JP2013251089A - Vacuum circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve withstand voltage performance without increasing contact separation of a movable electrode and, especially, to improve interruption performance in a leading small current interruption testing and a capacitor bank opening/closing testing.SOLUTION: A vacuum circuit breaker is provided with a movable electrode 1 and a fixed electrode 2 both of which are freely brought into contact with each other and into separation from each other and another movable electrode 9 provided at a central portion of a contact surface of the fixed electrode 2. At the time of closing of the vacuum circuit breaker, a pre-arc is generated at a contact point of another movable electrode 9 by protruding another movable electrode 9 from the contact surface of the fixed electrode 2. At the time of contact separation, another movable electrode 9 is brought into a state where another movable electrode 9 is pressed into the fixed electrode 2. Accordingly, damage to contact points due to deposition and peeling occurs on a contact surface of another movable electrode 9 and a surface opposite thereto only, and peripheral portions of electrode contact surfaces are free of occurrence of the deposition and the peeling. On account of this, local increases in electric fields are free of occurrence, withstand voltage between electrodes is improved and interruption performance is improved.

Description

  The present invention relates to a vacuum circuit breaker, and more particularly to a vacuum circuit breaker having a high rated voltage and a high breaking performance in an advanced small current breaking test and a capacitor bank switching test.

  In the vacuum valve used in the conventional vacuum circuit breaker, the basic structure is to secure both the breaking performance and the withstand voltage performance using a pair of movable electrode and fixed electrode contacts. In order to cope with the increase in capacity, the number of contacts inside the vacuum valve is increased to two pairs in series, the breaking performance is shared by parallel magnetic field type electrodes with a short gap, and the withstand voltage performance is shared by a withstand voltage electrode with a long gap. There is something that was solved by doing. (For example, Patent Document 1)

JP 58-68818 A

  In a vacuum valve used in a conventional vacuum circuit breaker, a parallel magnetic field type electrode for breaking and a withstand voltage electrode with a large opening distance for withstand voltage are provided in series, so that the size of the electrode portion increases and the withstand voltage movable electrode The movable distance becomes larger. Accordingly, there is a problem that the sealed container for storing the electrode portion becomes large, the bellows for sealing the withstand voltage movable electrode becomes long, and the vacuum valve becomes large accordingly. In addition, the movable electrode of the vacuum valve needs to be opened at a high speed of, for example, 1 m / s or more, and the vacuum valve with a higher rated voltage needs to increase the opening speed. There is also a problem that it is likely to occur. Furthermore, when the opening distance of the movable electrode is increased, there is a problem that a drive mechanism for opening and closing the electrode is also increased.

  The present invention has been made to solve the above-described problems, and improves the withstand voltage performance without increasing the size of the sealed container or the opening distance of the movable electrode. The purpose is to obtain.

  A vacuum circuit breaker according to the present invention includes a movable electrode and a fixed electrode that are detachably provided in a sealed container, and a central portion of a contact surface of one of the movable electrode and the fixed electrode. And the other movable electrode is held in a state where it is pushed into the contact surface of the electrode when the contact of the electrode is opened, and the contact surface of the electrode is closed when the contact of the electrode is closed And a holding mechanism for protruding and holding.

  According to the vacuum circuit breaker of the present invention, another movable electrode is provided at the center of the contact surface of either one of the movable electrode and the fixed electrode that are detachably provided in the sealed container. Therefore, the withstand voltage performance can be improved without increasing the opening distance of the sealed container or the movable electrode. Further, since the opening distance of the movable electrode is not increased, it is not necessary to lengthen the bellows and the vacuum valve is not increased. Further, the holding mechanism holds the other movable electrode in a state of being pushed into the contact surface of the electrode when the contact of the electrode is opened, and holds the movable electrode protruding from the contact surface of the electrode when the contact of the electrode is closed. Therefore, the advanced small current interruption test performance indicating the interruption performance and the capacitor bank switching test performance are improved.

