JP2003217411A - Gas circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small gas circuit breaker with high reliability capable of sufficiently securing insulation to the ground isolation voltage at a terminal end of an exhaust cylinder when shutting current, even though it is small, and avoiding the occurrence of ground fault. <P>SOLUTION: The exhaust cylinder 9a for guiding hot gas 8 from a generation space of an arc 7 to the outside of a fixed contact part A is mounted on the fixed contact part A. The exhaust cylinder 9a is made of an insulating material made of fluorine contained resin. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas circuit breaker for electric power, and more particularly to a gas circuit breaker for discharging hot gas by an arc.

[0002]

2. Description of the Related Art Generally, a gas circuit breaker filled with an insulating gas is installed in a power transmission and distribution facility in order to protect a system. Among them, a large-capacity gas circuit breaker with a large breaking current employs a method of extinguishing an arc generated between two electrodes by blowing a pressurized arc-extinguishing gas. FIG. 7 shows a conventional example of this system. FIG. 7 is a lateral cross-sectional view of the gas circuit breaker, showing a state in the middle of the breaking operation.

A tank 1 which is a grounded metal container is filled with arc-extinguishing gas 2 as an insulating gas and has a fixed contact portion A.
And the movable contact portion B is arranged to face each other. A fixed arc contact 6 is provided on each of the fixed contact portion A and the movable contact portion B.
a and a movable arc contactor 6b are provided. These arc contacts 6a and 6b are in a contact conducting state during normal operation, and are opened by relative movement during a breaking operation, and an arc 7 is generated in the space between both contacts 6a and 6b. .

A puffer chamber 5 including a piston 3 and a cylinder 4 is installed in the movable contact portion B as a gas flow generating means. During the shutoff process, the piston 3 compresses the internal space of the cylinder 4 and increases the pressure in the puffer chamber 5. Therefore, the arc-extinguishing gas 2 in the puffer chamber 5 becomes a high-pressure gas flow, and the arc 7 is extinguished by spraying the gas flow on the arc 7. The arc-extinguishing gas 2 near the arc 7 becomes a hot gas 8 of high temperature and low density.
The exhaust pipe 9 is a member for guiding the hot gas 8 to the outside of the fixed contact portion A. The exhaust pipe 9 is made of metal and is attached to the fixed contact portion A. The exhaust stack 9 is moved by the high pressure gas flow blown from the puffer chamber 5 into the arc contactor 6
The hot gas 8 generated between a and 6b is taken in, and this is quickly exhausted from the exhaust tube end portion 10 into the tank 1.

In recent years, the gas circuit breaker of the above type has been downsized in order to save the installation area and reduce the cost. Further, particularly when SF6 gas having a high global warming effect is used as the arc extinguishing gas 2, it is desirable to reduce the amount of SF6 gas used as much as possible. Therefore, there is a social demand for a compact gas circuit breaker in terms of the global environment. Under such circumstances, the sizes of the tank 1 and the exhaust pipe 9 which are the constituent elements of the gas circuit breaker tend to become smaller and smaller.

[0006]

However, when the tank 1 and the exhaust pipe 9 are downsized, the arc contacts 6a, 6b.
The processing volume for cooling the hot gas 8 generated during the period becomes small, and the time for the hot gas 8 to reach the exhaust tube end portion 10, that is, the time spent for cooling the hot gas 8 inside the exhaust tube 9 is also reduced. It gets shorter. As a result, the hot gas 8 immediately after being discharged from the exhaust tube end portion 10 is in a higher temperature state.

On the other hand, after the current is cut off, the transient recovery voltage generated due to the system condition is applied to the exhaust pipe 9, so that the exhaust pipe 9
Has a high potential, but when the size of the tank 1 is reduced, the distance between the tank 1 having the ground potential and the exhaust pipe 9 is inevitably reduced. Therefore, the electric field strength at the exhaust tube end portion 10 becomes higher. Generally, when the pressure is constant, the higher the electric field and the higher the gas temperature, the lower the dielectric strength of the gas. In other words, if the tank 1 and the exhaust pipe 9 are downsized and downsized with the downsizing of the gas circuit breaker,
As described above, the electric field strength and the hot gas temperature in the exhaust tube end portion 10 become higher after the current is cut off. For this reason, the dielectric strength is significantly reduced, and the dielectric breakdown occurs between the exhaust tube end portion 10 and the tank 1 (hereinafter, this phenomenon is referred to as "ground fault").
However, there is a problem in that

Therefore, according to the present invention, a small and highly reliable gas, which is small in size, can sufficiently secure the withstand voltage against the ground at the end of the exhaust stack when current is cut off, and can avoid the occurrence of a ground fault. It is intended to provide a circuit breaker.

