JPH11111090A - Epoxy resin mould bushing for gas tight installation of gas filled switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin mould bushing for gas tight installation of a gas filled switch in which an inner circuit voltage of the switch is improved to achieve compactness, in which gas seal performance of the switch is improved, in which a CT installation structure of the switch is simplified, and in which insulation is reinforced. SOLUTION: In a bushing, a center conductor 1a is put through a center part of a thermosetting resin insulation body 1h comprising epoxy resin or the like to be moulded, an insert 1d for fixing the bushing disposed concentrically to the center conductor 1a is embedded in a recessed part formed at a root of a flange part of the heat-setting resin insulation body to be bound and moulded, a female thread is formed in an inner circumference of the insert metal, and a space for introducing insulation gas such as SF6 gas is provided between the inner circumference of the insert metal and the heat-setting resin. In this case, a bottom of the recessed part formed at the flange part of the heat-setting resin insulation body 1h as a tip part on the depth of a presser metal 3 is formed in spherical form of a curvature radius Ra.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention, through-air-tight bushing of a gas insulated switchgear in which insulating gas is sealed, such as SF ₆ gas, to underground distribution gas switchgear bushings particularly direct power cable terminal portion Things.

[0002]

2. Description of the Related Art Referring to the drawings, a description will be given of a through / airtight bushing portion of a conventional gas insulated switchgear. FIG. 5 is a partial cross-sectional view showing the structure of a mold bushing disclosed in Japanese Patent Application Nos. 5-175899 and 6-17756, which are prior applications of the present applicant. That is, the mold bushing is composed of a rod-shaped center conductor 8a and an epoxy resin member 8f molded integrally with the outer periphery of the rod-shaped center conductor 8a. The structure is such that the fitting is performed via the packing 4 of the ring and the airtight mounting is performed by tightening the screws. A ring-shaped insert 8d having a female screw formed on the inner peripheral surface at the base of the flange portion is provided so as to be integrally embedded in the epoxy resin member 8f. An end face that is molded into the member 8f and that comes into contact with the casing 2 of the gas switch at a portion facing the flange portion of the epoxy resin member 8f is formed.

A convex portion is formed on the epoxy resin member 8f so that a ring-shaped holding member 9 having an L-shaped cross section and having an external thread at the base of the flange portion is screwed into the epoxy resin member 8f. The structure surface and the inner surface of the ring-shaped press fitting 9 and the insert fitting 8d are formed in a structure in which they are separated from each other via a positive space in the radial direction of the bushing (vertical direction in the figure).

A cable connecting screw 8b and a busbar connecting screw 8c for the gas switch are provided at both ends of the central conductor 8a, and a tapered cable terminal fitting is fitted on the outer periphery of the epoxy resin member 8f. It has a portion 8e.
In addition, a current transformer for conducting current measurement (hereinafter referred to as CT)
In the case of mounting the CT 6, a CT having a ground potential is attached to the casing 2 by a CT fixing bracket 7 with bolts, and the CT is fixed at a sufficient distance from the center conductor 8a.

[0005]

The mold bushing constructed as described above has the following problems. Since the electric field at the boundary of the recess of the insert fitting 8d and epoxy resin member 8f is large, SF ₆ gas pressure has become less margin for a standard value of the internal fault voltage during reduction.
Conversely, if the space between the constituent surface of the concave portion of the epoxy resin member 8f, the inner surface of the holding member 9 and the inner surface of the insert member 8d is reduced in order to reduce the size of the structure, the entanglement value decreases. Needed to be improved. In the CT mounting structure, the tolerance for the standard value of the internal voltage between the end of the CT 6 and the center conductor 8a is small, and effective means for reducing the size is required. The structure of the CT6 fixing method is also complicated, and it is desired to simplify the method. The gas seal is a shield formed by one of the O-ring packings 4, and it is desired that the packing be doubled in order to improve the airtight performance.

[0006] The present invention has been made in view of such a point, and is intended to improve compactness by improving the inner voltage of the gas switch, and to improve the gas sealing property of the gas switch. It is another object of the present invention to provide an epoxy resin mold bushing for airtight mounting of a gas switch, which simplifies a CT mounting structure of the gas switch and reinforces insulation performance.