It is side surface sectional drawing which shows the vacuum circuit breaker which concerns on Embodiment 1 of this invention. It is explanatory drawing explaining the movement of each electrode in the injection | throwing-in operation | movement of the vacuum valve which concerns on Embodiment 1 of this invention. It is explanatory drawing explaining the motion of each electrode in the interruption | blocking operation | movement of the vacuum valve which concerns on Embodiment 1 of this invention. It is side surface sectional drawing which shows the structure by the side of the fixed electrode of the vacuum valve in the vacuum circuit breaker concerning Embodiment 1 of this invention. It is explanatory drawing explaining the latch mechanism of the holding mechanism in the vacuum circuit breaker concerning Embodiment 1 of this invention. It is a graph which shows the time change of the electric field in the contact center part at the time of opening of the vacuum valve which concerns on Embodiment 1 of this invention. It is explanatory drawing explaining operation | movement of the holding mechanism in the vacuum circuit breaker concerning Embodiment 2 of this invention. It is explanatory drawing explaining the state of each electrode of the vacuum valve which concerns on Embodiment 2 of this invention. It is side surface sectional drawing which shows the structure by the side of the movable electrode of the vacuum valve in the vacuum circuit breaker concerning Embodiment 3 of this invention. It is explanatory drawing explaining the opening / closing operation | movement of the electrode of the vacuum valve in the conventional vacuum circuit breaker.

Embodiment 1 FIG.
FIG. 1 is a side sectional view showing a vacuum circuit breaker according to Embodiment 1 of the present invention, and FIG. 4 is a side sectional view showing a structure on the fixed electrode side of the vacuum valve. In the figure, the vacuum circuit breaker includes a tank 27, a vacuum valve 19 installed in the center of the tank 27, a holding mechanism 12 provided outside the tank 27, an opening / closing mechanism and a bushing not shown. The bushing conductor 28 and the vacuum valve 19 constitute an electric circuit, and the current is turned on and off by opening and closing the contacts of the pair of electrodes in the vacuum valve 19 by the opening and closing mechanism.
The vacuum valve 19 includes a pair of the movable electrode 1 and the fixed electrode 2 which are disposed in an insulating cylinder 18 held in a sealed state so as to be opposed to and away from each other in the axial direction of the insulating cylinder 18. The movable electrode rod 3 fixed to the back side of the contact surface 1 is attached to the insulating cylinder 18 via the bellows 5 and the movable flange 7, and is attached to the tank 27 via the movable insulating rod 21 and the tank side bellows 26. 1 is opened and closed in the left-right direction in FIG. 1 by an opening / closing mechanism (not shown). The fixed electrode rod 4 fixed to the back side of the contact surface of the fixed electrode 2 is attached to the insulating cylinder 18 via the fixed side flange 8.

  Further, the fixed electrode rod 4 has a hollow shape, and another movable electrode 9 is provided at the center of the contact surface of the fixed electrode 2, and another movable electrode fixed to the back side of the contact surface of the other movable electrode 9. An electrode rod 10 is provided so as to penetrate through the hollow fixed electrode rod 4 and is attached to the fixed flange 8 via the fixed bellows 6, and the tank via the fixed insulating rod 20 and the tank bellows 26. 27, connected to the rod 25 of the holding device 12, and the holding device 12 holds the other movable electrode 9 at a predetermined position described later. In addition, a support block 32 that serves as a strength reinforcement and a current passage is fixed to the fixed-side flange 8, and the support block 32 is fixed in the tank 27 via a support frame 30 and an insulating bushing 31. The bushing conductor 28 (not shown) is electrically connected to the support block 32 via the flexible conductor 34, and is connected by the flexible conductor 34, so that the shaft alignment when the vacuum valve 19 is fixed, etc. Workability is improved. On the movable side, the bushing conductor 28 is attached to a split terminal fixed to the movable electrode rod 3 via a flexible conductor 34.

