JP2539531Y2 - Bushings for power equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bushing attached to a power device such as a transformer or a reactor in order to draw a conductor from the device.

[0002]

2. Description of the Related Art As shown in FIG. 6, a bushing attached to a power device such as a transformer includes an insulator tube 1 made of porcelain integrally having an insulator tube main body 1A and a cylindrical portion 1B. The porcelain body 1A has a large number of caps 100 on its outer periphery, and its tip 1a1 is hermetically closed by an end cap 2. The end cap 2 includes a cylindrical body 2A having a substantially square cross section. The cylindrical body 2A is disposed so as to concentrically surround the distal end 1a1 of the insulator tube main body 1 and is fixed to the insulator tube main body by cement. An end plate 2B is fixed to the cylindrical body 2A with bolts 13, and an external terminal 3 is attached to the end plate 2B. A terminal attached to an overhead electric wire or the like is connected to this external terminal.

The cylindrical portion 1B is provided on the rear end 1a2 side of the porcelain tube main body. When the cylindrical portion 1B is mounted on a power device, the cylindrical portion is provided with a mounting hole 5 provided in a case 4 or the like of the power device. It is arranged in a penetrating state. The outer diameter of the cylindrical portion 1B is set smaller than the outer diameter of the rear end 1a2 of the porcelain tube main body 1A, and the end surface of the rear end 1a2 of the porcelain tube main body becomes an annular gasket contact surface 1c surrounding the cylindrical portion. I have.

A flange fitting 6 is provided at the rear end 1a2 of the porcelain body.
Has been fixed. The flange 6 has a cylindrical portion 6a concentrically surrounding the outer periphery of the rear end 1a2 of the insulator body, and a flange portion 6b formed at the end of the cylindrical portion 6a. Is fixed to the rear end 1a2 by cement.

[0005] A conductive rod 8 is provided so as to pass through the inside of the insulator tube 1, and one end of the conductive rod 8 is connected to the end cap 2. The other end of the conductive rod 8 penetrates through a washer 9 attached so as to close the open end of the cylindrical portion 1B, and is introduced into the case 4 of the electric device. This conductive rod is connected to a lead wire drawn from an electric device in the case 4.

When this bushing is mounted on an electric device, an annular gasket 10 is arranged between the gasket contact surface 1c at the rear end of the insulator tube main body and the peripheral portion of the mounting hole 5, and is attached to the case of the electric device. Welded stud bolt 11
And the nut 12 meshed with the bolt fixes the flange portion 6b of the flange fitting to the electric device.

In this type of bushing, when a high voltage is applied to the conductive rod 8, a corona discharge may occur between the conductive rod 8 and the case 4 at the ground potential.

Accordingly, the outer surface of the insulator tube main body 1A and the cylindrical portion 1
B is coated with a semi-conductive glaze on the outer surface, and a conductive glaze is coated on the inner surface of the insulator tube 1 and fired with porcelain, so that the outer surface of the insulator tube main body 1A and the outer surface of the cylindrical portion 1B have a large resistance. A bushing in which the inner surface of the insulator tube 1 (the surface surrounding the conductive rod) is covered with a conductive film while being covered with a conductive film has been proposed (JP-A-2-40906).

In this type of bushing, after the porcelain tube is fired, the tip of the porcelain tube main body 1A has a tip end of the porcelain tube main body 1A in order to improve the contact surface with the end plate 2B. Polish the end face of the part. In order to obtain the dimensional accuracy of the entire length of the insulator tube, the tubular portion 1B is formed to be longer,
The cylindrical portion 1 is set so that the length of the porcelain tube falls within a predetermined dimension range.
Polish the opening end of B. Further, in order to improve the accuracy of the gasket contact surface 1c, the corresponding contact surface 1c is polished.

Therefore, the end face of the tip 1a1 of the insulator tube, the end face of the open end (lower end in the figure) of the tubular portion 1B, and the gasket contact surface 1c are not covered with the semiconductive coating. The surface not covered by the semiconductive coating is
Coated with a metallikon layer. Further, the end cap 2 and the flange fitting 6 are electrically connected to the semiconductive coating by the metallikon layer.

