JPS60205926A - Vacuum switching device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a vacuum switchgear, and more particularly to a vacuum switchgear suitable for being housed in an insulating gas-filled container.

[Background of the invention]

Conventionally, since vacuum switchgears are used in the atmosphere, flexible sealing members (bellows) for driving movable electrodes have been manufactured on the assumption that they will be used under a pressure difference of 1 atmosphere. However, with recent technological advances in higher voltage and miniaturization, vacuum switchgear is housed in a container filled with insulating gas, especially SF6 gas, to improve the external insulation properties of vacuum switchgear. What was planned has been put into practical use. (Utility Model Publication No. 38-26415) Furthermore, as disclosed in JP-A-57-185628, in a hybrid circuit breaker in which a buffer type gas cutoff section and a vacuum cutoff section are configured in series, the vacuum cutoff section is arranged. It has also been proposed to airtightly partition the space in which the gas is removed so that the pressure in that area is lower than the gas pressure in the tank housing the buffer-type gas cutoff part.

FIG. 1 shows an embodiment of the above-mentioned hybrid circuit breaker,
A buffer cutoff section 3 and a space 5 airtightly separated from the gas space 2 by an airtight container 4 are provided in a gas space 2 surrounded by a tank 1 filled with SF6 gas, and the gas filling pressure is lower than that of the gas space 2. A vacuum cutoff section 6 is housed in a space 5 filled with pressurized gas.

When the insulated operating rod 7 is driven in the direction of the arrow in the figure by an operating device (not shown), the link 8. The buffer cutoff section 3 and the vacuum cutoff section 6 are driven via the lever 9.

Hybrid circuit breakers utilize the high withstand voltage characteristics of the buffer circuit breaker and the extremely fast insulation recovery characteristics of the vacuum circuit breaker.
This realizes a high voltage/large current circuit breaker. The gas space 2 in which the buffer cutoff part is housed is normally filled with SF6 gas at a pressure of 4 to 6 atmospheres. If the vacuum cut-off part is used under such high pressure conditions, there is a risk that the bellows 10 will be mechanically damaged, so the pressure in the space where the vacuum cut-off part is housed is lowered to reduce the stress on the bellows 10. do.

This structure requires gas tightness between the gas space 2 and the gas space 5, and a straight gas seal is used in this embodiment. With this type of seal, it is difficult to completely eliminate leakage, and it is necessary to monitor gas leakage. Also,
Since the container has a double structure, there are drawbacks such as the need for maintenance and inspection.

[Purpose of the invention]

An object of the present invention is to provide a vacuum switch which can be housed and placed directly in a relatively high-pressure gas space without providing an airtight gas section in the container when a vacuum switchgear is placed in a container filled with an insulating gas. To provide switchgear.

[Summary of the invention]

The key point of the present invention is to make the bellows of the vacuum switch device double or triple or more, to provide an airtight space between the vacuum part and the insulating gas space, and to create a gas-tight space in this space at a pressure lower than the gas filling pressure of the insulating gas space. This is because the stress acting on the bellows due to the pressure difference between the inside and outside of the bellows is reduced by filling the bellows with gas.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG. science fiction
6 In a gas space 2 surrounded by a tank 1 filled with gas,
A vacuum cutoff section 6 is housed. The vacuum cutoff section 6 is
Fixed electrode 21. The movable electrode 22 is made of an insulating tube 23. It has a structure in which it is housed in a vacuum space 27 that is completely sealed by end plates 24, 25 and bellows 26. The bellows 26 is completely hermetically joined to the rod 28 of the movable electrode 22 at one end and to the end plate 25 at the other end. In one embodiment, another bellows 29 is connected to the end plate 2.
5, it is completely hermetically joined to the rod 28 at one end and to the end plate 25 at the other end at a position opposite to the bellows 26.

The rod 28 of the movable electrode 22 is driven by a not-shown operating device via a link 30.

The current flows from the bushing terminal (not shown) through the conductor 31 and from the end plate 24 of the vacuum circuit breaker to the fixed electrode 21, the movable electrode 22, and so on. Via rod 28, current collector 32. Flexible conductor 33
It then leads to the conductor 34 and flows to the bushing at the other end via a buffer type gas cutoff (not shown).

The stress on the bellows used in vacuum switchgear is usually expressed by the following formula proposed by Kellogg. Taking a welded bellows as an example, the maximum stress σ is: where, E: Longitudinal elasticity Coefficient t: Thickness of bellows δ: Amount of expansion/contraction H Double height ■l: Number of ridges P: Pressure The first term of formula (1) is the term due to the deflection of the bellows, the second
The figure shows terms due to pressure difference. When used at atmospheric pressure, the pressure is 1 atm, but when a vacuum switch is placed inside a container containing a buffer type gas cutoff part, the gas pressure inside the container is usually as high as 4 to 6 atm. As the second term of equation (1) increases, the maximum stress σ increases. Bellows life depends on stress and Kellogg
According to the relationship proposed by the company, in the case of stainless steel bellows, the stress is inversely proportional to the 3.5th power of the maximum stress value. In order to avoid an increase in stress, the thickness of the bellows can be increased according to equation (1), and the number of ridges can be increased proportionally. However, this method is undesirable because it increases the overall length of the bellows and also increases manufacturing costs.