  The insulating cylinder 18 is made of ceramic, and a thin metallized layer is provided on the ceramic and fixed to the flanges 7 and 8 by brazing. For this reason, since the end portion of the metallized layer becomes a high electric field, the shield 33 is provided so as to surround both left and right end portions of the insulating cylinder 18. Further, the other movable electrode rod 10 is electrically connected to the support block 32 via a flexible conductor 35 and a support 36, and is axially aligned by a guide 37 and supported so as to be slidable in the left-right direction in FIG. Yes. Although the tank 27 is at ground potential, the bushing conductor 28 and each conductor in the vacuum valve 19 have a high voltage, so that the insulating rod 20, the insulating rod 21, and the insulating bushing 31 positioned between them are made of an insulating material. Assure the withstand voltage. The tank 27 is filled with SF6 gas, air, nitrogen gas, etc., which are insulating gases. In addition, there is a longitudinal magnetic field electrode as means for improving the breaking performance of the vacuum circuit breaker. As shown in FIG. 2A, the pair of movable electrode 1 and fixed electrode 2 are fixed to the movable electrode bar 3 and the fixed electrode bar 4 via a coil 17 that generates a vertical magnetic field during the blocking operation, respectively. The reinforcing member 50 is provided for reinforcing the strength of the coil 17.

  Next, the detailed configuration of the holding mechanism 12 will be described. The spring 11 is housed in a spring box 22 provided on a spring support plate 13 fixed to the tank 27. The spring box 22 includes a compression plate 24 fixed to a rod 25, and the spring 11 presses the compression plate 24 so that the other movable electrode rod 10 is parallel to the axis of the other movable electrode rod 10, A force in a direction from another movable electrode 9 toward the opposed movable electrode 1 is generated. For this reason, another movable electrode 9 can be protruded from the contact surface of the fixed electrode 2. In order to regulate the protruding length to 5 mm, for example, the spring box 22 is provided with a stopper portion 23. Further, the holding mechanism 12 is provided with a latch mechanism shown in FIG. Another movable electrode 9 is connected to a rod 25 via another electrode rod 10 and an insulating rod 20. The movement of the rod 25 is transmitted to the arm 59 by the connecting portion 61. The arm 59 rotates around the fulcrum 58, and the distance between the fulcrum 58 and the protrusion 60 is larger than the distance between the fulcrum 58 and the connecting portion 61. Even if the moving distance is small, the latch mechanism can be operated.

  The protrusion 60 is fitted in a reverse-curved groove 55 provided on the rotating plate 54. The rotating plate 54 is rotatably supported by a fulcrum 57, and a force in the direction of arrow 65 is applied by a spring (not shown), and a force in the direction of arrow 56 is applied by a solenoid (not shown). For this reason, when another movable electrode 9 protrudes from the contact surface of the fixed electrode 3, the force of the spring 11 acts on the rod 25 in the direction of the arrow 64 as shown in FIG. Further, the projection 60 is positioned at the right end of the groove 55 by applying a force in the direction of the arrow 56 exceeding a force in the direction of the arrow 65 of the spring (not shown) by a solenoid (not shown). In a state where another movable electrode 9 is pushed into the contact surface of the fixed electrode 3, the rod 25 moves to the right as shown in FIG. 5B, so that the protrusion 60 tends to move to the left. If the force in the direction of the arrow 56 by the solenoid (not shown) is not applied, the rotary plate 54 is rotated by the force in the direction of the arrow 65 (not shown), and the protrusion 60 is placed at the left end of the groove 55. Moving. Even if a force in the direction of the arrow 64 by the spring 11 is applied to the rod 25, the protrusion 60 does not move to the right due to the shape of the groove 55. Therefore, even if the contact is opened in this state, the other movable electrode 9 is fixed electrode 3 The state of being pushed into the contact surface of is maintained.

