JPS5925324B2 - Butching cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for installing a bushing having a center conductor in the form of an insulator tube and a hollow tube through the tank wall of an electrical device in which an insulating cooling medium is sealed and circulated, and the center conductor is placed inside the bushing. The present invention relates to a bushing cooling device that cools the electrical equipment by introducing an insulating cooling medium therein.

In low-voltage, high-current bushings used in large-capacity transformers, etc., the heat loss generated in the center conductor is large, and the temperature rise in the center of the center conductor may become excessive.

In order to keep such temperature rise in conventional bushings within predetermined limits, the cross section of the conductor is increased to reduce the current density. However, an increase in the cross section of the conductor directly leads to an increase in the size of the bushing as a whole, which inevitably increases costs, such as not only increasing the cost of the conductor material but also requiring a large-sized insulator tube. Therefore, the first
A forced cooling type bushing as shown in the figure has also been proposed. In FIG. 1, numeral 1 is a tank for an electrical device, for example a transformer, and is filled with oil as an insulating cooling medium. 2 is a bushing that is installed through the ceiling wall of the electrical equipment 1, and includes a hollow cylindrical center conductor 3, an insulator tube 4 concentrically surrounding it with a slight interval, and a bushing at both upper and lower ends of the center conductor 3. Terminal 5 which is arranged and also acts as a closure cap
, 6 as the main members.

The bushing 2 contains oil 7 as an insulating cooling medium of the same type as that inside the electrical equipment 1 to such an extent that the center conductor 3 is immersed therein. The annular space between the center conductor 3 and the insulator tube 4 is communicated with the inner hollow part of the center conductor 3 through small holes 8 and 9 formed at the upper and lower ends of the center conductor 3. Conduits 10 and 11 are led out from the bushing 2 so as to communicate with the upper and lower ends of the annular space between the center conductor 3 and the insulator tube 4, and the latter conduit 11 further penetrates the side wall of the electrical equipment 1. Both are led out to the outside. Conduits 10 and 11 are connected externally via a radiator 12 and a pump 13.
In the apparatus shown in FIG.
3 and a conduit 11, and during the circulation process, the heat of the oil is radiated by a radiator 12.

In other words, the oil absorbs the heat of the center conductor 3 within the bushing 2 and continues to radiate the heat within the radiator 12, thereby cooling the center conductor 3. This cooling method is certainly effective in terms of cooling performance, but on the other hand, it requires separate auxiliary equipment such as the radiator 12 and pump 13, and the bushing body also has a complicated structure around the terminals. This has the disadvantage that it is not only very expensive, but also requires additional maintenance of the auxiliary equipment.
The object of the present invention is to eliminate this drawback and provide a bushing cooling device that is small, inexpensive, does not require additional maintenance, and can effectively cool the center conductor. .

To achieve this object, the present invention provides a bushing cooling device in which the center conductor of the bushing is cooled by an insulating cooling medium in an electrical device, in which an opening is provided at the bottom of the insulator tube between the insulator tube and the center conductor. It is configured so that the insulated cooling medium in the tank of the electrical equipment can flow in, and five openings are provided at the top of the center conductor so that the insulated cooling medium outside the center conductor can flow into the inside of the center conductor. Or, one end of a tube made entirely of insulating material and placed entirely within electrical equipment is opened at the bottom of the center conductor to communicate with the inside of the center conductor, and the other end of the tube is an insulator that flows inside the electrical equipment. The tube is configured to have an opening in a constricted portion of the cooling medium flow and to create a negative pressure in the tube due to a relatively high flow rate of the insulating cooling medium in the electrical equipment flowing around the opening. The insulated cooling medium inside the electrical equipment is guided from the outside of the central conductor to the inside of the central conductor and circulated by leading the insulated cooling medium inside the central conductor into four channels. This will be explained in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which electrical equipment 15
For example, a transformer with a bushing 20 attached is shown.
Oil is sealed in the tank 16 as an insulating cooling medium. This oil is passed through a conduit 17 attached to the upper side wall of the tank 16.
The water is guided to a cooler (not shown) through the tank 16, and then reintroduced into the tank 16 from the lower part of the side wall of the tank 16. The bushings 20 are basically the same as shown in FIG. 1, and include a hollow cylindrical center conductor 21, an insulator tube 22 concentrically surrounding the center conductor 21 at a predetermined interval, and attached to both upper and lower ends of the center conductor 21. It has terminals 23 and 24. Bushing 20
is attached to the tank 16 in an oil-tight manner by penetrating the ceiling wall of the tank 16 by means of a mounting flange 25 joined to the insulator pipe 22. The upper ends of the center conductor 21 and the insulator tube 22 are oil-tightly closed by a removable cover plate 26 and a terminal 23. The space between the insulator tube 22 and the center conductor 21 communicates with the inside of the tank 16 through an opening 32 formed at the lower end of the insulator tube 22, so that the insulating cooling medium in the tank 16 flows therein. ing. Further, an opening 21a consisting of a large number of communication holes is formed in the upper part of the center conductor 21, and the insulating cooling medium outside the center conductor 21 flows into the inside of the center conductor 21 through the opening 21a. There is. Reference numeral 27 is a tube that is partially or entirely made of an insulating material and is entirely disposed within the electrical equipment 15, one end of which is 27b.
is attached to a perforated cap-shaped mounting auxiliary member 29 joined to the center conductor 21 at the lower end of the center conductor 21 by means of a support piece 28, and is open into the center conductor 21.