[0009]

To achieve the above object, according to the present invention, a fixed contact portion and a movable contact portion are arranged to face each other in a grounded metal container filled with an insulating gas, and the fixed contact portion is provided. A fixed arc contactor and a movable arc contactor are provided on the contact portion and the movable contact portion, respectively, and the fixed arc contactor and the movable arc contactor are in a contact conducting state during normal operation and by relative movement during a breaking operation. It is configured to generate an arc in the space between the contacts while opening and closing, further the movable contact portion is provided with a gas flow generating means for blowing an arc extinguishing gas for extinguishing the arc to the arc, In the gas circuit breaker, in which the exhaust pipe for guiding the hot gas blown to the arc from the space where the arc is generated to the outside of the fixed contact part is attached to the fixed contact part, It has a feature of Naruue.

The invention of claim 1 is characterized in that the exhaust stack is made of an insulator made of fluororesin. According to the invention of claim 1, since the exhaust pipe is made of the insulator made of fluororesin such as tetrafluoroethylene, the heat of the hot gas passing through the exhaust pipe can be suppressed by the fluororesin. . For this reason, it is possible to obtain a sufficient path distance between the conductive portion and the grounded metal container through the hot gas even if the hot gas is not sufficiently cooled as compared with the conventional exhaust tube of the conductive material. It is possible to obtain excellent dielectric strength. Therefore, the exhaust stack can be shortened as compared with the conventional one, and the grounded metal container can be downsized accordingly. As a result, a compact and highly reliable gas circuit breaker that is small and that can sufficiently secure the dielectric strength of the end of the exhaust stack to ground even when breaking a large current and can avoid the occurrence of a ground fault is provided. can do.

According to a second aspect of the present invention, a tubular exhaust cover is attached in the vicinity of the exhaust outlet of the exhaust pipe in the axial direction of the exhaust pipe, and the exhaust cover is made of an insulating material made of fluororesin. It is characterized by that. According to the invention of claim 2, since the exhaust cover is attached in the vicinity of the exhaust outlet of the exhaust stack, it is possible to prevent the release of hot gas to the high electric field portion at the end of the exhaust stack, and to further improve the dielectric strength. Can be improved. Therefore, as in the case of the first aspect of the present invention, it is possible to prevent the occurrence of a ground fault and to reduce the size and improve the reliability.

According to a third aspect of the present invention, in the gas circuit breaker according to the second aspect, a metal shield having the same potential as the exhaust pipe is arranged outside the exhaust cover. According to the invention of claim 3, although the electric field at the outer peripheral portion of the exhaust pipe is slightly increased by disposing the metal shield having the same potential as the exhaust pipe on the outside of the exhaust cover,
Due to the electric field shielding effect, it is possible to suppress the electric field on the inner surface of the insulating cylinder in which hot gas having low insulating properties is present, particularly the electric field at the junction with metal. In addition, the electric field slightly rises near the metal shield on the outer periphery of the exhaust stack, but the hot gas passing through the exhaust stack does not come into direct contact therewith, so the insulation of the entire exhaust stack is as follows:
The configuration will be more reliable.

According to a fourth aspect of the present invention, in the gas circuit breaker according to the second or third aspect, the exhaust cover is formed so as to suppress release of the hot gas to a branch portion or a high electric field portion of the grounded metal container. It is characterized by being done. According to the invention of claim 4, the discharge direction of the hot gas is regulated by the exhaust cover, and the hot gas is discharged to the branch portion or the high electric field portion of the grounded metal container, that is, the portion where dielectric breakdown is likely to occur. Can be deterred. This makes it possible to further improve the dielectric strength.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be specifically described below with reference to FIGS. It should be noted that each of the following embodiments is a gas circuit breaker of a type in which an arc extinguishing gas is blown to the arc to extinguish the arc, as in the conventional example shown in FIG. 7. Therefore, the same members as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.
Like FIG. 7, FIGS. 1 to 6 are lateral cross-sectional views of the gas circuit breaker, showing a state in the middle of the breaking operation.

