JPH09213508A - Three phases collective type arrestor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize a voltage distribution along the axis direction of an inner conductor which is made by a non-linear resistor laminating, to reduce its degradation and to intend to minimize, by suppressing sudden change of a capacitance distribution of the inner element near a cylinder shaped shield by means of electromagnetic shielding having connecting support and a spherical part SOLUTION: Spherical capped shields 19a and 19b are junctioned with a low voltage side of a cylinder shaped shield 17 via connecting supports 18a and 18, respectively, each internal element 14a-14c located at near each spherical capped shield 19a and 19b generates a capacitance between an earthing vessel 12. A capacitance between a part which belongs to lower voltage side than the inner elements 14a-14c and the spherical capped shields 19a and 19b is made to minimize, a capacitance between the inner elements 14a-14c and the earthing vessel 12 is made to be larger and a capacitance distribution of the axis direction of the inner elements 14a-14c is made to approach an ideal condition This means can equalize a potential distribution of each internal element 14a-14c along the axis direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase collective arrester incorporated in a gas-insulated switchgear or the like, and more particularly to a three-phase collective arrester with improved metal shield for improved reliability.

[0002]

2. Description of the Related Art In general, a gas-insulated switchgear is a device in which SF6 gas, which is an electrically insulating medium, is enclosed in a metal grounding container to improve the electrical insulating performance, and it is possible to make the substation equipment compact. Widely used. This gas insulated switchgear incorporates various devices, one of which is a lightning arrester.

As this type of gas-insulated switchgear, a three-phase batch type gas-insulated switchgear has been developed which corresponds to the further downsizing of substation equipment, and as a lightning arrester, a three-phase batch type arrester has also been developed and applied. ing.

A lightning arrester is intended to protect other devices from lightning surges and switching surges, and in a high voltage system, a lightning arrester having further excellent protection characteristics has been developed and applied.

This type of lightning arrester tends to be used with a high average stress (electric charge rate) at a system voltage that is always applied. Therefore, in order to ensure long-term reliability, individual internal elements are required. It is particularly important to develop a voltage sharing equalization technique for making the sharing voltage of the zinc oxide element uniform.

As an example of the conventional example of such a three-phase collective type lightning arrester, there is one constructed as shown in FIGS. The three-phase collective type lightning arrester 1 is a three-phase internal structure in which SF6 gas 3 as an electrically insulating medium is enclosed in a grounded metal grounding container 2 and a non-linear resistor containing zinc oxide as a main component is laminated. It contains the elements 4a, 4b, 4c.
One axial end of each of the internal elements 4a-4c is connected to a substation bus (not shown) via a high-voltage conductor 6 supported by an electrically insulating spacer 5, and the other end is connected to a ground potential portion 2a. The internal elements 4a to 4c are arranged such that when a triangle is formed around the central axis O of the grounding container 2 as shown in FIG. 8, the central axes of the internal elements 4a to 4c coincide with the vertices thereof. It is located in. Each internal element 4a
Metallic shields 7, which are cylindrical electromagnetic shields, are provided on the high-voltage side of ~ 4c, respectively.

[0007]

However, such a conventional three-phase collective type arrester 1 has the following problems. That is, in this lightning arrester 1, the potential distribution along the axial direction of each of the internal elements 4a to 4c is non-uniform, so that the non-linear resistors of the internal elements 4a to 4c deteriorate when used at a high charge rate. Is a concern.

Next, the reason why such a problem occurs is as follows.
This will be described with reference to FIGS. 5A, 5B and 6. 5A and 5B are explanatory views showing the potential distribution control,
In order to make the potential distribution along the axial direction of each of the internal elements 4a to 4c uniform, a current equal to the charging current leaking from each of the internal elements 4a to 4c to the ground container 2, which is the ground potential, is made to flow from the shield on the high voltage side. You can do it. Therefore, first, the following equations (1) and (2) are established.