[0007]

According to the present invention, there is provided a bushing fixed to a center portion of a thermosetting resin insulator such as an epoxy resin in a state where the center conductor is penetrated and arranged in a cylindrical shape concentric with the center conductor. An insert metal fitting is embedded in the recess formed at the base of the flange portion of the thermosetting resin insulator and adhesively molded, and an inner thread of the insert metal fitting is processed with a female screw. A bushing having a space for introducing an insulating gas such as SF ₆ gas between the thermosetting resin and a thermosetting resin formed at a flange portion of a thermosetting resin insulator, which is a distal end portion behind a holding bracket. An epoxy resin mold bushing for hermetically mounting a gas switch, wherein a bottom of a concave portion is formed in a spherical shape. Further, in a holding metal fitting having an external thread on the outer periphery for fitting with a female screw portion of an insert metal fitting embedded in a thermosetting resin insulator, a mold insulating reinforcing layer having rubber elasticity was integrally molded and coated on inner and both end faces. It is an epoxy resin mold bushing for gas switch airtight mounting.

In addition, the radius of curvature R at the tip of the mold reinforcing portion at the tip of the holding member is processed to be smaller than the radius of curvature R of the recess formed at the base of the flange portion of the thermosetting resin insulator. An epoxy resin mold bushing for airtight mounting of a gas switch that presses and adheres to the recess formed at the base of the flange portion of the thermosetting resin insulator, and faces the switch case of the presser fitting. A gas switch airtight mounting epoxy resin mold bushing with an O-ring insertion groove machined on the surface.Furthermore, a rubber elastic mold insulation reinforcing layer covering the presser fitting is extended, and the outer periphery of the mold insulation reinforcement layer is extended. Epoxy resin mold bushing for security installation of gas switch with groove formed so that current transformer (CT) can be mounted and fixed A.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional side view of the upper half of the structure of an epoxy resin mold bushing for airtightly mounting a gas switch according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a state of attachment to a switch casing. . That is, the bushing main body 1 is formed by integrally molding the epoxy resin insulator 1h around the center conductor 1a, and a part of the bushing main body 1 is formed with a flange for attaching to the hole of the switch casing 2. An insert fitting 1d having a female screw is integrally molded and fixed on the outer periphery of the concave portion formed at the base of the flange portion, and a groove for mounting the O-ring 4 is provided.

A flange 3 of the epoxy resin insulator 1h is clamped and fixed via an O-ring 5 to an annular holding member 3 having an L-shaped cross section with the switch casing 2 interposed therebetween. An insulating rubber mold reinforcing member 3a is formed by adhesive molding on the inner surface and both end surfaces of the holding member 3, and the radius of curvature Rb of the tip of the insulating rubber mold reinforcing member 3a on the bushing body 1 side is the flange of the epoxy insulator 1h. It is formed smaller than the radius of curvature Ra of the concave portion formed at the base of the portion.
The insulating rubber mold reinforcing member 3a is an epoxy resin insulator 1
The space is designed so that an insulating gas enters between the electrodes and the space h to enhance insulation. This space is formed so that the work can easily be performed when the holding metal fitting 3 is rotated and tightened. That is, if there is no space, the tightening becomes difficult due to friction between the rubber material of the insulating rubber mold reinforcing portion 3a and the epoxy resin of the epoxy resin insulator 1h.

At both ends of the center conductor 1a, a cable connecting screw 1b and a gas switch busbar connecting screw 1c are machined and provided, and as shown in an explanatory view showing an assembled state of FIG. 11 is fixed with a predetermined bolt, and the gas switch busbar 1 is fixed.
0 is used with bolts fixed. Further, a part of the outer surface of the bushing body 1 is a cable terminal fitting portion 1e formed in a tapered shape, and is in close contact with the tapered insulating fitting surface inside the cable terminal portion 11 in combination. Will be used in

Therefore, by providing two O-rings, the sealing performance of the gas insulator is remarkably improved.
Since the insulating gas is introduced between the concave portion provided at the base of the flange portion of the epoxy resin insulator 1h and the insulating reinforcing portion of the holding member 3, the inner voltage is improved and the size is reduced.

