Gas Circuit Breaker

Abstract

To provide a gas circuit breaker capable of preventing or suppressing an increase in sliding friction force of movable contacts.SOLUTION: A gas circuit breaker (1) includes a fixed contact (13), a movable contact (17), a boost chamber (R) which serves as a thermal puffer chamber, and a conductive cylindrical guide (18) into which the movable contact (17) is inserted and which guides a linear motion of the movable contact (17). The cylindrical guide (18) has a small diameter part (18a) located on an edge side of the fixed contact (13) and a large diameter part (18b) with an inner diameter larger than the small diameter part (18a). The movable contact (17) has a thin shaft part (17c) guided by the small diameter part (18a) and a thick shaft part (17d) with an outer diameter larger than the thin shaft part (17c) and guided by the large diameter part (18b). An inner peripheral surface of the large diameter part (18b) and an outer peripheral surface of the thick shaft part (17d) make sliding contact to conduct the movable contact (17) and the cylindrical guide (18).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas circuit breaker of a thermal puffer arc extinguishing type, which is used to interrupt a fault current in an electric power system and interrupts an arc generated between contacts by blowing gas thereto. [Background technology]

[0002] Conventionally, as the above-mentioned gas circuit breaker, for example, the gas circuit breaker disclosed in Patent Document 1 is known.

[0003] In the gas circuit breaker disclosed in Patent Document 1, a fixed contact is disposed in a booster chamber provided in an upper electrode. A movable contact enters the booster chamber through a nozzle located in the lower part of the booster chamber and comes into contact with the fixed contact. The movable contact is inserted into an opening provided in the center of the lower electrode, and a sliding contact is provided on the inner periphery of the opening. The movable contact is disposed so as to be in sliding contact with the sliding contact.

[0004] When the current (fault current) is interrupted, the moving contact moves downward. As the moving contact tip comes out of the nozzle, the high-temperature gas that had been building up in the booster chamber is released from the nozzle to the outside of the booster chamber. The released gas is blown against the arc, causing an arc-extinguishing action due to the thermal puffer effect. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-25819 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional gas circuit breaker disclosed in Patent Document 1, the gas discharged from the nozzle is sprayed toward the moving contact, so decomposition products generated by the arc and grease burned by the arc heat adhere to the surface of the moving contact. If these deposits adhere to the moving contact, there is a risk that the sliding friction force between the moving contact and the sliding contact will increase.

[0007] One aspect of the present invention has been made in consideration of the above-mentioned problems in the conventional technology, and an object of the present invention is to provide a gas circuit breaker capable of preventing or suppressing an increase in the sliding friction force of the movable contact. [Means for solving the problem]

[0008] In order to solve the above problems, a gas circuit breaker according to one embodiment of the present invention comprises a fixed contactor, a rod-shaped movable contactor that moves linearly to come into and out of contact with the fixed contactor, a thermal puffer chamber in which the fixed contactor is located and which accumulates gas expanded by an arc generated between the fixed contactor and the movable contactor, and a cylindrical, conductive guide tube through which the movable contactor is inserted and which guides the linear motion of the movable contactor, wherein the guide tube has a first inner diameter portion located at an end side on the fixed contactor side and a second inner diameter portion having an inner diameter larger than that of the first inner diameter portion, the movable contactor has a first shaft portion guided by the first inner diameter portion and a second shaft portion having an outer diameter larger than that of the first shaft portion and guided by the second inner diameter portion, and an inner peripheral surface of the second inner diameter portion and an outer peripheral surface of the second shaft portion are in sliding contact with each other to provide electrical conductivity between the movable contactor and the guide tube.

[0009] According to the above configuration, the second inner diameter portion is not directly exposed to the high-temperature gas flow that causes an arc-extinguishing action due to the thermal puffer effect, and is therefore less susceptible to adhesion of decomposition products and other deposits caused by the arc. Therefore, by sliding the movable contact in this portion to electrically connect the movable contact and the guide tube, it is possible to prevent or suppress an increase in the sliding friction force of the movable contact. In addition, by providing a guide tube, it is possible to stabilize the linear motion of the movable contact.

[0010] The gas circuit breaker according to one embodiment of the present invention may further be configured so that an air hole is provided in the second axial portion or in the vicinity of the boundary between the second inner diameter portion and the first inner diameter portion to allow gas to flow into the space partitioned by the inner surface of the second inner diameter portion and the second axial portion.