[0009]

[Equation 1]

[0010]

## EQU00002 ## V (x) = 1-x (2) In this formula, C (x) is the axial direction x of the inner conductors 4a to 4c.
Is the capacitance between the high voltage shield at and the zinc oxide element of the internal elements 4a-4c, and Cs (x) is the capacitance between the zinc oxide element at position x and the ground potential. Then, by rearranging the above equations (1) and (2), the following equation (3) is obtained.

[0011]

(Equation 3)

Further, FIG. 6 is a graph expressing this equation (3), in other words, a graph showing the capacitance distribution in the ideal state. That is, this formula (3)
Also, by realizing the shield shape that satisfies the capacitance distribution shown in FIGS. 5A and 5B, a uniform potential distribution can be obtained along the axial direction of the internal elements 4a to 4c.

On the other hand, in the prior art, the capacitance distribution in the vicinity of the low voltage side of the cylindrical shield 7 changes abruptly, so that it deviates from the ideal capacitance distribution. Therefore, a uniform potential distribution cannot be obtained.

On the other hand, in general, a lightning arrester having an excellent protection characteristic is used with a high charge rate, and therefore, when the axial potential distribution of the lightning arrester 1 is not uniform, it is added to each non-linear resistor of the internal elements 4a to 4c. Since the voltage is different, the charge rate may become too high depending on the position of the non-linear resistor, which may deteriorate the non-linear resistor.

The three-phase collective type arrester 1 is a device that meets the demand for downsizing of substation equipment. However, the complicated shield shape increases the electric field of the shield, resulting in an increase in the diameter of the grounding container 2. .

The present invention has been proposed in order to solve the problems of the prior art as described above, and an object thereof is to make uniform the potential distribution in the axial direction of the internal conductor formed by laminating non-linear resistors. And to provide a three-phase collective type arrester capable of reducing the deterioration and reducing the size.

[0017]

According to the first aspect of the present invention,
While enclosing an electrical insulating medium, a grounded container that is grounded and a non-linear resistor that contains zinc oxide and is housed in each grounded container and connected to the ground potential part on each low-voltage side are laminated. Phase internal elements, cylindrical electromagnetic shields connected to the high voltage side of each of these internal elements, and connections connected symmetrically to the central axis on the low voltage side of each of these cylindrical electromagnetic shields. While being connected to the support and the tip of each of these connection supports, each has a spherical surface portion, and each spherical surface portion is arranged so as to face the inner peripheral surface of the grounding container, and each spherical surface portion is opposed to each internal element. And electromagnetic shields arranged symmetrically.

Therefore, according to the first aspect of the invention, the electromagnetic shield having the connection support and the spherical portion can suppress or prevent a rapid change in the capacitance distribution of the internal elements in the vicinity of the cylindrical shield. Therefore, the capacitance distribution of the internal elements can be brought close to the ideal state. As a result, the potential distribution of the internal elements can be made uniform along the axial direction.

Further, since the spherical portion of the electromagnetic shield is opposed to the inner peripheral surface of the grounded container, the electric field is relaxed, and the two electromagnetic shields are symmetrically arranged with respect to each internal element. Can be reduced or prevented.

According to a second aspect of the present invention, in the three-phase collective arrester according to the first aspect, when each internal element forms a concentric equilateral triangle or an isosceles triangle around the central axis of the grounding container, Arranged concentrically at each vertex, the electromagnetic shield of each phase, the central axis of each pair,
It is characterized in that the internal elements are arranged so as to be substantially parallel to the opposite sides of the triangle in which the internal elements are arranged.

Therefore, according to the second aspect of the present invention, when an equilateral triangle or an isosceles triangle is formed around the central axis of the grounding container, the interior of the three phases arranged so as to be located at each vertex of the equilateral triangle or the isosceles triangle. For each element, the lines connecting the centers of the electromagnetic shields having the spherical parts of each phase are arranged so as to be substantially parallel to the opposing sides of the triangle formed by the internal elements. The facing parts of the container are the same for all three phases. Therefore, the voltage sharing of the internal elements of each phase is almost the same. Further, the electric field in the interphase direction is also relaxed in the interphase direction because the spherical surfaces of the electromagnetic shields of the respective phases face each other.