Next, an embodiment of the CT mounting specification will be described with reference to FIG. The insulating rubber mold reinforcing portion 3e of the holding member 3 is extended to attach the CT6 to form a groove on the upper surface,
Here, it is formed so as to house CT6. Therefore, CT
6 was simplified, and insulation reinforcement was enabled.

Although the above embodiments have been described with reference to a gas switch as an example, it is apparent that the present invention is not limited to the gas switch but is effective as an insulating reinforcing means for a gas-insulated (including air) conductor penetrating portion. is there. In addition, one end does not need to have a cable end direct connection structure, and may be a lead wire drawing method using an air bushing or an insulated wire and an insulating cover. Also,
It is desirable that the magnitude of the radius of curvature of the tip of the insulating reinforcing portion of the holding metal is slightly smaller than the radius of curvature of the bottom of the concave portion at the base of the flange portion of the epoxy resin insulator, but the effect can be obtained even if the same radius of curvature is formed. .

[0015]

As described above, according to the epoxy resin mold bushing for hermetically mounting the gas switch of the present invention, the sealing property of the insulating gas is remarkably improved and the inner voltage of the gas switch is improved. And compactness is achieved. Moreover, an excellent epoxy resin mold bushing for hermetic mounting of a gas switch with simplified CT mounting structure and reinforced insulation can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of an upper half showing a configuration of an epoxy resin mold bushing for airtight mounting of a gas switch of an embodiment;

FIG. 2 is an enlarged sectional view showing an assembled state of an epoxy resin mold bushing for hermetically mounting a gas switch of the present invention;

FIG. 3 is an explanatory view for explaining a mounting state of a cable terminal on an epoxy resin mold bushing for airtight mounting of a gas switch of the present invention;

FIG. 4 is a cross-sectional view of an upper half portion showing a configuration of an epoxy resin mold bushing for airtight mounting of a gas switch of a modification.

FIG. 5 is a cross-sectional view of an upper half showing a configuration of an epoxy resin mold bushing for hermetically mounting a gas switch in the prior application.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bushing main body 1a Center conductor 1b Screw for cable terminal connection 1c Screw for gas switch busbar connection 1d Insert fitting 1e Cable terminal fitting part 2 Gas switch casing 3 Holding metal 3a Insulation rubber mold reinforcement 3b Insulation rubber mold reinforcement tip 4,5 O-ring 6 CT 10 Gas switch busbar 11 Cable terminal 11a Blade terminal 11b Insulation fitting surface

Claims (5)

[Claims] 1. A bushing-fixing insert fitting which is molded in a state where a center conductor penetrates a central portion of a thermosetting resin insulator such as an epoxy resin and is disposed concentrically with the center conductor. It is embedded in the recess formed at the base of the flange portion of the insulating resin insulator, and is adhesively molded.The internal thread of the insert metal fitting is processed with a female screw. A bushing with a space for introducing an insulating gas such as SF ₆ gas. The bottom of the recess formed in the flange portion of the thermosetting resin insulator at the back end of the holding metal is formed into a spherical shape. An epoxy resin mold bushing for hermetically mounting a gas switch. 2. A press fitting having an external thread on an outer periphery fitted with a female thread portion of an insert fitting embedded in a thermosetting resin insulator, wherein a mold insulating reinforcing layer having rubber elasticity is molded and integrated on inner and both end faces. The epoxy resin mold bushing for airtight mounting of a gas switchgear according to claim 1, which is coated with the resin. 3. A process in which the radius of curvature R at the tip of the mold reinforcing portion at the tip of the holding member is processed to be smaller than the radius of curvature R of the recess formed at the base of the flange portion of the thermosetting resin insulator. 3. The epoxy resin mold bushing for airtight mounting of a gas switch according to claim 1, wherein a tip of the mold reinforcing portion is pressed and adhered to a concave portion formed at a base of a flange portion of the thermosetting resin insulator. 4. An epoxy resin mold bushing for gas-tightly mounting a gas switch according to claim 1, wherein an O-ring insertion groove is formed in a surface of the holding member facing the switch case. 5. A mold insulating reinforcing layer having rubber elasticity and covering a presser fitting is extended, and a groove is formed on an outer periphery of the mold insulating reinforcing layer so that a current transformer (CT) can be attached and fixed. The epoxy resin mold bushing for airtight mounting of a gas switch according to any one of claims 1 to 4.