(1) First Embodiment Corresponding to Claim 1 <Structure> A first embodiment according to the invention of claim 1 will be described with reference to FIG. The first embodiment is characterized by including an exhaust pipe 9a made of an insulating material. The exhaust pipe 9a is made of a fluororesin containing fluorine in the molecule. The fluororesin is a synthetic polymer material represented by tetrafluoroethylene resin (polytetrafluoroethylene, PTFE) and has excellent insulating properties.

<Operation / Effect> The heat of the hot gas 8 generated between the arc contacts 6a and 6b is suppressed during the period of flowing inside the exhaust tube 9a. Therefore, as compared with the exhaust pipe 9 made of a conventional conductive material, a sufficient path distance between the conductive portion and the tank 1 via the hot gas 8 can be obtained even if the hot gas 8 is not sufficiently cooled. You can Therefore,
It is possible to secure dielectric strength, and it is possible to obtain a sufficient dielectric strength against ground even when a large current is cut off, despite its small size. This makes it possible to avoid the occurrence of a ground fault, and it is possible to obtain a compact and highly reliable gas circuit breaker.

(2) Second Embodiment Corresponding to Claim 2 <Structure> Next, a second embodiment according to the invention of claim 2 will be described with reference to FIG. In the second embodiment, a tubular exhaust cover 11 is attached to the exhaust tube end portion 10 in the axial direction of the exhaust tube 9. This exhaust cover 1
Reference numeral 1 is made of an insulator made of fluororesin.

<Operation / Effect> In the second embodiment as described above, since the exhaust cover 11 is attached to the exhaust pipe 9,
It is possible to prevent the hot gas 8 from being released to the high electric field portion of the exhaust tube end portion 10, and it is possible to further improve the dielectric strength. Therefore, similar to the first embodiment, the exhaust tube end portion 10 is small even when the large current is cut off despite its small size.
It is possible to sufficiently secure the dielectric strength against ground, prevent the occurrence of ground fault, and downsize the device and improve the reliability.

(3) Third Embodiment Corresponding to Claim 3 <Structure> Next, a third embodiment according to the invention of claim 3 will be described with reference to FIGS. 3 and 4. A feature of the third embodiment is that a metal shield 12 having the same potential as the exhaust pipe 9a is arranged outside the exhaust pipe 9a formed of an insulating material (see FIG. 3).

<Operation / Effect> In the third embodiment as described above, the metal shield having the same potential as that of the exhaust tube end portion 10 is provided so that the exhaust tube end portion 10 covers the joint with the exhaust cover 11. Since 12 is arranged, the electric field at the outer peripheral portion of the exhaust pipe 9a is slightly increased, but the electric field on the inner surface of the exhaust pipe 9a where the hot gas 8 having low insulating property is present due to the electric field shielding effect, particularly the electric field at the joint with metal is suppressed. be able to.
Further, although the electric field slightly rises in the vicinity of the metal shield 12 on the outer peripheral portion of the exhaust pipe 9a, the hot gas 8 does not directly impinge on it, so that the insulation of the entire exhaust pipe 9a portion is more reliable. . As a result, it is possible to sufficiently secure the dielectric strength of the exhaust tube end portion 10 to the ground even when a large current is cut off even though it is small, and to avoid the occurrence of a ground fault.
A small and highly reliable gas circuit breaker can be obtained.

As shown in FIG. 4, the exhaust tube end portion 1
The same function and effect can be obtained by configuring the shape of 0 to cover the outer periphery of the joint with the exhaust cover 11. That is, in this case, it can be considered that the metal shield 12 is integrally formed with the exhaust pipe 9a, and the structure can be further simplified.

(4) Fourth Embodiment ... Corresponding to Claim 4 <Structure> A fourth embodiment according to the invention of claim 4 will be described with reference to FIGS. 5 and 6. The fourth embodiment is characterized in that the exhaust cover 11 is formed so as not to release the hot gas 8 toward the branch portion or the high electric field portion of the tank 1. More specifically, the exhaust cover 11 of FIG. 5 has a semicircular cross section and is configured to discharge the hot gas 8 obliquely downward in the drawing. Further, the exhaust cover 11 of FIG. 6 has a cylindrical shape having a bottom surface, and is provided with an exhaust outlet 11a on the right side surface in the drawing to discharge the hot gas 8 to the right side in the drawing.

