Vacuum circuit breaker

Abstract

A vacuum circuit breaker includes: an insulating rod disposed within a grounded tank; a drive conductor connected to the insulating rod; a first bushing and a second bushing connected to the side of the grounded tank; vacuum valves including movable contacts; levers rotatably coupled at end portions on one side to the insulating rod or the drive conductor; movable conductors electrically connected at end portions on one side to the movable contacts; and links rotatably coupled at end portions on one side to the end portions on the other side of the movable conductors and rotatably coupled at end portions on the other side to the end portions on the other side of the levers.

Description

FIELD

The present invention relates to a vacuum circuit breaker that includes a vacuum valve in a bushing.

BACKGROUND

Patent Literature 1 discloses a vacuum circuit breaker in which bushings are provided on the side of a grounded tank and vacuum valves for current interruption are provided in the bushings. To transmit the driving force of an operating device provided on the exterior of the grounded tank to the movable side of the vacuum valves, the vacuum circuit breaker as described above needs to include a mechanism for changing the direction of the driving force within the grounded tank.

CITATION LIST

Patent Literature

• Patent Literature 1: Japanese Patent Application Laid-open No. 2016-127744

SUMMARY

Technical Problem

The grounded tank is filled with an insulating gas and is thus required to be reduced in size. The vacuum circuit breaker disclosed in Patent Literature 1 includes a link mechanism that includes a housing for guiding a member that receives the driving force of the operating device or a link mechanism for moving a member that receives the driving force of the operating device in the direction perpendicular to the longitudinal direction, within the grounded tank to change the direction of the driving force. Accordingly, the grounded tank is difficult to miniaturize and thus the entire vacuum circuit breaker is difficult to miniaturize.

The present invention has been achieved in view of the above and an object of the present invention is to provide a vacuum circuit breaker in which a mechanism disposed within a grounded tank to change the direction of a driving force is reduced in size.

Solution to Problem

In order to solve the above problems and achieve the object, the present invention includes: a tubular grounded tank; an insulating rod disposed within the grounded tank to be movable in an axial direction of the grounded tank; an operating device provided at one end portion of the grounded tank, the operating device applying a driving force in the axial direction of the grounded tank to one end portion of the insulating rod; a drive conductor disposed within the grounded tank and connected to another end portion of the insulating rod to move together with the insulating rod; a tubular first bushing connected to a side of the grounded tank; a tubular second bushing connected to the side of the grounded tank at a greater distance from the one end portion of the grounded tank than the first bushing in the axial direction of the grounded tank; and bushing terminals provided at end portions of the first bushing and the second bushing opposite the grounded tank. The present invention includes: a first vacuum valve including a first vacuum container, a first fixed contact, and a first movable contact, the first vacuum container being provided within the first bushing, the first fixed contact and the first movable contact facing each other and being disposed within the first vacuum container; a second vacuum valve including a second vacuum container, a second fixed contact, and a second movable contact, the second vacuum container being provided within the second bushing, the second fixed contact and the second movable contact facing each other and being disposed within the second vacuum container; a first fixed conductor connecting the first fixed contact and the bushing terminal of the first bushing; a second fixed conductor connecting the second fixed contact and the bushing terminal of the second bushing; a first movable conductor electrically connected at one end portion to the first movable contact; and a second movable conductor electrically connected at one end portion to the second movable contact. The present invention includes: a first lever rotatably coupled at one end portion to the insulating rod, a portion between the one end portion and another end portion of the first lever being rotatably provided within the grounded tank; a second lever rotatably coupled at one end portion to the drive conductor, a portion between the one end portion and another end portion of the second lever being rotatably provided within the grounded tank; a first link rotatably coupled at one end portion to another end portion of the first movable conductor and rotatably coupled at another end portion to the another end portion of the first lever; and a second link rotatably coupled at one end portion to another end portion of the second movable conductor and rotatably coupled at another end portion to the another end portion of the second lever. The present invention includes: a first flexible conductor having a flexibility and electrically connecting the first movable conductor and the drive conductor; and a second flexible conductor having a flexibility and electrically connecting the second movable conductor and the drive conductor.

Advantageous Effects of Invention

According to the present invention, an effect is obtained where a vacuum circuit breaker can be obtained in which a mechanism disposed within a grounded tank to change the direction of a driving force is reduced in size.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a transverse cross-sectional view of a vacuum circuit breaker according to a first embodiment of the present invention in the closed state.

