JP7612893B2 - Gas Circuit Breaker - Google Patents

Description

An embodiment of the present invention relates to a gas circuit breaker .

Gas circuit breakers, which switch current in power systems, mechanically separate contacts during the interruption process within a sealed container filled with arc-extinguishing gas, and extinguish the arc discharge between the contacts that occurs when the contacts are separated by spraying the arc-extinguishing gas. Gas circuit breakers attempt to restore the dielectric strength between the contacts by quickly removing the gas heated by the arc discharge from between the contacts. If the smooth exhaust of hot gas is hindered, hot gas may remain between the contacts, reducing the dielectric strength and current-interrupting performance.

Japanese Patent Application Publication No. 2018-113189

An object of the present invention is to provide a gas circuit breaker capable of smoothly discharging gas.

The gas circuit breaker of the embodiment has a sealed container, a counter contact, a movable contact, an insulating nozzle, a pressure accumulator, an exhaust chamber, and an operating rod. The sealed container is filled with an arc-extinguishing gas. The counter contact is disposed in the sealed container. The movable contact is disposed in the sealed container. The movable contact is in contact with the counter contact in a closed state. The movable contact is displaced in a first direction relative to the counter contact from the closed state to separate from the counter contact and form an arc space in which an arc discharge occurs between the counter contact and the counter contact. The insulating nozzle is displaced integrally with the movable contact. The insulating nozzle is formed in a cylindrical shape surrounding the counter contact and the arc space in a fully open state in which the movable contact is farthest from the counter contact. The insulating nozzle has a nozzle opening at an end in a second direction opposite to the first direction. The insulating nozzle forms a first exhaust flow path between the counter contact and the insulating nozzle in a fully open state, which communicates the arc space and the nozzle opening. The pressure accumulator accumulates the arc-extinguishing gas. The pressure accumulator releases the arc-extinguishing gas into the arc space and sprays it against the arc discharge. The exhaust chamber is formed in a cylindrical shape. The internal space of the exhaust chamber is opened in a first direction and communicates with the nozzle opening in a completely open state. The operating rod is coupled to the movable contact. The operating rod has an internal space communicating with the arc space. A vent hole communicating the inside and outside is formed in the operating rod. The internal space of the operating rod forms a second exhaust flow path that communicates the arc space and the vent hole. The second exhaust flow path has a contraction portion, a minimum portion connected to the vent hole side of the contraction portion, and an expansion portion connected to the vent hole side of the minimum portion. The flow path cross-sectional area of the contraction portion gradually decreases from the arc space side toward the vent hole side. The flow path cross-sectional area of the expansion portion gradually increases toward the vent hole. Based on the distribution of the gas flow rate of the first exhaust flow path and the gas flow rate of the second exhaust flow path determined according to the likelihood of a ground fault occurring in the exhaust chamber, a ratio between the minimum flow path cross-sectional area and the flow path cross-sectional area of the minimum portion in the first exhaust flow path is set. The gas flow rate ratio was set as a function of the ratio of the minimum flow cross-sectional area in the first exhaust flow passage to the flow cross-sectional area of the minimum portion.

1 is a longitudinal sectional view showing a gas circuit breaker according to a first embodiment; FIG. 2 is an enlarged longitudinal sectional view of a portion of the gas circuit breaker shown in FIG. 1 . 5A to 5C are diagrams showing the operation of the gas circuit breaker of the first embodiment; FIG. 4 is a diagram showing a change in gas temperature in an arc space after arc generation during an interruption operation in the gas circuit breaker according to the first embodiment. FIG. 4 is a diagram showing the relationship between a flow passage cross-sectional area and a flow rate in the gas circuit breaker according to the first embodiment. FIG. 6 is an enlarged longitudinal sectional view showing a portion of a gas circuit breaker according to a second embodiment. FIG. 11 is an enlarged longitudinal sectional view showing a portion of a gas circuit breaker according to a third embodiment.

Hereinafter, the gas circuit breaker and the design method of the gas circuit breaker of the embodiment will be described with reference to the drawings. In the following description, the same reference numerals are used for components having the same or similar functions. Furthermore, duplicate descriptions of those components may be omitted.

First Embodiment
Fig. 1 is a longitudinal sectional view showing a gas circuit breaker according to a first embodiment. Fig. 1 shows a completely open state of the gas circuit breaker, and in the following description of the arrangement of each member, the arrangement in the completely open state will be described unless otherwise specified.
As shown in Fig. 1, the gas circuit breaker 1 is a switchgear for opening and closing an electric circuit in a power system. The gas circuit breaker 1 includes a sealed container 2 filled with an arc-extinguishing gas, and an opposing unit 3 and a movable unit 4 disposed in the sealed container 2. The arc-extinguishing gas is a gas having excellent arc-extinguishing and insulating properties, such as sulfur hexafluoride ( _SF6 ) gas. The opposing unit 3 and the movable unit 4 are stored in the sealed container 2 together with the arc-extinguishing gas.