In the bushing of FIG. 6, a metallikon layer M1 is formed by spraying lead or the like on the end face of the cylindrical body 2A of the end cap 2 and the end face of the tip end of the porcelain body 1A. An electrical connection is made between the inner conductive film and the end plate 2B of the end cap 2, and a metallikon layer M2 is similarly formed between the outer surface of the end cap 2 and the outer surface of the insulator body 1A. Thereby, electrical connection between the end cap 2 and the semiconductive coating on the outer surface of the insulator tube main body 1A is achieved. Further, a metallikon layer M3 is formed over the outer surface of the rear end portion side of the porcelain tube main body 1A and the flange metal fitting 6, and
By this metallikon layer, electrical connection between the semiconductive film on the outer surface of the insulator tube main body 1A and the flange fitting 6 is achieved.
Furthermore, the flange surface of the flange fitting 6 and the gasket contact surface 1
A metallikon layer M4 is formed over the outer surface of the cylindrical portion 1B and the metallicon layer M4, and the metallicon layer M4 establishes electrical continuity between the semiconductive coating on the outer surface of the cylindrical portion 1B and the case 4. I'm trying. Further, a metallikon layer M5 is formed so as to straddle the outer peripheral portion on the opening end side of the cylindrical portion 1B, the end surface of the cylindrical portion 1B, and the inner surface of the end portion of the cylindrical portion 1B. Electrical conduction between the washer 9 and the semiconductive coating on the outer surface of the cylindrical portion 1B is achieved. In this way, a semiconductive coating is formed on the outer peripheral surface of the insulator tube, and a conductive coating is formed on the inner peripheral surface, respectively, and the two coatings are electrically connected. Are electrically connected to each other, the potential difference between the inner peripheral surface and the outer peripheral surface of the insulator tube, in particular, the potential difference between the inner peripheral surface and the outer peripheral surface of the cylindrical portion 1B becomes small. In this case, the possibility that corona discharge occurs between the conductive rod and the ground potential portion can be eliminated, and the insulation performance can be improved.

Instead of covering the inner peripheral surface of the insulator tube 1 with a conductive film, it may be covered with a semiconductive film.

[0013]

The conventional bushing has a problem that it is difficult to maintain airtightness and liquid tightness when it is attached to a power device. This may be for the following reasons.

That is, in the conventional bushing, since the gasket contact surface 1c of the insulator tube is covered by the metallikon layer M4, the gasket 10 comes into contact with the contact surface 1c via the metallikon layer M4. However, the metallikon layer formed by spraying a molten metal such as lead with compressed air is composed of an aggregate of metal particles when viewed microscopically, and has a gap between the metal particles. It is inevitable that gas and liquid flow through. Therefore, when the gasket 10 is brought into contact with the gasket contact surface 1c via the metallikon layer M4, gas, rainwater, and the like flow through the gaps between the particles in the metallikon layer M4, and the airtightness inside the electric equipment is reduced. Properties and liquid tightness cannot be maintained.

An object of the present invention is to provide a bushing for electric power equipment capable of maintaining good airtightness and liquid tightness of the equipment.

[0016]

SUMMARY OF THE INVENTION A bushing to which the present invention is directed is a bushing whose front end is closed by an end cap, and a mounting provided at a mounting point on the rear end side of the main body. A porcelain tube integrally having a cylindrical portion disposed in a state penetrating the hole, a flange fitting fixed to the rear end of the porcelain tube main body, and one end connected to an end cap provided through the inside of the porcelain tube And an annular gasket used to maintain airtightness when attached to equipment. The cylindrical portion of the porcelain tube is formed to have a smaller diameter than the porcelain tube main body, and the rear end portion of the porcelain tube main body has an annular gasket contact surface surrounding the cylindrical portion. A gasket is disposed between the gasket and the peripheral portion. Further, a semiconductive coating is formed so as to cover the outer peripheral surface and the inner peripheral surface of the insulator tube, respectively.

The present invention is intended to prevent the gasket from hindering the maintenance of airtightness and liquid tightness in such a bushing, and has the following features.

In the present invention, an inner metallikon layer is formed so as to straddle a limited annular region near the inner periphery of the gasket contact surface and a semiconductive film covering the outer peripheral surface of the cylindrical portion. An outer metallikon layer electrically connected to the semiconductive coating covering the outer surface of the insulator tube body is formed so as to reach near the outer peripheral portion of the gasket contact surface. Further, the gasket is formed of rubber having conductivity or semi-conductivity, and the gasket is formed by forming an inner metallikon layer, a gasket contact surface not covered by the metallikon layer, and an outer gasket contact surface near the outer periphery of the gasket contact surface. Contact with metallikon layer.