[0011] According to the above configuration, it is possible to allow gas to flow into the space surrounded by the inner circumferential surface of the guide tube and the second shaft portion of the movable contact, and it is possible to avoid a load during operation of the movable contact.

[0012] The gas circuit breaker according to an aspect of the present invention may further be configured such that a gap between the first inner diameter portion and the first shaft portion is larger than a gap between the second inner diameter portion and the second shaft portion.

[0013] According to the above configuration, it is possible to prevent or suppress an increase in the sliding friction force of the movable contactor due to the above-mentioned decomposition products and the like adhering to the first shaft portion of the movable contactor.

[0014] The gas circuit breaker according to an aspect of the present invention may further be configured so that a piston ring is provided on an inner circumferential surface of the first inner diameter portion.

[0015] According to the above-mentioned configuration, not only is the sliding property between the first inner diameter portion and the first shaft portion improved, but also high-temperature gas containing decomposition products and the like can be effectively prevented from entering the inside of the guide tube, thereby making it possible to more effectively prevent an increase in the sliding friction force of the movable contact.

[0016] The gas circuit breaker according to one aspect of the present invention may further be configured such that a groove is formed on an inner peripheral surface of the second inner diameter portion or an outer peripheral surface of the second shaft portion, and a sliding contact is attached to the groove.

[0017] According to the above configuration, sliding contact between the inner peripheral surface of the second inner diameter portion and the outer peripheral surface of the second shaft portion can be easily achieved. Effect of the Invention

[0018] According to one aspect of the present invention, an increase in the sliding friction force of the movable contact can be prevented or suppressed. [Brief description of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view showing a configuration of a gas circuit breaker according to a first embodiment, illustrating a closed state. [Diagram 2] FIG. 2 is an enlarged view of a region B1 shown in FIG. [Diagram 3] 1 is a cross-sectional view showing a configuration of a gas circuit breaker in a first embodiment, illustrating a state during current interruption. [Figure 4] 1 is a cross-sectional view showing a configuration of a gas circuit breaker according to a first embodiment, illustrating an open state. [Diagram 5] FIG. 11 is a cross-sectional view showing the configuration of a gas circuit breaker according to a second embodiment, illustrating a closed state. [Figure 6] FIG. 11 is a cross-sectional view showing the configuration of a gas circuit breaker according to a modified example of the second embodiment, illustrating a closed state. [Figure 7] FIG. 4 is a cross-sectional view showing the configuration of a gas circuit breaker according to a modified example of the first embodiment, illustrating a closed state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [Embodiment 1] An embodiment of the present invention will be described in detail below. The gas circuit breaker of this embodiment is a thermal puffer arc-extinguishing type gas circuit breaker used to interrupt a fault current in, for example, an electric power system, and interrupts an arc generated between contacts by blowing gas onto the arc. The gas circuit breaker is suitable for use in an insulating switchgear (GIS), and is housed in a container filled with an arc-extinguishing gas.

[0021] (1. Configuration of Gas Circuit Breaker) The configuration of the gas circuit breaker 1 of this embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing the configuration of the gas circuit breaker 1 of this embodiment. For convenience of explanation, the gas circuit breaker 1 is arranged in a vertical direction, and a movable contact 17, which will be described later, is assumed to move in the vertical direction.

[0022] As shown in Fig. 1, the gas circuit breaker 1 is installed in a case (not shown) in which an arc-extinguishing gas (hereinafter simply referred to as gas) G is sealed, and the gas G is present around the gas circuit breaker 1. The gas G is, for example, SF 6 , Dry Air, N 2 , CO 2 , O 2 , C.F. 4 , fluoronitriles, fluoroketones and mixed gases thereof.

[0023] The gas circuit breaker 1 includes an upper conductor 11, a lower conductor 12, a fixed contact 13, a drive coil 14, an arc runner 15, an insulating nozzle 16, a movable contact 17, a cylindrical guide (guide tube) 18, a sliding contact 19, a piston ring 20, and an operating rod 21.

[0024] The upper conductor 11 and the lower conductor 12 are disposed to be spaced apart in the vertical direction. The upper conductor 11 and the lower conductor 12 are each supported and insulated by a supporting member (not shown).

[0025] The insulating nozzle 16 is attached to the lower surface of the upper conductor 11. The insulating nozzle 16 is a cup-shaped member with a bottom surface that is recessed inwardly into a cone shape. The center of the bottom surface of the insulating nozzle 16, which forms the bottom of the cone shape, is opened to form a through hole 16a. The space surrounded by the upper conductor 11 and the insulating nozzle 16 is the pressurizing chamber R, which is a thermal puffer chamber. The pressurizing chamber R is filled with gas G, and stores gas expanded by arc A (see FIG. 3) generated between the fixed contact 13 and the movable contact 17.

