JPH04126323A - Gas circuit breaker - Google Patents

Abstract

PURPOSE:To obtain a gas circuit breaker of which dielectric strength is improved by preventing gas pressure at an end part of a fixed contact from lowering, by forming first and second throat parts in an insulation nozzle, and making a gas flowing sectional area to be formed between the first throat part and the fixed contact larger than that to be formed between the second throat part and the fixed contact. CONSTITUTION:Diameters of a fixed contact 4 and both throat parts 9, 10 are decided so that the value of a gas flowing sectional area S1 formed between the first throat part 9 positioned on the upper stream side of a puffing gas flow and a fixed contact 4 and the value of a gas flowing sectional area S2 formed between the second throat part 10 positioned on the down stream side of the puffing gas flow and the fixed contact 4 satisfy an inequality I. With this constitution, high pressure puffing gas can be maintained in a gas pocket formed between both throats, gas pressure at an end part of the fixed contact 4 is heightened in the wide range of a breaking stroke until the second throat part 10 passes through the end part of the fixed contact 4, thereby dielectric strength between the contacts can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gas circuit breaker, and particularly to a gas circuit breaker having an insulating nozzle that guides gas to blow against an arc generated due to separation between contacts. Regarding.

[Prior Art] Generally, this type of gas circuit breaker is constructed as shown in FIG. That is, the insulating nozzle 1 is provided so as to surround the contact portion between the movable contact 2 and the fixed contact 4 forming a pair, and the insulating nozzle 1 is attached to the buffer cylinder 3 together with the movable contact 2.

Further, the buffer cylinder 3 is fitted in a slidable relationship with the piston 7, and each part shown in the figure is arranged in a closed container filled with an arc-extinguishing gas.

Therefore, when the central shaft 13 integrated with the buffer cylinder 3 is driven by an operating device (not shown), the gas in the buffer chamber 14 is compressed and the movable contact 2 is separated from the fixed contact 4. , - are opened, an arc is generated between the surface contacts 2 and 4, but the gas compressed in the buffer chamber 14 is blown onto the arc by the insulating nozzle l to extinguish it.

When spraying in the second case, the gas is at the throat part 5 of the insulated nozzle l.
The gas is accelerated at the throat portion 5, and the spray becomes subsonic or supersonic at the diverging portion 6 located downstream of the gas flow. According to experiments, when the throat portion 5 of the insulating nozzle 1 passes the tip portion 4a of the fixed contact 4, if gas flows at the high speed described above, the gas pressure at the tip portion 4a becomes higher than the filling pressure. The dielectric strength between the contacts 2 and 4 decreases transiently, and the dielectric strength between the contacts 2 and 4 decreases significantly compared to the case where there is no gas flow, leading to a decrease in the small current interrupting performance.

In order to improve this problem, a gas circuit breaker disclosed in Japanese Patent Application Laid-open No. 59-103238 is equipped with a gas closing plate on the fixed contact, and this gas closing plate allows the gas to be discharged from the wide end side of the insulating nozzle. This is intended to prevent pressure drop at the tip of the fixed contact. Furthermore, in the gas circuit breaker disclosed in Japanese Patent Application Laid-Open No. 60-218722, a reflecting wall is formed on the downstream side of the gas flow from the throat portion of the insulating nozzle, and the gas colliding with this reflecting wall is reflected. This prevents a drop in pressure at the tip of the fixed contact.

[Problems to be Solved by the Invention] However, the gas shutoff plate in the former conventional gas circuit breaker described above acts to obstruct the gas flow even when the gas is sprayed afterwards, and when a large current is interrupted. The same effect also occurs in the case of , and as a result, the interrupting performance is reduced. Furthermore, the reflecting wall in the latter conventional gas circuit breaker described above is configured to increase the gas pressure at the tip of the fixed contact in a positional relationship such that the reflected gas flow acts on the tip of the fixed contact. Its effective range is narrow.

An object of the present invention is to provide a gas circuit breaker that prevents a drop in gas pressure at the tip of a fixed contact and improves dielectric strength.

[Means for Solving the Problems] In order to achieve the above object, the present invention forms at least first and second throat parts in an insulated nozzle that guides the gas, and the blowing is performed on the upstream side of the gas flow. a gas flow cross-sectional area Sl formed between the first throat part and the fixed contact located at , and a second throat part located downstream of the gas flow from the first throat part. What is the relationship between the gas flow cross-sectional area S and the fixed contact S1?
≧S yo.

[Function] Since the gas circuit breaker according to the present invention is configured as described above, a gas pocket is inevitably formed between the first and second throat portions, and pressure is applied to this gas pocket due to the relationship of the gas flow cross-sectional area described above. A high blowout can hold the gas and allow high pressure gas to act on the tip of the stationary contact over a wide range until the second throat part exits the stationary contact, thus insulating the tip. A gas circuit breaker with improved proof strength can be obtained.

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

FIG. 1 is a longitudinal sectional view of a gas circuit breaker in a closed state according to an embodiment of the present invention.