As shown in FIG. 2, bellows 26 and 29 are attached to the vacuum container side of the end plate 25 of the vacuum switchgear 6 and to the SF 6 container side, and are hermetically sealed with the rod 28 of the movable electrode 22. By changing the pressure at 35, the stress at bellows 26 and 29 can be appropriately suppressed.

For example, when using the same 26.29 mm bellows, it is preferable to fill and seal the space 35 with gas at a pressure of about 172 mm, which is the absolute value of the SF6 filling gas pressure in the container 1. By doing so, the increase in stress due to pressure on both bellows 26 and 29 can be equally halved.

Further, when using an existing vacuum switchgear that is intended to be used in the atmosphere, it is preferable that the space 35 be filled with gas at a pressure approximately equal to atmospheric pressure and sealed off. In this case, the bellows 29 should preferably have a shape suitable for a pressure difference that is approximately 1 atm lower than the gas filling pressure in the container 1.
Although it may be larger than the bellows of the end plate 25,
There are no restrictions on the shape of the F6 gas space, so there is no problem.

By selecting the shape, dimensions, method, material, etc. of the bellows 26, 29, it is possible to set the filling pressure in the space 35 such that the stress due to the pressure difference on each bellows is set to a value that makes the life of each bellows approximately the same. can.

The present invention is characterized in that gas leakage is completely eliminated by sealing off the gas within the space 35. In the figure, 36 indicates a sealing device for sealing off gas.

Note that 31 is a lead wire, and 36 is an end plate.

Although the same type of gas as the gas filled in the tank 1 may be used to fill the space 35, it is preferable to use a different type of gas. That is, if the bellows 29 should break, the gas filled in the space 35 will be released into the gas space 2 in the tank 1. By monitoring the composition of the gas in the tank 1, damage to the bellows can be detected.

When three or more bellows are installed and there are two or more spaces airtightly partitioned by each bellows, the stress can be reduced by changing the pressure in each space and making the mechanical stress on the bellows approximately equal. In addition, a highly reliable vacuum interrupter can be realized.

FIG. 3 shows another embodiment of the vacuum switchgear according to the present invention. In this embodiment, two bellows 40° 41 are both arranged inside the end plate 25.

This structure has the effect of reducing the size because the bellows is inside the vacuum switchgear.

FIG. 4 shows still another embodiment of the vacuum switchgear of the present invention. In this embodiment, the two bellows 50, 51 are
Both are arranged outside the end plate 25. According to this structure, since the bellows is in a compressed state when the vacuum switchgear is closed, the mechanical stress that the bellows receives due to the pressure difference between the inside and outside of the bellows is reduced. Circuit breakers remain closed for an overwhelmingly long time, and reducing stress while in the closed state will extend their lifespan.

〔Effect of the invention〕

According to the present invention, the vacuum switchgear can be housed in an insulating gas atmosphere with relatively high pressure, so the structure is simple.
A vacuum switchgear with excellent insulation properties can be provided.

Further, in a switchgear having a structure in which the vacuum switchgear is simply housed in an insulating gas atmosphere, the insulating gas pressure can be increased, and a high withstand voltage can be easily obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the prior art, FIG. 2 is a vertical cross-sectional view of an embodiment of the vacuum switchgear of the present invention, and FIGS. 3 and 4 are:
It is a longitudinal cross-sectional view of another Example of the vacuum switchgear of this invention. l... Container, 2... Insulating gas space, 6... Vacuum switchgear, 26, 29, 40, 41, 50.51...
Bellows (flexible sealing member), 35...airtight space. Agent Patent Attorney Akio Takahashi also 1st year 2nd page 1st page continuation 0 Inventor Yes 1) Hiroshi Hitachi City Saiwaicho Shonai

Claims (1)

[Claims] 1. In a vacuum switchgear housed in a container filled with an insulating gas, one end is hermetically connected to a conductive rod that drives a movable electrode of the vacuum switchgear, and the other end is connected to a conductive rod that drives a movable electrode of the vacuum switchgear. a plurality of flexible seal members hermetically joined to an end plate of a vacuum container of the opening/closing device;
The flexible sealing member fills and seals a space airtightly separated from the vacuum space within the vacuum switchgear and the space inside the container filled with insulating gas with a gas having a pressure lower than the filling pressure of the insulating gas. A vacuum switch device characterized by being provided with means. 2. The gas filled and sealed by the flexible sealing member into a space airtightly separated from the vacuum space and the insulating gas filling space is a gas different from the insulating gas. A vacuum switchgear according to claim 1.