls have become an extremely important issue from the standpoint of ensuring safety during inspections.

Therefore, as a solution to these problems,
In order to reduce eddy current loss due to magnetic flux leakage from the coil and to prevent overheating of the side wall of the tank of the transformer, a method has been adopted in which a magnetic shield is installed inside the tank wall facing the coil. on the other hand,
Measures to prevent local overheating of the tank side wall due to the magnetic field of the large current lead include using non-magnetic steel for the tank component facing the large current lead, installing an electromagnetic shield made of a good conductor such as aluminum on the tank wall, or Methods such as widening the gap between the high current lead and the tank wall to weaken the influence of the magnetic field have been adopted.

FIGS. 2 and 3 are cross-sectional views of essential parts of an oil-immersed transformer configured to take this type of measure. In FIGS. 2 and 3, a transformer main body consisting of an iron core 1 and a coil 2 wound around the iron core 1 is housed inside a tank 5 filled with insulating oil 4. As shown in FIG. Further, a large current lead 3 led out from the coil 2 is arranged near and along the tank top wall 5a, and led out to the outside of the tank 5 via a bushing 6. On the other hand, a magnetic shield 7 made of, for example, a silicon steel strip is attached to the side wall 5b of the tank 5 facing the coil 2 to reduce eddy current loss due to leakage magnetic flux from the coil 2 and prevent overheating of the tank side wall 5b. I'm starting to do that. In addition, as shown in FIG. 2, a tank top wall 5 facing the high current lead 3
a. A non-magnetic steel material 8 may be used for a part of the tank side wall 5b, or an electromagnetic shield 9 may be installed with a gap provided in the tank 5 as shown in the cross-sectional view of the main part in FIG. This prevents local overheating of the tank components due to the magnetic field.

However, the large current lead 3 as mentioned above
In order to prevent overheating of the tank components, the method shown in FIG. There is a problem in that the cost is extremely high, such as the need to use non-magnetic steel for the other parts. In addition, in the method shown in Fig. 3, although the electromagnetic shield 9 has the effect of suppressing the magnetic field of the large current lead 3, the magnetic field concentrates at the end of the electromagnetic shield 9 and damages the tank wall. Because of overheating, it is not only necessary to install the electromagnetic shield 9 over a wide area, but also the electromagnetic shield 9 needs to be installed insulated on the tank wall, making the configuration extremely complicated and costly. There is a problem with that.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned problems, and its purpose is to prevent local overheating of the tank wall due to the magnetic field of the large current lead without complicating the device configuration. To provide a high-quality, inexpensive, highly reliable oil-immersed transformer with excellent safety and which can reliably prevent damage.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the oil-immersed transformer of the present invention provides a large current drawn from a coil that is wound around an iron core and constitutes the main body of the transformer together with the iron core. The tank is equipped with an oil feed type cooler in which a lead is placed near the top wall of the tank and communicates with the inside of the tank via cooling piping, wherein at least one side is open on the inside surface of the tank top wall. The present invention is characterized in that a channel-shaped oil pipe is installed along the large current lead, and the cooling pipe and the channel-shaped oil pipe are communicated with each other.

(Function) In the oil-immersed transformer described above, an oil channel is formed on the inner surface of the top wall of the tank near the large current lead, parallel to the large current lead, and this oil channel is used for intensive oil feeding type cooling. Because it communicates with the tank piping, a strong oil flow is generated inside the oil pipe, and the cooling effect of the insulating oil evens out local overheating of the tank wall caused by the magnetic field of the high current lead. It will be cooled down.

(Example) The present invention will be described below with reference to an example shown in the drawings.

FIG. 1 is a cross-sectional view showing an example of the main part configuration of an oil-immersed transformer according to the present invention, and the same parts as in FIGS. This will be omitted and only the different parts will be described here.

