GB2452356A

GB2452356A - Gas circuit breaker

Info

Publication number: GB2452356A
Application number: GB0807323A
Authority: GB
Inventors: Daisuke Yoshida; Haruhiko Kohyama; Yuji Yoshitomo
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2007-08-31
Filing date: 2008-04-22
Publication date: 2009-03-04
Anticipated expiration: 2028-04-22
Also published as: CN101377984A; GB2452356B; GB0807323D0; JP2009059581A

Abstract

A gas circuit breaker (100) includes a moving mechanism (40) that moves two movable contacts (13) toward or away from respective fixed contacts (9). The moving mechanism (40) includes one coupling rod (20), two coupling shafts (24), and two linking members (21). Each of the linking members (21) couples a corresponding one of the movable contacts (13) to the coupling rod (20) via a corresponding one of the coupling shafts (24).

Description

GAS CIRCUIT BREAKER

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gas circuit breaker having a plurality of breaker units.

2. Description of the Related Art

Gas circuit breakers with multiple breaking points are used in power transmission systems that operate at high voltage of more than 72 kilovolt (kV). For example, Japanese Utility Model Application Laid-open No. S60-115428 discloses a conventional puffer-type gas circuit breaker having two breaking points for use in such power transmission systems.

Fig. 3 is a schematic diagram of the conventional puffer type gas circuit breaker 90. The puffer type gas circuit breaker 90 includes a tank 1, two puffer-type breaker units 30, and a moving unit 39. The tank 1 is grounded and it is filled with arc-extinguishing gas. One puffer-type breaker unit 30 is respectively mounted on the right and left sides of the tank 1 (the right-side breaker unit 30 is not shown in Fig. 3) . The puffer-type breaker units 30 perform switching operation. The moving unit 39 is positioned between the breaker units 30 and an external driving device 10, and transmits force generated by the driving device 10 to the breaker units 30.

The arc-extinguishing gas can be sulfur hexafluoride gas. A cylindrical insulating supporting member 2 and two cylindrical insulating supporting members 5 (the right-side cylindrical insulating supporting members 5 is not shown in Fig. 3) are mounted in the tank 1. The insulating supporting member 2 supports a bracket 3 and a part of the breaker units 30. Each of the insulating supporting members 5 supports a central conductor 7 extending through a bushing 6, a conductor 8, and a fixed contact 9 of the breaker unit 30. The driving device 10 is arranged outside the tank 1.

Each of the breaker units 30 includes the fixed contact 9 and a movable contact 13. The fixed contact 9 is fixed, i.e., it does not move, while the movable contact 13 can move toward or away from the fixed contact 9. The movable contact 13, a puffer cylinder 11, and a rod 12 are formed as one piece. An insulating nozzle 14 is attached to the puffer cylinder 11. A puffer chamber 16 is defined by the puffer cylinder 11 and a puffer piston 15 fixed to the bracket 3.

The breaker units 30 perform breaking operation when the driving device 10 applies driving force to the moving unit 39 and the moving unit 39 transmits the driving force to the breaker units 30. More specifically, the driving device 10 generates a driving foice in the direction of an arrow F shown in Fig. 3. Because of the driving force, an operating rod 17 is pulled in the direction of the arrow F. Because of the movement of the operating rod 17, the driving force is transmitted to the breaker units 30 through a link 18, a lever 19, an insulating rod 20, a link 21, a V- shaped link 22, and a link 23. The movable contact 13 and the puffer cylinder 11 then move in the direction of an arrow G shown in Fig. 3. The link 18, the lever 19, the insulating rod 20, the link 21, the V-shaped link 22, and the link 23 are included in the moving unit 39. The movable contact 13 and the puffer cylinder 11 mounted in the right-side breaker unit 30 (not shown) move in the opposite direction to the arrow G. If an electric arc is generated when the movable contact 13 moves away from the fixed contact 9, the arc-extinguishing gas compressed in the puffer chamber 16 is ejected from the insulating nozzle 14 to the electric arc, thereby extinguishing the electric arc.