The sealed container 2 has an internal space where the current flowing through the electric circuit is interrupted. The sealed container 2 is made of a metal material or the like. The sealed container 2 is grounded. A pair of conductors (only one conductor 5 is shown) are led into the sealed container 2 from the outside.

The opposing unit 3 and the movable unit 4 constitute a part of an electric circuit. The opposing unit 3 has an opposing contact portion 20 that is electrically connected to one conductor 5. The movable unit 4 has a movable contact portion 40 that is electrically connected to the other conductor (not shown). The gas circuit breaker 1 opens and closes an electric circuit and conducts or interrupts a current by bringing the opposing contact portion 20 and the movable contact portion 40 into contact with or away from each other. In the following description, the state in which the opposing contact portion 20 and the movable contact portion 40 are in contact with each other is referred to as a closed state, and the state in which the opposing contact portion 20 and the movable contact portion 40 are separated from each other is referred to as an open state. In addition, the state that is normally applied in the closed state is particularly referred to as a closed state. In addition, in the open state, the state in which the current interruption operation is completed is particularly referred to as a fully open state. In addition, the process of separating the opposing contact portion 20 and the movable contact portion 40 from each other from the closed state to the fully open state is referred to as an open process.

The opposing unit 3 and the movable unit 4 are each formed of a plurality of cylindrical or columnar members. Each cylindrical or columnar member is arranged coaxially with the common axis O. The opposing unit 3 and the movable unit 4 are arranged to face each other in the axial direction of the common axis O. In the following description, the axial direction of the common axis O is simply referred to as the axial direction. The direction that rotates around the common axis O is referred to as the circumferential direction. The direction perpendicular to the common axis O is referred to as the radial direction. In this embodiment, the axial direction is parallel to the horizontal direction, and one direction along the axial direction is defined as the forward direction (second direction), and the opposite direction is defined as the backward direction (first direction).

The facing unit 3 is disposed in front of the movable unit 4. The facing unit 3 is fixedly disposed relative to the sealed container 2. The facing unit 3 includes an exhaust chamber 10, a support 15, and a facing contact portion 20.

The exhaust chamber 10 has an inner cylinder 11 and an outer cylinder 13 that are electrically connected to each other. The inner cylinder 11 and the outer cylinder 13 are each formed into a cylindrical shape from a metal material or the like. The inner cylinder 11 and the outer cylinder 13 are electrically connected to one of the conductors 5 described above.

The inner tube 11 includes a peripheral wall portion 11a and a blocking portion 11b. The peripheral wall portion 11a extends in the axial direction with a constant inner diameter and a constant outer diameter. The blocking portion 11b blocks the front end portion of the peripheral wall portion 11a. The blocking portion 11b protrudes radially inward from the front end portion of the peripheral wall portion 11a. As a result, the inner tube 11 is formed in a bottomed cylindrical shape that opens to the rear. However, a through hole may be formed in the blocking portion 11b.

The peripheral wall portion 11a of the inner cylinder 11 is formed with through holes 12 that penetrate in the radial direction. A plurality of through holes 12 are provided at intervals in the circumferential and axial directions. The through holes 12 communicate between the inside and outside of the inner cylinder 11.

The outer cylinder 13 is formed to surround the inner cylinder 11. The front end of the outer cylinder 13 is in close contact with the outer circumferential surface of the front end of the inner cylinder 11 over the entire circumference. The outer cylinder 13 opens to the rear. As a result, the space between the outer cylinder 13 and the inner cylinder 11 is closed at the front end and is open to the rear. The outer cylinder 13 has a rear half 13a and a front half 13b.

The rear half 13a extends forward from the rear end of the outer tube 13. The rear half 13a gradually expands in diameter from the rear end of the outer tube 13 toward the front. In other words, the inner diameter of the rear half 13a gradually increases from the front end of the outer tube 13 toward the rear.

The front half 13b is located forward of the rear half 13a. The front half 13b extends rearward from the front end of the outer tube 13. The rear end of the front half 13b is connected to the front end of the rear half 13a. The front half 13b extends in the axial direction with a constant inner diameter and a constant outer diameter. The front half 13b is radially spaced apart from the outer circumferential surface of the inner tube 11 over the entire circumferential direction. The front half 13b overlaps all of the through holes 12 formed in the inner tube 11 when viewed from the outside in the radial direction. A conductor 5 is coupled to the front half 13b.

The support 15 is formed from a metal material or the like. It protrudes radially inward from the inner peripheral surface of the outer cylinder 13. The support 15 is connected to the boundary between the rear half 13a and the front half 13b of the outer cylinder 13. The support 15 is electrically connected to the outer cylinder 13. The support 15 penetrates the peripheral wall portion 11a of the inner cylinder 11. An opposing arc contact 26 (described later) is connected to the support 15 on the inside of the inner cylinder 11.

The opposing contact portion 20 includes an opposing current-carrying contact 21 and an opposing arc contact 26 (opposing contact).
The opposing electric contact 21 is made of a metal material and formed into a cylindrical shape. The opposing electric contact 21 is coupled to the rear end of the inner cylinder 11. The opposing electric contact 21 protrudes rearward beyond the exhaust chamber 10. The opposing electric contact 21 is open to the rear. The rear end of the opposing electric contact 21 bulges radially inward. The opposing electric contact 21 is electrically connected to the exhaust chamber 10.

