JPH05299154A - Tank-shaped lightning arrester - Google Patents

Abstract

PURPOSE:To provide a tank-shaped lightning arrester capable of unifying the voltage sharing of a nonlinear element group with a simple structure. CONSTITUTION:A nonlinear element group 1 stacked with nonlinear resistors is arranged in a grounded tank 3 filled with an insulating medium 2. An umbrella-like shield 6 is provided at one end in the axial direction of the nonlinear element group 1, and a ground potential section is connected to the other end in the axial direction. A circular arc-shaped shield 9 is arranged on the ground potential section side of the umbrella-like shield 6 via connecting supporters 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tank type arrester,
In particular, the present invention relates to a tank type lightning arrester which is constructed by stacking resistors having excellent non-linearity such as a zinc oxide element and does not require a series gap.

[0002]

2. Description of the Related Art A lightning arrester using a zinc oxide element takes advantage of its excellent characteristics (voltage-current non-linearity, discharge withstand voltage characteristic, chemical stability, etc.) to prevent conventional series gaps and silicon carbide non-linear resistors. It has been changing to a lightning arrester using a lightning arrester, and in recent years, in a high voltage system such as 275 KV and 500 KV, 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 (charge rate) at the system voltage that is always applied, and in order to ensure long-term reliability, the shared voltage of each zinc oxide element is increased. The voltage sharing and equalization technology that makes the voltage uniform becomes more and more important.

By the way, the conventional tank type arrester is shown in FIG.
Non-linear element group 1 in which zinc oxide elements are stacked as shown in
Is housed in a grounding tank 3 in which an insulating medium 2 having an excellent insulating property such as SF ₆ gas is sealed. One end is connected to a substation bus bar (not shown). The tank type arrester shown in FIG. 7 is disclosed in Japanese Examined Patent Publication No. Sho 64-1913.
As disclosed in the publication, a voltage applied to a zinc oxide element of a non-linear element group 1 by an umbrella-shaped shield 6 and two or more annular shields 8 supported and connected by a connection support 7 having a narrow circumferential width. We are trying to make the sharing even.

[0005]

By the way, even in the tank type arrester shown in FIG. 7, it is possible to equalize the voltage distribution with sufficient accuracy for practical use up to the 500 KV class, but research is currently underway. In the 1000 KV class, there is a problem that sufficient accuracy cannot be secured.

That is, the reason will be described. FIG. 8 is a schematic diagram for studying the principle of potential distribution control. The same parts as those in FIG. 7 are designated by the same reference numerals and the description thereof will be omitted. In order to make the potential distribution completely uniform, a current equal to the charging current leaking to the ground tank 3, which is the ground potential, may be passed from the high voltage side shield. Therefore, the following formula is established.

[0007]

## EQU1 ## C (x) .dx [1-V (x)] = Cs (x) .dx.V (x) (1)

V (x) = 1−x (2) where C (x) is the capacitance per unit length between the high voltage shield and the zinc oxide element at the position x, and C (x)
s (x) is the capacitance per unit length between the zinc oxide element at position x and the ground potential.

The formulas (1) and (2) are summarized as follows.

[0009]

## EQU00003 ## C (x) / Cs (x) = 1 / x-1 (3) FIG. 9 shows the equation (3). If a shield shape that satisfies this is realized, Even if the zinc oxide element itself has no capacitance, uniform voltage sharing can be obtained along the axial direction.

However, in reality, it is difficult to completely realize the shield shape shown in FIG. 9, so that various approximate shapes have been proposed, and FIG. 7 is an example thereof. In fact, the zinc oxide element is always applied with the system voltage,
It has a function as a dielectric having a relatively large dielectric constant (about 700), and due to the effect of its self-capacitance, even if it is an approximate shield shape, the variation of the voltage distribution may be varied depending on the voltage class (500 KV class). It can be suppressed to a practically sufficient range.

By the way, since the annular shield 8 is used in the shield shape of FIG. 7, the capacitance Cs (x) between the non-linear element group 1 and the ground tank 3 in the vicinity of the position opposed to the annular shield 8 has an annular shield. Since it is masked by 8 and becomes almost zero, C (x) / Cs shown in FIG.
The value of (x) greatly deviates from the ideal state and disturbs the potential distribution. Therefore, in the 1000 KV class in which the self-capacitance of the non-linear element group 1 becomes smaller, it is impossible to suppress the variation in voltage sharing to a practically sufficient range with the shield shape shown in FIG.

Further, in the lightning arrester disclosed in Japanese Patent Laid-Open No. 54-8854, a rod-shaped or plate-shaped shield is configured to project obliquely. However, this lightning arrester has a complicated structure and is difficult to analyze. When the configuration of the non-linear element group 1 changes, it is necessary to confirm it by actual measurement each time, so that there is a problem that it lacks versatility.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tank type arrester capable of equalizing the voltage sharing of a non-linear element group with a simple structure.

[0014]

In order to solve the above-mentioned problems, a tank type arrester according to the present invention has a non-linear element group in which non-linear resistors are stacked in a grounded tank containing an insulating medium. Then, in the tank type arrester in which an umbrella-shaped shield is provided at one end in the axial direction of this non-linear element group, and a ground potential part is connected to the other end in the axial direction, it is connected to the ground potential part side of the umbrella-shaped shield. An arcuate shield is arranged via a support.

[0015]

In the present invention having the above structure, a capacitance is generated between the non-linear element group near the position facing the arcuate shield and the ground tank, and the non-linear element group near the ground side and the arcuate shield are formed. Between the non-linear elements and the grounded tank is larger, closer to the ideal distribution, resulting in a more uniform voltage sharing along the axial direction of the non-linear elements. can get.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are sectional views showing a first embodiment of a tank type arrester according to the present invention. Note that the same or corresponding portions as those of the conventional configuration will be described using the same reference numerals.

