JPS5925325B2 - Butching cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves installing a bushing having a hollow tubular center conductor through a tank wall of an electrical device that encloses and circulates an insulating cooling medium, and inserting the center conductor inside the bushing. The present invention relates to a bushing cooling device that cools an electrical device by introducing an insulating cooling medium therein.

As is well known, in bushings, especially low-voltage, high-current bushings used in large-capacity transformers, the heat loss generated in the center through conductor is large, and the temperature rise in the center of the conductor may become excessive.

Conventionally, in order to keep such temperature rise in the bushing within predetermined limits, the cross-sectional area of the conductor is increased to reduce the current density. However, an increase in the cross-sectional area of the conductor directly leads to an increase in the size of the entire bushing, which not only increases the cost of the conductor material, but also requires a large-sized insulator tube of one rank or more, which also reduces costs from this point of view. becomes higher. Therefore, a forced cooling type as shown in FIG. 1 has also been proposed. In Fig. 1, 1 is a tank for electrical equipment, for example, a transformer.Although not shown in the figure, the contents of the equipment, such as iron cores and windings, are housed in the tank, and oil is sealed as an insulating cooling medium. It is assumed that there is

A bushing 2 is attached to the tank 1 by penetrating its ceiling wall. The bushing 2 is a hollow cylindrical center conductor 3
and an insulator tube 4 that surrounds this concentrically at a slight interval.
The main components are terminals 5 and 6, which are arranged at both the upper and lower ends of the central conductor 3 and act as closing caps. Oil 7 is stored in the bushing 2 as an insulating cooling medium of the same type as in the tank 1 to such an extent that the core 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 tank 1 and is connected to the upper and lower ends of the annular space between the center conductor 3 and the insulator tube 4. Externally derived. Both conduits 10, 11 are connected externally via a radiator 12 and a pump 13. 1st
In the device shown in the figure, the insulating cooling medium, that is, oil, in the bushing 2 is forcibly circulated by the pump 13 through the conduit 10, the radiator 12, the pump 13, and the conduit 11, and during the circulation process, the radiator 12 heats the oil. dissipate.

That is, the oil absorbs the heat of the center conductor 3 within the bushing 2,
The center conductor 3 is cooled by continuing to radiate heat within the radiator 12. 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 old Bushing type also has a complicated structure around the air terminal. Therefore, it 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 cooling device for bushings that is small, inexpensive, does not require additional maintenance, and is capable of effectively cooling the center conductor. .

To achieve this object, the present invention provides a bushing cooling device of the type mentioned at the outset, in which one end of a tube partially or entirely made of an insulator is connected from the interior side of a tank of an electrical equipment to the side of the center conductor of the bushing. The tube opening is placed in the tube opening and the other end is opened to a constricted part of the insulating cooling medium flowing through the electrical equipment, and the insulating cooling medium flowing in the electrical equipment flows around the tube opening placed in this constricted part. It is characterized in that the insulated cooling medium in the electrical equipment is guided into the central conductor and circulated by using the negative pressure generated in the tube due to the relatively high flow rate of the cooling medium. This will be explained in detail with reference to the following page.

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.

The contents of the electrical equipment 15, ie, the iron core and windings, are housed in the tank 16, but illustration thereof is omitted. tank 16
Oil is sealed inside as an insulating cooling medium. This oil is led to a cooler (not shown) through a conduit 17 attached to the upper part of the side wall of the tank 16, and is reintroduced into the tank 16 from the lower part of the side wall of the tank 16. The bushing 20 is basically the same as that shown in FIG. 1, and includes a hollow cylindrical center conductor 21, an insulator tube 22 concentrically surrounding the center conductor 21 at a predetermined interval, and a bushing 22 attached to both upper and lower ends of the center conductor 21. It has terminals 23 and 24. Bushing 20 is insulator tube 2
The mounting flange 25 connected to the tank 16 penetrates the ceiling wall of the tank 16 and is oil-tightly mounted to the tank 16.
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 lower end of the insulator tube 22 is also oil-tightly sealed to the center conductor 21 via a seal member 27. center conductor 21
The lower end of the center conductor 21 is open, and the hollow part of the center conductor 21 is
The center conductor 21 is in communication with the tank 16 of No. 5, and is filled with oil up to the upper end of the center conductor 21, as shown by an oil level 28.

