Grounding switch

Abstract

The grounding switch (50a) comprises a fixed contact (53) fixed to an electrical circuit conductor (52) installed inside the tank (51), a movable contact (54) movably installed inside the tank (51), a vacuum valve (56) installed outside the tank (51), and an operating device (55) installed outside the tank (51) that causes the movable contact (54) to perform closing and closing operations. The operating device (55) has a power source (550) that generates rotational force, a rotating output shaft (551) that outputs rotational force, a slider-crank mechanism (60) that converts the rotational force into a force that moves the movable contact (54) in a straight line, and a cam mechanism (70) that converts the rotational force into a force that moves the movable electrode (56a) of the vacuum valve (56) in a straight line. The cam mechanism (70) separates the movable electrode (56a) from the fixed electrode (56b) while the movable contact (54) is moving between the closing position and the closing position.

Description

Technical Field

[0001] The present disclosure relates to an earthing switch that discharges the charge remaining in a circuit to the ground.

Background Art

[0002] In the earthing switch of a gas-insulated switchgear, a structure that performs an opening operation and a closing operation by linearly driving or rotationally driving a movable contact is used. The earthing switch includes a circuit conductor that forms a part of a circuit. During normal operation of the gas-insulated switchgear, it is in an off state where the circuit conductor is not connected to the ground, and during maintenance inspection of the gas-insulated switchgear, etc., it is in an on state where the circuit conductor is connected to the ground. By disconnecting the circuit where the earthing switch is installed with a circuit breaker and a disconnector and then putting the earthing switch into the on state, the charge remaining in the disconnected circuit can be discharged to the ground, and the potential of the circuit can be made equal to the ground potential.

[0003] The circuit where the earthing switch is installed is disconnected from other parts of the circuit when the earthing switch is put into the on state. However, in a gas-insulated device connected to a transmission line with two or more circuits installed side by side, an induced current flows through the earthing switch installed in the circuit at the end of the disconnected transmission line due to the magnetic flux of the adjacent operating circuit. When restarting operation, it is necessary to put the earthing switch installed in the circuit at the end of the transmission line into the off state prior to connecting the disconnected circuit to other parts of the circuit. However, since an induced current flows through the earthing switch installed in the circuit at the end of the transmission line as described above, the earthing switch installed in the circuit at the end of the transmission line is required to have a breaking performance for interrupting the induced current.

[0004] In the earthing switch of a gas-insulated switchgear filled with a gas having low insulation performance and arc extinguishing performance such as dry air, the arc generation time and arc distance when interrupting the induced current are longer than those of a gas-insulated switchgear filled with sulfur hexafluoride gas. Therefore, measures to improve the arc extinguishing performance are required.

[0005] Patent Document 1 discloses a grounding switch that improves arc extinguishing performance by interrupting induced current within a vacuum valve located inside a tank. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-156351 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the grounding switch disclosed in Patent Document 1 requires a complex mechanism to perform opening and closing operations at two locations: the disconnecting section and the electrodes of the vacuum valve, and also requires a large tank capable of housing the vacuum valve. Thus, a grounding switch that extinguishes the arc using a vacuum valve installed inside a tank has problems such as an increase in the number of parts inside the tank and an increase in the size of the equipment.

[0008] This disclosure has been made in view of the above, and aims to provide an earthing switch that can interrupt induced current while suppressing an increase in the number of parts in the tank filled with insulating gas and an increase in the size of the equipment. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the objective, the earthing switch according to this disclosure comprises: a circuit conductor installed in a tank filled with insulating gas; a fixed contact fixed to the circuit conductor; a movable contact installed in the tank so as to be movable between an on position in which it contacts the fixed contact and an off position where there is a gap between it and the fixed contact; a vacuum valve installed outside the tank, the movable electrode connected in series with the movable contact, and which, when the movable contact is in the on position or off position, the movable electrode contacts the fixed electrode; and an operating device installed outside the tank that causes the movable contact to perform an on operation to move from the off position to the on position and an off operation to move from the on position to the off position. The operating device comprises a power source that generates rotational force, a rotary output shaft that outputs rotational force, a slider-crank mechanism that converts the rotational force into a force that moves the movable contact linearly, and a cam mechanism that converts the rotational force into a force that moves the movable electrode of the vacuum valve linearly. The cam mechanism separates the movable electrode from the fixed electrode while the movable contact is moving between the on position and the off position. [Effects of the Invention]

[0010] According to this disclosure, it is possible to obtain an earthing switch that can interrupt induced current while suppressing an increase in the number of parts in the tank filled with insulating gas and an increase in the size of the equipment. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the configuration of a gas-insulated switchgear using a grounding switch according to Embodiment 1. [Figure 2] Cross-sectional view showing the configuration of the grounding switch according to Embodiment 1 [Figure 3] Cross-sectional view showing the configuration of the grounding switch according to Embodiment 1 [Figure 4] Side view of the grounding switch in the closed position according to Embodiment 1 [Figure 5] This figure shows the state in which the cam plate of the grounding switch according to Embodiment 1 pushes down one end of the driven joint member. [Modes for carrying out the invention]

[0012] The earthing switch according to the embodiment will be described in detail below with reference to the drawings.

