JPH10283860A - Bushing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent heat radiation near an oil-immersed terminal by forming grooves composing a cooling fin of the oil-immersed terminal of a bushing in a manner that the depth near the connection conductor is made shallow and the depth of each groove is made deeper step by step toward the center of the conductor. SOLUTION: Main flow 6 of electric current flows along an oil-immersed terminal 5b to a connection conductor 4 and while leaving the part along the flow of a cooling fin 7b grooves of the cooling fin 7b are formed by using the parts out of the main flow. Consequently, since no significant difference is caused between the surface area of the oil-immersed terminal 5b and the surface area of a conventional oil terminal, approximately same cooling function can be obtained and abnormal electric resistance increase can be prevented. Moreover, since the electric conductive route is sufficiently retained, the temperature elevation due to electric current concentration is reliably moderated. Furthermore, the strength against the vibration of the cooling fan can be improved by using a structural aluminum material provided with a mechanical strength for a center conductor of the bushing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bushing having a cooling fin provided in a submerged terminal, and more particularly to a technique for suppressing heat generated in a submerged terminal portion by energizing the bushing to improve a cooling effect.

[0002]

2. Description of the Related Art The structure of a conventional bushing will be described with reference to FIG. The bushing 1 is used for a lead portion of an electric device such as a transformer. The bushing 1 transmits an electric current sent from the outside via the center conductor 3 and then connects the electric device via a connection conductor 4 as shown in FIG. Is energized. Here, the bushing 1 has an in-oil terminal 5 as a seat for connecting the connection conductor 4 to the center conductor 3. This terminal 5 in oil is
There are several configurations depending on the type of bushing,
Here, a terminal in oil made from a material such as a solid round bar will be described. As a material of the solid round bar conductor, copper having a small resistivity is preferable, but a conductive aluminum material is generally used because the mass is too heavy for installation in electric equipment. In addition, since the current flowing is substantially proportional to the cross-sectional area of the conductor, such a conductor made of a solid material is applied to a bushing having a high rated current. However, the current is difficult to flow inside the conductor due to the skin effect and mainly flows outside, so the current tends to concentrate at the periphery of the conductor, and a high temperature is generated around the concentrated portion and the electrical resistance value Rises. Therefore, when a large current flows, it is not necessary to simply increase the diameter of the conductor, but it is more effective to increase the surface area of the conducting part so that heat can be diffused to the outside of the conductor. In other words, the larger the surface area of the conductive material is, the more the thermal diffusion is achieved and the electric resistance value is kept constant, so that the quality of the bushing is improved. In particular, as shown in FIG. 4, in the vicinity of the connection portion between the in-oil terminal 5 a and the connection conductor 4 connecting the electric device, the current 6 flowing through the in-oil terminal 5 a concentrates to move to the connection conductor 4. Therefore, it is considered that the temperature rises significantly.

Therefore, as shown in FIG. 4, heat is diffused by adopting a structure in which a groove is formed in the in-oil terminal 5a and a slit-shaped cooling fin 7a is provided to increase the surface area. In such a case, as shown in FIG. 4, the cooling fins are dug all the way to the edge of the connection portion, and the first main focus is to secure a surface area for cooling, and a uniform high position is provided so that the surface area can be fully covered. Up to this point, the cooling fin 7a was formed with a groove.

[0004] Fig. 5 is a configuration diagram of the bushing when the cooling fins 7a are provided, as viewed from below. In addition, if the skin effect of the current is considered in this drawing,
If a groove is formed in the outer peripheral edge portion of the in-oil terminal 5a, it is considered that energization is hindered. However, as described above, since current concentrates near the connection conductor 4, the groove is formed in the connection conductor 4 itself. Such a problem does not occur as long as is not formed.
Further, the groove bottom surface of the conventional cooling fin has a shape processed into a plane having a constant horizontal height as shown in FIG. 6 for ease of processing.