Reference numeral 29 is a tube partially or entirely made of an insulating material, and one end of the tube is wired from the inner chamber side of the tank 16 to the adapter 30 on the side surface of the center conductor 21.

The inner surface of this adapter 30 has a ring-shaped groove 31, and the center conductor 21 facing this groove 31 has one or more communication ports, which connect the inside of the center conductor 21 and the tube 29. They are communicated via an adapter 30. A cylinder 18 made of metal or an insulator is attached to the center conductor 21. One end of the cylinder 18 is held in an oil-tight manner at the lower terminal 24, and the other end is held slightly below the oil level 28. While opening, a support member is appropriately placed between the center conductor 21 and the center conductor 21 in order to maintain a concentric position with the center conductor 21, but its illustration is omitted. The other end of the tube 29 is introduced into and held within the conduit 17 by a support member 32 attached to the side wall of the tank 16, and opens therein. Its opening is 29
Indicated by a. In the apparatus shown in Fig. 2, electrical equipment 1
5 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, an oil flow 33a with a considerably high flow velocity V occurs in the conduit 17, which has a significantly smaller cross-sectional area than the cross-sectional area of the tank 16. Therefore, there is a gap between the opening 29a of the tube 29 disposed in the conduit 17 and the opening 29b of the tube 29 disposed in the adapter 30 on the side of the center conductor 21, according to Bernoulli's theorem, which is well known in itself. As a result, a pressure difference is generated such that the opening 29a has a negative pressure with respect to the opening 29b, and an oil flow 33b is generated between the cylinder 18 and the center conductor 21 as shown by the solid arrow. Therefore, the oil in the tank 16 flows through the opening 19 of the lower terminal 24 of the bushing to the center conductor 21.
An oil flow 33c flows upward inside the cylinder 18, and part of the oil in the tank 16 as a whole circulates between the center conductor 21 and the annular portion of the cylinder 18 as shown by the solid arrow. Flow velocity V of the oil flow 33b on the inner surface of the center conductor 21 of the bushing
can be determined as a function of the flow velocity V of the oil flow 33a in the conduit 17 using the cross-sectional areas and fluid resistance of the tube 29, center conductor 21, cylinder 18, and conduit 17, and an example of this is shown in Fig. 3. Become. Therefore, in the bushing cooling device according to the present invention, the center conductor 21 of the bushing 20
An insulating cooling medium, such as oil, filled in a tank 16 of an electrical device 15 such as a transformer can be circulated inside the center conductor 21 for cooling.
Since the fluid circulates by rising inside the tube 18 and then descending outside, the cross section of the flow path in the center conductor 21 becomes smaller and the flow rate becomes faster. Furthermore, the presence of the cylinder 18 forms a continuous flow path within the central conductor 21, so that the oil flows smoothly without stagnation. For this reason, the center conductor 21
cooling becomes even better, and the current density of the center conductor 21 can be increased. In addition, for oil circulation in the bushing, one opening 29a is connected to the tank 1 of the electrical equipment 15.
The other opening 29 is arranged in the part where the oil flow is restricted in 6.
b is performed by the negative pressure of the tube 29 attached to the side of the center conductor 21, so there is no need for separate auxiliary equipment for butting, such as a heat radiator or pump separate from those for the main body of the electrical equipment. Therefore, the bushing as a whole becomes small and lightweight, and an inexpensive bushing cooling device can be provided. Moreover, since the tube 29 is disposed within the tank 16 and does not require a special oil-tight structure, there is almost no need for maintenance and maintenance costs are reduced. Also, since the tube 29 is attached to the side of the center conductor 21, the center conductor 21
The internal connection between the lower terminal 24 of the tube and the contents of the electrical equipment can be easily made, and the center conductor 21 can be easily connected no matter where the other end of the tube 29 is placed around the bushing.
If you rotate it and place it facing that direction, tube 2
9 can be configured with the shortest length, and there is no need to wrap the tube 29 around the bushing.
Configuration becomes easier. Note that the number of tubes provided according to the present invention is not limited to one; for example, as shown in FIG. Among the plurality of open tubes 35, 36, 37, the other end of the tube 35 is opened into the first conduit 17 as in the case of FIG. It opens into a conduit 38 for an insulating fluid cooling circuit configured on the opposite side, and the other end of the third tube 37 can also open into a conduit of another cooling circuit, not shown. With this configuration, even if the oil flow in one of the cooling circuits should stop, the bushings can continue to be cooled by the oil flow in other healthy cooling circuits. Further, the electrical equipment 15 usually has a plurality of bushings 20A, 2 as shown in FIG.
0B, but in this case, attach one end to each bushing 20
Tube 40 arranged on the side of center conductor 21 of A, 20B
The other ends of A and 40B may be connected together through a common tube 41, and one end of the common tube 41 may be introduced into the conduit 17/\ of the cooling circuit. As explained above, according to the present invention, without requiring additional maintenance,
It is possible to provide a bushing cooling device that can be constructed in a small size and at low cost, and can cool the center conductor well.