[0026] The fixed contact 13, the drive coil 14, and the arc runner 15 are disposed inside the boost chamber R. The fixed contact 13 is a cylindrical contact provided on the lower surface of the upper conductor 11. The fixed contact 13 is integral with the upper conductor 11 or is supported by the upper conductor 11 and is electrically connected to the upper conductor 11.

[0027] The movable contact 17 is a rod-shaped contact arranged below the fixed contact 13, and is provided so as to be capable of being brought into and out of contact with the fixed contact 13. The movable contact 17 is inserted (housed) inside a cylindrical guide 18. The movable contact 17 moves linearly along the cylindrical guide 18 in the up-down direction, which is the axial direction of the cylindrical guide 18, to come into and out of contact with the fixed contact 13.

[0028] When the movable contact 17 is driven upward, the tip 17a enters the pressure increasing chamber R and is inserted into the fixed contact 13, coming into contact with the fixed contact 13. When the movable contact 17 is driven downward, the tip 17a is pulled out from the inside of the fixed contact 13, and is no longer in contact with the fixed contact 13. An operating rod 21 is attached to the rear end 17b of the movable contact 17, which is opposite to the tip 17a.

[0029] The cylindrical guide 18 is tubular, the movable contact 17 is inserted therein, and guides the linear motion of the movable contact 17. The cylindrical guide 18 is conductive, supported by the lower conductor 12, and electrically connected to the lower conductor 12. The movable contact 17 is in sliding contact with the inner peripheral surface of the cylindrical guide 18 at the rear end 17b side. In this embodiment, a sliding contact 19 is provided, and the movable contact 17 is in sliding contact with the inner peripheral surface of the cylindrical guide 18 via the sliding contact 19. The movable contact 17 is electrically connected to the lower conductor 12 via the conductive cylindrical guide 18 and the sliding contact 19.

[0030] (2. Movable contact 17 and cylindrical guide 18) Here, the movable contact 17 and the cylindrical guide 18 will be described in more detail with reference to Fig. 2. Fig. 2 is an enlarged view of region B1 shown in Fig. 1. As shown in Fig. 2, the cylindrical guide 18 has an inner diameter that varies in the axial direction, and has a small diameter portion (first inner diameter portion) 18a and a large diameter portion (second inner diameter portion) 18b having an inner diameter larger than that of the small diameter portion 18a. The small diameter portion 18a is located at the upper portion, which is the end portion on the fixed contact 13 side.

[0031] Corresponding to the cylindrical guide 18 having such a shape, the movable contactor 17 also has an outer diameter that varies in the axial direction, and has a thin shaft portion (first shaft portion) 17c and a second shaft portion 17d having an outer diameter larger than that of the thin shaft portion 17c.

[0032] The small diameter portion 18a of the cylindrical guide 18 corresponds to the thin shaft portion 17c of the movable contactor 17, and when the movable contactor 17 moves, the thin shaft portion 17c is guided by the small diameter portion 18a. Similarly, the large diameter portion 18b of the cylindrical guide 18 corresponds to the thick shaft portion 17d of the movable contactor 17, and when the movable contactor 17 moves, the thick shaft portion 17d is guided by the large diameter portion 18b. An annular groove 17e is formed on the outer circumferential surface of the thick shaft portion 17d, and a sliding contactor 19 is attached to the groove 17e.

[0033] The gap (gap) between thick shaft portion 17d and large diameter portion 18b is set smaller than the gap between small diameter portion 18a and thin shaft portion 17c. In other words, the gap between small diameter portion 18a and thin shaft portion 17c is set larger than the gap between thick shaft portion 17d and large diameter portion 18b.

[0034] That is, the thick shaft portion 17d and the large diameter portion 18b are fitted together firmly. This is to ensure that the sliding contact 19 located on the outer circumferential surface of the thick shaft portion 17d and the inner circumferential surface of the large diameter portion 18b slide with certainty. In contrast, the thin shaft portion 17c and the small diameter portion 18a are fitted together loosely (with a large gap) compared to the thick shaft portion 17d and the large diameter portion 18b. Since the thin shaft portion 17c does not function as a sliding contact, the fit between the thin shaft portion 17c and the small diameter portion 18a only needs to be such that it guides the movement of the thin shaft portion 17c.