  Next, the operation in the first embodiment will be described with reference to FIG. 2 and FIG. FIG. 2 is an explanatory diagram for explaining the movement of each electrode in the closing operation of the vacuum valve according to Embodiment 1 of the present invention, and FIG. 3 is the movement of each electrode in the shutoff operation of the vacuum valve according to Embodiment 1 of the present invention. It is explanatory drawing explaining these. In FIG. 2A, in the state where the movable electrode 1 and the fixed electrode 2 are open, another movable electrode 9 provided at the center of the contact surface of the fixed electrode 2 is pushed into the fixed electrode 2. The latch mechanism of the holding mechanism 12 is in the state shown in FIG. When the closing operation of the vacuum circuit breaker is started from this state, first, before the closing operation, a force in the direction of the arrow 56 is applied to the rotating plate 54 of FIG. When the latch is removed, another movable electrode 9 is projected from the contact surface of the fixed electrode 2 as shown in FIG. In this state, when the movable electrode 1 is moved in the right direction in FIG. 1 by the opening / closing mechanism (not shown) and the movable electrode 1 and the fixed electrode 2 are closed, first, as shown in FIG. The movable electrode 1 and another movable electrode 9 are in contact with each other. Subsequently, when the movable electrode 1 and the fixed electrode 2 are completely closed by an opening / closing mechanism (not shown) as shown in FIG. 2D, another movable electrode 9 is pushed into the fixed electrode 2, and the holding mechanism 12 is 5B, the other working electrode 9 is held at a position where it is pushed into the fixed electrode 9. In the state shown in FIG.

  On the other hand, in the blocking operation, as shown in FIG. 3A, the movable electrode 1 is moved leftward in FIG. 1 by an opening / closing mechanism (not shown) with another movable electrode 9 pushed into the fixed electrode 2. Therefore, the movable electrode 1 and the fixed electrode 2 are opened. Since the holding mechanism 12 remains in the state shown in FIG. 5B even when the pole is opened, the other movable electrode 9 is held at the position where it is pushed into the fixed electrode 2 as shown in FIG. 3B. The

  In the vacuum circuit breaker of the present invention configured as described above, the movable electrode 1 and the fixed electrode 2 provided in the container held in a sealed state so as to be able to come into contact with and away from each other, and the central portion of the contact surface of the fixed electrode 2 Since the other movable electrode 9 is provided, the opening distance of the sealed container or the movable electrode 1 is not increased, and the opening distance of the movable electrode 1 is not increased. The vacuum valve 19 does not become large.

  Next, the breaking performance and the withstand voltage performance of the vacuum circuit breaker configured as described above will be described in comparison with the electrode structure of a conventional vacuum valve for easier understanding. In general, a vacuum circuit breaker used for opening / closing a transmission line or a capacitor bank is required to have an ability to cut off a small advance current determined by the ground capacitance of the transmission line or the capacitance of the capacitor bank. For this reason, it is necessary to detect the breaking performance by conducting a progressive small current breaking test and a capacitor bank switching test. As a result of conducting contact surface analysis of the electrode of the vacuum circuit breaker in which this advanced small current interruption test and capacitor bank switching test were conducted, it was found that the following phenomenon occurred. When the electrode is closed with the circuit voltage applied, the electric field between the fixed electrode 2 and the movable electrode 1 becomes high, and dielectric breakdown occurs before the electrode is closed. The heat of the arc generated at this time (hereinafter referred to as pre-arc) causes melting on the contact surface of the electrode. Thereafter, the electrode is closed, and the melted portion is welded with the temperature lowered by thermal diffusion. Subsequent opening operation causes the welded site to be peeled off, causing damage to the contact surface. Due to this damage, a minute protrusion having a height of several tens to several hundreds of μm is generated on the contact surface of the electrode, and a high electric field is generated at the tip thereof, so that the breaking performance and the withstand voltage performance are lowered.

  This phenomenon will be described with reference to the operation explanatory diagram of the electrode in the conventional vacuum circuit breaker shown in FIG. In FIG. 10, a normal vacuum valve has only a fixed electrode and a movable electrode, but the vacuum valve of Patent Document 1 includes an intermediate holder 90, and a pair of voltage-resistant movable electrodes 91 are provided at both ends of the intermediate holder 90. And a withstand voltage intermediate electrode 92 and a pair of parallel magnetic field type intermediate electrodes 93 and a parallel magnetic field type fixed electrode 94 are provided. In order to improve the blocking performance by the stopper 95, the pair of parallel magnetic field type electrodes 93 and 94 are opened. The distance is set to a short distance of 10 and 10 mm, which is optimal for interruption, and the pair of voltage-resistant electrodes 91 and 92 has a long opening distance of 10 and more mm in order to improve the voltage resistance performance. A compression spring 97 is provided between the intermediate holder guide plate 96 and the withstand voltage intermediate electrode.

