Patent Application
20180277323
The present invention relates to a puffer type gas circuit breaker. Particularly, the present invention relates to a gas circuit breaker utilizing heating and pressure rising effect by arc heat.
The gas circuit breaker is used in an electric power system for interrupting a fault current occurring due to interphase short circuit, ground fault or the like. Heretofore, the puffer type gas circuit breakers have been used widely. In this puffer type gas circuit breaker, a high-pressure gas flow is generated by mechanically compressing an arc-extinguishing gas by means of a movable puffer cylinder directly connected to a movable arc contact. The resultant gas flow is blown onto an arc generated between the movable arc contact and a stationary arc contact so that an electric current is interrupted.
The current interruption performance of the gas circuit breaker is dependent on pressure buildup in a puffer chamber. In this connection, a heat puffer combination type gas circuit breaker adapted for pressure buildup by active use of the heat energy of arc as well as for hitherto known pressure buildup based on mechanical compression is also used extensively. The heat puffer combination type gas circuit breaker utilizes the heat energy of arc for generating a pressure for applying a blast of arc-extinguishing gas. As compared with the conventional device based on mechanical compression, this type of gas circuit breaker can reduce operational energy required for interruption operation.
On the other hand, the heat energy of arc is proportional to the fault current. In the interruption of a large current, the arc has such large heat energy as to generate a high pressure. In the interruption of a small to medium current, however, the arc heat provides a small pressure buildup. Therefore, the pressure generated by mechanical compression is used for blowing the arc-extinguishing gas onto the arc so as to interrupt the electric current.
Patent Literature 1 discloses a puffer type gas circuit breaker which includes: a heat gas chamber formed in the puffer chamber; a separator substantially shaped like a cylinder and disposed between an insulation nozzle and a movable arcing contact; a first release path for guiding an insulation gas from the heat gas chamber to a vicinity of a through hole (arc space); and a second release path for guiding the insulation gas from the puffer chamber to the vicinity of the through hole.
Patent Literature 1: Japanese Unexamined Patent Application Publication No. Hei2(1990)-129822
According to the patent literature 1, the high temperature gas supplied from the heat gas chamber and the gas at relatively low temperature supplied from the puffer chamber are each directly guided into the arc space. Hence, a high-temperature gas portion providing a starting point of dielectric breakdown, which is detrimental to the interruption of a small to medium current, is directly blown into the arc space. This leads to a fear of deterioration of the current interruption performance as a result of the dielectric breakdown. The puffer type gas circuit breaker of this patent literature is faced with a problem of improving the current interruption performance in a small to medium current region where the pressure buildup by the heat gas is small.
The present invention has been accomplished in view of the above problem, and an object thereof is to provide a heat puffer combination type gas circuit breaker which is further improved in the current interruption performance in the small to medium current region.
According to an aspect of the present invention for achieving the above object, a gas circuit breaker includes: a cylindrical movable-side main conductor supportively fixed by an insulation cylinder disposed in a gas-filled envelope containing an insulation gas having an arc-extinguishing property, connected to a movable-side leading conductor connected to an electric power system, and including an exhaust hole for exhausting a high temperature and pressure gas as the insulation gas raised in temperature and pressure by a generated arc; a hollow exhaust shaft disposed in the movable-side main conductor and movable in an axial direction of the movable-side main conductor; an operation mechanism coupled to the exhaust shaft and outputting a force operating in an axial direction of the exhaust shaft; a cylinder coaxially coupled to the exhaust shaft and axially slidable on an inside surface of the movable-side main conductor, a piston coupled to the cylinder, an insulation nozzle coupled to the piston, and a heat puffer chamber enclosed by the cylinder; a blast-gas flow path communicating the heat puffer chamber and an arc space, and defined by a gap between the insulation nozzle and a movable element cover; a puffer piston fixed to the inside of the movable-side main conductor, and including an opening which is opened in the axial direction of the movable-side main conductor and whose inside surface allows the exhaust shaft to slide thereon; a hole communicating a movable-side conductor inner circumferential space defined on the operation mechanism side as seen from the puffer piston and a machine puffer chamber formed on the opposite side from the operation mechanism; a release valve for releasing the insulation gas from the machine puffer chamber into the movable-side conductor inner circumferential space when the machine puffer chamber is compressed by the exhaust shaft and the cylinder axially moved by the operation mechanism; a movable contact electrically connected to the movable-side leading conductor; and a contact which is electrically connected to a stationary-side leading conductor connected to the electric power system and is in contactable/separable relation with the movable contact, the gas circuit breaker featuring: a separation cylinder disposed in a manner to radially partition the heat puffer chamber; an inner circumferential flow path defined by the separation cylinder on an inner circumferential side of the heat puffer chamber; and a straightening mechanism for opening or closing a communication hole communicating the inner circumferential flow path and the machine puffer chamber.