The opposing arc contact 26 is made of a metal material and formed into a cylindrical shape. The opposing arc contact 26 is arranged inside the opposing current-carrying contact 21. The opposing arc contact 26 is connected to the support 15. The opposing arc contact 26 extends rearward from the connection with the support 15. The rear end surface of the opposing arc contact 26 is formed into a semispherical shape and is rounded. The opposing arc contact 26 is electrically connected to the exhaust chamber 10 via the support 15.

FIG. 2 is an enlarged longitudinal sectional view of a portion of the gas circuit breaker shown in FIG.
As shown in FIG. 2 , the movable unit 4 includes an operating rod 30 , a cylinder 34 , a piston 37 , a movable contact portion 40 , and an insulating nozzle 50 .

The operating rod 30 is formed of a metal material or the like. The operating rod 30 is connected to a driving device (both not shown) at the rear end via an insulating rod, and is capable of being displaced in the axial direction relative to the sealed container 2 and the opposing unit 3. The operating rod 30 is electrically connected to the other conductor (not shown). The operating rod 30 is formed in a cylindrical shape and opens forward. The operating rod 30 is formed with a vent hole 31 penetrating in the radial direction. The vent holes 31 are arranged at predetermined positions in the axial direction at intervals in the circumferential direction. The vent holes 31 are arranged rotationally symmetrically around the common axis O. The portion of the operating rod 30 located rearward of the vent hole 31 may be formed solid. An outer flange 32 that protrudes outward in the radial direction is formed on the outer circumferential surface of the operating rod 30. The outer flange 32 is located forward of the vent hole 31. The outer flange 32 is formed in a circular ring shape that extends continuously throughout the entire circumferential direction.

The cylinder 34 is fixedly disposed relative to the operating rod 30. The cylinder 34 is displaced in the axial direction integrally with the operating rod 30 in conjunction with the operating rod 30. The cylinder 34 is formed in a cylindrical shape using a metal material or the like. The cylinder 34 is electrically connected to the operating rod 30. The cylinder 34 includes a peripheral wall 34a extending along the axial direction, and a first flange 34b and a second flange 34c protruding radially inward from the peripheral wall 34a. The peripheral wall 34a surrounds the operating rod 30 from the outside in the radial direction. The first flange 34b protrudes radially inward from the front end of the peripheral wall 34a. The first flange 34b is formed in the shape of an annular plate. The inner peripheral edge of the first flange 34b faces the outer peripheral surface of the operating rod 30 in the radial direction. The first flange 34b is located forward of the outer flange 32 of the operating rod 30. An exhaust hole 35 is formed in the inner peripheral portion of the first flange 34b, penetrating in the axial direction. The exhaust hole 35 is formed rotationally symmetrically about the common axis O. The second flange 34c is located rearward of the first flange 34b. The inner peripheral edge of the second flange 34c faces the outer peripheral surface of the operating rod 30 in the radial direction. The inner peripheral edge of the second flange 34c faces the outer peripheral edge of the outer flange 32 of the operating rod 30 in the radial direction. The entire inner peripheral edge of the second flange 34c extends radially with a gap from the outer peripheral edge of the outer flange 32 of the operating rod 30.

The piston 37 is formed in an annular shape. The piston 37 is disposed between the operating rod 30 and the peripheral wall 34a of the cylinder 34. The piston 37 is fixedly disposed relative to the sealed container 2. The piston 37 is located rearward of the second flange 34c of the cylinder 34. The piston 37 is located forward of the air vent 31 of the operating rod 30. The piston 37 is disposed so as to fill the gap between the operating rod 30 and the peripheral wall 34a of the cylinder 34.

The cylinder 34, the piston 37 and the operating rod 30 define a first puffer chamber 71 and a second puffer chamber 72 (accumulator section) that accumulate the arc-extinguishing gas. The first puffer chamber 71 is formed between the second flange 34c of the cylinder 34 and the piston 37. The second puffer chamber 72 is formed between the first flange 34b and the second flange 34c of the cylinder 34. The first puffer chamber 71 has a variable volume in conjunction with the displacement of the operating rod 30. The first puffer chamber 71 increases the pressure of the arc-extinguishing gas inside by decreasing its volume in accordance with the rearward displacement of the cylinder 34 and the operating rod 30. The arc-extinguishing gas increased in pressure in the first puffer chamber 71 flows into the second puffer chamber 72 through the gap between the second flange 34c and the outer peripheral surface (outer flange 32) of the operating rod 30. The pressure of the arc-extinguishing gas inside the second puffer chamber 72 increases with the inflow of the arc-extinguishing gas from the first puffer chamber 71. The arc-extinguishing gas pressurized in the second puffer chamber 72 is discharged from the second puffer chamber 72 through the exhaust hole 35.

