JPH1023620A - Electric field relief device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve an electric field in an insulating gas by a composite insulation structure, improve the withstanding voltage characteristics and reduce the dimensions as a whole by a method wherein a protrusion is formed in the circumferential direction of conductor end electrode or along the outer circumference of the conductor end electrode, and the protrusion is cover with an approximately semispherical insulating layer whose tip part has a required curvature. SOLUTION: A semicircular protrusion 12a is formed on the end part of an electrode 12, along the outer circumference. Further, an insulating layer 13, made by molding of epoxy resin is formed, so as to overlap the straight part in the axial direction of the electrode 12 by several millimeters. the tip part of the insulating layer 13 has a proper curvature and faces a grounding metal plate 14. Even if the grounding metal plate 14 is replaced by the conductor of the other phase, etc., the condition is the same. That is, the insulating layer 13 is formed, so as to face a part where a potential difference produced. If the thickness (t) of the insulating layer 13 is about 1/2 of the distance (1) between the electrode, the electric field intensity can be minimized, and the voltage withstanding characteristics can be improved most.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electric field relaxation device.

[0002]

2. Description of the Related Art In a gas insulated switchgear shown in FIG. 5 as an example of the structure of a switchgear, the inside of a box 1 whose outer periphery is hermetically surrounded by a mild steel plate is vertically provided near the left front side in the figure. The partition wall 2 separates the circuit breaker chamber 1a in the front and the busbar chamber 1b in the rear, and each of the chambers 1a and 1b is filled with sulfur hexafluoride gas (hereinafter abbreviated as insulating gas) at a gas pressure of substantially atmospheric pressure. Sealed.

A circuit breaker 3 having a vacuum interrupter 3a is housed in a circuit breaker chamber 1a.
The circuit breaker 3 is connected to an insulating spacer 9 attached to a through hole (not shown). This insulating spacer 9
Has the same structure at the top and bottom.

A disconnector 4A is provided at the ceiling of the bus room 1b.
Is attached, one terminal is connected to the upper insulating spacer 9 via the connection conductor 8, and the other terminal is connected to the connection conductor 8
Is connected to the bus 5 fixed to the insulator 6. The bus 5 interconnects the adjacent boards.

On the other hand, a disconnector 4B having the same shape as the disconnector 4A is attached to the bottom of the bus bar 1b. One terminal is connected to a lower insulating spacer 9 via a connecting conductor 8, and the other terminal is connected. The conductor 8 is connected to the upper terminal of the cable head 7 attached to the bottom plate. The power is received by the cable 7a connected to the cable head 7.

[0006] At the end of the movable contact 4b connected to the operation plate 4a of the disconnectors 4A and 4B, a metal shield 4c is provided to alleviate the electric field. FIG. 6 shows an enlarged view of this part. A spherical metal shield 11 having a large radius of curvature is fixed to the electrode 10 at the end of the movable contact 4b by rotating a bolt 11a provided on the shield side. I have. As a result, the electric field at the ends can be relaxed, and the dielectric strength between the ground and the phases can be kept good.

[0007]

In these arrangements, the electric field mitigation device used in the insulating gas is constituted by a round metal shield as disclosed in, for example, Japanese Patent Application Laid-Open No. 128807/128. I have. This is because the electric field strength is suppressed by providing the roundness. That is, as the radius of curvature of the shield 11 increases, the electric field strength decreases and the withstand voltage characteristics improve. In particular, since the breakdown voltage of the insulating gas strongly depends on the electric field strength, the suppression of the electric field strength leads to an improvement in the withstand voltage characteristics.

However, as the radius of curvature of the shield 11 is increased, the electric field strength is reduced, but the size of the shield 11 itself is increased. Therefore, the gas gap between the shield 11 and the ground and between the phases is narrowed, and the withstand voltage characteristic is reduced.

Further, when the size of the shield 11 itself is increased, the arrangement of connection conductors to be connected must be detoured so as not to contact the shield 11. Thereby, the arrangement of each electric device is restricted, and the overall shape is enlarged. This goes against the recent trend of shrinking.