[0035] In this embodiment, a piston ring 20 is attached to the inner circumferential surface of the small diameter portion 18a. The piston ring 20 is fitted into an annular groove 17f formed on the inner circumferential surface of the small diameter portion 18a. In this embodiment, the piston ring 20 is fitted at two positions in the upper and lower directions. In this embodiment, an air hole 25 is formed in the thick shaft portion 17d, penetrating in the axial direction. The air hole 25 allows gas, i.e., gas G, to flow into the space S defined by the inner circumferential surface of the large diameter portion 18b and the thick shaft portion 17d.

[0036] (3. Operation of Gas Circuit Breaker) The operation of the gas circuit breaker 1 of this embodiment will be described with reference to Figs. 1, 2, 3, and 4. Figs. 3 and 4 are cross-sectional views showing the configuration of the gas circuit breaker 1 of this embodiment, similar to Fig. 1. However, Fig. 1 shows a closed state, Fig. 3 shows a state during current interruption, and Fig. 4 shows an open state. The closed state is a state in which the movable contact 17 is in an upper closed position, and the upper conductor 11 and the lower conductor 12 are electrically connected. The open state is a state in which the movable contact 17 is in a lower open position, and the upper conductor 11 and the lower conductor 12 are not electrically connected. The current interruption state is a state in which the movable contact 17 is halfway between the closed position and the open position, and an arc A is generated.

[0037] 1, when the movable contact 17 is driven upward, the tip 17a of the movable contact 17 passes through the through hole 16a of the insulating nozzle 16 and enters the inside of the boost chamber R, and is inserted into the fixed contact 13 to come into contact with the fixed contact 13. This results in a closed state, and the upper conductor 11 and the lower conductor 12 are electrically connected via the fixed contact 13, the movable contact 17, the sliding contact 19, and the cylindrical guide 18.

[0038] When the movable contact 17 is rapidly moved downward from the closed contact state of FIG. 1 and separated from the fixed contact 13, an arc A is generated between the fixed contact 13 and the movable contact 17 as shown in FIG.

[0039] Arc A moves from fixed contact 13 to arc runner 15 attached to drive coil 14. Then, current flows through drive coil 14, and arc A is magnetically driven. As a result, arc A rotates at high speed in the gas atmosphere, and gas G is blown relatively to arc A, and an extinguishing action of arc A occurs due to the magnetic driving effect.

[0040] Furthermore, the arc A rotates at high speed within the pressurization chamber R, causing the surrounding gas G to expand due to heat. Since the through hole 16a of the insulating nozzle 16 is sealed by the movable contact 17, the expanded gas G is stored in the pressurization chamber R. When the end of the tip 17a side of the movable contact 17 comes out of the through hole 16a of the insulating nozzle 16, the stored high-temperature gas G becomes a high-temperature gas flow G1 and is ejected from the pressurization chamber R through the through hole 16a to the outside. Since the high-temperature gas flow G1 is blown against the arc A, an arc-extinguishing action occurs due to a thermal puffer effect.

[0041] As shown in FIG. 4, in a closed state where the movable contact 17 is driven downward, the movable contact 17 is sufficiently separated from the fixed contact 13, and the upper conductor 11 and the lower conductor 12 are not electrically connected.

[0042] 1, the space S surrounded by the inner circumferential surface of the cylindrical guide 18 and the thick shaft portion 17d of the movable contact 17 has a piston structure, and therefore a load is applied. In the above configuration, the thick shaft portion 17d has an air hole 25, so that gas G is drawn into the space S from the outside through the air hole 25, and the load caused by the piston structure can be avoided. In addition, when the movable contact 17 is moved upward, the gas G in the space S is released to the outside through the air hole 25, and the above load can be avoided.

[0043] (4. Effects) The high-temperature gas flow G1, which brings about an arc-extinguishing action by the thermal puffer effect, contains decomposition products generated by the arc. As shown in FIG. 3, this high-temperature gas flow G1 is blown toward the movable contact 17, so that the decomposition products adhere to the surface of the part of the movable contact 17 that protrudes from the cylindrical guide 18. In addition, grease that has been burned by the arc heat also adheres to this part. Furthermore, when the high-temperature gas G containing the decomposition products penetrates into the cylindrical guide 18, the decomposition products also adhere to the inner peripheral surface of the cylindrical guide 18.

[0044] If such deposits (decomposition products and burnt grease) adhere to the inner peripheral surface of the cylindrical guide 18 on which the sliding contact 19 slides, the sliding friction force between the sliding contact 19 and the movable contact 17, i.e., the sliding friction force between the movable contact 17 and the cylindrical guide 18, increases. If the sliding friction force increases, the movable contact 17 cannot operate at an appropriate speed, and the operating characteristics change before and after breaking a large current.