The movable contact portion 40 includes a movable arc contact 41 (movable contact) and a movable current-carrying contact 46 .
The movable arc contact 41 is formed in a cylindrical shape from a metal material. The movable arc contact 41 is electrically connected to the operation rod 30. Both ends of the movable arc contact 41 are open in the axial direction. The rear end edge of the movable arc contact 41 is connected to the front end edge of the operation rod 30 over the entire circumference. The movable arc contact 41 is provided so as to extend the operation rod 30 forward. In this embodiment, the movable arc contact 41 is formed integrally with the operation rod 30. However, the movable arc contact 41 may be provided separately from the operation rod 30 and connected to the front end of the operation rod 30. The internal space of the movable arc contact 41 is connected to the internal space of the operation rod 30. The front end of the movable arc contact 41 bulges out toward the inside in the radial direction. The inner diameter of the front end of the movable arc contact 41 is approximately the same as the outer diameter of the counter arc contact 26. The inner diameters of the movable arc contact 41 and the operating rod 30 are constant in the portion forward of the vent hole 31 , except for the front end portion of the movable arc contact 41 .

The movable arc contact 41 has a number of slits (not shown). The slits are cut rearward from the front edge of the movable arc contact 41. The slits are formed at approximately equal intervals in the circumferential direction. As a result, the movable arc contact 41 has a number of fingers provided between adjacent slits. The fingers are formed in the shape of a leaf spring and are capable of bending and deforming in the radial direction.

The movable arc contact 41 is displaced in the axial direction in conjunction with the operating rod 30. The opposing arc contact 26 and the movable arc contact 41 are provided so that they can approach and separate from each other in the axial direction in accordance with the displacement of the operating rod 30. The opposing arc contact 26 and the movable arc contact 41 contact each other in a closed state and separate from each other in an open state. The opposing arc contact 26 and the movable arc contact 41 contact each other and conduct electricity when the opposing arc contact 26 is inserted into the opening of the movable arc contact 41. In the opening process, the opposing arc contact 26 and the movable arc contact 41 separate from each other, and an arc space 76 in which an arc discharge occurs between the opposing arc contact 26 and the movable arc contact 41 is formed. The internal space of the movable arc contact 41 communicates with the arc space 76 through the opening at the front end of the movable arc contact 41. As a result, the internal space of the movable arc contact 41 communicates with the internal space of the operating rod 30 and the arc space 76. The internal spaces of the movable arc contact 41 and the operating rod 30 serve as a movable-side gas flow passage 90 (second exhaust flow passage) communicating with the arc space 76 as part of a gas exhaust flow passage for exhausting gas from the arc space 76 .

The movable current contactor 46 is formed into a cylindrical shape from a metal material. The movable current contactor 46 is arranged to surround the movable arc contactor 41. The movable current contactor 46 protrudes forward from the first flange 34b of the cylinder 34. The movable current contactor 46 is electrically connected to the cylinder 34. The front end of the movable current contactor 46 opens forward. The outer diameter of the movable current contactor 46 matches the inner diameter of the rear end of the opposing current contactor 21.

The movable current contactor 46 is fixed to the operating rod 30 via the cylinder 34. The movable current contactor 46 is displaced in the axial direction together with the operating rod 30 in conjunction with the operating rod 30. The opposing current contactor 21 and the movable current contactor 46 are provided so as to be able to approach and separate from each other in the axial direction in accordance with the displacement of the operating rod 30. The opposing current contactor 21 and the movable current contactor 46 contact each other in the closed state and separate from each other in the open state. The opposing current contactor 21 and the movable current contactor 46 come into contact with each other and are conductive when the movable current contactor 46 is inserted into the opening of the opposing current contactor 21. The opposing current contactor 21 and the movable current contactor 46 separate from each other earlier than the opposing arc contactor 26 and the movable arc contactor 41 during the open process.

The insulating nozzle 50 is formed into a cylindrical shape from an insulating material. The insulating nozzle 50 protrudes forward from the first flange 34b of the cylinder 34 between the movable arc contact 41 and the movable current contact 46. The insulating nozzle 50 protrudes forward from the movable arc contact 41 and the movable current contact 46. In other words, the front edge of the insulating nozzle 50 is located forward of the front edge of the movable arc contact 41 and the front edge of the movable current contact 46. The insulating nozzle 50 has a nozzle opening 51 at its front end. The nozzle opening 51 opens forward inside the exhaust chamber 10 and communicates with the internal space of the inner cylinder 11. The rear edge of the insulating nozzle 50 is in close contact with the first flange 34b of the cylinder 34 over the entire circumference. The rear end opening of the insulating nozzle 50 directly communicates with the exhaust hole 35.

The inner circumferential surface of the insulating nozzle 50 includes a throat portion 52 , an upstream guide portion 53 , and a downstream guide portion 54 .
The throat portion 52 includes a portion of the insulating nozzle 50 with a smallest inner diameter. The throat portion 52 is provided in a midway portion of the insulating nozzle 50 in the axial direction. The throat portion 52 is located forward of the movable arc contact 41. The throat portion 52 surrounds the opposing arc contact 26 in the closed state. The throat portion 52 defines the arc space 76 from the radial outside in the open state and surrounds the arc discharge. The throat portion 52 is located rearward of the opposing arc contact 26 in the completely open state.