Preferably, the gasket is provided with a relief for accommodating the metallikon layer covering the gasket contact surface.

[0020]

The airtightness and the liquid tightness can be improved by providing a region which is not covered with the metallikon layer on the gasket contact surface as described above and bringing the gasket into contact with the region.

If the gasket is formed of a rubber having conductivity or semi-conductivity as described above, and the gasket is brought into contact with the outer metallicon layer and the inner metallikon layer, the gasket contact surface is exposed. It is possible to eliminate the possibility that a discharge is generated between the ends of the metallicon layer divided between the metallicon layers (between the end of the outer metallicon layer and the end of the inner metallicon layer), so that the insulating performance of the bushing is not impaired at all.

[0022]

1 to 4 show an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an insulator made of porcelain similar to a conventional one having an insulator body 1A and a cylindrical portion 1B integrally. It is. A large number of caps 100 are provided on the outer peripheral portion of the insulator tube main body 1A.

The end cap 2 is connected to the tip 1 of the porcelain body 1.
A cylindrical body 2A is disposed concentrically around a1, and an end plate 2B fixed to the cylindrical body 2A by bolts 13 is provided with an external terminal 3 attached to the end plate 2B. The cylindrical body 2A is formed so as to have a substantially rectangular cross section, and is fixed to the porcelain tube main body 1A with cement 7.
A gasket 14 for maintaining air-tightness and liquid-tightness is arranged between the end plate 2B and the tip of the insulator tube main body.

The outer diameter of the cylindrical portion 1B is set smaller than the outer diameter of the rear end 1a2 of the insulator main body 1A.
The end face of a2 is an annular gasket contact surface 1c surrounding the cylindrical portion. A flange fitting 6 having a cylindrical portion 6a and a flange portion 6b is attached to a cement
It is fixed by.

A conductive rod 8 is provided through the inside of the insulator tube 1, and one end of the conductive rod is connected to the end plate 2 of the end cap 2.
B.

The other end of the conductive rod 8 penetrates through a washer 9 arranged so as to close the open end of the cylindrical portion 1B, and is introduced into the case 4 of the electric equipment. A screw is provided at the other end of the conductive rod 8, and nuts 15 and 1 are attached to the screw.
6 are engaged with each other, and the washer 9 is fastened and fixed to the insulator tube by the nut 15. The terminal fitting 17 is inserted between the nuts 15 and 16, and the terminal fitting 17 is fixed to the rod 8 by tightening the nut 16.

The above-mentioned bushing is arranged with the cylindrical portion 1B penetrating through the mounting hole 5 provided in the case 4 of the electric device, and is formed between the peripheral portion of the mounting hole 5 and the gasket contact surface 1c. Gasket 20 is disposed. In this embodiment, a step 5a is provided around the mounting hole 5, and the step 5a is provided.
The gasket 20 is disposed between a and the gasket contact surface 1c of the insulator tube main body. The stud bolt 11 welded to the case of the electric device is used as the flange 6b of the flange fitting.
The flange portion 6b of the flange fitting is fastened and fixed to the case 4 of the electric device by a nut 12 fitted in a bolt insertion hole 6c provided in (see FIG. 2) and meshed with a bolt 11.

A semiconductive glaze having a large resistance is applied to the inner and outer surfaces of the insulator tube 1, and the glaze is fired to form a semiconductive coating on the inner and outer surfaces of the insulator tube. After the porcelain tube is fired, the end surface of the tip portion 1a1 of the porcelain tube main body 1A, the gasket contact surface 1c, and the end surface of the open end of the cylindrical portion 1B are polished, respectively. The semiconductive coating is removed. Accordingly, the inner peripheral surface and the outer peripheral surface of the porcelain tube 1 are covered with a semiconductive coating, and the end surface of the tip 1a1 of the porcelain tube main body 1A, the gasket contact surface 1c and the opening end of the cylindrical portion 1B are formed. The semiconductive coating on the end face has been removed.

The semiconductive coatings formed on the inner and outer surfaces of the insulator tube 1 are necessary for securing the dielectric strength between the washer 9 and the flange fitting 6 and between the flange fitting 6 and the end cap 2. And has a sufficiently large resistance value.