[0045] 1) In the gas circuit breaker 1, as described above, the end side of the cylindrical guide 18 on the fixed contact 13 side is made into the small diameter portion 18a and the opposite side is made into the large diameter portion 18b, the movable contact 17 is made into the thin shaft portion 17c guided by the small diameter portion 18a and the thick shaft portion 17d guided by the large diameter portion 18b, and the sliding contact 19 is disposed on the thick shaft portion 17d. With this configuration, the following operational effects are achieved.

[0046] The inner circumferential surface of the large diameter portion 18b is not directly exposed to the high-temperature gas flow G1. Therefore, the above-mentioned deposits are unlikely to adhere to the inner circumferential surface of the large diameter portion 18b. Therefore, by disposing the sliding contact 19 in this portion, it is possible to more effectively prevent an increase in the sliding friction force between the movable contact 17 and the cylindrical guide 18.

[0047] The area of ​​the inner peripheral surface of the large diameter portion 18b is larger than the area of ​​the inner peripheral surface of the small diameter portion 18a. The "area of ​​the inner peripheral surface" here does not refer to the axial cross-sectional area of ​​the inner circumference, but the area of ​​the inner wall surface. Therefore, even if high-temperature gas G enters the large diameter portion 18b from the gap between the small diameter portion 18a and the thin shaft portion 17c, the area of ​​the inner peripheral surface of the large diameter portion 18b is so large that the area of ​​the inner peripheral surface of the large diameter portion 18b that adheres to it is limited to a small portion of the entire inner peripheral surface. Therefore, this does not cause a problem.

[0048] - Deposits adhere to the surface of the thin shaft portion 17c of the movable contact 17, especially the portion protruding from the cylindrical guide 18. However, the fit between the small diameter portion 18a and the thin shaft portion 17c is sufficient as long as it is sufficient to guide the vertical movement (axial movement) of the thin shaft portion 17c. Therefore, the gap between the small diameter portion 18a and the thin shaft portion 17c can be made larger than the gap between the large diameter portion 18b, where the sliding contact 19 is located, and the thick shaft portion 17d. Therefore, the increase in sliding frictional force due to deposits on the thin shaft portion 17c does not become a problem.

[0049] 2) In addition, in the gas circuit breaker 1, a piston ring 20 is attached to the inner peripheral surface of the small diameter portion 18a. By providing the piston ring 20, not only is the sliding property between the small diameter portion 18a and the thin shaft portion 17c improved, but also the high-temperature gas G containing decomposition products can be effectively prevented from entering the inside of the cylindrical guide 18. This makes it possible to more effectively prevent an increase in the sliding friction force between the movable contact 17 and the cylindrical guide 18.

[0050] 3) The space S surrounded by the inner circumferential surface of the cylindrical guide 18 and the thick shaft portion 17d of the movable contact 17 has a piston structure, and therefore may become a load during operation of the movable contact 17. However, in the gas circuit breaker 1, the thick shaft portion 17d is provided with the ventilation hole 25, so that such a load can be avoided.

[0051] 4) Since the cylindrical guide 18 is provided, the linear motion of the movable contact 17 is more stable than in a configuration without the cylindrical guide 18. This allows the movable contact 17 to slide on the sliding axis without deviation.

[0052] [Embodiment 2] Another embodiment of the present invention will be described below with reference to Figures 5 and 6. Note that configurations other than those described in this embodiment are the same as those in the above-mentioned embodiment 1. For ease of explanation, members having the same functions as those shown in the drawings of the above-mentioned embodiment 1 are given the same reference numerals, and their explanation will be omitted.

[0053] In the gas circuit breaker 1 of the first embodiment, the sliding contact 19 is attached to the outer peripheral surface of the thick shaft portion 17d of the movable contact 17. In contrast, in the gas circuit breaker 1A of the present embodiment, the sliding contact 19 is attached to the inner peripheral surface of the large diameter portion 18b of the cylindrical guide 18. This point is different from the gas circuit breaker 1.