[0005]

However, in the configuration in which the grooves of the cooling fins 7a of the in-oil terminals 5a are provided at a uniform high position as shown in FIG.
In this case, the processing is performed without taking into account the electrical conductivity, so that the cooling fin 7a narrows the current path for the current 6 to be transferred, and a sufficient current path cannot be secured. Was. Even so, the current has the property of flowing only in the surface layer due to the skin effect, so that current concentration is likely to occur. In the portion where the current at the connection portion between the terminal 5a in oil and the connection conductor 4 is further concentrated, the temperature is reduced. This could cause a spike and significantly reduce the quality of the bushing. A possible method is to reduce the number of cooling fins 7a of the in-oil terminal 5a to secure an energizing path. However, as the number of cooling fins 7a decreases, the surface area of the in-oil terminal 5a decreases. There is a possibility that the cooling effect by the cooling fins 7a will be reduced if it is left as it is.

In the groove structure in which the cooling fins are horizontally processed as shown in FIG. 6, the oil liquid 8 circulating in the transformer tank flows along the groove wall surfaces of the cooling fins 7a to the bottom of the groove. Since there is no escape path for the oil flow, the oil flow 8 stagnates near the groove bottom surface, and the oil that has received heat from the in-oil terminal 5a and has become hot does not leave the vicinity of the in-oil terminal forever. As a result, there is a problem that the cooling effect by the oil flow cannot be expected much.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the problems of the prior art described above, and its object is to provide a simple improvement to the structure of the cooling fins of the terminal in the oil of the bushing so as to improve the oil. An object of the present invention is to provide a bushing capable of preventing heat generation near a middle terminal portion and improving cooling efficiency.

[0008]

In order to achieve the above object, according to the present invention, as a first aspect of the present invention, a conductor made of a solid material, and a conductor fastened to the conductor and connected to the main body of the electric equipment. In a bushing provided with a connecting conductor for connecting to the connecting conductor and a cooling fin formed by forming a plurality of grooves from below in the conductor, the groove forming the cooling fin is a groove near the connecting conductor. Is formed to be the shallowest, and each groove is formed to be gradually deeper toward the center of the conductor.

By employing such a configuration, the cooling efficiency can be improved without obstructing the flow of current. Further, in the present invention, as a second aspect of the present invention, a conductor made of a solid material, a connecting conductor fastened to the connecting material and connecting the conductor to an electric device main body, and a And a cooling fin formed by forming a groove, wherein each groove forming the cooling fin is formed such that a bottom surface of the groove is inclined toward a groove bottom end. To provide a bushing.

[0010] By adopting such a configuration, when the hot oil rises in the cooling fins, it can flow outside the cooling fins without stagnation. According to the present invention, there is provided the bushing according to the second aspect, wherein the groove bottom surface is the shallowest at the central portion and becomes deeper toward both end portions.

By adopting such a configuration, it is possible to control the direction of oil flow of oil that has become high temperature in the cooling fins. Further, in the present invention, as a fourth aspect of the present invention, a conductor made of a solid material, a connecting conductor fastened to the connecting material and connecting the conductor to an electric equipment body, A cooling fin configured by forming a groove, in the groove forming the cooling fin, a groove near the connection conductor is formed to be the shallowest, and individual grooves are formed toward the center of the conductor. The present invention provides a bushing characterized in that it is formed stepwise deeper, and each groove is formed such that the bottom surface of the groove is inclined toward both ends of the groove bottom.