The upstream guide portion 53 is provided between the rear end of the insulating nozzle 50 and the throat portion 52. The upstream guide portion 53 surrounds the movable arc contact 41. The upstream guide portion 53 faces the outer peripheral surface and the front end surface of the movable arc contact 41. The upstream guide portion 53 is spaced apart from the movable arc contact 41 over its entire length. The upstream guide portion 53 cooperates with the outer peripheral surface of the movable arc contact 41 to define a connection space 77 that communicates with the second puffer chamber 72 through the exhaust hole 35. The connection space 77 communicates directly with the arc space 76. The connection space 77 guides the arc-extinguishing gas released from the second puffer chamber 72 to the arc space 76 and blows it onto the arc discharge.

The downstream guide portion 54 is provided between the front end of the insulating nozzle 50 and the throat portion 52. The downstream guide portion 54 extends so that its inner diameter gradually increases toward the front. The downstream guide portion 54 surrounds the rear end of the opposing arc contact 26 in the fully open state. The space between the downstream guide portion 54 and the opposing arc contact 26 is directly connected to the arc space 76. The space between the downstream guide portion 54 and the opposing arc contact 26 becomes the opposing gas flow path 80 (first exhaust flow path) as part of the gas exhaust flow path that exhausts gas from the arc space 76.

In the fully open state, the downstream guide portion 54 forms, between the opposing arc contact 26, a minimum section 81 where the flow passage cross-sectional area is minimum, and an opposing side expansion section 82 where the flow passage cross-sectional area gradually expands from the minimum section 81 to the downstream nozzle opening 51. The minimum section 81 and the opposing side expansion section 82 are part of the opposing side gas flow passage 80. The minimum section 81 is formed between the middle of the downstream guide portion 54 and the rear end edge of the outer circumferential surface of the opposing arc contact 26. The flow passage cross-sectional area is defined on a cross section perpendicular to the common axis O.

The flow guide 60 is disposed in the internal space of the operating rod 30. The flow guide 60 is formed in a rotating body shape centered on a common axis O. The outer diameter of the flow guide 60 changes along the axial direction. The flow guide 60 is formed so as to taper forward. The outer diameter of the flow guide 60 gradually increases toward the rear. The front end of the flow guide 60 is located forward of the vent hole 31. The rear end of the flow guide 60 is located rearward of the vent hole 31 and blocks the inside of the operating rod 30. That is, the flow guide 60 is disposed in a region extending from the rear to the front of the vent hole 31. The flow guide 60 changes the flow path cross-sectional area of the movable gas flow path 90 according to the axial position. It is preferable that the flow guide 60 is formed of a material having heat resistance against high-temperature gas (hot gas) heated by arc discharge.

Between the inner surface of the operating rod 30, the flow guide 60 forms a reduction section 91 in which the flow passage cross-sectional area gradually decreases toward the downstream side, a minimum section 92 in which the flow passage cross-sectional area is the smallest, and an expansion section 93 in which the flow passage cross-sectional area gradually increases toward the downstream side. These reduction section 91, minimum section 92, and expansion section 93 are part of the movable gas flow passage 90. The reduction section 91 is formed in a range from the front end of the flow guide 60 to the front edge of the ventilation hole 31. The expansion section 93 is formed in a range from the front edge to the rear edge of the ventilation hole 31. The expansion section 93 is formed larger than the reduction section 91 in the axial direction. However, the expansion section 93 may be formed to be smaller than the reduction section 91 in the axial direction. The minimum section 92 is between the reduction section 91 and the expansion section 93, and is formed between the middle part of the flow guide 60 and the front edge of the ventilation hole 31. However, the minimum section 92 may be formed forward of the front edge of the ventilation hole 31.

Next, the interrupting operation of the gas circuit breaker 1 will be described.
In the closed state, the movable current-carrying contact 46 is inserted into and in contact with the opposing current-carrying contact 21, and the opposing arc contact 26 is inserted into and in contact with the movable arc contact 41. This establishes electrical continuity between the opposing unit 3 and the movable unit 4.

When the gas circuit breaker 1 interrupts a current, it displaces the operating rod 30 backward, separating the opposing contact portion 20 and the movable contact portion 40 from each other. When the operating rod 30 is displaced backward, the movable arc contact 41, the movable current contact 46, the insulating nozzle 50 and the cylinder 34 are displaced backward in conjunction with the operating rod 30. When the cylinder 34 is displaced backward, the volume of the first puffer chamber 71 decreases, and the arc-extinguishing gas inside the first puffer chamber 71 is pressurized. The arc-extinguishing gas pressurized in the first puffer chamber 71 flows into the second puffer chamber 72. As a result, the arc-extinguishing gas inside the second puffer chamber 72 is pressurized.

When the operating rod 30 is displaced backward from the closed state, the opposing current-carrying contact 21 and the movable current-carrying contact 46 separate. In this state, the opposing arc contact 26 and the movable arc contact 41 are in contact with each other, so that the opposing unit 3 and the movable unit 4 are electrically connected.

