JPS6240495Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement of a bushing for high-voltage electrical equipment filled with an insulating gas, such as SF ₆ gas, and particularly to a structure that improves withstand voltage performance and airtightness. It is.

In recent years, high-voltage equipment with high insulation performance that uses SF ₆ gas as an insulating medium or an arc-extinguishing medium has become popular. In this case, the bushing portion of the equipment is required to be small and at the same time have excellent insulation performance. For example, in the case shown in FIG. 1, a porcelain insulator is placed in the metal case 1, the center conductor 3 is inserted, and an alumina porcelain is inserted into the space a formed between the center conductor 3 and the inner wall of the porcelain tube 2. At the same time, one end of the inner cylinder 4 and the center conductor 3 and between the metal case 1 and the inner cylinder 4 are sealed with metal pieces 5 and 6, respectively. The case has an airtight structure, thereby preventing the SF ₆ gas 7 filled in the case from leaking.

However, in the above structure, since the edge A of the joint between the metal case and the metal piece, which is on the ground potential side, and the edge B of the metal case in the vicinity thereof are formed in a protrusion shape, the electric field concentration part of the protrusion Electric field concentration occurs and corona discharge occurs in the same area, leading to deterioration of the insulating medium and even causing flashover between the center conductor 3 on the live part side that is close to and opposite to the insulation performance. I had the above flaws.

The present invention is intended to solve the above-mentioned drawbacks.The base 2a side of the insulator tube 2 is fixed to the metal case 1, and the center conductor 3 is inserted into the center of the inside, and the center conductor 3 and the inner wall 2c of the insulator tube 2 are connected to each other. An inner cylinder 4 made of alumina porcelain is inserted into the space a formed by the inner cylinder 4, and the inner cylinder end face 4a, which is open at one end of the inner cylinder 4, and the center conductor 3 are sealed with an annular metal piece 5. The space between the outer circumferential surface 4b of the other end of the inner cylinder 4 and the metal case 1 is sealed by an annular metal piece 6 to maintain airtightness of the arc-extinguishing medium such as SF ₆ gas 7 filled in the metal case 1. In this case, on the ground potential side, the metal case 1 or the case 1 and the metal piece 6
The protruding electric field concentration part located on the arc-extinguishing medium side formed by The electric field relaxation ring 13 surrounds and shields the central conductor 3, and on the live part side, an insulating support member 25 is provided along the axial direction of the conductor 3 on the outer peripheral surface of the center conductor 3 near the ring where the electric field relaxation ring 13 approaches and opposes the electric field relaxation ring 13. The present invention provides a bushing for high-voltage electrical equipment characterized by being coated with an insulating coating.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. In FIG. 2, the same or equivalent parts as in FIG. 1 are given the same reference numerals.

2 is an insulator made of porcelain or resin;
The base 2a side thereof is fixed to the metal case 1 with bolts 8 and nuts 9. 10 is a gasket interposed between the case and the end face of the insulator, 3 is a center conductor inserted through the center between the insulators, and 4 is an alumina porcelain inserted in the space a formed between the center conductor 3 and the inner wall 2c of the insulator. 5 is an annular metal piece brazed between the inner cylinder end surface 4a and the center conductor 3 in order to close one end of the open inner cylinder 4, and 6 is the outer peripheral surface 4b of the other end of the inner cylinder 4. 13 is an annular metal piece that closes the gap between the metal piece 6 and the metal case 1, and 13 is an insulating medium (such as the edge of the joint between the metal piece 6 and the metal case 1, and also the right-angled edge of the metal case formed near the same area). A metallic electric field relaxation ring with an arc-shaped cross section is designed to surround and shield the protruding electric field concentration areas located on the _SF6 gas side where high electric fields are concentrated, thereby relaxing the electric field at the concentration areas. It is provided opposite to the center conductor 3 on the side of the charging part that approaches and opposes it.