FIG. 2 is a longitudinal cross-sectional view of the vacuum circuit breaker according to the first embodiment in the closed state.

FIG. 3 is an enlarged view of a portion A in FIG. 1.

FIG. 4 is a transverse cross-sectional view of the vacuum circuit breaker according to the first embodiment in the tripped state.

FIG. 5 is a transverse cross-sectional view of a vacuum circuit breaker according to a second embodiment of the present invention.

FIG. 6 is a transverse cross-sectional view of a vacuum circuit breaker according to a third embodiment of the present invention.

FIG. 7 is a transverse cross-sectional view of a vacuum circuit breaker according to a fourth embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

A vacuum circuit breaker according to embodiments of the present invention will be explained below in detail with reference to the drawings. This invention is not limited to the embodiments.

First Embodiment

FIG. 1 is a transverse cross-sectional view of a vacuum circuit breaker according to a first embodiment of the present invention in the closed state. FIG. 2 is a longitudinal cross-sectional view of the vacuum circuit breaker according to the first embodiment in the closed state. FIG. 1 illustrates a cross-section taken along line I-I in FIG. 2. FIG. 2 illustrates a cross-section taken along line II-II in FIG. 1. FIG. 3 is an enlarged view of a portion A in FIG. 1. A vacuum circuit breaker 1 includes a grounded tank 5, an insulating rod 18, an operating device 19, a cover 191, a drive conductor 17, bushings 4a and 4b, vacuum valves 2 and 3, and insulating support tubes 8a and 8b. The grounded tank 5 has a cylindrical shape with opening portions 5a and 5b formed in the tubular surface. The grounded tank 5 is electrically grounded. The insulating rod 18 is disposed within the grounded tank 5 to be movable in the axial direction of the grounded tank 5. The operating device 19 is provided at one end portion 5c of the grounded tank 5 and applies the driving force in the axial direction of the grounded tank 5 to one end portion 18a of the insulating rod 18. The cover 191 covers the operating device 19 and is connected to the end portion of the grounded tank 5. The drive conductor 17 is disposed within the grounded tank 5. The drive conductor 17 is connected at one end portion 17a to the other end portion 18b of the insulating rod 18 and thus moves together with the insulating rod 18. The bushing 4a is a tubular first bushing connected to the side of the grounded tank 5. The bushing 4b is a tubular second bushing connected to the side of the grounded tank 5 at a greater distance from the end portion 5c of the grounded tank 5 than the bushing 4a in the axial direction of the grounded tank 5. The bushings 4a and 4b are disposed above the opening portions 5a and 5b of the grounded tank 5 and communicate with the grounded tank 5 through the opening portions 5a and 5b.

The vacuum valve 2 is a first vacuum valve provided within the bushing 4a. The vacuum valve 2 includes a vacuum container 2a that is a first vacuum container, a movable contact 2b that is a first movable contact, and a fixed contact 2c that is a first fixed contact. The vacuum container 2a is formed of an insulating material and has a tubular shape. The movable contact 2b and the fixed contact 2c facing each other are disposed within the vacuum container 2a. One end portion 162a of a movable conductor 16a that is a first movable conductor is coupled to the movable contact 2b. The other end portion 161a of the movable conductor 16a projects outside of the vacuum container 2a and is movably coupled to one end portion 141 of a link 14 that is a first link. One end portion 811a of a fixed conductor 81a that is a first fixed conductor is coupled to the fixed contact 2c. The other end portion 812a of the fixed conductor 81a projects outside of the vacuum container 2a and is connected to a bushing terminal 82a of the bushing 4a. The movable contact 2b and the movable conductor 16a are movable as a unit. The movable contact 2b moves between the position in contact with the fixed contact 2c and the position spaced from the fixed contact 2c.

The vacuum valve 3 is a second vacuum valve provided within the bushing 4b. The vacuum valve 3 includes a vacuum container 3a that is a second vacuum container, a movable contact 3b that is a second movable contact, and a fixed contact 3c that is a second fixed contact. The vacuum container 3a is formed of an insulating material and has a tubular shape. The movable contact 3b and the fixed contact 3c facing each other are disposed within the vacuum container 3a. One end portion 162b of a movable conductor 16b that is a second movable conductor is coupled to the movable contact 3b. The other end portion 161b of the movable conductor 16b projects outside of the vacuum container 3a and is movably coupled to one end portion 151 of a link 15 that is a second link. One end portion 811b of a fixed conductor 81b that is a second fixed conductor is coupled to the fixed contact 3c. The other end portion 812b of the fixed conductor 81b projects outside of the vacuum container 3a and is connected to a bushing terminal 82b of the bushing 4b. The movable contact 3b and the movable conductor 16b are movable as a unit. The movable contact 3b moves between the position in contact with the fixed contact 3c and the position spaced from the fixed contact 3c.