In this embodiment, a metallikon layer m1 is formed by spraying lead or the like on the outer periphery of the tip end of the insulator tube main body 1A, and the metallikon layer m1 and the cylindrical body 2A of the end cap are formed.
Is filled with cement 7. Further, a metallikon layer m2 is formed over the metallikon layer m1 protruding from the end cap 2 and the end of the cylindrical body 2A of the end cap 2, and the metal cap layers m1 and m2 form the end cap 2 and the porcelain body. The semiconductive coating on the outer surface is electrically connected.

An outer metallikon layer m3 is formed from the back surface of the lowermost shade 100 of the porcelain body to the outer peripheral surface of the rear end 1a2 of the porcelain body, and the outer metallikon layer m3 and the cylindrical portion 6a of the flange fitting 6 are formed. A metallikon layer m4 is formed over the outer periphery. The outer metallikon layer m3 is provided such that its end reaches near the outer periphery of the gasket contact surface 1c, and the end of the outer metallikon layer m3 that reaches near the outer periphery of the gasket contact surface 1c is
0 is contacted.

As shown in FIG. 3, the gasket contact surface 1c has a limited annular region near the inner periphery and the cylindrical portion 1B.
An inner metallikon layer m5 is formed so as to extend over the outer periphery. Since the inner metallicon layer m5 is provided so as to cover only the limited annular region near the inner periphery of the gasket contact surface 1c, as shown in FIG. There is an annular area 1c1 not covered by the layer.

At the open end (lower end in FIG. 1) of the cylindrical portion 1B of the insulator tube, a metallikon layer m6 extending from the outer surface of the cylindrical portion 1B to the end surface of the open end is formed.
Thereby, electrical conduction between the semiconductive film on the outer peripheral surface of the cylindrical portion 1B and the washer 9 is achieved. An inner peripheral portion of the washer 9 is provided with a protruding portion 9a which fits into the inner peripheral portion of the open end portion of the cylindrical portion 1B. By doing so, the washer 9 and the semiconductive film on the inner peripheral surface of the insulator tube are electrically connected.

The metallikon layer m6 is formed so as to reach the inner peripheral portion of the opening end of the cylindrical portion 1B.
The semiconductive film on the inner peripheral surface of the cylindrical portion 1B may be electrically connected to the semiconductive film on the outer peripheral surface through the through hole.

The metallikon layers m1 and m3 inside the cement 7 are formed in order to prevent the electric field from concentrating on the bubbles or voids generated inside the cement, thereby reducing the dielectric strength.

The gasket 20 is made of rubber having conductivity or semi-conductivity. The inner portion of the gasket 20 has an inner portion covering an annular region near the inner periphery of the gasket contact surface 1c as shown in FIG. An annular relief 20a for accommodating the metallikon layer m5 is formed. The depth of the escape 20a is
The size is set to a size equivalent to the thickness of the metallikon layer m5. As a rubber constituting the gasket, a rubber having oil resistance (when used for oil-insulated equipment) or insulation gas resistance (when used for gas-insulated equipment) having conductivity or semi-conductivity is used. For example, when used for oil-filled equipment, nitrile synthetic rubber (specific resistance 1 × 10 ¹⁰
Semi-conductive nitrile synthetic rubber having a specific resistance of about 500 to 3 × 10 ⁴ Ω-cm obtained by mixing carbon black powder into the carbon black powder can be used. When used for gas-insulated equipment, ethylene propylene rubber having conductivity or semi-conductivity can be used.

The gasket 20 is formed on the inner metallikon layer m5, the gasket contact surface 1c1 not covered by the metallikon layer, and the end of the outer metallikon layer m3 near the outer periphery of the gasket contact surface 1c. Make contact.

With the above configuration, the gasket 20
Directly contacts the polished gasket contact surface 1c1 that is not covered by the metallikon layer, so that air-tightness and liquid-tightness can be maintained well, and gas flows into and out of the case of the electrical equipment. Rainwater and the like can be prevented.

In the above embodiment, if the gasket 20 is formed of an insulating material, a discharge may occur between the end of the outer metallikon layer m4 and the end of the inner metallikon layer m5. When the conductive layer 20 has conductivity or semi-conductivity, the outer metallicon layer and the inner metallicon layer can be electrically connected to each other, so that it is possible to prevent the occurrence of discharge in this portion.

