JPH0487126A - Gas circuit breaker - 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] [Industrial Application Field] The present invention relates to a gas circuit breaker, and particularly to a gas circuit breaker, in which arc-extinguishing gas such as SFe gas is sprayed onto an arc that occurs between a movable electrode and a fixed electrode when interrupting a large current. The present invention relates to a gas circuit breaker equipped with an insulating nozzle with high withstand voltage characteristics placed near an arc generating part for extinguishing an arc.

[Conventional technology]

In conventional gas circuit breakers, a high-temperature plasma-like arc is generated between the movable electrode and the fixed electrode. In order to extinguish this arc, an arc-extinguishing gas such as SFe gas is sprayed onto the arc using the insulating nozzle mentioned above, but the energy rays generated from the arc cause voids and carbon to form inside the nozzle. , the insulation performance may deteriorate. In order to improve this point, for example, as shown in Japanese Patent Publication No. 1-37822, the nozzle is made of a fluororesin insulator, which contains boron nitride powder bundles as a filler. .

[Problem to be solved by the invention]

In the above-mentioned conventional technology, as the interrupting part becomes smaller and larger in capacity, the amount of filler such as boron nitride filled into the nozzle is increased in order to improve the arc resistance of the nozzle due to the energy rays of the arc. For this reason.

The relative dielectric constant of the nozzle tends to increase. As described above, when the dielectric constant of the nozzle increases, the electric field strength at the tip of the movable electrode, which affects the blocking performance, increases, and there is a concern that the blocking performance may deteriorate. In other words, some types include a cylinder on the outer periphery of the movable electrode that forms a gas flow path with the inner wall of the nozzle, while others do not, but in either case, the electric field strength on the tip side of the movable electrode must be lowered. The problem is that the dielectric strength between the fixed electrode and the movable electrode decreases, and the switching performance of small currents, especially in the small current region such as leading small current switching characteristics, is not good. was there.

The purpose of the present invention is to reduce the electric field strength on the tip side of the movable electrode,
It is an object of the present invention to provide a gas circuit breaker that can improve switching performance in a small current region and also improve large current interrupting performance.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a fixed electrode, a movable electrode facing the fixed electrode, a nozzle for blowing and guiding gas to an arc generated between these electrodes, and a gas flow path together with the nozzle. A cylindrical body that covers the outer periphery of the movable electrode so as to form a cylindrical body, wherein the cylindrical body is made of an insulator having a dielectric constant higher than that of the nozzle.

[Effect]

In the present invention, by making the dielectric constant of the cylinder covering the movable electrode larger than that of the nozzle, the equipotential line at the tip of the movable electrode shifts to the fixed electrode side, thereby relaxing the electric field at the tip of the movable electrode. can do.

As a result, it is possible to improve the switching performance in a small current region and the large current breaking performance, and to provide a circuit breaker that can handle higher voltages.

〔Example〕

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

FIG. 1 shows the main parts of the interrupting part in the gas circuit breaker of the present invention. In this figure, 1 is a fixed electrode, 2 is a movable electrode provided opposite to the fixed electrode 1, and this movable electrode 2
is equipped with a contactor 21 divided into a plurality of pieces. 3 is an annular spring provided on the outer periphery of the contactor 21, 4 is a cylindrical conductor that holds the movable electrode 2, 5 is a drive shaft, 6 is a movable cylinder integrally provided with the drive shaft 5, 7 is a fixed piston, 8 is a buffer chamber defined by the fixed piston 72, movable cylinder 6, and drive shaft 5, and 9 is an opening formed at the end of the movable cylinder 5 so as to communicate with the buffer chamber 8. 1o is an insulating nozzle attached to the cylindrical conductor 4; 11 is a cylinder attached to the cylindrical conductor 4 so as to be located inside the nozzle 10; this cylinder 11 is connected to the inner wall surface of the nozzle 10; It forms the gas flow path 12 and covers the end surface of the movable electrode 2 on the tip side.