A buffer cylinder 3 is connected to a central shaft 13 connected to an operating device (not shown), and a movable contact 2 and an insulating nozzle 1 surrounding the movable contact 2 are attached to the buffer cylinder 3. A fixed contact 4 that comes into contact with and separates from the movable contact 2 is fixed to a member (not shown), and the insulating nozzle 1 surrounds the contact portion of the solid contacts 2 and 4 in the shown closed state. The buffer cylinder 3 is slidably fitted into a fixed piston 7, and the buffer chamber 14 is opened by both of them.
is formed, and when the central shaft 13 is driven in the opening direction of the movable contact 2, the arc-extinguishing gas in the buffer chamber 14 is compressed, and an insulating nozzle is formed so that the compressed gas is guided by the insulating nozzle 1. 1 is in communication with a buffer chamber 14. Furthermore, the insulating nozzle l has first and second throat portions 9.10 separated in its axial direction, ie along the flow of gas, forming a gas pocket 12 between these throat portions 9.10. are doing.

Furthermore, due to the structure in which the fixed contact 4 is inserted into the first and second throat parts 9 and 10 of the insulating nozzle 1, there is a gap between the fixed contact 4 and the first and second throat parts 9 and 10. Therefore, a predetermined gas flow cross-sectional area exists between both throat portions 9 and 10 and the fixed contact 4.

Here, the blowing refers to the gas flow cross-sectional area S1 formed between the first throat portion 9 located on the upstream side of the gas flow and the fixed contact 4, and the blowing refers to the second gas flow cross-sectional area S1 located on the downstream side of the gas flow. What is the relationship between the gas flow cross-sectional area S formed between the throat portion lO and the fixed contact 4? has been selected. That is, in this embodiment, the fixed contact 4 in the portion where the first and second throat parts 9.10 are inserted has the same diameter in the axial direction, so the diameter of the first throat part 9 and the diameter of the second throat part 9 are the same. The diameter of the throat portion 10 of , which relationship can be expressed as D, ≧D, (
2).

Next, the first and second throat portions 9.
The effect of No. 10 will be explained.

When the center shaft 13 is driven in the direction of opening the movable contact 2 from the closed state shown in FIG. Occur. The first throat portion 9 is the tip portion 4 of the fixed contact 4.
The high-pressure gas from the buffer chamber 14 is supplied into the gas pocket 12 through the gas flow cross-sectional area S1 before passing through a, and furthermore, the second throat portion 10 and the fixed contact 4 supply the high-pressure gas from the gas pocket 12 to the insulating nozzle. Since the gas flow discharged toward the divergent portion of the gas pocket 12 is restricted, the gas pocket 12 is filled with high-pressure gas.

Therefore, as shown in FIG.
The tip 4a is a gas pocket 12 filled with high pressure gas.
Therefore, the gas pressure decrease phenomenon that occurs immediately after the tip portion 4a of the fixed contact 4 passes through the first throat portion 9 unlike the conventional case does not occur.

Thereafter, the second throat portion 10 comes out of the tip 4a of the fixed contact 4, and the tip 4a of the fixed contact 4 is positioned at the 0 point in FIG. When the positional relationship is established, the tip 4a of the fixed contact 4
Although the gas pressure in the vicinity of is lower than before, the electric field strength at the tip 4a of the fixed contact 4 is sufficiently reduced in the zero point positional relationship as shown in Fig. 3, so this is not actually a problem. It won't happen. This corresponds to the point A in FIG. 3 showing the relationship between the electric field strength and the stroke at the tip 4a of the fixed contact 4, that is, the tip 4a of the fixed contact 4 as shown in FIG.
However, the blowing at the first throat section 9 depends on the electric field strength at the tip section 4a when it is located at the upstream end of the gas flow, and at point B in FIG. 3, that is, at the stationary contact 4 as shown in FIG. As can be seen from the comparison with the electric field strength of the tip 4a when the tip 4a is located at the downstream end of the gas flow, the blowing at the first throat 9 corresponds to approximately 50% of the total stroke. The electric field strength at the tip 4a at point 0 in the figure, that is, when the tip 4a comes out from the second throat portion lO, is sufficiently reduced by the separation between the contacts, and even if the gas pressure decreases, the electric field strength at the tip 4a is sufficiently reduced. This will not reduce the dielectric strength between the two.

FIG. 4 shows the tip 4a of the fixed contact 4 with respect to the stroke.
FIG. 3 is a gas pressure characteristic diagram showing changes in gas pressure in FIG.

As can be seen from the comparison between the gas pressure characteristic P1 of this embodiment shown in FIGS. The gas pressure near point B can be increased by about 30% in the structure according to this embodiment than in the conventional structure. Therefore, according to this embodiment, the tip portion 4 of the fixed contact 4
The dielectric strength can be improved by increasing the gas pressure of a over a wide range.

FIG. 5 is a longitudinal sectional view showing an insulating nozzle of a gas circuit breaker according to another embodiment of the present invention.

