JPS5843842B2 - butsushinnoreiyakusouchi - Google Patents

Description

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

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 a temperature rise in the bushing within a predetermined limit, 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, in which the contents of the equipment consisting of iron cores, windings, etc. (not shown) are stored, and oil is sealed as an insulating cooling medium. It is assumed that

A bushing 2 is attached to the tank 1 by penetrating its ceiling wall.

The bushing 2 includes a hollow cylindrical center conductor 3, an insulator tube 4 concentrically surrounding the center conductor 3 at a slight interval, and a center conductor 3.
The main components are terminals 5 and 6, which are arranged at both upper and lower ends of the terminal and also act as a closing cap.

Oil 1 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 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 connected from the bushing 2 to the upper and lower ends of the annular space between the center conductor 3 and the insulator pipe 4.
The latter conduit 11 further passes through the side wall of the tank 1 and is led out together.

Both conduits 10, 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.

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 bushing itself has a complicated structure around the air terminal. 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 and inexpensive, does not require additional maintenance, and can effectively cool the center conductor. be.

To achieve this object, the present invention provides a cooling device for a bushing of the type mentioned at the beginning, in which an opening is formed at the end of the bushing on the side of the electrical equipment tank for introducing the insulating cooling medium into the bushing in the tank. , one end of the tube, which is partially or entirely made of an insulating material and which is placed entirely inside the electrical equipment, is inserted into the bushing from the interior of the tank of the electrical equipment to open it, and the other end is inserted into the bushing. Insulation in electrical equipment that is placed along the flow direction and opens downstream in a constricted section of the insulating cooling medium flow, and that flows around a tube opening placed in this constricted section. It is characterized in that the insulating cooling medium in the electrical equipment is guided and circulated through the opening into the bushing 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 drawings.

FIG. 2 shows an embodiment of the present invention, in which electrical equipment 15
, for example, shows a transformer with a bushing 20 attached thereto.

The contents of the electrical equipment 15, ie, the iron core and windings, are housed in the tank 16, but illustration thereof is omitted.

Oil is sealed in the tank 16 as an insulating cooling medium.

This oil is led to a cooler (not shown) via 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. It has attached terminals 23 and 24.

The bushing 20 is a mounting flange 2 joined to the insulator pipe 22.
5 penetrates the ceiling wall of the tank 16 and is attached to the tank 16 in an oil-tight manner.

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 also has a seal member 2 against the center conductor 21.
Oil-tightly sealed via γ.

The lower end of the center conductor 21 is open, and the hollow part of the center conductor 21 communicates with the inside of the tank 16 of the electrical equipment 15, and the oil level 2
As shown at 8, the center conductor 21 is filled with oil up to its upper end.

Reference numeral 29 is a tube partially or entirely made of an insulating material, one end of which is inserted into the center conductor 21 from the interior side of the tank 16 and opens slightly below the oil level 28.

The tube 29 has a perforated cap-shaped mounting auxiliary member 30 connected to the center conductor 21 at the lower end of the center conductor 21.
and the supporting piece 31 attached to the central conductor 21.
It is held almost concentrically with respect to the

A supporting member is appropriately arranged between the tube 29 and the center conductor 21 in order to maintain a concentric position at the upper end thereof, but the illustration thereof is omitted.

The other end of the tube 29 is introduced into the conduit 17 along the oil flow direction and held by a support member 32 attached to the side wall of the tank 16, and is open toward the downstream side of the oil flow.

Its opening is indicated at 29a.

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 this case, an oil flow 33a having a considerably high flow rate 2 is generated in the conduit 1γ having a cross-sectional area significantly smaller than that of the tank 16.

Therefore, according to Bernoulli's theorem, which is well known per se, there is , opening 29a
A pressure difference such as a negative pressure is generated with respect to the open LI portion 29b, and an oil flow 33b as shown by the solid arrow is generated within the tube 29.