[0054] Fig. 5 is a cross-sectional view showing the configuration of a gas circuit breaker 1A in this embodiment, showing a closed state. As shown in Fig. 5, in the gas circuit breaker 1A, an annular groove 18c is formed on the inner peripheral surface of the large diameter portion 18b of the cylindrical guide 18, and a sliding contact 19 is attached to the groove 18c. A plurality of grooves 18c are formed along the axial direction, and in the example of Fig. 5, four grooves 18c are formed, and a total of four sliding contacts 19 are arranged. When the movable contact 17 moves up and down, the thick shaft portion 17d always comes into contact with one of the plurality of sliding contacts 19 arranged in the axial direction.

[0055] 6 is a cross-sectional view showing the configuration of a gas circuit breaker 1B according to a modified example of this embodiment, showing a closed state. As shown in FIG. 6, in the gas circuit breaker 1B, the thick shaft portion 17d of the movable contact 17 is a thick shaft portion 17d' that is long in the axial direction. The sliding contact 19 is provided on the inner circumferential surface of the large diameter portion 18b of the cylindrical guide 18 at a position where the thick shaft portion 17d' contacts the thick shaft portion 17d' at both the lowermost position (position in the open state) and the uppermost position (position in the closed state). When the movable contact 17 moves up and down, the thick shaft portion 17d' always contacts the sliding contact 19.

[0056] <Modification> In the above-mentioned gas circuit breakers 1, 1A, and 1B, the vent hole 25 is provided in the thick shaft portion 17d, 17d', but it may be provided in the large diameter portion 18b of the cylindrical guide 18 near the boundary with the small diameter portion 18a, as shown in Fig. 7. When providing it in the large diameter portion 18b, it may be provided in a portion located above the upper surface of the thick shaft portion 17d in the closed state. Fig. 7 is a cross-sectional view showing the configuration of a gas circuit breaker 1C according to a modification of the first embodiment, showing the closed state.

[0057] In the gas circuit breakers 1, 1A, and 1B, the grooves 17e, 18c are formed on the outer circumferential surface of the thick shaft portion 17d or the inner circumferential surface of the large diameter portion 18b to attach the sliding contact 19. However, the outer circumferential surface of the thick shaft portion 17d or the inner circumferential surface of the large diameter portion 18b may be machined to have a shape that functions as the sliding contact 19. Also, as described above, the outer circumferential surface of the thick shaft portion 17d and the inner circumferential surface of the large diameter portion 18b may slide against each other without using the sliding contact 19 made of a separate member.

[0058] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0059] 1, 1A, 1B Gas Circuit Breaker 11 Upper conductor 12 Bottom conductor 13 Fixed contact 17 Movable contact 17c Thin shaft part (1st shaft part) 17d, 17d' Thick shaft part (second shaft part) 18 Cylindrical guide (guide tube) 18a Small diameter part (1st inner diameter part) 18b Large diameter section (second inner diameter section) 17e, 18c groove 19 Sliding contact 20 Piston rings 25 Ventilation holes A Arc G Arc-extinguishing gas G1 Hot Gas Flow R Pressure booster chamber (heat puffer chamber)

Claims

1. A fixed contact; a rod-shaped movable contact that moves linearly to come into contact with and separate from the fixed contact; a heat puffer chamber in which the fixed contact is located and which stores gas expanded by an arc generated between the fixed contact and the movable contact; a conductive guide tube having a cylindrical shape, through which the movable contact is inserted and which guides the linear motion of the movable contact; the guide tube has a first inner diameter portion located on an end side of the fixed contact and a second inner diameter portion having an inner diameter larger than that of the first inner diameter portion, the movable contactor has a first shaft portion guided by the first inner diameter portion, and a second shaft portion having an outer diameter larger than that of the first shaft portion and guided by the second inner diameter portion, a second shaft portion having an outer circumferential surface and an inner circumferential surface of the second inner diameter portion, the outer circumferential surface of the second shaft portion being in sliding contact with each other, thereby providing electrical continuity between the movable contact and the guide tube.

2. 2. The gas circuit breaker according to claim 1, characterized in that a vent hole is provided in the second shank or in the vicinity of the boundary between the second inner diameter portion and the first inner diameter portion, which allows gas to flow into a space partitioned by an inner surface of the second inner diameter portion and the second shank.

3. 3. The gas circuit breaker according to claim 1, wherein a gap between the first inner diameter portion and the first shaft portion is larger than a gap between the second inner diameter portion and the second shaft portion.

4. 4. The gas circuit breaker according to claim 1, wherein a piston ring is provided on an inner circumferential surface of the first inner diameter portion.

5. 5. The gas circuit breaker according to claim 1, wherein a groove is formed on an inner peripheral surface of the second inner diameter portion or an outer peripheral surface of the second shaft portion, and a sliding contact is attached to the groove.

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