In the gas circuit breaker 90, a pin coupling unit 24 is arranged on the insulating rod 20. The pin coupling unit 24 is connected to the links 21, each coupled to each of the movable contacts of the right and left side breaker units 30.

Fig. 4 is a view of the moving unit 39 seen from the direction of an arrow E shown in Fig. 3. The links 21 are connected to the pin coupling unit 24 in such a manner that the links 21 sandwich the insulating rod 20. More specifically, one of the links 21 is connected to one side of the pin coupling unit 24 and it is coupled to one of the right and left side breaker units. The other link 21 is connected to the other side of the pin coupling unit 24 and it is coupled to the other one of the breaker units. Thus, the V-shaped links 22, the links 23, and the breaker units on the right and left sides of the tank]. are arranged on substantially the same plane that is in the plane of the paper of Fig. 4.

As shown in Fig. 4, however, the moving unit 39 is not symmetric with respect to a plane including the central axis of the pin coupling units 24. When the driving force is applied to the insulating rod 20 from the links 21 during the switching operation, the insulating rod 20 is affected by torsional forces (torques) indicated by arrows Hi, H2 shown in Fig. 4. Therefore, the insulating rod 20 must be strong enough to withstand those torsional forces.

Furthermore, because of the configuration of the moving unit 39, pins 25 that connect the links 21 to the V-shaped links 22, respectively, are affected by the torsional forces indicated by the arrows Hi, H2 during the switching operation. The upper and lower portions (as shown in Fig. 4) of each of the pins 25 are then twisted in the opposite directions. Therefore, the pins 25 must be strong enough to withstand those torsional forces.

As described above, in the gas circuit breaker 90, the moving unit 39 is not symmetric with respect to a plane including the central axis of the pin coupling units 24.

To withstand torque generated during the switching operation, the insulating rod 20 and the pin 25 must be made stronger, which makes it difficult to reduce the size and cost of the gas circuit breaker 90.

SUI'IMARY OF THE INVENTION It is an object of the present invention to at least partially solve the problems in the conventional technology.

According to an aspect of the present invention, there is provided a gas circuit breaker that includes a tank filled with an arc-extinguishing gas; a breaker unit including a fixed contact fixed inside the tank, and a movable contact configured to move toward and away from the fixed contact inside the tank; and a transmission unit that includes a coupling rod coupled to the movable contact, and transmits a driving force to move the movable contact through the coupling rod. A plurality of the movable contacts are coupled to the coupling rod, and the coupling rod is provided with a plurality of coupling shafts, and the plurality of the movable contacts are coupled to the plurality of the coupling shafts.

According to another aspect of the present invention, there is provided a gas circuit breaker that includes a tank filled with an arc-extinguishing gas; first and second breaker units each including first and second fixed contacts each fixed inside the tank, and first and second movable contacts configured to move toward and away from the first and second fixed contacts inside the tank; and a transmission unit that includes a coupling rod coupled between the first and second movable contacts, the coupling rod being moved by a driving device, and moves both the first and second movable contacts in accordance with movement of the coupling rod. First and second coupling shafts are attached to two points on the coupling rod, a rotatable link member is attached to each of the first and second coupling shafts, and the rotatable link members are respectively coupled to the first and second movable contacts.

The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of a puffer type gas circuit breaker having two breaking points according to an embodiment of the present invention; Fig. 2 is a view of a moving unit shown in Fig. 1 from the direction of an arrow A; Fig. 3 is a schematic diagram of a conventional puffer type gas circuit breaker having two breaking points; and Fig. 4 is a view of a moving unit shown in Fig. 3 from the direction of an arrow E.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are explained in detail below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a puffer type gas circuit breaker 100 having two breaking points according to an embodiment of the present invention. Fig. 2 is a view of a moving unit 40 shown in Fig. 1 from the direction of an arrow A. The puffer type gas circuit breaker 100 includes the tank 1, the two puffer-type breaker units 30, and a moving unit 40. The tank 1 is grounded and it is filled with arc-extinguishing gas. One puffer-type breaker unit 30 is respectively mounted on the right and left sides of the tank 1 (the right-side breaker unit 30 is not shown in Fig. 1) . The puffer-type breaker units 30 perform switching operation. The moving unit 40 is positioned between the breaker units 30 and the external driving device 10, and transmits force generated by the driving device 10 to the breaker units 30.