The ring is provided to airtightly connect the inner cylinder 4 and the metal case 1, and is electrically at ground potential like the metal case, and mechanically acts as a sealing member along with the metal piece 6. It has a double airtight function. Reference numeral 14 denotes an auxiliary electric field relaxation ring having an arc-shaped cross section that shields the air side a so as to surround the joint edge A and the edge portion B' of the metal case to alleviate the electric field in these parts. Although it is provided to prevent flashover between a certain metal piece 6 and the above-mentioned portion, it is not particularly necessary and can be omitted if the space a on the air side is filled with an insulating material and no space is formed at all. . Reference numeral 15 is an insulator made of epoxy resin that is integrally molded into a cone shape with the inner cylinder outer circumferential surface 4b, the outer circumferential surface 5a of the charging side metal piece 5, and the outer circumferential surface 3a of the central conductor 3, and has some elasticity even in the hardened state. Epoxy resin for casting is used. 16 is the slope portion 15 of the insulator 15
This is an auxiliary insulator that is interposed between the inner wall of the insulating tube 2 and the slope portion 2d of the insulating tube 2, and is in close contact with the inner wall of the insulator 2. Silicone grease is applied to the contact surface 16a with the insulator 15 in order to allow the insulator to slide along the slope so as to avoid as much stress as possible on the inner cylinder when it expands or contracts due to heat. Note that the auxiliary insulator 16 is made of epoxy resin, which is the same material as the insulator 15. 17 is a through hole 2e at the tip of the insulator tube.
18 is a sponge bushing, 19 is a filling material, 20 is a positioning nut, 21 is a mounting bracket adhered with cement, 22 is a locking nut, and 23 is an insulated pipe. The connecting terminal is shown crimp-connected to the center conductor 3 protruding from the tip. Reference numeral 25 denotes an insulating support member formed in the shape of a cap with a brim, and is used to fix the center conductor 3 to the case 1 to prevent it from wobbling. It penetrates the center conductor 3 near the edge part B of the metal case 1 where the electric field is concentrated, and covers the outer circumferential surface of the conductor along its axial direction. The supporting member 25 attached in this way is designed to block the opening end 4c of the inner cylinder 4 on the case side, as can be seen from the drawing, so the supporting member is equipped with a center conductor. An elongated small hole 25a for gas circulation is formed along the axial direction of the case 1 and the inside of the inner tube 4 to communicate with each other. 7
2 shows SF ₆ gas filled in the case, the pressure of the gas is 2.5 kg/cm ^{2 ,} and the gas is also filled inside the inner cylinder through the small hole 25a for gas circulation.

The present invention has the above-mentioned configuration, and uses protruding electric field concentration areas such as the edge of the joint between the metal case and the metal piece on the ground potential side where high electric fields are concentrated, and the edges of the metal case in the vicinity. The central conductor is surrounded and shielded by a metallic electric field relaxation ring having an arc-shaped cross section, and the outer circumferential surface of the central conductor that approaches and opposes this ring is covered with an insulating support member to relieve the electric field in this vicinity. As a result, the occurrence of corona discharge during use (when applying voltage) is suppressed, and the withstand voltage performance between the relaxation ring and the center conductor can be improved, and the relaxation ring is airtightly connected between the case and the inner cylinder. As a result of double-maintaining the airtightness of the edges of the joints, etc., the reliability of the airtightness can be further increased, making it extremely effective as a bushing for high-voltage electrical equipment. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a conventional bushing for high-voltage electrical equipment, and FIG. 2 is a longitudinal cross-sectional view of a bushing for high-voltage equipment according to an embodiment of the present invention. 1...Metal case, 2...Insulator tube, 2c...Inner wall, a...Space, 3...Center conductor, 4...Inner tube, 5...Metal piece, 6...Metal piece, A...Joining edge, 13... electric field relaxation ring, 14... insulator, 25... support member.

Claims (1)

[Claims for Utility Model Registration] 1. A space formed by fixing the base 2a side of the insulator tube 2 to the metal case 1, inserting the center conductor 3 into the center thereof, and forming the center conductor 3 and the inner wall 2c of the insulator tube 2. In part a, an inner cylinder 4 made of alumina porcelain is inserted, and a ring-shaped metal piece 5 is used to seal between the inner cylinder end surface 4a, which is open at one end of the inner cylinder 4, and the center conductor 3. The space between the outer circumferential surface 4b of the other end and the metal case 1 is sealed with an annular metal piece 6 to keep the arc extinguishing medium such as SF ₆ gas 7 filled in the metal case 1 airtight. In this case, on the ground potential side, the protruding electric field concentration part located on the insulating medium side formed by the metal case 1 or the case 1 and the metal piece 6 is connected to the outer peripheral surface 4b of the inner cylinder 4 on the case 1 side. It is surrounded and shielded by a metallic electric field relaxation ring 13 having an arcuate cross section that airtightly connects with the case 1, and furthermore, on the live part side, the center of the vicinity of the electric field relaxation ring 13 that approaches and opposes the electric field relaxation ring 13 is shielded. A bushing for high voltage electrical equipment, characterized in that the outer peripheral surface of the conductor 3 is insulated and coated with an insulating support member 25 along the axial direction of the conductor 3. 2 At least the outer peripheral surface 5a of the metal piece 5 on the side of the live part
The utility model registration claim 1) is characterized in that the central conductor 3 and the outer peripheral surface 4b of the inner cylinder to which the metal piece 5 connects are covered by integrally molding an insulator 15. Bushings for high voltage electrical equipment.