According to the present invention, the gas circuit breaker improved in the current interruption performance for a small to medium current is provided which is adapted to blow the arc-extinguishing gas from the machine puffer chamber onto the arc without allowing the arc-extinguishing gas to flow through the heat puffer chamber.
While the examples of the present invention will hereinbelow be described with reference to the accompanying drawings as needed, the present invention is not limited to the following examples. In the drawings referred to herein, some of the members may not be illustrated for the sake of simplicity. In the following description of the examples, like reference characters refer to the corresponding components, the detailed description of which is dispensed with.
The gas circuit breaker 100 shown in
The exhaust shaft 18 is coupled with an operation mechanism 1 for outputting an operation force in the axial direction of the exhaust shaft 18. Referring to
The cylinder 17 is coupled to the exhaust shaft 18 in a coaxial relation with the exhaust shaft 18. In conjunction with the axial movement of the exhaust shaft 18, the cylinder 17 is slidably movable in the movable-side main conductor 9 shaped like a cylinder. A piston 20 is disposed rearward of the cylinder 17. A machine puffer chamber 32 is formed in the movable-side main conductor 9, as interposed between the piston 20 and the puffer piston 33 (to be described herein later). Therefore, the insulation gas in the machine puffer chamber 32 is compressed by the cylinder 17 moved rearward along with the exhaust shaft 18. The movable-side main conductor 9 is supported by a movable-side insulation cylinder 7.
The movable main contact 5 is mounted to a forward end of the cylinder 17. On the other hand, the movable arc contact 11 is mounted to a forward end of the exhaust shaft 18 in a manner to be surrounded by this movable main contact 5. This movable arc contact 11 is faced to the interior of exhaust shaft 18 and is covered with a movable element cover 13. An insulation nozzle 4 is mounted to the forward end of the cylinder 17 in a manner to enclose the movable arc contact 11 and the stationary arc contact 12. A blast-gas flow path 16 communicating an arc space 31 and a heat puffer chamber 19 is defined between the insulation nozzle 4 and the movable element cover 13.
The heat puffer chamber 19 is formed in the cylinder 17 forward of the piston 20. A high temperature and pressure gas generated by the arc is fed into the heat puffer chamber 19, the details of which will be described herein later. This heat puffer chamber 19 is radially partitioned by a separation cylinder 21 so that an inner circumferential flow path 24 is formed between the separation cylinder 21 and the exhaust shaft 18 along with the movable element cover 13. The arc space 31 and the above-described machine puffer chamber 32 are communicated with each other via the blast-gas flow path 16, the inner circumferential flow path 24 and a communication hole 23. A flow of the insulation gas will be described herein later with reference to
A disk-like check valve 22 is disposed in space defined by the separation cylinder 21 and the piston 20 axially opposed to each other. The check valve 22 closes the communication hole 23 when the check valve 22 is shifted to a rightward position on the drawing surface.
The puffer piston 33 is a disk-like element fixed in the movable-side main conductor 9. The puffer piston 33 has an opening (not shown) in the vicinity of the center thereof. The exhaust shaft 18 is inserted through this opening. Thus, the exhaust shaft 18 is allowed to move axially, sliding on an inside peripheral surface of the opening of the fixed puffer piston 33.
A movable-side conductor inner circumferential space 35 is defined in the movable-side main conductor 9 and rearward of the puffer piston 33. Further, the machine puffer chamber 32 is formed in the movable-side main conductor 9 and forward of the puffer piston 33, as described above. The puffer piston 33 is formed with a hole 36 configured to surround the exhaust shaft 18 and to communicate the movable-side conductor inner circumferential space 35 and the machine puffer chamber 32.
The release valve 34 is adapted to release the insulation gas in the machine puffer chamber 32 into the movable-side conductor inner circumferential space 35 when the machine puffer chamber 32 is compressed by the operation mechanism 1 operating to move the exhaust shaft 18, the cylinder 17 and the piston 20 rearward in the axial direction. The release valve 34 is spring loaded against the puffer piston 33 so as to close the hole 36. The release valve 34 is opened when the internal pressure of the machine puffer chamber 32 being compressed exceeds the spring force. Thus, the insulation gas in the machine puffer chamber 32 is released into the movable-side conductor inner circumferential space 35.