The other end 27a of the tube 27 is introduced into and held within the conduit 17 by a support member 30 attached to the side wall of the tank 16, and opens therein. In the apparatus shown in FIG. 2, while the electrical equipment 15 is in operation, a cooler (not shown) is also operated, and the oil in the tank 16 is circulated as shown by the chain arrow.

In that case, the oil flow 31a with a considerably high flow rate V flows through the conduit 17, which has a significantly smaller cross-sectional area than the tank 16.
occurs. Therefore, the tube 2 disposed within this conduit 17
A pressure difference is generated between the opening 27a of the tube 27 and the opening 27b of the tube 27 which is opened in the center conductor 21 of the bushing 20, and an oil flow 3 is generated in the tube 27 as shown by the solid arrow.
1b occurs. Therefore, the oil in the tank 16 flows through the opening 32 at the lower end of the insulator tube 22 and flows into the insulator tube 22 and the center conductor 21.
The liquid flows upward through the space between the center conductor 21, flows into the center conductor 21 through the opening 21a provided above the center conductor 21, and then descends and is led out through the tube 27. That is, Tanta 1
A portion of the oil in the center conductor 21 circulates outside and inside the center conductor 21, as shown by the solid arrow. As described above, in the bushing cooling device according to the present invention, the center conductor 21 can be cooled by circulating an insulating cooling medium, such as oil, filled in the tank 16 of the electrical equipment 15 in the bushing 20. And in this case, the oil is the center conductor 2
Since the central conductor 21 can be efficiently cooled by circulating in contact with both the outer wall surface and the inner wall surface of the central conductor 21, the current density of the central conductor 21 can be increased.

Further, the oil circulation in the bushing 20 is controlled by a tube in which one opening 27a is arranged in a part where the oil flow is restricted in the tank 16 of the electrical equipment 15, and the other opening 27b is arranged in a tube attached to the lower end of the center conductor 21. 27 negative pressure, there is no need for separate auxiliary equipment dedicated to cooling the bushings, such as a separate radiator or pump for electrical equipment, and the entire bushing becomes smaller and lighter, making it an inexpensive bushing. cooling equipment can be provided. Furthermore, the tube 27 is entirely located within the electrical equipment 15, and the oil inlet/outlet of the bushing 20 is located within the tank 16, so there is no need for a special oil-tight structure, which eliminates the need for maintenance and reduces maintenance costs. . FIG. 3 shows another embodiment of the present invention, in which a cylindrical barrier 33 is attached to a hollow portion within the center conductor 21 to form a circulation path for an insulating cooling medium.

In FIG. 3, the insulated cooling medium in the tank 16 passes through the opening 32, rises in the space between the insulator tube 22 and the center conductor 21, and flows inside the center conductor 21 from the opening 21a provided in the center conductor 21. It enters, descends between the barrier 33 and the center conductor 21, passes through the center conductor side opening 27b of the tube 27, flows out into the conduit 17, passes through a cooler (not shown), and is introduced into the tank 16 again. . By providing the barrier 33 in this manner, the cross section of the insulating cooling medium flow within the center conductor 21 becomes smaller and the flow velocity increases, so that the cooling efficiency of the center conductor 21 is further improved. Moreover, if you adjust the diameter of the barrier 33, the bushing 20
The flow rate of the insulating cooling medium flowing therein can be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing a conventional bushing cooling device, FIG. 2 is a partially sectional front view showing an embodiment of the bushing cooling device according to the present invention, and FIG. 3 is a partially sectional front view showing an embodiment of a bushing cooling device according to the present invention. FIG. 2 is a partially sectional front view showing an example. 15...Electrical equipment, 16...Tank,
17... Cooling conduit, 20... Bushing, 21... Center conductor, 22... Insulator tube, 21a, 32... Opening, 27...
Tuyub, 33...Bariya.

Claims (1)

[Claims] 1. A bushing having an insulating pipe penetrating the tank wall and a hollow tubular center conductor arranged at a predetermined interval within the insulating pipe is attached to the wall of an electrical equipment tank in which an insulating cooling medium is sealed and circulated, The center conductor is cooled by introducing an insulating cooling medium in the electrical equipment into the center conductor, wherein an opening is provided at a lower part of the insulator tube to cool the insulating cooling medium between the insulator tube and the center conductor. The structure is configured such that an insulated cooling medium in a tank of the electrical equipment can flow in, and an opening is provided in the upper part of the center conductor so that the insulated cooling medium outside the center conductor can flow into the inside of the center conductor. One end of the tube, part or all of which is made of an insulator and which is placed inside the electrical equipment, is opened at the bottom of the central conductor and communicates with the inside of the central conductor, and the other end of the tube is placed inside the electrical equipment. The tube is configured to have an opening in a constricted portion of the insulating cooling medium flowing through the tube so that a negative pressure is generated in the tube due to a relatively high flow rate of the insulating cooling medium flowing around the opening in the electrical equipment. The insulating cooling medium in the electrical equipment is guided and circulated from the outside to the inside of the central conductor by drawing out the insulating cooling medium in the central conductor using negative pressure inside the central conductor. bushing cooling device.