JPS61135107A - Gas insulated transformer for instrument - Google Patents

Abstract

PURPOSE:To make shorten the insulation distance to the optimum value and to the transformer small and light by constituting the high tension shield composed of four parts by a methode wherein the high tension shield is divided into two parts in the least radius direction and is furthermore divided into two parts in the peripheral direction which are assembled to make a high tension shield. CONSTITUTION:The high tension shield 101 has a cross section of bag form with at least three kinds of curvature radius. The first part has the radius r1 at least necessary to decrease the electric stress along the surface of the high tension coil 4. The second part has the radius r2 determined by the insulating distance (a) from the grounding shield 6. The third part has the radius r3 determined by the insulating distance (c) from the tank 8. These are divided into two parts in the radius direction, and furthermore the peripheral surfaces are divided at the contact point of the r2 part and r3 part, resulting in four parts. As the cross section of the high tension shield has a bag form, such curvature radius as making the insulating distance from the grounding part shortest can be arbitrarily selected. The grounding part confronts with the high tension shield. The size of the fixing washer of the high tension shield can also be freely selected within the size of the cross section of bag form. Thus the high tension shield is made small and the insulation distance is shortened to the optimum value.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a gas-insulated voltage transformer, and particularly to a gas-insulated voltage transformer that alleviates the creeping stress of a high-voltage coil and reduces the electric field with the grounding part. This invention relates to improvements in high-voltage shields provided for the purpose of alleviating stress.

[Technical Background of the Invention and Problems Therewith] As shown in FIGS. 5 and 6, a conventional gas-insulated instrument transformer 1 has an annular iron core 2 formed in a closed magnetic circuit so as to be interlinked with the annular iron core 2. low voltage coil 3 and high voltage coil 4 from the inside.
is coaxially wound, and on the outer periphery of the high voltage coil 4, a radius of curvature of 270° is formed at both ends with one or two types of radius of curvature for the purpose of mitigating the electric field.
A rounded cylindrical high pressure shield 5 is provided. Further, a grounding shield 6 is arranged to cover the iron core 2 facing the high voltage shield 5. These transformer elements, which have reduced the electric field between the high voltage and the ground, are mechanically fixed to the base 7 with bolts, etc., and the tank 8, cover 9, and insulating spacer 10 are installed with gaskets, etc. to surround the transformer elements. It is assembled in such a way that it is airtight with the outside air.

One end of the high voltage coil 4 is connected by a lead wire to a high voltage terminal 12 airtightly attached to the insulating spacer 10 through the inside of a shield guide 11 fixed to the insulating spacer 10.
It is pulled outside.

On the other hand, the other end of the high voltage coil 4 is pulled out to the outside through an outlet bushing (not shown) provided in the tank 8 and is grounded. Although not shown, the lead wire of the low-voltage coil 3 is electrically connected to a low-voltage terminal plate 13 provided on the side wall of the tank 8 and drawn out to the outside.

Inside the container, which consists of 8 tanks and 9 covers, there is an insulating gas 1 with high electrical insulation properties such as sulfur hexafluoride (SFs) gas.
4 is enclosed to constitute a gas-insulated instrument transformer 1.

The high-voltage shield 5 is installed for the purpose of alleviating the creeping stress of the high-voltage coil 4 and the electric field stress with respect to the grounding part.The high-voltage shield 5 faces the grounding shield 6 and the tank 8. It is rounded outward with a radius of curvature determined by the insulation distances a and bl with the ground shield 6 and the insulation distance C with the tank 8.

This radius of curvature needs to be increased as the insulation distances a, b, and c become shorter. In addition, when attaching the high voltage shield 5 to the high voltage coil 4, the gas gap between the high voltage coil 4 and the high voltage coil 4 should be made as close to O as possible to prevent electrical stress from concentrating on the gas gap. It is necessary to firmly attach the high voltage shield 5 to the high voltage coil 4 in order to prevent the high voltage shield 5 from moving or shifting due to external force.

The high voltage shield 5 is connected to the high voltage coil 4. Conventionally, as shown in FIG. 7, a cylindrical high-voltage shield 5 is divided into two parts in the radial direction, and a seat 15 is fixed to the central part where electrical stress is relatively low. After attaching it to the outer periphery of the high voltage coil 4, fastening parts such as bolts were passed through the seat 15 and the WA was firmly attached to the high voltage coil 4.

On the other hand, in recent years, there has been a particular demand for equipment to be smaller, more compact, more compact, and lighter in weight.
By increasing the radius of curvature at both ends, the insulation distances a and b from the grounding shield 6 and tank 8 are set.

It is essential to shorten C. However, in the conventional configuration of the high-voltage shield 5, if the radius of curvature at both ends is increased, the mounting seat 15 must be made smaller, making it impossible to securely attach the high-voltage shield 5 to the high-voltage coil 4. On the other hand, if the seat 15 is made to a required size, the width -0 of the high voltage shield 5 becomes large, which poses problems such as hindering the miniaturization and weight reduction of the gas insulated instrument transformer 1.