The arc-extinguishing gas can be sulfur hexafluoride gas. The cylindrical insulating supporting member 2 and the two cylindrical insulating supporting members 5 (the right-side insulating supporting members 5 is not shown in Fig. 1) are mounted in the tank 1. The insulating supporting member 2 supports the bracket 3 and a part of the breaker units 30. Each of the insulating supporting members 5 supports the central conductor 7 extending through the bushing 6, the conductor 8, and the fixed contact 9 of the breaker unit 30. The two breaker units 30 are symmetrically arranged with respect to the insulating rod 20 of the moving unit 40. The driving device 10 is arranged outside the tank 1.

Each of the breaker units 30 includes the fixed contact 9 and the movable contact 13. The fixed contact 9 is fixed, i.e., it does not move, while the movable contact 13 can move toward or away from the fixed contact 9. The movable contact 13, a puffer cylinder 11, and a rod 12 are formed as one piece. An insulating nozzle 14 is attached to the puffer cylinder 11. The puffer chamber 16 is defined by the puffer cylinder 11 and the puffer piston 15 fixed to the bracket 3.

The breaker units 30 perform breaking operation when the driving device 10 applies driving force to the moving unit 40 and the moving unit 40 transmits the driving force to the breaker units 30. More specifically, the driving device 10 generates adriving force in the direction of an arrow B shown in Fig. 1. Because of the driving force, the operating rod 17 is pulled in the direction of the arrow B. Because of the movement of the operating rod 17, the driving force is transmitted to the breaker units 30 through the link 18, the lever 19, the insulating rod 20, the links 21, the V-shaped links 22, and the links 23. The movable contact 13 and the puffer cylinder 11 then move in the direction of an arrow C shown in Fig. 1. The link 18, the lever 19, the insulating rod 20, the link 21, the V-shaped link 22, and the link 23 are included in the moving unit 40. The movable contact 13 and the puffer cylinder 11 mounted in the right-side breaker unit 30 (not shown) move in the opposite direction to the arrow C. If an electric arc is generated when the movable contact 13 moves away from the fixed contact 9, the arc-extinguishing gas compressed in the puffer chamber 16 is ejected from the insulating nozzle 14 to the electric arc, thereby extinguishing the electric arc.

The insulating rod 20 is inserted through the insulation supporting cylindrical member 2, and connects the linking members on the side of the driving device 10 to the liking members on the side of the breaker units 30.

The insulating rod 20 is made of electrical insulating material. The insulating rod 20 transmits the driving force from the driving device 10 to the breaker units 30, and electrically insulates the driving device 10 from the breaker units 30. The two pin coupling units 24 (coupling shafts) are arranged on the insulating rod 20, and each of the pin coupling units 24 connects the insulating rod 20 to each of the links 21. That is, one pin coupling unit 24 is arranged for each of the links 21 (coupling member to be connected to the insulating rod 20) that is coupled to each of the two breaker units 30.

Fig. 2 is a view of the moving unit 40 seen from the direction of an arrow A shown in Fig. 3. The two links 21 are arranged to sandwich the insulating rod 20 for each of the breaker units 30, so that the two links 21 for one of the breaker units 30 are symmetrically arranged to other two links 21 for the other one of the breaker units 30 with respect to the insulating rod 20. Thus, the insulating rods 20 and the links 21 are arranged in a symmetric manner with respect to a plane parallel to the pin coupling units 24 (a dashed-dotted line Dl in Fig. 2), and with respect to a plane perpendicular to the pin coupling units 24 (a dashed-dotted line D2 in Fig. 2) . With this configuration, it is possible to reduce torsional force applied to the insulating rod 20 and bending force applied to the pin 25.