The tank type arrester shown in FIGS. 1 and 2 is
A non-linear element group 1 in which zinc oxide elements are stacked is housed in a ground tank 3 in which an insulating medium 2 having an excellent insulating property such as SF ₆ gas is sealed, and a high voltage side conductor 5 supported by an insulating spacer 4 is One end of the non-linear element group 1 in the axial direction is connected to a substation bus bar (not shown) via the.

An umbrella-shaped shield 6 is fixed to the high-voltage side end of the non-linear element group 1, and a plurality of connection supports 7 having a narrow circumferential width are provided on the ground potential portion side of the umbrella-shaped shield 6. A metallic arc-shaped shield 9 is arranged via the.

An opening 9a is formed in the arc-shaped shield 9, and the opening 9a is formed to generate a capacitance Cs (x) between the non-linear element group 1 and the ground tank 3. ..

The connection support 7 is such that the arcuate shield 9 is electrically connected to the high-voltage side conductor 5 at substantially the same potential, and the circumferential width and the number thereof are appropriately selected. For example, a rod-shaped conductor or a ring. What is necessary is just to comprise a conductor, a lead wire, etc., which can be mechanically sufficiently supported and fixed.

Next, the operation of this embodiment will be described.

Since the arcuate shield 9 is arranged on the ground potential portion side of the umbrella-like shield 6 via the connection support 7 having a narrow circumferential width, the non-linear element group 1 near the position facing the arcuate shield 9 is arranged. Between the ground tank 3 and the grounding tank Cs
(X) occurs, the capacitance between the non-linear element group 1 close to the ground side and the arcuate shield 9 becomes smaller, and the capacitance between the non-linear element group 1 and the ground tank 3 becomes larger. The distribution approaches, and as a result, a more uniform voltage sharing can be realized along the axial direction of the nonlinear element group 1.

Here, the angle of the opening 9a of the arc-shaped shield 9 must be large to some extent in order to generate the capacitance Cs (x) between the non-linear element group 1 and the ground tank 3 as described above. However, for example, the capacitance Cs (x) cannot be generated only by dividing the arcuate shield into two and forming a small gap between them in order to facilitate manufacturing. Therefore, the angle of the opening 9a can be appropriately selected, and the optimum angle may be selected so that a more uniform voltage sharing can be obtained by analysis and actual measurement.

FIGS. 3 and 4 show a second embodiment of the tank type arrester according to the present invention, and FIGS. 5 and 6 show a third example of the tank type arrester according to the present invention. The same or corresponding portions as those of the embodiment will be described using the same reference numerals.

The tank type arrester shown in FIGS. 3 and 4 is
A high-voltage side conductor 5 is laterally supported by an insulating spacer 4 in the middle of the ground tank 3 in the longitudinal direction. According to this embodiment, since the high-voltage side conductor 5 can be taken out from the lower position,
It is possible to stabilize the lightning arrester and improve the degree of freedom in the arrangement of the lightning arrester.

The tank type arrester shown in FIGS. 5 and 6 is similar to the tank type arrester of the second embodiment except that the arc-shaped shield 9 is used.
Two arcs are provided, and the angle of the opening 9a of the lower arc-shaped shield 9 is formed larger than that of the upper arc-shaped shield 9. According to this embodiment, the arc-shaped shield 9
Since two are provided, a uniform distribution can be obtained even at a higher voltage rating, and the angle of the opening 9a of the lower arc-shaped shield 9 is made larger than that of the upper arc-shaped shield 9. The value of C (x) / Cs (x) shown in 9 can be brought close to the ideal state. The rest of the configuration and operation of the second and third embodiments are the same as those of the first embodiment, so a description thereof will be omitted.

[0028]

As described above, according to the tank type arrester according to the present invention, the arcuate shield is arranged on the ground potential portion side of the umbrella-shaped shield via the connection support, so that the structure is relatively simple. Thus, it is possible to equalize the voltage sharing of the non-linear element group of the high voltage class with sufficient accuracy for practical use. As a result, the reliability of the arrester can be significantly improved.

Further, since the structure is relatively simple, modeling such as three-dimensional electric field analysis is easy. Therefore, once the analysis and the actual measurement are compared and the model is established, the nonlinear element group The size, the number of parallels, and the change of the electrostatic capacity can be dealt with relatively easily.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of a tank type lightning arrester according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical cross-sectional view showing a second embodiment of the tank type lightning arrester according to the present invention.

FIG. 4 is a sectional view taken along line BB in FIG.

FIG. 5 is a vertical sectional view showing a third embodiment of the tank type lightning arrester according to the present invention.

6 is a cross-sectional view taken along the line CC of FIG.

FIG. 7 is a vertical sectional view showing a conventional tank type arrester.

FIG. 8 is a schematic diagram showing the principle of potential distribution control.

FIG. 9 is a graph showing a capacitance distribution in an ideal state.

[Explanation of symbols]

 1 Nonlinear Element Group 2 Insulating Medium 3 Grounding Tank 4 Insulating Spacer 5 High Voltage Side Conductor 6 Umbrella Shield 7 Connection Support 9 Arc Shield 9a Opening

Claims (1)

[Claims] 1. A non-linear element group in which non-linear resistors are stacked is arranged in a grounded tank enclosing an insulating medium, and an umbrella-shaped shield is provided at one end of the non-linear element group in the axial direction, and the axis thereof is provided. A tank type lightning arrester in which a ground potential portion is connected to the other end in the direction, wherein an arcuate shield is arranged on the ground potential portion side of the umbrella shield via a connection support.