  Next, the operation of the conventional electrode configured as described above will be described. In the open state, as shown in FIG. 10A, both the pair of parallel magnetic field type electrodes 93 and 94 and the pair of withstand voltage electrodes 91 and 92 are open. In the closing operation, as shown in the middle of closing in FIG. 10 (b), the pair of withstand voltage electrodes 91 and 92 are first closed, and the compression spring 97 is further compressed by an opening / closing mechanism (not shown), thereby a pair of parallel magnetic fields. The mold electrodes 93 and 94 are also closed, but the pre-arc generated at this time causes fusion 98 to occur between the pair of parallel magnetic field type electrodes 93 and 94 as shown in FIG. At the time of opening, since the pair of parallel magnetic field type electrodes 93 and 94 is opened first as in the case of 10 (d) opening, the minute protrusion 99 by the above-mentioned peeling is formed on the contact surface of the pair of parallel magnetic field type electrodes 93 and 94. However, since the arc is generated and the interruption performance is deteriorated, the pair of parallel magnetic field type electrodes 93 and 94 have high interruption performance, so that the arc is extinguished. Thereafter, as shown in FIG. 10 (e), the pair of withstand voltage electrodes 91 and 92 are opened at a long opening distance, so that the withstand voltage performance is improved.

  In general, when a voltage is applied between the electrodes, the peripheral portion of the contact surface of the electrode has a higher electric field than the central portion. Therefore, the welding 98 by the pre-arc and the minute protrusion 99 by the peeling are the electrodes. Since the breaking performance is lower in the peripheral part of the contact surface of the electrode than in the case where it occurs in the central part, the peripheral part of the electrode contact surface is subjected to R machining, Measures to improve the shut-off performance as much as possible by devising the electrode shape, such as projecting the center part of the contact surface of the electrode, but in the case where the periphery of the contact surface of the electrode is subjected to R processing, At the flat portion of the contact surface immediately inside, the above-mentioned fusion 98 and the protrusion 98 due to the peeling are generated, and the portion where the protrusion 98 is generated becomes a high electric field and the interruption performance is lowered. Moreover, in the shape where the center of the contact surface of the electrode protrudes, the contact center portion has a higher electric field because the gap length is shorter than the contact periphery portion. Since a minute protrusion is formed on the central projecting portion by welding and peeling, an extremely high electric field is generated and the interruption performance is lowered.

  On the other hand, in the electrode structure of the present invention, the opening distance of the vacuum valve is a value of several tens mm, and the opening distance increases as the rated voltage increases. On the other hand, the pre-arc at the time of charging occurs when the distance between the electrodes becomes a small value of several mm. Therefore, if the amount of protrusion of the other movable electrode 9 from the fixed electrode 2 is, for example, 5 mm, the surface electric field of the other movable electrode 9 becomes a discharge generating electric field before the peripheral portion of the contact surface of the fixed electrode 2. A pre-arc is generated at the movable electrode 9. As shown in FIG. 2 (c), the center of the contact surface of the movable electrode 1 on the opposite surface of the movable electrode 9 is first in contact with the other movable electrode 9 at the time of closing. Occurs only at the center of the contact surface of another movable electrode 9 and the contact surface of the movable electrode 1 which is the opposite surface. When the movable electrode 9 and the movable electrode 1 come into contact with each other, the movable electrode 1 and the fixed electrode 2 are the same. Since it becomes a potential, no pre-arcing occurs. Since the electric field at the center of the contact surface with another movable electrode 9 is lower than that at the periphery of the contact surface, the electric field at the tip of the protrusion is smaller than that at the periphery of the contact even if a minute protrusion is formed by welding peeling. Alleviated. Further, since the pre-arc does not occur in the peripheral portion of the contact surface of the movable electrode 1 and the contact surface of the fixed electrode 2, the electric field is not increased locally and the withstand voltage between the electrodes is improved. The cut-off performance in the advanced small current cut-off test and the capacitor bank switching test will be improved.