<Operation / Effect> According to the fourth embodiment as described above, the exhaust cover 11 regulates the emission direction of the hot gas 8 to cause the dielectric breakdown such as the branch portion of the tank 1 and the high electric field portion. It is possible to suppress the release of the hot gas 8 to the easy part. As a result, it is possible to further improve the dielectric strength, and it is possible to sufficiently secure the dielectric strength of the exhaust tube end portion 10 with respect to the ground even when the large current is cut off even though it is small. As a result, it is possible to obtain a small-sized and highly reliable gas circuit breaker capable of avoiding the occurrence of a ground fault.

(5) Other Embodiments The present invention is not limited to the above embodiment, and the exhaust pipe 9a and the exhaust cover 11 may be integrally formed. The fluororesin is not limited to tetrafluoroethylene resin, but tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, PFA).
Or tetrafluoroethylene / hexafluoropropylene copolymer resin (tetrafluoroethylene / hexafluoropropylene copolymer, FEP), or tetrafluoroethylene / ethylene copolymer resin (tetrafluoroethylene / ethylene copolymer, ETFE ) Is acceptable.

[0025]

As described above, according to the gas circuit breaker of the present invention, although it is small, it is possible to sufficiently secure the withstand voltage against the ground at the end of the exhaust stack when current is cut off, and to avoid the occurrence of a ground fault. It is possible to reduce the size and improve the reliability.

[Brief description of drawings]

FIG. 1 is a lateral sectional view of a first embodiment of the present invention.

FIG. 2 is a lateral sectional view of a second embodiment of the present invention.

FIG. 3 is a lateral cross-sectional view of the third embodiment of the present invention.

FIG. 4 is a lateral cross-sectional view of the third embodiment of the present invention.

FIG. 5 is a lateral sectional view of a fourth embodiment of the present invention.

FIG. 6 is a lateral cross-sectional view of the fourth embodiment of the present invention.

FIG. 7 is a lateral sectional view of a general gas circuit breaker conventionally used.

[Explanation of symbols]

1 ... tank 2 ... Arc extinguishing gas 3 ... piston 4 ... Cylinder 5 ... Puffer room 6 ... Arc contact 7 ... Ark 8 ... Hot gas 9, 9a ... Exhaust stack 10 ... Exhaust tube end 11 ... Exhaust cover 11a ... Exhaust outlet 12 ... Metal shield

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Uchii             2-1, Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa             Ceremony Company Toshiba Hamakawasaki Factory F-term (reference) 5G001 AA05 AA06 BB04 GG02

Claims (4)

[Claims] 1. A fixed contact portion and a movable contact portion are arranged to face each other in a grounded metal container filled with an insulating gas, and the fixed contact portion and the movable contact portion are fixed arc contact and movable arc contact, respectively. A child is provided, and the fixed arc contact and the movable arc contact are in a contact conducting state during normal operation, and are separated by relative movement during a breaking operation, and an arc is generated in a space between both contacts. Further, the movable contact portion is provided with a gas flow generating means for blowing an arc extinguishing gas for extinguishing the arc to the arc, and the fixed contact portion is provided with the hot gas blown to the arc. In a gas circuit breaker equipped with an exhaust pipe that guides the space outside of the fixed contact portion to the outside of the fixed contact portion, the exhaust pipe is made of an insulator made of fluororesin. Gas circuit breaker to. 2. A fixed contact portion and a movable contact portion are arranged to face each other in a grounded metal container filled with an insulating gas, and the fixed contact portion and the movable contact portion have fixed arc contacts and movable arc contacts, respectively. A child is provided, and the fixed arc contact and the movable arc contact are in a contact conducting state during normal operation, and are separated by relative movement during a breaking operation, and an arc is generated in a space between both contacts. Further, the movable contact portion is provided with a gas flow generating means for blowing an arc extinguishing gas for extinguishing the arc to the arc, and the fixed contact portion is provided with the hot gas blown to the arc. In a gas circuit breaker equipped with an exhaust pipe that guides the space outside of the fixed contact portion to the outside of the fixed contact portion, a gas exhaust cover that is cylindrical in the axial direction of the exhaust pipe is provided near the exhaust outlet of the exhaust pipe. Is attached, a gas circuit breaker, characterized in that the exhaust cover made of an insulating material made of a fluorine resin. 3. The gas circuit breaker according to claim 2, wherein a metal shield having the same electric potential as that of the exhaust pipe is arranged outside the exhaust cover. 4. The gas circuit breaker according to claim 2, wherein the exhaust cover is formed so as to suppress the release of the hot gas to the branch portion and the high electric field portion of the grounded metal container. .