An object of the present invention is to reduce the electric field in an insulating gas as a composite insulating structure by combining the insulating layer with an insulating layer having a relatively large insulating thickness, thereby improving the withstand voltage characteristics and reducing the overall shape. To provide an electric field relaxation device.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a projecting portion formed in the circumferential direction or the axial direction along the outer periphery of a conductor end electrode, the tip having a predetermined curvature. The gist of the invention is that it is included in a substantially hemispherical insulating layer.

In such a configuration, the electric field strength between the electrode end and the insulating layer surface is suppressed. In particular, the surface where the insulating layer is in contact with the insulating gas is where the maximum electric field strength is located on the insulating gas side, but the electric field strength is affected by the effect of the formed insulating layer (particularly, the effect of the relative permittivity of the insulating layer). Can be suppressed.

The conductor end electrode may be provided with a depression at a position facing a portion where the insulating layer has the maximum electric field strength. In such a configuration, the specific capacitance of the insulating layer is reduced, the potential sharing with the gas gap is improved, and the electric field strength can be suppressed. That is, although the potential sharing is performed between the insulating layer and the gas gap, the potential sharing of the gas gap is reduced due to the decrease in the specific capacity of the insulating layer,
Accordingly, the maximum electric field strength is suppressed.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an electric field relaxation apparatus according to an embodiment of the present invention. FIG. 1 is a partially enlarged view of an electric field relaxation device showing one embodiment of the present invention. In the figure, a semicircular protrusion 12a is provided at the end of the electrode 12 along the outer periphery. Further, an insulating layer 13 formed by wrapping the linear portion 12b in the axial direction of the electrode 12 by several mm and molding an epoxy resin, for example, is provided. Note that the tip of the insulating layer 13 has an appropriate radius of curvature, and is opposed to the ground metal plate 14. The ground metal plate 14 is the same for conductors of other phases and the like, and the insulating layer 13 is formed so as to face a portion where a potential difference occurs.

FIG. 2 shows the electric field strength characteristics when the insulation thickness is t and the distance between the electrodes is 1 in these configurations.
Here, the relative permittivity of the insulating layer 13 was set to 5. The electric field strength is
A U-shaped characteristic is obtained depending on the ratio of t / l, and t / l = about 50% becomes the minimum value. Therefore, if the thickness t of the insulating layer is set to about に 対 し て with respect to the distance l between the electrodes, the electric field intensity becomes the lowest and the withstand voltage characteristics are improved most. Here, the maximum electric field strength is a portion where the insulating layer 13 has a curvature facing the ground electrode 14, and is where the withstand voltage characteristic is determined. The portion where the insulating layer 13 and the electrode 12 are in contact is a triple junction having electric field peculiarity, but the linear portion 12b in the axial direction of the electrode 12 and the insulating layer 13 are wrapped by several mm, and Since 12a is formed, an increase in electric field strength can be suppressed.

Further, in the case of use in the disconnector 4 or the like, the ratio of t / l cannot be fixed due to the change of the intermetallic distance l. However, if the allowable electric field intensity is 100% in FIG. 2, t / l = 45.
It has been found by the inventors of the present invention that the allowable electric field strength falls below the allowable electric field strength in the range of% to 70%. Of these, the ratio of t / l at the point where the distance l between the electrodes becomes the shortest due to the movable disconnector 4 is
It has been found that, when the distance is set in the range of 50% to 70%, when the distance l between the electrodes is increased, the gas gap is also increased, and the electric field intensity is not increased. That is, the ratio of t / l is 50%
It can be understood that the center value may be allowed on the plus side.

FIG. 3 shows an example of the voltage characteristics when the ratio of t / l is set to 50%. Here, the relative dielectric constant of the insulating layer 13 was set to 5, and the impulse voltage characteristics when the gas pressure was changed were obtained. The characteristic (a) is a composite insulating electric field relaxation shield in which the insulating layer 13 is provided to share the potential with the gas cap, and the characteristic (b) is obtained when a metal shield having the same shape as the shape of the insulating layer 13 is used. is there. According to the figure, the voltage characteristics of the composite insulating shield provided with the insulating layer 13 are higher than those of the metal shield, and an improvement of about 1.5 times is seen. Also,
Assuming that the withstand voltage when the allowable electric field strength in FIG. 2 is 100% is the characteristic (c), the characteristic (a) is cleared at a gas pressure of 0.10 MPa, but the characteristic (b) is a pressure up to a gas pressure of 0.14 MPa. You will need it.