When the operating rod 30 is further displaced backward, the opposing arc contact 26 and the movable arc contact 41 separate, transitioning from a closed state to an open state. When the opposing arc contact 26 and the movable arc contact 41 separate, an arc discharge occurs between the opposing arc contact 26 and the movable arc contact 41. When the arc discharge occurs, the arc-extinguishing gas in the arc space 76 is heated and expands into high-temperature hot gas. A portion of the expanded arc-extinguishing gas flows into the second puffer chamber 72 through the connection space 77. This further increases the pressure of the arc-extinguishing gas inside the second puffer chamber 72.

As the interruption operation progresses, the distance between the opposing arc contact 26 and the movable arc contact 41 increases, the current decreases toward the zero current point, and the arc discharge decreases. When the arc discharge decreases, the flow of arc-extinguishing gas from the arc space 76 to the second puffer chamber 72 stops, and the pressure in the second puffer chamber 72 reaches a maximum near the zero current point. At this time, the pressure difference between the arc space 76 and the second puffer chamber 72 causes high-pressure arc-extinguishing gas to be released from the second puffer chamber 72.

FIG. 3 is a diagram showing the operation of the gas circuit breaker of the first embodiment.
As shown in Fig. 3, the arc-extinguishing gas discharged from the second puffer chamber 72 is blown onto the arc discharge through the connection space 77. This causes the arc discharge to be extinguished and the current to be interrupted. Then, the movable contact portion 40 reaches a completely open state at the position farthest from the counter contact portion 20, completing the interruption operation.

The arc-extinguishing gas sprayed onto the arc discharge is separated into the opposing gas flow passage 80 and the movable gas flow passage 90 and discharged from the arc space 76. The arc-extinguishing gas that has flowed into the opposing gas flow passage 80 is discharged from the nozzle opening 51. The arc-extinguishing gas discharged from the nozzle opening 51 flows from the internal space of the inner cylinder 11 through the through hole 12 to the space between the inner cylinder 11 and the outer cylinder 13, and is finally discharged into the sealed container 2 from the front end opening of the outer cylinder 13. The arc-extinguishing gas that has flowed into the movable gas flow passage 90 is discharged from the front end opening of the movable arc contact 41 through the movable gas flow passage 90 and into the sealed container 2 from the vent hole 31.

Here, when the pressure rise in the arc space 76 is relatively small during the small/medium current interruption process or the beginning of the large current interruption process, the gas flow discharged from the arc space 76 to the movable side gas flow passage 90 becomes a subsonic flow. In this case, the contraction section 91 of the movable side gas flow passage 90 acts as a nozzle, and the gas flow is accelerated. Thereafter, the gas flow reaches sonic speed when passing through the narrowing section 92 and diffuses toward the vent hole 31 at the expansion section 93, and is discharged from the vent hole 31 into the sealed container 2 without stagnation. As a result, it is possible to quickly discharge the hot gas from the arc space 76 through the movable side gas flow passage 90.

In addition, during the large current interruption process, if the pressure rise in the arc space 76 is large, the gas flow in the operating rod 30 may become a supersonic flow. In this case, the narrowing section 91 of the movable side gas flow passage 90 acts as a diffuser to decelerate the gas flow. The gas flow then slows down to the speed of sound when passing through the narrowing section 92 and diffuses toward the vent hole 31 at the expanding section 93, and is exhausted from the vent hole 31 into the sealed container 2 without stagnation. As a result, choking is less likely to occur in the operating rod 30, and hot gas can be quickly exhausted from the arc space 76 through the movable side gas flow passage 90.

Fig. 4 is a diagram showing a change in gas temperature in the arc space after arc generation during an interruption operation in the gas circuit breaker according to the first embodiment. The horizontal axis in Fig. 4 represents the elapsed time from the point in time when the arc discharge occurs. The vertical axis represents the gas temperature in the arc space 76.
4, the temperature of the arc space 76 can be rapidly reduced by blowing the arc-extinguishing gas onto the arc discharge and discharging the hot gas from the arc space 76 through the movable gas flow passage 90. As a result, the arc is extinguished and the hot gas is discharged from the arc space 76, thereby suppressing restrike.

Here, in this embodiment, the flow path cross-sectional areas of the opposing side gas flow path 80 and the movable side gas flow path 90 are set based on the distribution of gas flow rates of the opposing side gas flow path 80 and the movable side gas flow path 90. The flow path cross-sectional area Q1 of the opposing side gas flow path 80 is the mass flow rate downstream of the nozzle opening 51 of the insulating nozzle 50. The flow path cross-sectional area Q2 of the movable side gas flow path 90 is the mass flow rate downstream of the air hole 31 of the operating rod 30. The flow path cross-sectional area S1 (minimum flow path cross-sectional area) of the opposing side gas flow path 80 is the flow path cross-sectional area at the extremely small portion 81 (position shown by the A-A cross section in Figure 2). The flow path cross-sectional area S2 of the movable side gas flow path 90 is the flow path cross-sectional area at the smallest portion 92 (position shown by the B-B cross section in Figure 2).