  Here, when the change in the contact surface electric field in the advanced small current interruption test was examined, the contact surface electric field reached the maximum during the opening due to the relationship between the rising speed of the reactivation voltage and the increase in the gap length between the contacts due to the opening operation. I found out. FIG. 6 shows the result of electric field analysis using the electrode shape of the vacuum circuit breaker according to the present invention. In FIG. 6, the vertical axis represents the electric field at the center of the contact. The electric field of the first wave of the regenerative voltage is extremely high, and the subsequent peak electric field is constant. Furthermore, at the electric field peak of the first wave of the regenerative voltage, the electric field at the center of the contact was about 20% smaller than the electric field at the position where minute protrusions were formed by welding removal at the periphery of the contact. If the electric field multiplication factor due to the formation of minute protrusions is β, the electric field is multiplied by β in both the contact center and the contact periphery, so that a small protrusion can be formed at the center of the contact surface as in this structure. The electric field is about 20% smaller than in the case of the contact surface periphery. As a result, it is possible to withstand the high electric field of the first wave of the regenerative voltage, and the interruption performance is improved. Further, the electric field peak after the second wave of the regenerative voltage is in a fully open state, and the electric field at the center of the contact surface is relaxed by about 36% from the periphery of the contact surface, and the withstand voltage performance is also improved.

Further, in order to improve the withstand voltage performance of the vacuum circuit breaker, conditioning is generally performed in the manufacturing process. As a conditioning method, there are voltage conditioning for discharging by applying an AC voltage or an impulse voltage, and current conditioning for interrupting a large current of kA order. In the vacuum circuit breaker of the present invention, when another movable electrode 9 is pushed into the fixed electrode 2, the electric field tends to be higher in the peripheral part of the contact surface than in the central part as described above. There is a tendency for the conditioning of the central part to be insufficient. Therefore, in this structure, voltage conditioning is performed in a state where another movable electrode 9 is protruded, and both the contact surface of another movable electrode 9 and the contact surfaces of the movable electrode 1 and the fixed electrode 2 are sufficiently conditioned. In addition, current conditioning has the property that an arc is ignited and conditioned at the position where the contact surface finally leaves, so that the periphery of the contact surface is conditioned, but the condition at the center of the contact surface tends to be insufficient. There is. Therefore, in this structure, current conditioning with another movable electrode 9 protruding is also performed, and current conditioning at the center of the contact surface can be sufficiently performed.
In general, conditioning is performed as a vacuum circuit breaker after being performed by a single vacuum valve, but may be performed after being assembled as a vacuum circuit breaker in order to stabilize withstand voltage performance.

Embodiment 2. FIG.
In the holding mechanism 12 of the first embodiment, the state where another movable electrode 9 is pushed into the fixed electrode 2 at the time of opening is held. However, in the holding mechanism 12 of the second embodiment, the disc spring 66 is used. When the electrode is opened, another movable electrode 9 is pushed and held in a state of being recessed deeply with respect to the contact surface of the fixed electrode 2. FIG. 7 is an explanatory view for explaining the operation of the holding mechanism 12 in the vacuum circuit breaker according to Embodiment 2 of the present invention, and FIG. 8 is an explanatory view for explaining the state of each electrode of the vacuum valve. FIG. 8A shows a state in which another movable electrode 9 protrudes from the fixed electrode 2. At this time, the holding mechanism 12 is in the state shown in FIG. This holding mechanism 12 also uses the arm 59 to amplify the movement of the rod 25. When the movable electrode 1 and the fixed electrode 2 are closed as shown in FIG. 8B by the closing operation of the movable electrode 1, the disc spring 66 supported by the support plate 67 is inverted as shown in FIG. 7B. As a result of pulling the rod 25 further back, the other movable electrode 9 is pushed into a state of being recessed deeper than the contact surface of the fixed electrode 2 as shown in FIG. At the time of opening, the other movable electrode 9 is opened while being pushed into the recessed state.