The invention according to claim 3 is the invention according to claim 1 or 2
The three-phase collective type lightning arrester described above comprises an electrically insulating cylinder that houses at least a part of each internal element, and an electrically insulating spacer that is interposed between the electrically insulating cylinder and each electromagnetic shield. And

Therefore, according to the third aspect of the invention, since the electrically insulating spacer is interposed between the electromagnetic shield and the electrically insulating cylinder facing the electromagnetic shield, the applied system voltage can be increased. For this reason, even if the total height of the internal elements becomes high and the connection support body becomes long, it is possible to reduce or prevent the mechanical strength of the electromagnetic shield from being lowered.

According to a fourth aspect of the present invention, there is provided the first or second aspect.
The described three-phase collective arrester is characterized in that the outer surface of each electromagnetic shield is covered with alumite.

Therefore, according to the fourth aspect of the invention, by covering the outer surface of the electromagnetic shield with alumite, the electric field of the shield can be relaxed.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 to 6, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a partial vertical sectional view of a three-phase collective type lightning arrester 11 according to a first embodiment of the present invention. The three-phase collective type lightning arrester 11 is provided with an S in a grounded metal grounding container 12.
Inner elements 14a, 14b, 14 for three phases formed by enclosing an electrically insulating medium 13 such as F6 gas and stacking a plurality of non-linear resistors containing zinc oxide as a main component in series.
It contains c.

The internal elements 14a to 14c for the three phases are shown in FIG.
When a concentric equilateral triangle is formed around the central axis Oo of the grounding container 12 as shown in FIG. 5, the central axes of the internal elements 14a to 14c are arranged so as to coincide with the respective vertices thereof. . One end of each of these internal elements 14a to 14c in the axial direction is provided with a high-voltage conductor 16 supported by an electrically insulating spacer 15 that seals one end of the grounding container 12,
It is connected to a substation bus (not shown).

A cylindrical shield 17 of an electromagnetic shield is connected to the low-voltage side of each internal element 14a, 14b, 14c.

Two connecting supports 18a and 18b are connected to the low pressure side of each cylindrical shield 17 at symmetrical positions around the central axis of each cylindrical shield 17. On the low-voltage side of the tip of each of these connection supports 18a, 18b, spherical shields 19a, 19 which are electromagnetic shields are provided.
b are connected to each other. The connection supports 18a and 18b are members used to electrically connect the spherical crown-shaped shields 19a and 19b to the high-voltage side conductor 16 at substantially the same potential.
It is sufficient if the spherical crown-shaped shields 19a and 19b can be mechanically sufficiently supported and fixed.

These spherical coronal shields 19a and 19b are
The side facing the internal elements 14a to 14c is a flat surface portion 19c.
On the other hand, the spherical portion 19d is formed on the side facing the inner peripheral surface of the grounding container 12. Also, a pair of spherical coronal shields 19a and 19b for each phase is provided for each internal element 14
The spherical central shields 19a and 19b for each phase are arranged symmetrically with respect to the central axes of a to 14c, and the horizontal central axes Oa, Ob, and Oc connecting the centers thereof in the horizontal direction have three-phase internal elements. It is arranged so as to be parallel to the opposite sides of the equilateral triangles connecting the central axes of 14a to 14c.

Next, the operation of this embodiment will be described.

On the low-pressure side of each cylindrical shield 17, spherical caps 19a, 19 are provided via connection supports 18a, 18b.
By connecting b respectively, each spherical coronal shield 1
Capacitance is generated between each of the internal elements 14a to 14c near the positions of 9a and 19b and the ground container 12. Since the spherical coronal shields 19a and 19b of each phase are arranged at a predetermined distance from each other, unlike the case where only the cylindrical shield 17 is provided, the inner elements 14a to 14c and the grounded container 1 are different.
The part where 2 opposes is formed without interposing an electromagnetic shield.