Fig. 5 is a diagram showing the relationship between the flow passage cross-sectional area and the flow rate in the gas circuit breaker according to the first embodiment. The horizontal axis shown in Fig. 5 represents the ratio (S1/S2) of the flow passage cross-sectional area S1 of the opposing gas passage 80 to the flow passage cross-sectional area S2 of the moving side gas passage 90. The vertical axis represents the ratio (Q2/Q1) of the flow rate Q2 of the moving side gas passage 90 to the flow rate Q1 of the opposing side gas passage 80.
5, the flow rate ratio (Q2/Q1) is a function of the area ratio (S1/S2). In particular, when the pressures of the opposing gas flow passage 80 and the movable gas flow passage 90 are equal to each other at the positions that define the flow passage cross-sectional areas, if the flow passage cross-sectional area is S1=S2, then the flow rate is Q1=Q2.

However, when hot gas remains in the exhaust chamber 10, the insulation performance between the sealed container 2 and the exhaust chamber 10 decreases, making it easier for a ground fault to occur. In this embodiment, the flow rate distribution of the opposing side gas flow path 80 and the movable side gas flow path 90 is determined according to the likelihood of a ground fault occurring in the opposing unit 3. A ground fault in the opposing unit 3 becomes more likely as the current value increases. Also, a ground fault in the opposing unit 3 becomes more likely as the current period becomes longer. In this embodiment, the flow rate ratio (Q2/Q1) is set based on the specifications of the gas circuit breaker 1 (current value, AC frequency, etc.), and the area ratio (S1/S2) is determined.

As described above, according to the gas circuit breaker 1 of this embodiment, when the gas flow in the operating rod 30 becomes a supersonic flow, the contraction portion 91 of the movable gas flow passage 90 can be used as a diffuser to decelerate the gas flow. Therefore, the gas flow slows down to the sonic speed when passing through the narrowing portion 92 and diffuses toward the vent hole 31 at the enlarged portion 93, and is exhausted from the vent hole 31 into the sealed container 2 without stagnation. As a result, choking is less likely to occur in the operating rod 30, and hot gas can be quickly exhausted from the arc space 76 through the movable gas flow passage 90. Therefore, a gas circuit breaker 1 that can smoothly exhaust gas can be provided.

In addition, since the hot gas can be distributed and flowed to the opposing side gas flow passage 80 and the movable side gas flow passage 90, damage to each part of the gas circuit breaker 1 due to the hot gas can be suppressed.

Furthermore, the ratio of the flow passage cross-sectional area S1 at the very small portion 81 of the opposing gas passage 80 and the flow passage cross-sectional area S2 at the smallest portion 92 of the movable gas passage 90 is set based on the distribution of the gas flow rate Q1 of the opposing gas passage 80 and the gas flow rate Q2 of the movable gas passage 90. This configuration can prevent excessive inflow of hot gas into the exhaust chamber 10. Therefore, the occurrence of a ground fault in the exhaust chamber 10 can be suppressed.

The gas circuit breaker 1 also includes a flow guide 60 that forms a reduction section 91, a minimum section 92, and an expansion section 93 between itself and the inner surface of the operating rod 30. With this configuration, the operating rod 30 itself has a simple shape, making it easy to manufacture the operating rod 30.

In addition, the flow guide 60 gradually expands in diameter toward the rear at the same axial position as the ventilation hole 31, so that the gas flow along the flow guide 60 can be guided toward the ventilation hole 31. Therefore, the gas can be exhausted smoothly.

Second Embodiment
FIG. 6 is an enlarged longitudinal sectional view showing a part of the gas circuit breaker according to the second embodiment.
A gas circuit breaker 1A according to the second embodiment shown in Fig. 6 differs from the gas circuit breaker 1 according to the first embodiment in that it includes a throttle portion 61 and a blocking member 62 instead of the flow guide 60. Note that the configuration other than that described below is the same as that of the first embodiment.

As shown in FIG. 6, the gas circuit breaker 1A of this embodiment forms a contraction section 91, a minimum section 92, and an expansion section 93 in the movable gas flow passage 90 by the throttle section 61. The throttle section 61 is formed on the inner surface of the operating rod 30. The throttle section 61 protrudes radially inward and extends uniformly over the entire circumferential direction. The inner diameter of the throttle section 61 changes along the axial direction. The throttle section 61 is formed in a so-called Laval nozzle shape. The entire throttle section 61 is located forward of the vent hole 31. The throttle section 61 changes the flow passage cross-sectional area of the movable gas flow passage 90 depending on the axial position. It is preferable that the throttle section 61 is formed of a material having heat resistance against hot gas. The throttle section 61 may be formed integrally with the operating rod 30 or may be provided separately from the operating rod 30.

The blocking member 62 blocks the inside of the operating rod 30. The blocking member 62 is positioned rearward of the ventilation hole 31. The blocking member 62 is formed so as to taper forward. The front end of the blocking member 62 is located forward of the rear end of the ventilation hole 31. However, the entire blocking member 62 may be positioned rearward of the ventilation hole 31.