  In order to project another movable electrode 9 at the time of closing, the disc spring 66 is reversed by pushing the center shaft 68 with a force in the direction of arrow 56 by a solenoid, and the holding mechanism 12 is moved from the state of FIG. Set to the state of (a). By the above operation, a pre-arc at the time of charging is generated at the center of the contact surface of another movable electrode 9 and the movable electrode 1 on the opposite surface, and then another movable electrode 9 is moved as shown in FIG. When it is pushed into the recessed state of the contact surface of the fixed electrode 2, a minute protrusion is generated on the surface of the electrode contact at this portion due to welding and peeling. However, since the other movable electrode 9 is opened while the other movable electrode 9 is recessed at the time of opening, the electric field applied to the contact surface of the other movable electrode 9 is suppressed, and the electric field is further relaxed. For this reason, an arc can be generated at the contact surface peripheral portion of the movable electrode 1 and the contact electrode peripheral portion of the fixed electrode 2 when the short circuit is interrupted. Generally, in the longitudinal magnetic field electrode, when the arc is ignited around the contact point, the longitudinal magnetic field acting on the arc immediately after the arc is stronger, so that the breaking performance in the advanced small current interruption test and the capacitor bank switching test is improved. improves.

Embodiment 3 FIG.
FIG. 9 is a side sectional view showing the structure of the movable electrode side of the vacuum valve in the vacuum circuit breaker according to Embodiment 3 of the present invention. In the first and second embodiments, the case where another movable electrode 9 is provided on the fixed electrode 2 has been described. However, in the third embodiment, another movable electrode 9 is provided on the movable electrode 1. For this reason, the movable electrode rod 3 is hollow and another electrode rod 10 is provided inside. A small bellows 69 is provided for vacuum sealing inside the vacuum valve. Insulating rod 71 and insulating rod 72 of another electrode rod 10 are provided to insulate electrode rod 3 from tank 27. Further, a small tank bellows 70 is provided outside the tank side bellows 26. The holding mechanism 12 is provided on a rod 77 connected to the movable electrode rod 3 via an insulating rod 71, and a rod 73 for the holding mechanism 12 is provided on a rod 78 connected to another electrode rod 10 via an insulating rod 72. The holding mechanism 12 may use the structure shown in FIG. 5 or FIG. 7 or another structure. A contact pressure spring 74 is provided on the spring 11 and the rod 77 for projecting another movable electrode 9. In this structure, since the electrode rod is driven using the arm 75, the fact that the moving distance of another electrode rod 10 farther from the fulcrum 58 is larger is utilized. As a result, another movable electrode 9 comes into contact with the fixed electrode 2 first in the closing operation. FIG. 9 shows a state in the middle of closing and shows a state in which another movable electrode 9 protrudes. The operation of the other movable electrode 9 is basically the same as that described in the first embodiment. With this structure, there is no need to provide the holding mechanism 12 on the fixed electrode 2 side of the tank 27, and there is an effect that the structure becomes more compact.

  It should be noted that within the scope of the present invention, the embodiments can be freely combined, or the embodiments can be appropriately modified or omitted.

DESCRIPTION OF SYMBOLS 1 Movable electrode 2 Fixed electrode 9 Another movable electrode 12 Holding mechanism 19 Vacuum valve 66 Disc spring

Claims (4)

  A movable electrode and a fixed electrode that are detachably provided in a sealed container, and another movable electrode that is provided at the center of the contact surface of one of the movable electrode and the fixed electrode; A holding mechanism for holding the other movable electrode in a state where it is pushed into the contact surface of the electrode when the contact of the electrode is opened, and projecting from the contact surface of the electrode when the contact of the electrode is closed. A vacuum circuit breaker characterized by comprising.   2. The vacuum circuit breaker according to claim 1, wherein the contact surface of the other movable electrode is pushed and held in a state of being recessed with respect to the contact surface of the electrode.   The vacuum circuit breaker according to claim 1 or 2, wherein the holding mechanism is constituted by a disc spring, and the position of the other movable electrode is held by reversing the disc spring.   The another movable electrode is provided at the center of the contact surface of the movable electrode, and the holding mechanism is provided on a rod extending from the back side of the contact surface of the movable electrode to the outside of the container. The vacuum circuit breaker according to any one of claims 1 to 3.

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