In FIG. 1, the inner surface of the tank top wall 5a facing the large current lead 3 led out from the coil 2 and placed above the transformer interior has an appropriate cross-sectional area in consideration of the generated loss and the amount of circulating oil. A channel-shaped oil pipe 11 is installed along and parallel to the large current lead 3. This channel-shaped oil pipe 11 is open at one end or both ends, that is, at least one end, and the oil pipe 11 is opened on the side of the tank side wall 5b.
An oil guide hole 12 is opened according to the pressure loss in the oil pump 1, and a cooling pipe 15 is connected to a strong oil feed type cooler 14 equipped with an oil feed pump 13.

In an oil-immersed transformer with such a configuration, on the inner surface of the tank top wall 5a adjacent to the high current lead 3,
By configuring the oil conduit 11 in parallel with the large current lead 3 and communicating this oil conduit 11 with the piping of the strong oil feed type cooler, a strong oil flow is generated inside the oil conduit 11. Due to the cooling effect of the insulating oil, the local overheating of the tank wall in the vicinity due to the magnetic field of the large current lead 3 is uniformly and sufficiently cooled. As a result, local overheating of the nearby tank wall due to the magnetic field of the large current lead 3 can be reliably prevented.

As described above, in this embodiment, the large current lead 3 led out from the coil 2 that is wound around the iron core 1 and forms the main body of the transformer together with the iron core 1 is arranged near the tank top wall 5a, and In an oil-immersed transformer comprising an oil-feed type cooler 14 that communicates with the tank 5 via a cooling piping 15, an oil channel-shaped oil channel with at least one side open is provided on the inner surface of the tank top wall 5a. The pipe 11 is installed along the high current lead 3, and the cooling pipe 1 is installed along the high current lead 3.
5 and a channel-shaped oil pipe 11 are configured to communicate with each other.

Therefore, it is possible to reliably prevent local overheating of the tank wall due to the magnetic field of the large current lead 3.
In addition, in order to prevent this local overheating, as mentioned above, non-magnetic steel material is attached to the top wall 5a and side wall 5b of the tank 5, and a part of the tank reinforcing material 10 is also made of non-magnetic steel material. In addition, since there is no need to install electromagnetic shields over a wide area, it is possible to simplify the configuration and reduce costs, making it possible to create high-quality, safe, and extremely reliable oil-immersed transformers. You can get the equipment.

Note that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, a large current lead drawn out from a coil that is wound around an iron core and constitutes the main body of a transformer together with the iron core is arranged near the upper wall of the tank, and is placed inside the tank. In a device equipped with an oil feed type cooler that communicates via cooling piping, on the inner surface of the upper wall of the tank,
A channel-shaped oil pipe with at least one side open is installed along the high-current lead, and the cooling pipe and the channel-shaped oil pipe are connected to each other, so that the magnetic field of the high-current lead can cause damage to the tank wall. It is possible to provide a high-quality, inexpensive, extremely safe and extremely reliable oil-immersed transformer that can reliably prevent local overheating without complicating the device configuration.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an embodiment of an oil-immersed transformer according to the present invention, and FIGS. 2 and 3 are sectional views showing an example of the main part configuration of a conventional oil-filled transformer. 1...Iron core, 2...Coil, 3...High current lead, 4
…Insulating oil, 5…Tank, 5a…Tank top wall, 5
b... Tank side wall, 6... Bushing, 7... Magnetic shield, 8... Non-magnetic steel material, 9... Electromagnetic shield, 10...
Tank reinforcing material, 11...oil pipe, 12...oil guide hole, 13
...Oil pump, 14...Cooler, 15...Piping.

Claims (1)

[Claims] 1 A large current lead drawn out from a coil wound around an iron core and forming the main body of the transformer together with the iron core is placed near the upper wall of the tank, and a transmission line is connected to the inside of the tank via cooling piping. In the oil type cooler, a channel-shaped oil path with at least one side open is attached to the inner surface of the upper wall of the tank along the high current lead,
An oil-immersed transformer characterized in that the cooling pipe and the channel-shaped oil pipe are connected to each other.