In the above embodiment, the end of the outer metallikon layer m3 is terminated at a position flush with the gasket contact surface 1c. However, as shown in FIG. Can be extended to a limited annular area near the outer periphery of the gasket contact surface 1c. In this case, a relief for accommodating the metallikon layer is also provided on the outer peripheral side of the gasket 20.

In the above embodiment, the tip 1a1 of the insulator tube
A metallikon layer is formed over an annular region near the inner periphery of the end surface of the gasket and the inner peripheral surface of the tip portion, and the gasket 14 is formed.
The gasket 14 may be made to be in contact with a region of the end face of the front end portion 1a1 of the porcelain tube not covered by the metallikon layer and the metallikon layer by using a material made of rubber having conductivity or semiconductivity. . With this configuration, the semiconductive coating on the outer peripheral surface and the semiconductive coating on the inner peripheral surface of the insulator tube can be electrically connected also on the tip end side of the insulator tube.

In the above embodiment, the mounting hole is directly provided in the case of the electric device, but the present invention is not limited to the case where the mounting hole is directly provided in the case of the device. For example, the present invention can be applied to a case where a nozzle is connected to a periphery of a hole provided in a case of a device and a bushing is attached to a flange welded to an end of the nozzle. In this case, a hole inside the flange at the end of the nozzle serves as a mounting hole.
In some cases, an annular mounting seat is welded to the periphery of the hole provided in the case of the device, and a bushing is connected to the mounting seat.

[0043]

As described above, according to the present invention, the gasket abutment surface is provided with a region not covered by the metallikon layer, and the gasket is brought into contact with the region. Denseness can be improved.

In particular, in the present invention, the gasket is formed of conductive or semiconductive rubber, and the gasket is brought into contact with the outer metallicon layer and the inner metallikon layer, so that the gasket contact surface is exposed. Therefore, there is an advantage that it is possible to eliminate the possibility that a discharge is generated between the separated metallikon layers, and to improve airtightness and liquid tightness without impairing the insulating performance of the bushing at all.

[Brief description of the drawings]

FIG. 1 is a sectional front view of a half of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged sectional view of a main part of the embodiment of FIG. 1;

FIG. 4 is a sectional view of a gasket used in the embodiment.

FIG. 5 is an enlarged sectional view showing a main part of another embodiment of the present invention.

FIG. 6 is a front view showing a half of a conventional bushing in cross section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulator tube, 1A ... Insulator tube main body, 1B ... Cylindrical part, 2 ... End cap, 5 ... Mounting hole, 6 ... Flange fitting, 7 ... Cement, 8 ... Conductive rod, 20 ... Gasket, m3 ... Outer metallikon layer, m5 ... inner metallikon layer.

Claims (2)

(57) [Scope of request for utility model registration] 1. A porcelain tube main body having a front end closed by an end cap, and a tubular portion disposed at a rear end side of the porcelain tube main body and arranged so as to pass through a mounting hole provided at a mounting location. An annular gasket wherein the outer diameter of the cylindrical portion is set smaller than the outer diameter of the rear end of the porcelain body, and the end face of the rear end of the porcelain body surrounds the cylindrical portion. An insulator tube serving as an abutting surface, a flange fitting fixed to a rear end of the insulator tube main body, a conductive rod provided through the insulator tube and having one end connected to the end cap; An annular gasket disposed between the gasket contact surface at the rear end of the insulator tube main body and the peripheral portion of the mounting hole, and having a large resistance so as to cover the outer peripheral surface and the inner peripheral surface of the insulator tube, respectively; Bushing for power equipment with conductive coating An inner metallikon layer is formed so as to straddle a limited annular region near the inner periphery of the gasket contact surface and a semiconductive coating covering the outer peripheral surface of the cylindrical portion. An outer metallikon layer electrically connected to the semiconductive coating covering the outer peripheral surface is formed so as to reach near the outer peripheral portion of the gasket contact surface, and the gasket is made of conductive or semiconductive rubber. Wherein the inner metallikon layer, the gasket contact surface not covered by the metallikon layer, and the outer metallikon layer present near the outer peripheral portion of the gasket contact surface are arranged to be in contact with each other. Bushing for power equipment. 2. The bushing for an electric appliance according to claim 1, wherein the gasket is provided with a clearance for accommodating a metallikon layer covering the gasket contact surface.