Therefore, a capacitance is generated between the internal elements 14a to 14c and the ground container 12, and the internal element 14
a to 14c on the lower pressure side and the spherical crown-shaped shield 19
The capacitance between a and 19b becomes small. Moreover, since the capacitance between the internal elements 14a to 14c and the grounded container 12 becomes larger, the internal elements 14a to 14c
The axial capacitance distribution of 14c approaches the ideal state as shown in FIG. 6, and as a result, each internal element 14a ...
The voltage distribution of 14c can be made uniform along the axial direction.

The spherical coronal shields 19a, 19 of each phase are also provided.
The horizontal central axes Oa-Oc of b are the three-phase internal elements 14a-
Since they are arranged so as to be parallel to the opposite sides of the equilateral triangle formed by 14c, the facing portions of the grounding container 12 and the internal elements 14a to 14c that are not shielded are the same in each phase. Therefore, the voltage sharing of the internal elements 14a to 14c is the same for all three phases.

On the other hand, the spherical portions of the spherical crown-shaped shields 19a and 19b face the grounded container 12, and the spherical portion 19d faces the interphase direction of the spherical crown-shaped shields 19a and 19b, so that the electric field is relaxed. Therefore, the diameter of the ground container 12 can be reduced as much as possible.

As described above, in the three-phase collective arrester 11 of this embodiment, the spherical crown-shaped shields 19a and 19b are arranged on the low-voltage side of the cylindrical shield 17 via the connection supports 18a and 18b. Since the voltage sharing of the internal elements 14a to 14c of each phase can be made uniform with a practically sufficient accuracy by a simple structure, as a result, the reliability of the arrester can be greatly improved.

Also, a pair of spherical coronal shields 1 for each phase
Central axes Oa to Oc connecting 9a and 19b in the horizontal direction
Are arranged in parallel to the opposite sides of the equilateral triangle in which the three-phase internal elements 14a to 14c are arranged, respectively, the facing portions of the grounding container 12 and the internal elements 14a to 14c that are not shielded are the same in each phase. The voltage sharing of the internal elements 14a to 14c is almost the same in all three phases.

On the other hand, the spherical portions 19d of the spherical crown-shaped shields 19a and 19b face the inner peripheral surface of the grounding container 12, and the spherical portion 19d also faces the interphase direction of the spherical crown-shaped shields 19a and 19b. Therefore, the electric field is relaxed, and the diameter of the grounded container 12 can be reduced as much as possible. Furthermore, since the structure is relatively simple, modeling such as three-dimensional electric field analysis is easy, and once the analysis and actual measurements are compared and the model is established, the size of internal elements, capacitance This has the effect of being able to deal with changes in the above, etc., relatively easily.

The present invention is not limited to the above embodiment, and the three-phase internal elements 14a to 14c are formed around the central axis Oo of the grounding container 12 in an isosceles triangular shape concentric with the grounding container 12. You may arrange | position in a vertex, and also in this case, the effect similar to the said embodiment can be expected.

Further, as shown in FIG. 3, each internal element 14a is
14c are partially housed in the electric insulating cylinder 20, and a post spacer 21 made of an electric insulator is interposed between the outer peripheral surface of the insulating cylinder 20 and the flat surface portion 19c of each spherical coronal shield 19a, 19b. They may be connected and insulated and supported. According to this embodiment, the system voltage applied is high, and therefore the overall height of the internal elements 14a-14c is high, which reduces the mechanical strength of the shield even if the connection supports 18a, 18b are long. Can be reduced or prevented.

Further, as shown in FIG. 4, the outer surface of each spherical coronal shield 19a, 19b may be covered with alumite 22 to further alleviate the electric field of the shield. Therefore, the grounding container 12 can be further downsized.