The bushing 4a is provided with a current transformer (CT) 7a for detecting current flowing in the fixed conductor 81a. The bushing 4b is provided with a current transformer 7b for detecting current flowing in the fixed conductor 81b.

A lever 10 that is a first lever includes a shaft 10c between one end portion 10a and the other end portion 10b. The shaft 10c is rotatably supported by a support insulator 22a fixed within the grounded tank 5. Thus, the lever 10 is rotatable about the shaft 10c. The end portion 10a of the lever 10 is rotatably coupled to the insulating rod 18. The other end portion 10b of the lever 10 is rotatably coupled to the other end portion 142 of the link 14. When the vacuum circuit breaker 1 is in the closed state, the direction of the line connecting the end portion 10a and the other end portion 10b of the lever 10 is orthogonal to the longitudinal direction of the insulating rod 18. Moreover, when the vacuum circuit breaker 1 is in the closed state, the other end portion 142 of the link 14 is located at a position closer to the end portion 5c of the grounded tank 5 than the end portion 141. A lever 11 that is a second lever includes a shaft 11c between one end portion 11a and the other end portion 11b. The shaft 11c is rotatably supported by a support insulator 22b fixed within the grounded tank 5. Thus, the lever 11 is rotatable about the shaft 11c. The end portion 11a of the lever 11 is rotatably coupled to the other end portion 17b of the drive conductor 17. The other end portion 11b of the lever 11 is rotatably coupled to the other end portion 152 of the link 15. When the vacuum circuit breaker 1 is in the closed state, the direction of the line connecting the end portion 11a and the other end portion 11b of the lever 11 is orthogonal to the longitudinal direction of the drive conductor 17. Moreover, when the vacuum circuit breaker 1 is in the closed state, the other end portion 152 of the link 15 is located at a position closer to the end portion 5c of the grounded tank 5 than the end portion 151.

The rotational axes of the portions at which the members described above are rotatably coupled are parallel to each other, and they extend in the direction perpendicular to the direction of movement of the insulating rod 18.

The levers 10 and 11 and the links 14 and 15 may be formed of an insulating material or may be formed of a conductive material such as metal.

The movable conductor 16a and the drive conductor 17 are electrically connected by a flexible conductor 12 that is a first flexible conductor. The movable conductor 16b and the drive conductor 17 are electrically connected by a flexible conductor 13 that is a second flexible conductor. Even if the positional relationship between the drive conductor 17 and the movable conductors 16a and 16b changes, the flexible conductors 12 and 13 elastically deform to maintain the electrical connection between the drive conductor 17 and the movable conductors 16a and 16b.

Insulating spacers 9a and 9b through which the movable conductors 16a and 16b extend are provided within the bushings 4a and 4b, respectively. The space closer to the grounded tank 5 than the insulating spacers 9a and 9b within the bushings 4a and 4b, the space within the cover 191, and the space within the grounded tank 5 are filled with an insulating gas. Examples of the insulating gas include sulfur hexafluoride; however, this is not a limitation.

A tripping operation, or opening operation, of the vacuum circuit breaker 1 according to the first embodiment will be described. FIG. 4 is a transverse cross-sectional view of the vacuum circuit breaker according to the first embodiment in the tripped state. When the operating device 19 performs the tripping operation, the insulating rod 18 and the drive conductor 17 are pushed into the grounded tank 5. The portion between the end portion 10a and the other end portion 10b of the lever 10 is rotatably supported by the support insulator 22a, and the insulating rod 18 is rotatably coupled to the end portion 10a. Moreover, when the vacuum circuit breaker 1 is in the closed state, the direction of the line connecting the end portion 10a and the other end portion 10b of the lever 10 is orthogonal to the longitudinal direction of the insulating rod 18. Thus, when the insulating rod 18 is pushed into the grounded tank 5, the lever 10 rotates about the shaft 10c and the other end portion 10b of the lever 10 moves in the direction opposite to the direction of movement of the insulating rod 18. At this point in time, the other end portion 10b of the lever 10 approaches the insulating rod 18 with the rotation of the lever 10. When the other end portion 10b of the lever 10 approaches the insulating rod 18, the other end portion 142 of the link 14 rotatably coupled to the other end portion 10b of the lever 10 also moves together with the other end portion 10b of the lever 10, and the movable conductor 16a movably coupled to the end portion 141 of the link 14 is drawn toward the grounded tank 5 and thus the movable contact 2b and the fixed contact 2c are separated from each other. The flexible conductor 12 elastically deforms, so that even if the positional relationship between the drive conductor 17 and the movable conductor 16a changes, the electrical connection between the drive conductor 17 and the movable conductor 16a is maintained.