When the movable arc contact 11 is separated from the stationary arc contact 12 to place the circuit breaker in the open contact state, arc occurs between the movable arc contact 11 and the stationary arc contact 12 in the insulation nozzle 4, as described above. This arc occurs in the arc space 31 shown in
A flow of a blast gas during the interruption of a small to medium current is described as below with reference to
Next, a flow of the blast gas during the interruption of a large current is described with reference to
During the interruption of a small to medium current, as described above, the gas circuit breaker 100 of Example 1 is capable of blowing the gas from the machine puffer chamber 32 into the arc space 31 while circumventing the heat puffer chamber 19. Thus, the gas density of the arc space 31 is increased by blowing the low temperature gas therein. The gas circuit breaker can achieve an improved interruption performance for a small to medium current. Because of having the check valve 22, the gas circuit breaker does not unnecessarily raise the pressure of the machine puffer chamber 32 during the interruption of a large current. This leads to the reduction of influences of interruption operation stagnation or the like.
Description is made on the effect of Example 2. In a case where the distal end 21a of the separation cylinder 21 is located in the arc space 31, the blast gas flow from the heat puffer chamber 19 and the blast gas flow from the machine puffer chamber 32 are applied to the arc space 31 without being mixed together so that the high temperature gas being blown is likely to produce an origin of dielectric breakdown. According to Example 2, on the other hand, the distal end 21a of the separation cylinder 21 is located in the blast-gas flow path 16. Hence, the blast gas flow from the heat puffer chamber 19 and the blast gas flow from the inner circumferential flow path 24 are joined together in the blast-gas flow path 16. Therefore, the high temperature gas flowing in from the heat puffer chamber 19 and the low temperature gas flowing in through the inner circumferential flow path 24 can be mixed together in the blast-gas flow path 16. Thus, the high temperature gas potentially producing the origin of dielectric breakdown is prevented from entering the arc space 31. Since the gas flow from the inner circumferential flow path 24 into the heat puffer chamber 19 can be inhibited, the gas from the machine puffer chamber 32 can be efficiently blown into the arc space 31.
As described above, this example can achieve improved interruption performance for a small to medium current.
According to Example 3, the blast gas from the machine puffer chamber 32 is guided into the blast-gas flow path 16 through the communication hole 23, inner circumferential flow path 24, and movable element cover communication hole 13a, as indicated by the arrowed dash line in
According to the example, the high temperature gas flowing from the arc space 31 into the heat puffer chamber 19 and the inner circumferential flow path 24 through the blast-gas flow path 16 during the current interruption is actively guided into the heat puffer chamber 19 through the flow path of the larger path area or on the outside periphery of the separation cylinder 21 whereby the pressure in the heat puffer chamber 19 can be efficiently built up. As described above, the example can achieve an improvement in interruption performance for a large current as well as interruption performance for a small to medium current.
According to the example, the flow of the blast gas from the machine puffer chamber 32 through the communication hole 23 and the inner circumferential flow path 24 can be accelerated when the gas flows through the cross section defining the flow path area 44 during the current interruption. Accordingly, the blast gas from the machine puffer chamber 32 can be blown into the arc space 31 at high speed. The example can achieve an improvement in interruption performance for a small to medium current.
According to Example 6, the high temperature gas flowing from the arc space 31 into the heat puffer chamber 19 through the blast-gas flow path 16 exceeds the pressure of the machine puffer chamber 32 during the interruption of a large current in particular. Because of the pressure difference, the check valve 51 is moved toward the right of the drawing surface and is locked by a locking part 52 and the separation cylinder 21, so as to block the gas flow into the inner circumferential flow path 24. The locking part is disposed from the check valve 51 toward the machine puffer chamber 32. Since the gas flows only into the heat puffer chamber 19, the pressure in the heat puffer chamber 19 can be built up efficiently. During the interruption of a small to medium current, the pressure of the machine puffer chamber 32 exceeds the pressure of the blast-gas flow path 16. Hence, the check valve 51 is moved toward the left of the drawing surface, allowing the blast gas to be blown into the arc space 31 through a flow path defined between an inside periphery of the check valve and the outside periphery of the movable element cover 13 and the outside periphery of the exhaust shaft 18. As described above, the example can achieve an improvement in interruption performance for a large current as well as interruption performance for a small to medium current.
According to Example 7, in interruption performance for a small to medium current, the blast gas flowing from the machine puffer chamber 32 into the arc space 31 passes the radial outside surface of the check valve 51. Hence, the flow path has a larger area than the flow path defined by the radial inside surface, resulting in the reduction of flow path resistance. The example is capable of efficiently blowing the gas into the arc space and achieving an improvement in interruption performance for a small to medium current.
The puffer type gas circuit breaker of the present invention is not limited to the configurations illustrated by the foregoing examples and various changes in the shape, number, size and arrangement of components may be resorted to without departing from the spirit and scope of the present invention. Any of those embodiments can be implemented in combination as needed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-058393 | Mar 2017 | JP | national |