As described above, the gas circuit breaker 1A of this embodiment provides the same effects as those of the first embodiment. In addition, the throttle section 61 that forms the reduction section 91, the minimum section 92, and the expansion section 93 in the movable gas flow passage 90 is provided on the inner surface of the operating rod 30, so that the gas circuit breaker 1A that provides the above-mentioned effects can be obtained simply by changing the shape of the operating rod 30.

Third Embodiment
FIG. 7 is an enlarged longitudinal sectional view showing a part of the gas circuit breaker according to the third embodiment.
A gas circuit breaker 1B according to the third embodiment shown in Fig. 7 differs from the gas circuit breaker 1 according to the first embodiment in that it further includes a throttle portion 61 according to the second embodiment in addition to the flow guide 60. Note that the configuration other than that described below is the same as that of the first embodiment.

The front end of the flow guide 60 is located within the range in the axial direction where the throttling section 61 is formed. The front end of the flow guide 60 is located in the same position in the axial direction as the narrow portion of the throttling section 61 where the inner diameter is the smallest. However, the front end of the flow guide 60 may be located forward of the narrow portion of the throttling section 61. The flow guide 60 and the throttling section 61 form a contraction section 91, a minimum section 92, and an expansion section 93 in the movable gas flow passage 90. For example, the contraction section 91 is formed by the throttling section 61, and the expansion section 93 is formed by the flow guide 60 and the throttling section 61 in cooperation with each other.

As described above, the gas circuit breaker 1B of this embodiment achieves the same effects as the first embodiment.

In the above embodiment, the exhaust chamber 10 has an inner cylinder 11 and an outer cylinder 13. However, the exhaust chamber may be formed by a single cylinder.

In addition, the arc-extinguishing gas is not limited to sulfur hexafluoride gas. According to the above embodiment, since the occurrence of a ground fault in the exhaust chamber 10 can be suppressed, the arc-extinguishing gas may be, for example, air, carbon dioxide, oxygen, nitrogen, or a mixture thereof.

In addition, in the above embodiment, the opposing contact portion 20 is fixedly disposed relative to the sealed container 2, but this configuration is not limited to this. The opposing contact portion may be formed to displace in the opposite direction to the displacement direction of the movable contact in conjunction with the axial displacement of the movable contact portion.

According to at least one embodiment described above, the movable side gas flow path has a reduced section, a minimum section connected to the vent side of the reduced section, and an expanded section connected to the vent side of the minimum section. The flow path cross-sectional area of the reduced section gradually decreases from the arc space side toward the vent side. The flow path cross-sectional area of the expanded section gradually increases toward the vent. This makes it difficult for choking to occur within the operating rod, and makes it possible to quickly exhaust hot gas from the arc space through the movable side gas flow path. Therefore, a gas circuit breaker that can smoothly exhaust gas can be provided.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and gist of the invention.

Claims (1)

A sealed container filled with an arc-extinguishing gas;
A counter contact disposed in the sealed container;
a movable contactor that is disposed within the sealed container, that comes into contact with the opposing contactor in a closed state, and that displaces from the closed state in a first direction relative to the opposing contactor to separate from the opposing contactor and form an arc space in which an arc discharge is generated between the movable contactor and the opposing contactor;
an insulating nozzle which is displaceable integrally with the movable contact and is formed in a cylindrical shape surrounding the opposed contact and the arc space in a completely open state in which the movable contact is farthest from the opposed contact, the insulating nozzle having a nozzle opening at an end in a second direction opposite to the first direction, and which forms a first exhaust flow path between the opposed contact and the nozzle opening, communicating the arc space and the nozzle opening in the completely open state;
a pressure accumulator that accumulates the arc-extinguishing gas and releases the arc-extinguishing gas into the arc space to blow the gas against the arc discharge;
an exhaust chamber formed in a cylindrical shape, an internal space of which is opened in the first direction and communicates with the nozzle opening in the completely open state;
an operating rod coupled to said movable contact, having an internal space communicating with said arc space, with a vent hole communicating the inside and the outside formed therein, said internal space forming a second exhaust flow passage communicating between said arc space and said vent hole, said second exhaust flow passage having a contracted portion, a minimum portion connected to said vent hole side of said contracted portion, and an enlarged portion connected to said vent hole side of said minimum portion, a flow passage cross-sectional area of said contracted portion gradually decreasing from the arc space side toward the vent hole side, and a flow passage cross-sectional area of said enlarged portion gradually increasing toward the vent hole;
A flow guide, at least a portion of which is disposed in the internal space, forming the expanded portion between itself and an inner surface of the operating rod;
Equipped with
an inner surface of the operating rod has a throttle portion that forms the contraction portion, the minimum portion, and the expansion portion;
an end portion of the flow guide in the second direction is located in the second direction further than a narrow portion in the throttle portion, the narrow portion having the smallest inner diameter in an axial direction parallel to the first direction and the second direction;
Gas circuit breaker.

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