Therefore, the oil in the tank 16 is transferred to the center conductor 21 of the bushing.
Flows into the center conductor 21 from the lower opening of the center conductor 2
Oil flow 3 flowing upward in the annular portion between 1 and tube 29
3c occurs, and a portion of the oil in the tank 16 as a whole circulates within the center conductor 21 as shown by the solid arrow.

The flow velocity () of the oil flow 33c on the inner surface of the central conductor 21 of the bushing is determined by the flow velocity V of the oil flow 33a in the conduit 17 due to the cross-sectional areas and fluid resistance of the tube 29, the center conductor 21, and the conduit 17.
It can be found as a function of

In other words, by changing at least one of the cross-sectional areas and fluid resistance of the tube 29, the center conductor 21, and the conduit 17, the cooling capacity of the bushing can be adjusted almost independently of the cooling capacity of the main body of the electrical equipment 15. I can do it.

It should be noted that the negative pressure generated in tube 29 increases as the flow velocity V in cooling conduit 17 increases, and the flow velocity V in bushing center conductor 21 increases accordingly.

FIG. 3 shows an example of the relationship between the flow velocity ■ and the flow velocity V.

As described above, in the device of the present invention, the central conductor 21 of the bushing 20 is cooled by circulating an insulating cooling medium, such as oil, filled in the tank 16 of the electrical equipment 15 such as a transformer. 21, the current density can be high, and there is no need for separate auxiliary equipment for the bushing, such as a separate radiator or pump for the electrical equipment, and it has a liquid-tight structure against the existing tank wall. Since no piping is required, it is possible to provide an inexpensive bushing cooling device in which the entire bushing is small and lightweight.

Moreover, since the device of the present invention requires almost no maintenance,
Maintenance costs are also lower.

Note that the number of tubes provided according to the present invention is not limited to one; for example, as shown in FIG. The other end of the tube 35 is opened into the first conduit 17 as in the case of FIG. The other end of the third tube 3γ can also be opened into a conduit of another cooling circuit (not shown).

According to this configuration, even if the oil flow in one of the cooling circuits stops, the bushing can be continued to be cooled by the oil flow in other healthy cooling circuits.

Usually, a plurality of bushings 20A and 20B are attached to the electrical equipment 15, as shown in FIG.
Open tube 40A.

The other ends of 40B may be connected together with a common tube 41, and one common tube 41 may be introduced into the conduit 17 of the cooling circuit.

[Brief explanation of drawings]

FIG. 1 is a partially sectional front view showing a conventional cooling device, FIG. 2 is a partially sectional front view showing an embodiment of the device of the present invention, and FIG. A characteristic diagram showing an example of the relationship between the flow velocity and the flow velocity in the bushing, and FIGS. 4 and 5 are cross-sectional views showing other embodiments of the present invention, respectively. 15...Electrical equipment, 16...Tank,
1γ. 38... Cooling conduit, 20, 20A, 20B...
... Bushing, 21 ... Center conductor, 22
・・・・・・Insulator, 23.24・・・Terminal, 29
, 35, 36, 37° 40A, 40B, 41...
·tube.

Claims (1)

[Scope of Claims] 1. A bushing having a hollow tubular center conductor is installed through the tank wall of an electrical device in which an insulating cooling medium is sealed and circulated, and the insulating material inside the electrical device is installed inside this bushing. In a bushing cooling device that cools the center conductor by introducing a cooling medium, an opening for introducing an insulating cooling medium in the tank into the bushing is formed at an end of the bushing on the electrical equipment tank side, and a part Alternatively, one end of the tube, which is entirely made of an insulating material and which is entirely disposed within the electrical equipment, is inserted into the bushing from the inside of the tank of the electrical equipment to open it, and the other end is inserted into the electrical equipment. Insulation in electrical equipment that is placed along the flow direction in a constricted part of the flowing insulation coolant stream and opened toward the downstream side, and that flows around a tube opening placed in this constricted part. A cooling device for a bushing, characterized in that the insulating cooling medium in the electrical equipment is introduced into the bushing through the opening and circulated by using negative pressure generated in the tube due to a relatively high flow rate of the cooling medium.