For this reason, the shield of the composite insulation can obtain a high voltage characteristic with a small electrode shape, so that the electric field relaxation device itself can be downsized, and the equipment can be downsized and a rational arrangement can be achieved, and the overall shape can be reduced. Can be achieved. Further, since high voltage characteristics can be obtained at a low gas pressure, the thickness of the steel plate of the box 1 can be reduced, and the weight can be reduced.

Next, a configuration for further suppressing the maximum electric field intensity is shown in FIG. The maximum electric field strength is such that the insulating layer 15 is a vertex 15a having a curvature facing the other electrode, so that the electrode 16 has a depression 16a at the center thereof to increase the insulating thickness of the insulating layer 15. Thereby, the specific capacitance of the insulating layer 15 is reduced, the potential sharing with the gas gap is improved, and the electric field strength can be suppressed.

The electric field suppression at the triple junction is shown in FIG. In a portion where the insulating layer 17 and the electrode 18 are in contact with each other, a circumferential depression 18a is formed on the electrode side, and the insulating layer 17 is joined near the bottom of the depression 18a. Thereby, the electric field peculiarity due to the triple junction can be prevented. This is because the electric field relaxation effect works by the protruding portions 18b and 18c of the electrodes with respect to the triple junction.
This is for suppressing the electric field intensity.

In places where the triple junction does not need to be considered, as shown in FIG.
The insulating layer 20 may be formed such that the end of the electrode 19 has a constant curvature and the center in the axial direction is a vertex.

Next, the structure using an insulating material such as Teflon, polyethylene or silicon rubber which has a certain degree of flexibility and a low dielectric constant such as a relative dielectric constant of 3 or less is shown in FIG. It is shown in d). A conductive layer in which an insulating layer 21 has been manufactured in advance, and a conductive paint has been applied to a portion in contact with the electrode 22.
23 are formed. The end of the electrode 22 protrudes coaxially
22a is provided, and the end 21a of the insulating layer 21 is
It is fitted and fixed to 22a. The insulating layer end 21a can be easily fitted to the protruding portion 22a because the insulating thickness is thin and flexible. In addition, if the electrode 22 and the conductive layer 23 are in contact at any one place, they have the same potential, and a defect such as a void is not formed between the electrode 22 and the conductive layer 23, so that good insulating characteristics can be maintained. .

As a result, the potential sharing between the low dielectric constant insulating layer 21 and the gas gap is improved, and the electric field intensity on the surface of the insulating layer 21 where the maximum electric field intensity is located is reduced. That is, when the relative dielectric constant of the insulating layer 21 is lower than the relative dielectric constant of the insulating gas, the potential sharing of the gas gap is reduced. Therefore,
Voltage characteristics can be further improved, and downsizing can be achieved.
According to the results obtained by the present inventors, when Teflon having a relative dielectric constant of 2.7 was used, an improvement of about 20% was observed from the result of an epoxy resin having a relative dielectric constant of 5.

FIG. 3E shows a method in which the insulating layer 24 having a low dielectric constant is fixed by a screw portion 25 a provided at the center of the electrode 25. In this case, a male screw is provided on the insulating layer 24 to be manufactured in advance, and is fixed by a female screw of the electrode 25. In addition, a conductive layer 26 is provided at a portion where the insulating layer 24 is in contact with the electrode 25 so as to have the same potential as the electrode 25. The presence or absence of the conductive layer 26 of the screw portion 25a may be either, and the electric field relaxation in which the electrode 25 is depressed inward is performed in this portion.