As shown in FIG. 2, the above-mentioned interrupting section shown in FIG.
In addition, the fixed piston 7 is connected to the grounded tank 1 via the insulator 15.
It is fixed within 4. An insulating medium such as SFe gas is sealed inside the grounded tank 14.

In the circuit breaker described above, when the N moving shaft 6 is driven rightward in the drawing in response to a shutdown command, the nozzle 10° cylinder 11. The movable electrode 29, the cylindrical conductor 4 and the movable cylinder 6 similarly move to the right relative to the fixed piston 6. As a result, an arc A is generated between the fixed electrode 1 and the movable electrode 2,
As the drive shaft 6 is driven in the right direction in the drawing, the high-pressure gas in the buffer chamber 8 is blown toward the arc A through the opening 9 and the gas flow path 12 to cool it. As a result, arc A disappears, completing the interruption.

Since the cylindrical body 11 forming the gas flow path 12 by the nozzle 10 described above covers the end face of the movable electrode 2,
The electric field E on the surface of the cylinder 11. The electric field E at the tip of the movable electrode 2 becomes higher. The electric field Ec on the surface of the cylinder 11 can be set higher than the surface electric field E of the movable electrode 2 as a permissible value in terms of electric field strength. Focusing on this point,
The relative dielectric constant EC of the cylinder 11 is set to be larger than that of the nozzle 1o. In this way, in order to change the dielectric constant fc of the nozzle 10 and the cylinder 11, the nozzle 10
This is possible by adding a filler to the base material of the cylinder 11. That is, the insulating material used around the interrupting part is usually made of a material that has excellent heat resistance and arc resistance, and has a low dielectric constant that does not easily affect the electric field. An example of this is a fluorine-based resin such as tetrafluoroethylene (relative dielectric constant ts=2.1). Therefore, by adding a filler to the base material of this fluororesin, the dielectric constant can be changed. The filler mentioned above is preferably one that takes into account the arc resistance of the nozzle 10. An example of this is boron nitride (BN). By changing the amount of boron nitride filled into the fluorine-based resin, the dielectric constant can be changed from about 2.1 to 3.0.

As described above, by increasing the dielectric constant of the cylinder 11, the electric field on the tip side of the movable electrode 2 can be relaxed. That is, by configuring as described above, the third
As shown in the figure, regarding the equipotential lines on the tip side of the movable electrode after being cut off, the equipotential lines as shown by the solid line 30 are It can be transferred to the fixed electrode 1 side. As a result, the electric field strength on the tip side of the movable electrode can be reduced,
It is possible to improve switching performance in a small current region, such as advanced small current switching performance. To further explain this point using FIG. 4, FIG. 4 shows the relative dielectric constant ε of the cylinder 11. and a movable electrode 2. It shows the relationship between the electric field strength at the tip end side of the cylinder 11. In this figure, the characteristic curve E shows the electric field strength of the movable electrode 2, and the characteristic curve Ec shows the electric field strength of the cylinder 11. As is clear from this figure, the cylindrical body 11
The movable electrode is The electric field strength E at the tip of No. 2 can be reduced. On the other hand, the electric field strength Ec at the tip of the cylinder 11 increases as the dielectric constant of the cylinder 11 increases, but in general, when comparing the allowable electric fields between the electrode part and the insulating material surface, it is found that Depending on the situation, field emission occurs on the electrode surface of the electrode portion, so the allowable electric field is lower than that of an insulator.

That is, the allowable electric field can be set higher on the surface of the insulator. Focusing on this point, the present invention focuses on this point.

The electric field strength at the tip of the movable electrode 2 is relaxed by increasing the dielectric constant of the cylinder. When the nozzle 10 is made of only tetrafluoroethylene resin, the cylindrical body 11
The relative permittivity of the nozzle 10 may be set to be larger than the relative permittivity of the nozzle 10, which is 2.1. Further, when the nozzle 10 is filled with boron nitride powder, the relative dielectric constant of the cylinder 11 is
Boron nitride powder may be added to the cylindrical body 11 so that the dielectric constant becomes larger than zero.