Therefore, the insulating rod 20 and the pin 25 need not be as strong as those in the conventional art. In other words, the insulating rod 20 and the pin 25 can be reduced in size.

As described above, the gas circuit breaker 100 is configured in such a manner that the two pin coupling units (coupling shafts) 24 are provided on the insulating rod (coupling rod) 20, and each of the two movable contacts 13 is coupled to each of the pin coupling units 24. Therefore, it is possible to reduce the torsional force that may be applied to the insulating rod 20 and the pin 25. Thus, the insulating rod 20 and the pin 25 can be reduced in size, resulting in reducing size and manufacturing costs of the gas circuit breaker 100.

Although it is explained above that the pin coupling unit 24 connects the insulating rod 20 to the link 21, the present invention is not limited to this configuration.

The coupling unit can be configured in a different manner as long as the coupling unit supports the insulating rod 20 and the link 21 in such a manner that the insulating rod 20 and the link 21 can rotate with each other.

Furthermore, it is explained above that the insulating rod 20 serves as a coupling member for arranging the pin coupling units 24. However, the coupling member needs not be an insulating member. If other members included in the moving unit 40 are made of electrical insulating material, the coupling member needs not be made of electrical insulating material.

In the document, "couple" and "connect" mean that components are coupled or connected directly or indirectly with a coupling member interposed between the components.

According to an aspect of the present invention, the moving unit is made symmetric with respect to the insulating rod. Therefore, it is possible to reduce torsional forces that may be applied to the insulating rod and the pin coupling units. As a result, the insulating rod and the pin coupling units can be reduced in size and the gas circuit breaker can be reduced in size and cost.

Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

Claims

CLAIMS: 1. A gas circuit breaker comprising: a tank (1) filled with an arc-extinguishing gas; a breaker unit (30) including a fixed contact (9) fixed inside the tank (1), and a movable contact (13) configured to move toward and away from the fixed contact (9) inside the tank (1); and a transmission unit (40) that includes a coupling rod (20) coupled to the movable contact (13), and transmits a driving force to move the movable contact (13) through the coupling rod (20), wherein a plurality ofthe movable contacts (13) are coupled to the coupling rod (20), and the coupling rod (20) is provided with a plurality of coupling shafts (24), and the plurality of the movable contacts (13) are coupled to the plurality of the coupling shafts (24)
2. A gas circuit breaker according to claim 1, wherein the transmission unit (40) is symmetric with respect to a plane including the coupling rod (20).
3. A gas circuit breaker according to claim 1 or 2, wherein the breaker unit (30) includes two breaker units (30), and the two breaker units (30) are symmetrically mounted with respect to the coupling rod (20) with the coupling rod (20) arranged therebetween.
4. A gas circuit breaker according to claim 3, wherein the transmission unit (40) includes two link members that couple the coupling rod (20) and each of the movable contacts (13) for each of the two breaker units (30), wherein the two link members are symmetrically arranged with respect to the coupling rod (20) with the coupling rod (20) arranged therebetween.
5. A gas circuit breaker according to any one of claims 1 to 4, wherein the coupling rod (20) is an insulating rod made of electrical insulating material.
6. A gas circuit breaker comprising: a tank (1) filled with an arc-extinguishing gas; first and second breaker units (30) each including first and second fixed contacts (9) each fixed inside the tank (1), and first and. second movable contacts (13) configured to move toward and away from the first and second fixed contacts (9) inside the tank (1); and a transmission unit (40) that includes a coupling rod (20) coupled between the first and second movable contacts (13), the coupling rod (20) being moved by a driving device, and moves both the first and second movable contacts (13) in accordance with movement of the coupling rod (20), wherein first and second coupling shafts (24) are attached to two points on the coupling rod (20), a rotatable link member is attached to each of the first and second coupling shafts (24), and the rotatable link members are respectively coupled to the first and second movable contacts (13)
7. A gas circuit breaker substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.