As a result, the potential sharing between the insulating layer 24 having a low dielectric constant and the gas gap is improved, and the maximum electric field intensity is suppressed. In FIG. 1F, the insulating layers 27 and 28 are formed by a multi-stage mold. That is, the insulating layer 27 close to the electrode 29 is a high dielectric constant layer in which a relative dielectric constant is increased by, for example, mixing a large amount of filler such as quartz with epoxy resin. On the gas gap side where the maximum electric field intensity is located, the filler is made finer and the amount thereof is reduced to form a low dielectric constant layer. As a result, at the end of the electrode 29 where the radius of curvature is small and the protrusion 29a is formed, the insulating layer having a high relative dielectric constant is formed.
27 suppresses the electric field. Therefore, the electric field intensity near the electrode 29 in contact with the insulating layer 27 can be suppressed. On the gas gap side, the maximum electric field strength can be suppressed by improving the potential sharing with the insulating layer having a low relative dielectric constant.

As a result, the electric field at the end of the electrode 29 is relaxed, and the withstand voltage characteristics are improved. As another embodiment, a shield with an insulating layer added is provided on the protruding portion of the conductor connection portion or the electric field relaxation shield portion of the conductor of the electric device without limiting to the conductor end portion, so that the electric field relaxation portion can be reduced. Can be planned.

[0027]

As described above, according to the present invention, a protrusion provided on the conductor end electrode and formed in the axial direction along the outer periphery of the electrode, and a substantially hemispherical end having a predetermined curvature And an insulating layer having an insulating thickness so as to include the protruding portion, so that the electric field strength on the conductor end electrode portion and the insulating layer surface is suppressed, the withstand voltage characteristics are improved, and the overall shape is improved. The size can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an electric field relaxation device according to an embodiment of the present invention.

FIG. 2 is a view showing a relationship between a ratio t / l of an insulating thickness t of an insulating layer and a distance l between electrodes to another electrode and an electric field intensity in the electric field relaxation device according to the present invention.

FIG. 3 is a diagram comparing impulse flashover voltage characteristics of an electric field relaxation device according to the present invention and a metal electrode having the same shape as an insulating layer.

FIG. 4 is a cross-sectional view of a main part of an electric field relaxation device according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a typical gas-insulated switchgear.

FIG. 6 is a sectional view of a main part of a conventional electric field relaxation device.

[Explanation of symbols]

12,16,18,19,22,25,29 ... electrodes, 13,15,17,20,
21, 24, 27, 28 ... insulating layer, 23, 26 ... conductive layer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuo Masaki 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba head office

Claims (7)

[Claims] 1. A protruding portion provided on a conductor end electrode and formed in an axial direction along an outer periphery of the electrode, and a tip is substantially hemispherical having a predetermined curvature, and includes the protruding portion. And an insulating layer having such an insulating thickness. 2. A protruding portion provided on the conductor end electrode and formed in the axial direction along the outer periphery of the electrode, and a tip is substantially hemispherical having a predetermined curvature, and includes the protruding portion. An insulating layer having an insulating thickness as described above, wherein a recess is formed in the conductor end electrode at a position facing a portion where the insulating layer has a maximum electric field strength. . 3. A recess provided in a conductor end electrode and formed in a circumferential direction of the electrode, and a tip is substantially hemispherical having a predetermined curvature, and is joined to the electrode at a bottom of the recess. And an insulating layer having an insulating thickness so as to cover the conductor end electrode. 4. A protruding portion provided on the conductor end electrode and formed in the axial direction along the circumferential direction or the outer circumference of the electrode, and the end is substantially hemispherical having a predetermined curvature. An electric field relaxation device, comprising: an insulating layer having a conductive layer formed thereon and having an insulating thickness including the protrusion. 5. A plurality of projections provided on the conductor end electrode, the projections being formed in the axial direction along the circumferential direction or the outer circumference of the electrode, and a substantially hemispherical tip having a predetermined curvature. A multi-stage insulating layer having a multi-stage insulating layer and a total size of each insulating thickness including the protruding portion;
An electric field relaxation device, wherein the relative dielectric constant of each of the multi-stage insulating layers is increased as the dielectric constant is closer to the conductor end electrode. 6. The electric field relaxation device according to claim 4, wherein the insulating layer is made of a flexible material having a relative dielectric constant of 3 or less. 7. The insulating layer according to claim 1, wherein an insulating thickness of the insulating layer is 50% to 70% of a distance between an electrode provided with the insulating layer and another electrode. The electric field relaxation device according to claim 6.