In a similar manner, the portion between the end portion 11a and the other end portion 11b of the lever 11 is rotatably supported by the support insulator 22b, and the drive conductor 17 is rotatably coupled to the end portion 11a. Moreover, when the vacuum circuit breaker 1 is in the closed state, the direction of the line connecting the end portion 11a and the other end portion 11b of the lever 11 is orthogonal to the longitudinal direction of the drive conductor 17. Thus, when the drive conductor 17 is pushed into the grounded tank 5 together with the insulating rod 18, the lever 11 rotates about the shaft 11c and the other end portion 11b of the lever 11 moves in the direction opposite to the direction of movement of the drive conductor 17. At this point in time, the other end portion 11b of the lever 11 approaches the drive conductor 17 with the rotation of the lever 11. When the other end portion 11b of the lever 11 approaches the drive conductor 17, the other end portion 152 of the link 15 rotatably coupled to the other end portion 11b of the lever 11 also moves together with the other end portion 11b of the lever 11, and the movable conductor 16b movably coupled to the end portion 151 of the link 15 is drawn toward the grounded tank 5 and thus the movable contact 3b and the fixed contact 3c are separated from each other. The flexible conductor 13 elastically deforms, so that even if the positional relationship between the drive conductor 17 and the movable conductor 16b changes, the electrical connection between the drive conductor 17 and the movable conductor 16b is maintained.

The movable contact 2b and the fixed contact 2c are separated from each other and the movable contact 3b and the fixed contact 3c are separated from each other, so that current flowing between the bushing terminals 82a and the bushing terminal 82b is interrupted.

A closing operation of the vacuum circuit breaker 1 according to the first embodiment will be described. When the operating device 19 performs the closing operation, the insulating rod 18 and the drive conductor 17 are drawn from the grounded tank 5. The portion between the end portion 10a and the other end portion 10b of the lever 10 is rotatably supported by the support insulator 22a, and the insulating rod 18 is rotatably coupled to the end portion 10a. Thus, when the insulating rod 18 is drawn from the grounded tank 5, the lever 10 rotates about the shaft 10c and the other end portion 10b of the lever 10 moves in the direction opposite to the direction of movement of the insulating rod 18. At this point in time, the other end portion 10b of the lever 10 moves away from the insulating rod 18 with the rotation of the lever 10. When the other end portion 10b of the lever 10 moves away from the insulating rod 18, the other end portion 142 of the link 14 rotatably coupled to the other end portion 10b of the lever 10 also moves together with the other end portion 10b of the lever 10, and the movable conductor 16a movably coupled to the end portion 141 of the link 14 is pushed toward the bushing 4a and thus the movable contact 2b and the fixed contact 2c come into contact with each other.

In a similar manner, the portion between the end portion 11a and the other end portion 11b of the lever 11 is rotatably supported by the support insulator 22b, and the drive conductor 17 is rotatably coupled to the end portion 11a. Thus, when the drive conductor 17 is drawn from the grounded tank 5 together with the insulating rod 18, the lever 11 rotates about the shaft 11c and the other end portion 11b of the lever 11 moves in the direction opposite to the direction of movement of the drive conductor 17. At this point in time, the other end portion 11b of the lever 11 moves away from the drive conductor 17 with the rotation of the lever 11. When the other end portion 11b of the lever 11 moves away from the drive conductor 17, the other end portion 152 of the link 15 rotatably coupled to the other end portion 11b of the lever 11 also moves together with the other end portion 11b of the lever 11, and the movable conductor 16b movably coupled to the end portion 151 of the link 15 is pushed toward the bushing 4b and thus the movable contact 3b and the fixed contact 3c come into contact with each other.