[Brief explanation of drawings]

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 an equipment related to an insulating cooling medium. A characteristic diagram showing an example of the relationship between the flow velocity in the cooling conduit and the flow velocity in the bushing in the main body, and FIGS. 4 and 5 are partially sectional front views showing other embodiments of the present invention. 15...Electrical equipment, 16...Tank,
17, 38... Cooling conduit, 18, 18A, 18
B...tube, 20, 20A, 20B...
Bushing, 21... Center conductor, 22...
...Insulator tube, 23,24...Terminal, 29,35,
36, 37, 40A, 40B, 41... tube, 30... adapter.

Claims (1)

[Claims] 1. A bushing having a hollow tubular center conductor is attached to the tank wall of an electrical device in which an insulating cooling medium is sealed and circulated, so as to pass through the tank wall, and a bushing having a hollow tubular center conductor is installed inside the center conductor. The central conductor is cooled by introducing an insulating cooling medium inside the electrical equipment, wherein a cylinder having both ends in the axial direction open is disposed inside the central conductor, and one opening of the cylinder is provided. The other opening of the tube is arranged in communication with the outside of the bushing so that an insulating cooling medium in the electrical equipment can flow therein, and the other opening of the tube is disposed in the insulating cooling medium in the center conductor so as to be connected to the inside of the tube. The insulating cooling medium of the bushing is configured to be able to move to the outside of the tube through the other opening, and one end of the tube, which is partially or entirely made of an insulating material and is entirely disposed within the electrical equipment, is connected to the center of the bushing. An insulating cooling medium having an opening in the side surface of the conductor and communicating with the outside of the tube, and having the other end of the tube open to a narrowed part of the insulating medium flow flowing in the electrical equipment, and flowing around this opening. Negative pressure is generated in the tube due to a relatively high flow rate of A cooling device for a bushing, characterized in that a medium is circulated from the inside of the cylinder in the center conductor to the outside. 2. One end of each of the plurality of tubes is opened in a circumferentially distributed manner on the side surface of the center conductor, and the other ends of these plurality of tubes are opened in different parts where the flow of the insulating cooling medium is restricted. Claim 1 characterized by
Cooling device for the bushing as described in section. 3. One end of each of the plurality of tubes is opened to the center conductor of the plurality of bushings, and the plurality of tubes are communicated with each other so that one end is opened to a part where the flow of the insulating cooling medium is constricted. A bushing cooling device according to claim 1.