[0043]

As described above, the invention according to claim 1 of the present application suppresses or prevents a rapid change in the capacitance distribution of the internal elements near the cylindrical shield by the electromagnetic shield having the connection support and the spherical portion. Therefore, the capacitance distribution of the internal elements can be brought close to the ideal state. As a result, the potential distribution of the internal elements can be made uniform along the axial direction.

Further, since the spherical portion of the electromagnetic shield is opposed to the grounded container, the electric field is relaxed, and since the two electromagnetic shields are symmetrically arranged with respect to each internal element, the electric field of the internal element becomes asymmetric. Can be reduced or prevented.

According to a second aspect of the present invention, when an equilateral triangle or an isosceles triangle is formed around the central axis of the grounded container, the interior of the three-phase is arranged so as to be located at each vertex of the equilateral triangle or the isosceles triangle. The lines that connect the centers of the electromagnetic shields that have spherical parts of each phase are arranged so as to be substantially parallel to the opposing sides of the triangle formed by the internal elements. The facing parts of the container are the same for all three phases. Therefore, the voltage sharing of the internal elements of each phase is almost the same. Further, the electric field in the interphase direction is also relaxed in the interphase direction because the spherical surfaces of the electromagnetic shields of the respective phases face each other.

According to the third aspect of the invention, since the electrically insulating spacer is interposed between the electromagnetic shield and the electrically insulating cylinder facing the electromagnetic shield, the applied system voltage can be increased.
For this reason, even if the total height of the internal elements becomes high and the connection support body becomes long, it is possible to reduce or prevent the mechanical strength of the electromagnetic shield from being lowered.

According to the fourth aspect of the present invention, the electric field of the shield can be relaxed by coating the outer surface of the electromagnetic shield with alumite.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a three-phase collective arrester according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged vertical sectional view of an essential part of another embodiment of the present invention.

FIG. 4 is an enlarged vertical sectional view of a main part of still another embodiment of the present invention.

5A and 5B are explanatory views showing the principle of potential distribution control of a general three-phase collective type arrester.

FIG. 6 is a graph showing a capacitance distribution in an ideal state of a general three-phase lightning arrester.

FIG. 7 is a partial vertical sectional view of a conventional three-phase collective type lightning arrester.

8 is a sectional view taken along the line VIII-VIII of FIG.

[Explanation of symbols]

 11 Three-Phase Collective Lightning Arrester 12 Grounding Container 13 Electrical Insulation Medium 14a, 14b, 14c Inner Element 15 Insulating Spacer 16 High Voltage Conductor 17 Cylindrical Shield 18a, 18b Connection Support 19a, 19b Spherical Crown Shield 20 Insulation Tube 21 Post Spacer 22 Alumite

Claims (4)

[Claims] 1. A grounding container which is grounded while enclosing an electrically insulating medium, and a non-linear resistor containing zinc oxide, which is housed in each grounding container and each low-voltage side is connected to a grounding potential portion. Laminated three-phase internal elements, tubular electromagnetic shields connected to the high-voltage side of each of these internal elements, and the low-voltage side of each of these tubular electromagnetic shields, symmetrically with respect to its central axis. Each of the connection support bodies is connected to the other, and each of the connection support bodies is connected to the tip end of each of the connection support bodies, and has a spherical surface portion. A three-phase collective type arrester, comprising: electromagnetic shields arranged symmetrically with respect to each element. 2. The three-phase collective arrester according to claim 1, wherein each internal element is concentric with each vertex when a concentric equilateral triangle or an isosceles triangle is formed around the central axis of the grounding container. The electromagnetic shield of each phase is arranged so that the central axis of each pair is substantially parallel to the opposite sides of the triangle in which the internal elements are arranged. A three-phase collective type arrester. 3. The three-phase collective arrester according to claim 1 or 2, and an electrically insulating cylinder that houses at least a part of each internal element,
A three-phase collective type lightning arrester comprising an electric insulating spacer interposed between the electric insulating cylinder and each electromagnetic shield. 4. The three-phase collective arrester according to claim 1 or 2, wherein the outer surface of each electromagnetic shield is covered with alumite.