The movable contact 2b and the fixed contact 2c come into contact with each other and the movable contact 3b and the fixed contact 3c come into contact with each other, so that current flows between the bushing terminal 82a and the bushing terminal 82b.

In the vacuum circuit breaker 1 according to the first embodiment, the drive conductor 17 is responsible for transmission of the driving force and electrical connection, and the direction of the driving force of the operating device 19 is changed with a simple configuration including the levers 10 and 11 and the links 14 and 15. Therefore, the structure disposed within the grounded tank 5 can be reduced in size and thus the overall size of the grounded tank 5 can be reduced.

Second Embodiment

FIG. 5 is a transverse cross-sectional view of a vacuum circuit breaker according to a second embodiment of the present invention. The vacuum circuit breaker 1 according to the second embodiment is different from the vacuum circuit breaker 1 according to the first embodiment in that the bushings 4a and 4b are disposed to be inclined relative to the axial direction of the grounded tank 5 such that the interval between the bushings 4a and 4b on the side closer to the bushing terminals 82a and 82b is wider.

In the vacuum circuit breaker 1 according to the second embodiment, the insulation distance between the bushing terminals 82a and 82b is longer than that in the vacuum circuit breaker 1 according to the first embodiment, so that the withstand voltage of the vacuum circuit breaker 1 can be improved. Moreover, the same insulation distance as that in the vacuum circuit breaker 1 according to the first embodiment can be ensured with the shorter bushings 4a and 4b; therefore, the vacuum circuit breaker 1 can be reduced in size.

Third Embodiment

FIG. 6 is a transverse cross-sectional view of a vacuum circuit breaker according to a third embodiment of the present invention. The vacuum circuit breaker 1 according to the third embodiment does not include the vacuum valve 3 but includes a central conductor 21 disposed across the bushing 4b and the grounded tank 5. One end portion 21a of the central conductor 21 is electrically connected to the bushing terminal 82b. The central conductor 21 includes a bent portion 21c having the same angle as the angle formed by the grounded tank 5 and the bushing 4b. The other end portion 21b of the central conductor 21 is electrically connected to the movable conductor 16a by the flexible conductor 12. The portion between the other end portion 21b and the bent portion 21c of the central conductor 21 is supported by an insulating support base 20. The current transformer 7b is provided on the lower portion of the bushing 4a.

In the vacuum circuit breaker 1 according to the third embodiment, only the central conductor 21 is disposed within the bushing 4b; therefore, the diameter of the bushing 4b can be reduced and thus the entire vacuum circuit breaker 1 can be reduced in size.

Fourth Embodiment

FIG. 7 is a transverse cross-sectional view of a vacuum circuit breaker according to a fourth embodiment of the present invention. The vacuum circuit breaker 1 according to the fourth embodiment is different from the vacuum circuit breaker 1 according to the third embodiment in that the insulating support base 20 is not provided and the other end portion 21b of the central conductor 21 is fixed to the shaft 10c that is the rotational shaft of the lever 10.

In the vacuum circuit breaker 1 according to the fourth embodiment, the insulating support base 20 does not need to be provided within the grounded tank 5; therefore, the grounded tank 5 can be reduced in size.

The configurations described in the above embodiments are only examples of an aspect of the present invention. The configurations can be combined with other well-known techniques, and can be partly omitted or modified without departing from the scope of the present invention.

REFERENCE SIGNS LIST

• • 1 vacuum circuit breaker; 2, 3 vacuum valve; 2a, 3a vacuum container; 2b, 3b movable contact; 2c, 3c fixed contact; 4a, 4b bushing; 5 grounded tank; 5a, 5b opening portion; 5c, 10a, 11a, 17a, 18a, 21a, 141, 151, 162a, 162b, 811a, 811b one end portion; 7a, 7b current transformer; 8a, 8b insulating support tube; 9a, 9b insulating spacer; 10, 11 lever; 10b, 11b, 17b, 18b, 21b, 142, 152, 161a, 161b, 812a, 812b other end portion; 10c, 11c shaft; 12, 13 flexible conductor; 14, 15 link; 16a, 16b movable conductor; 17 drive conductor; 18 insulating rod; 19 operating device; 20 insulating support base; 21 central conductor; 21c bent portion; 22a, 22b support insulator; 81a, 81b fixed conductor; 82a, 82b bushing terminal; 191 cover.