[Object of the invention] The present invention was made in view of the above problems, and
The purpose of this is that the high-voltage shield can be firmly attached to the high-voltage coil, and that the high-voltage shield can be configured with the necessary radius of curvature corresponding to the insulation distance determined by the diameter of the tank with a circular cross section into which the transformer element can be inserted. Sex is hidden,
The object of the present invention is to provide a gas-insulated instrument transformer that is smaller and lighter.

[Summary of the Invention] In order to achieve the above object, the present invention has a bag-shaped cross-section with a radius of curvature commensurate with the insulation distance between the high-voltage shield and the opposing ground shield and the tank, at least at two locations in the radial direction and in the outer circumferential direction. It is characterized in that it is composed of four parts cut at two places, and these parts are combined to form a high-voltage shield.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, the cross-sectional shape of the high-voltage shield 101 has a radius of curvature r2 determined from the minimum required radius of curvature 11 to relieve the creeping stress of the high-voltage coil 4 and the insulation distance a from the ground shield 6. It has a bag-like cross-sectional shape with at least three different radii of curvature, the radius of curvature 13 determined by the insulation distance C between the tank 8 and the tank 8. The outer peripheral surface is divided into a total of four parts.

Among the four divided parts, the inner peripheral part 101a.

High pressure shield 1 is installed on the four cut surfaces of 101b in the radial direction.
01 fixing seats 102 are fixed respectively. The fixing seat 102 is for attaching the high voltage shield 101 to the outer periphery of the high voltage coil 4 and then firmly fixing it to the high voltage coil 4 using fastening parts such as bolts.

In addition, the inner peripheral side portion 1018° 101 of the high voltage shield 101
In b, two or more bosses 103 each having a female thread are provided on the outer peripheral surface side. On the other hand, the outer peripheral portions 101c and 101d of the high voltage shield 101 are provided with holes 104 at positions that match the internal threads of the boss 103, and the outer peripheral portions 101c and 101d are connected to the inner peripheral portion 101a.

101b, a fastening component such as a countersunk head screw 105, which does not produce harmful protrusions on the surface of the high-pressure shield 101, is used to fix the high-pressure shield 101 as shown in FIG.

Note that in the above embodiment, the radius of curvature r2. Although a peripheral cut surface is provided at the contact point of the r3 part,
As shown in Fig. 4, it goes without saying that if the types of curvature radii are further increased and the dimensions are larger than the width of the fixing radius 102, the same purpose can be achieved without affecting the function no matter where the cut surface is placed. .

Further, if the inner circumferential portions 101a, 101b and the outer circumferential portions 1010, 101d cannot be manufactured to the exact dimensions, the outer circumferential cut surface may disturb the electric field and cause stress to concentrate. To prevent this stress concentration, the outer cut surface has a small radius of curvature r.
It goes without saying that the reliability can be further improved by providing 11 parts.

[Effects of the Invention] As described above, according to the present invention, the cross-sectional shape of the high-voltage shield is bag-shaped, and the radius of curvature can be arbitrarily selected so as to minimize the insulation distance from the opposing grounding part. The size of the seat for fixing the high voltage shield can be freely selected as long as it is within the bag-shaped cross-sectional dimensions.Therefore, not only the high voltage shield can be made smaller, but also the insulation distance can be shortened to the optimum value. , it is possible to supply gas-insulated voltage transformers that are more compact and lightweight.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of the high-voltage shield according to the present invention, Fig. 2 is a radial cross-sectional view thereof, and Fig. 3 is a line x-x in Fig. 1.
4 is a sectional view showing another embodiment of the present invention, FIG. 5 is a front sectional view of a conventional gas-insulated voltage transformer, and FIG. 6 is a plan view thereof. The sectional view, FIG. 7, is a perspective view of a conventional high voltage shield. 1...Gas insulated instrument transformer, 2...Iron core, 3...
・Low voltage coil, 4... High voltage coil, 5... High voltage shield, 6... Ground shield, 8... Tank, 9...
・Cover, 14... Insulating gas, 15... Seat, a, b
, c... Insulation distance, 101-... High voltage shield, 10
1a, 101b...High pressure shield inner peripheral side parts, 101
0.101 (1... High pressure shield outer peripheral part, 102
...Fixing degree, 105-...Countersunk head screw, r 1,
r2, r3, r3 - radius of curvature of the high pressure shield.

Claims (1)

[Claims] An iron core, a low-voltage coil and a high-voltage coil coaxially wound around the iron core, a cylindrical high-voltage shield provided around the outer periphery of the high-voltage coil, and a tank that hermetically stores the iron core, coil, and high-voltage shield together with an insulating gas. 1. A gas insulated instrument transformer comprising: a gas insulated instrument transformer, characterized in that the cross-sectional shape of the high voltage shield is formed into a bag shape having three or more different radii of curvature.