As mentioned above, since the cylinder 11 is made of fluorine-based resin containing boron nitride, the cylinder 11 reduces the electric field strength at the tip of the movable electrode 2 and has extremely good arc resistance. , there is little damage even when interrupting large currents.

In the above embodiment, boron nitride was used as the filler to make the dielectric constant of the cylinder 11 larger than that of the nozzle 10, but for example, alumina, titanium oxide, kaolin clay, zinc white, sulfuric acid, etc. Powders such as barium and Bengara may also be added.

In the above embodiment, the cylinder 11 is provided on the outer periphery of the movable electrode 2, but as shown in FIG. 5, it is also possible to provide a metal cylinder 50 inside the cylinder 11. In this case, the shape of the tip of the cylindrical body 50 not only reduces the electric field at the tip of the movable electrode 2, but also has a shielding effect against electric field concentration in the spring 3, etc., and improves insulation. Even with this configuration, the electric field on the tip side of the movable electrode 2 can be relaxed, as in the embodiments of the present invention described above.

〔Effect of the invention〕

According to the present invention, even when using a nozzle made of an insulating material with high relative dielectric constant and excellent arc resistance,
Since the electric field strength at the tip of the movable electrode can be relaxed, it is possible to improve the switching performance in a small current region such as advanced small current switching performance, and it is also possible to improve the large current interrupting performance.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the cut-off part of the gas circuit breaker of the present invention, FIG. 2 is a cross-sectional view of a gas circuit breaker equipped with the cut-off part according to the present invention shown in FIG. 1, and FIG. FIG. 4 shows the electric field state at the tip of the movable electrode of the gas circuit breaker of the present invention, and FIG. The characteristic diagram and FIG. 5 are cross-sectional views showing another embodiment of the gas circuit breaker of the present invention. 1...Fixed electrode, 2...Movable electrode, 3...Spring, 4
... Cylindrical conductor, 5... Drive shaft, 6... Movable cylinder, 6... Fixed piston, 8... Buffer chamber, 9...
・Opening, 10... Nozzle, 11... Cylindrical body, 12...
・Gas flow path. Fig. 1 Fig. 3 Fig. 14 Grounding tank Fig. 4 ε Relative permittivity of the cylindrical body 11: ε.

Claims (1)

[Claims] 1. A fixed electrode, a movable electrode facing the fixed electrode,
A circuit breaker comprising a nozzle that blows and guides gas to an arc generated between these electrodes, and a cylindrical body that covers the outer periphery of the movable electrode so as to form a gas flow path together with the nozzle, the cylindrical body comprising: A gas circuit breaker characterized by being constructed of an insulator with a dielectric constant higher than that of the nozzle. 2. The gas circuit breaker according to claim 1, wherein the cylindrical body is a fluororesin insulator having a dielectric constant higher than that of the nozzle. 3. The gas circuit breaker according to claim 2, wherein the cylindrical body contains boron nitride powder as a filler in a fluororesin insulator. 4. The gas circuit breaker according to claim 2, wherein the cylindrical body contains boron nitride powder as a filler in tetrafluoroethylene resin. 5. The gas circuit breaker according to claim 1, wherein the nozzle and the cylindrical body contain boron nitride powder as a filler in a fluororesin insulator. 6. The gas circuit breaker according to claim 5, wherein the fluororesin insulator is a tetrafluoroethylene resin. 7. The gas circuit breaker according to claim 1, further comprising a metal cylindrical body provided inside the cylindrical body. 8. A fixed electrode, a movable electrode facing the fixed electrode,
A circuit breaker includes a nozzle that blows and guides gas to an arc generated between these electrodes, and a cylindrical body that covers the outer periphery of the movable electrode so as to form a gas flow path together with the nozzle. A gas circuit breaker characterized by being an insulator that moves equipotential lines on the movable electrode side to the fixed electrode side when the is opened.