Claims

1. A vacuum circuit breaker comprising: a tubular grounded tank;an insulating rod disposed within the grounded tank to be movable in an axial direction of the grounded tank;an operating device provided at one end portion of the grounded tank, the operating device applying a driving force in the axial direction of the grounded tank to one end portion of the insulating rod;a drive conductor disposed within the grounded tank and connected to another end portion of the insulating rod to move together with the insulating rod;a tubular first bushing connected to a side of the grounded tank;a tubular second bushing connected to the side of the grounded tank at a greater distance from the one end portion of the grounded tank than the first bushing in the axial direction of the grounded tank;bushing terminals provided at end portions of the first bushing and the second bushing opposite the grounded tank;a first vacuum valve including a first vacuum container, a first fixed contact, and a first movable contact, the first vacuum container being provided within the first bushing, the first fixed contact and the first movable contact facing each other and being disposed within the first vacuum container;a second vacuum valve including a second vacuum container, a second fixed contact, and a second movable contact, the second vacuum container being provided within the second bushing, the second fixed contact and the second movable contact facing each other and being disposed within the second vacuum container;a first fixed conductor connecting the first fixed contact and the bushing terminal of the first bushing;a second fixed conductor connecting the second fixed contact and the bushing terminal of the second bushing;a first movable conductor electrically connected at one end portion to the first movable contact;a second movable conductor electrically connected at one end portion to the second movable contact;a first lever rotatably coupled at one end portion to the insulating rod, a portion between the one end portion and another end portion of the first lever being rotatably provided within the grounded tank;a second lever rotatably coupled at one end portion to the drive conductor, a portion between the one end portion and another end portion of the second lever being rotatably provided within the grounded tank;a first link rotatably coupled at one end portion to another end portion of the first movable conductor and rotatably coupled at another end portion to the another end portion of the first lever;a second link rotatably coupled at one end portion to another end portion of the second movable conductor and rotatably coupled at another end portion to the another end portion of the second lever;a first flexible conductor having a flexibility and electrically connecting the first movable conductor and the drive conductor; anda second flexible conductor having a flexibility and electrically connecting the second movable conductor and the drive conductor.

2. The vacuum circuit breaker according to claim 1, wherein an interval between the first bushing and the second bushing on a side closer to the bushing terminals is wider than an interval between the first bushing and the second bushing on a side closer to the grounded tank.

3. A vacuum circuit breaker comprising: a tubular grounded tank;an insulating rod disposed within the grounded tank to be movable in an axial direction of the grounded tank;an operating device provided at one end portion of the grounded tank, the operating device applying a driving force in the axial direction of the grounded tank to one end portion of the insulating rod;a tubular first bushing connected to a side of the grounded tank;a tubular second bushing connected to the side of the grounded tank at a greater distance from the one end portion of the grounded tank than the first bushing in the axial direction of the grounded tank;bushing terminals provided at end portions of the first bushing and the second bushing opposite the grounded tank;a vacuum valve including a vacuum container, a fixed contact, and a movable contact, the vacuum container being provided within the first bushing, the fixed contact and the movable contact facing each other and being disposed within the vacuum container;a fixed conductor connecting the fixed contact and the bushing terminal of the first bushing;a movable conductor electrically connected at one end portion to the movable contact;a lever rotatably provided within the grounded tank and rotatably coupled at one end portion to the insulating rod;a link rotatably coupled at one end portion to another end portion of the movable conductor and rotatably coupled at another end portion to another end portion of the lever;a central conductor connected at one end portion to the bushing terminal of the second bushing, another end portion of the central conductor being disposed within the grounded tank; anda flexible conductor having a flexibility and electrically connecting the movable conductor and the central conductor.

4. The vacuum circuit breaker according to claim 3, wherein the central conductor includes a bent portion bent at a same angle as an angle formed by the grounded tank and the second bushing, andthe vacuum circuit breaker includes an insulating support base to support, in the grounded tank, a portion between the another end portion and the bent portion of the central conductor.

5. The vacuum circuit breaker according to claim 3, wherein the another end portion of the central conductor is supported by a rotational shaft of the lever.

6. The vacuum circuit breaker according to claim 3, wherein an interval between the first bushing and the second bushing on a side closer to the bushing terminals is wider than an interval between the first bushing and the second bushing on a side closer to the grounded tank.