In addition to the structure of the previous embodiment, the insulating nozzle 1 in this embodiment has a third throat section 11 and a second throat section 1.
0 and a gas pocket 15 formed between the third throat portion 11 and the third throat portion 11. If the fixed contact 4 has the same diameter in the axial direction, the diameter of each throat portion 9, 10.11 is D
,, D, is D≧D,≧D,
(3), and the gas flow cross-sectional area S, S, formed between each throat portion 9, 10.11 and the fixed contact 4.

S, is S, ≧85≧S, (4).

According to this embodiment, it is possible to increase the gas pressure at the tip of the fixed contact at a position where the stroke is further expanded than in the previous embodiment, thereby increasing the dielectric strength between the contacts. In other words, the high pressure gas supplied from the buffer chamber side via the first and second throat parts 9 and 10 also enters the gas pocket 15, so that the second throat part 10 is removed from the tip of the fixed contact. Even after the tip comes out, the high pressure gas in the gas pocket 15 acts on the tip, so that the dielectric strength is prevented from decreasing.

FIG. 6 is a longitudinal sectional view showing an insulating nozzle of a gas circuit breaker according to still another embodiment of the present invention.

The difference from the insulating nozzle l shown in FIG. 1 is that a reflecting wall 16 is formed downstream of the second throat portion 10 in the gas flow. When forming this reflective wall 16, the third
This third throat part 17 will be provided.
The diameter of the throat portion 17 is the same as that of the first and second throat portions 9.
．． larger than the diameter of lO. The reflective wall 16 includes first and second reflective walls.
The blowing gas flowing through the throat portions 9 and 10 reflects a part of the gas to the tip of the fixed contact, thereby suppressing a drop in the gas pressure at the tip. Although this effect has a narrow range of effectiveness for the stroke, the second throat portion 10 can provide the same effect as the embodiment shown in FIG. 1, and the second throat portion 10 This makes it possible to improve the drop in gas pressure at the tip after exiting the tube.

In each of the above-mentioned embodiments, the diameter of the fixed contact is the same in the axial direction, but if the diameter of the tip of the fixed contact is made smaller than that of the base, the above equation (2) is changed as a condition. It is preferable to select the diameter of each throat portion so as to satisfy the equation (1).

[Effects of the Invention] According to the present invention described above, the first and second throat portions are formed in the insulating nozzle, and the gas flow cross-sectional area S1 formed between the first throat portion and the fixed contact, A gas flow cross-sectional area S formed between the second throat part and the fixed contact,
Since S1≧S, the gas can be held in the gas pocket formed between these two throat parts by high-pressure blowing, and the second throat part can hold the gas at the tip of the fixed contact. It is possible to increase the gas pressure at the tip over a wide range of the interrupting stroke until the contact passes through, improve the breakdown strength between the contacts, and improve the small current interrupting performance.

[Brief explanation of the drawing]

1 and 2 are vertical cross-sectional views of a gas circuit breaker according to an embodiment of the present invention in a closing state and a halfway state;
FIG. 4 is a characteristic diagram showing changes in electric field strength at the tip of the fixed contact, FIG. 4 is a characteristic diagram showing changes in gas pressure at the tip, and FIGS. A vertical cross-sectional view showing an insulating nozzle of a gas circuit breaker according to an embodiment, and FIG. 7 is a vertical cross-sectional view showing a conventional gas circuit breaker. l... Insulated nozzle, 2... Movable contact, 4... Fixed contact, 4a... Tip, 9... No. Throat part of 1, 10...
Second throat part, 11...Third throat part, 12.15...Gas pocket, 16...
...Reflective wall. Figure Figure Figure Figure Figure

Claims (1)

[Claims] 1. The insulating nozzle has a fixed contact inserted into the throat and a movable contact paired with the fixed contact, and an arc generated when these contacts separate. A gas circuit breaker that sprays high-pressure arc-extinguishing gas guided by the insulating nozzle to the insulating nozzle, the insulating nozzle having at least first and second throat portions located upstream of the blown gas flow. a gas flow cross-sectional area S_1 formed between the first throat section and the fixed contact; and a second throat section located downstream of the blown gas flow from the first throat section. A gas circuit breaker characterized in that the relationship between the gas flow cross-sectional area S_2 formed between the fixed contact and the fixed contact is as follows: S_1≧S_2. 2. In the device according to claim 1, the fixed contact includes:
The diameters of the portions into which the first and second throat parts are inserted are approximately the same in the axial direction, and the diameter D of the first throat part is
A gas circuit breaker characterized in that the relationship between D_1 and the diameter D_2 of the second throat portion is D_1≧D_2. 3. The insulating nozzle according to claim 1,
A third throat portion is formed on the downstream side of the blown gas flow than the second throat portion, and the gas flow cross-sectional area formed between the third throat portion and the fixed contact is S.
A gas circuit breaker characterized in that, when _2, S_1≧S_2≧S_3. 4. The device according to claim 1, wherein the second throat portion allows a portion of the blown gas flow to escape from the fixed contact on a downstream side of the blown gas flow than the second throat portion. 1. A gas circuit breaker, characterized in that a reflective wall is formed on the tip end side of the fixed contact to reflect when the fixed contact is exposed.