By employing such a configuration, the cooling efficiency can be further improved in combination with the above-described operation. According to the present invention, there is provided a bushing according to the fourth aspect, wherein the conductor uses an aluminum alloy having excellent mechanical strength characteristics. By employing such a configuration, it is possible to improve mechanical strength without significantly impairing the cooling efficiency.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a bushing according to the present invention will be described below with reference to the drawings. The same parts as those of the conventional configuration are denoted by the same reference numerals, and description thereof will be omitted.
The first embodiment shown in FIG.
b cooling fins 7b are provided stepwise. That is, the depth of the formed groove is changed stepwise. The main current 6 of the current is, as shown in FIG.
Flows into the connection conductor 4, and the structure of the cooling fin 7b forms a groove of the cooling fin using a part deviating from the main flow, leaving a part along the flow. By adopting such a configuration, the surface area of the terminal 5b in oil is not so different from the surface area of the conventional terminal in oil, so that the cooling performance can be expected to be equivalent to that of the conventional product. Can be prevented. In addition, since the current supply path is sufficiently provided, the temperature rise due to the current concentration can be reliably mitigated.

In the second embodiment shown in FIG. 2, the bottom surface of the groove of the cooling fin, which has been conventionally processed horizontally, is inclined from the center to both ends. , It is possible to guide the oil flow 8 to a constant flow to the peripheral portion. For this reason, the oil which has received heat from the in-oil terminal 5b and has become high temperature rises by buoyancy and flows to the outside of the in-oil terminal 5b. Flows into the groove of the cooling fin 7b. As described above, since the oil flow is lubricated, the temperature rise of the terminal in the oil is reduced.

Further, in conjunction with adoption of the above-described embodiment, a structural aluminum material (for example, an aluminum alloy) having a mechanical strength in the center conductor of the bushing may be used. Therefore, since the strength of the cooling fin against vibration is improved, the thickness of the cooling fin is reduced,
The number of fins can be increased. Although the structural aluminum material is excellent in mechanical strength, it has poor electrical conductivity. However, if the above-described embodiment is adopted, some poor electrical conductivity can be covered.

[0016]

As described above, according to the present invention, while maintaining the cooling effect of the in-oil terminal, the current-carrying characteristics are improved to prevent heat generation in the in-oil terminal portion and further increase the cooling effect. Can be provided.

[Brief description of the drawings]

FIG. 1 is a structural view of a terminal in oil of a bushing according to a first embodiment of the present invention.

FIG. 2 is a structural view of a cooling fin groove bottom surface of a submerged terminal according to a second embodiment of the present invention.

FIG. 3 is an overall structural view of a conventional bushing.

FIG. 4 is a structural view of a terminal in oil of a conventional bushing.

FIG. 5 is a view showing cooling fins formed on the terminal in oil when the bushing is viewed from below.

FIG. 6 is a structural diagram of a bottom surface of a cooling fin groove of a conventional underwater terminal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... bushing, 3 ... center conductor, 4 ... connection conductor, 7a,
7b: cooling fin.

Claims (5)

[Claims] 1. A conductor made of a solid material, a connecting conductor fastened to the conductor and connecting the conductor to an electric equipment body, and a plurality of grooves formed in the conductor from below. In the bushing provided with the cooling fins, the grooves constituting the cooling fins are formed so that a groove near the connection conductor is formed most shallowly, and individual grooves are formed gradually deeper toward the conductor center. A bushing characterized by the following. 2. A conductor made of a solid material, a connecting conductor fastened to the connecting member and connecting the conductor to an electric device body, and a plurality of grooves formed in the conductor from below. A bushing comprising a cooling fin, wherein each groove constituting the cooling fin is formed such that a bottom surface of the groove is inclined toward a groove bottom end. 3. The bottom surface of the groove is shallowest at a central portion and becomes deeper toward both end portions.
The bushing described in the above. 4. A conductor made of a solid material, a connecting conductor fastened to the connecting member and connecting the conductor to a main body of the electric device, and a plurality of grooves formed in the conductor from below. In the bushing provided with the cooling fins, the grooves constituting the cooling fins are formed so that the groove near the connection conductor is formed at the smallest depth, and the individual grooves are formed stepwise deeper toward the conductor center. A bushing characterized in that each groove is formed such that the bottom surface of the groove is inclined toward both ends of the groove bottom. 5. The bushing according to claim 4, wherein the conductor uses an aluminum alloy having excellent mechanical strength characteristics.