[0013] Embodiment 1. Figure 1 shows the configuration of a gas-insulated switchgear using a grounding switch according to Embodiment 1. The gas-insulated switchgear 100 includes a circuit 10 with two or more circuits, and disconnectors 20, circuit breakers 30, surge arresters 40, and grounding switches 50a, 50b installed in the circuit 10. Each of the disconnectors 20 and circuit breakers 30 constitutes a part of the circuit 10 when closed. The circuit breaker 30 has the ability to interrupt current during normal operation and fault current. When interrupting the current flowing through the circuit 10, the circuit breaker 30 is first set to the interrupted state, and then the disconnector 20 is set to the interrupted state. The surge arrester 40 protects the circuit 10 and the equipment installed in the circuit 10 by releasing the charge in the circuit 10 to earth when a voltage exceeding a preset protection voltage is applied to the circuit 10.

[0014] Of the multiple grounding switches 50a and 50b provided by the gas-insulated switchgear 100, the grounding switch 50a installed in the circuit 10 at the end of the transmission line 80 is subject to induced current flow due to the magnetic flux of the adjacent circuit that is in operation. Therefore, the grounding switch 50a installed in the circuit 10 at the end of the transmission line 80 is required to interrupt the induced current. The induced current needs to be interrupted when switching either of the grounding switches 50a installed at both ends of the transmission line 80 from a state where the disconnector 20 installed at the end of the transmission line 80 is in the interrupted state and the grounding switch 50a installed at the end of the transmission line 80 is closed.

[0015] Figures 2 and 3 are cross-sectional views showing the configuration of the earthing switch according to Embodiment 1. Figure 2 shows a cross-section when the earthing switch is in the closed state, and Figure 3 shows a cross-section when the earthing switch is in the closed state. Figure 4 is a side view of the earthing switch according to Embodiment 1 in the closed state. The cross-section shown in Figure 2 is a cross-section along the line II-II in Figure 4. The cross-section shown in Figure 3 is a cross-section at the same position as in Figure 2.

[0016] The grounding switch 50a comprises a tank 51 filled with insulating gas, a circuit conductor 52 installed inside the tank 51 and forming part of the circuit 10, a fixed contact 53 installed on the circuit conductor 52, a movable contact 54 installed inside the tank 51 so as to be movable between an on position in contact with the fixed contact 53 and an off position where there is a gap between the fixed contact 53 and the movable contact 54, and an operating device 55 installed outside the tank 51 that causes the movable contact 54 to perform an on operation to move from the off position to the on position and an off operation to move from the on position to the off position.

[0017] The grounding switch 50a is kept in an interrupted state during normal operation of the gas-insulated switchgear 100, not connecting the circuit conductor 52 to the earth, and is set to an closed state, connecting the circuit conductor 52 to the earth, during maintenance and inspection of the gas-insulated switchgear 100. By disconnecting the portion of the circuit 10 on which the grounding switch 50a is installed from the rest of the circuit 10 using the circuit breaker 30 and disconnector 20, and then setting the grounding switch 50a to the closed state, any residual charge in the circuit 10 disconnected by the circuit breaker 30 and disconnector 20 is discharged to the earth, and the potential of the circuit 10 disconnected by the circuit breaker 30 and disconnector 20 can be made equal to the earth potential.

[0018] Furthermore, the grounding switch 50a includes a vacuum valve 56 installed outside the tank 51. The movable electrode 56a of the vacuum valve 56 is connected in series to the movable contact 54 via conductive conductors 581, 582, 583, 584 and an insulated wire 59. Conductive conductor 581 slidably supports the movable contact 54 within the tank 51. Conductive conductor 581 is electrically insulated from the tank 51 by an insulating member 587. Conductive conductors 582 and 583 are electrically insulated from the tank 51 by an insulating member 588. Note that Figures 2 and 3 show an example in which the vacuum valve 56 is arranged on a cross section along line II-II in Figure 4, but the vacuum valve 56 does not have to be arranged on a cross section along line II-II in Figure 4.

[0019] The operating device 55 includes a power source 550 that generates a rotational force, a rotational output shaft 551 that outputs the rotational force generated by the power source 550, a lever 552 installed on the rotational output shaft 551, a first link member 553 whose one end 553a is rotatably fixed to the lever 552, an insulating rod 554 whose one end 554a is rotatably fixed to the other end 553b of the first link member 553 and whose other end 554b is fixed to the movable contact 54, a cam plate 555 installed on the rotational output shaft 551, a driven joint member 556 provided with a contact on one end 556a, a second link member 557 whose one end 557a is rotatably fixed to the other end 556b of the driven joint member 556 and whose other end 557b is fixed to the movable-side electrode 56a of the vacuum valve 56, and a spring 558 that presses the contact of the driven joint member 556 against the cam plate 555. The second link member 557 is formed of an insulating material. The driven joint member 556 is rotatably supported at an intermediate portion, such that when one end 556a side rises, the other end 556b side descends, and when one end 556a side descends, the other end 556b side rises.

[0020] The lever 552, the first link member 553, and the insulating rod 554 constitute a slider-crank mechanism 60, and the rotational motion of the rotational output shaft 551 is converted into the linear motion of the insulating rod 554.

[0021] The cam plate 555, the driven joint member 556, and the second link member 557 constitute a cam mechanism 70. The cam plate 555 fixed to the rotational output shaft 551 serves as the driving joint, and the rotational motion of the rotational output shaft 551 is converted into the linear motion of the movable-side electrode 56a of the vacuum valve 56.

[0022] When the movable contact 54 is in the closed or closed position, the vacuum valve 56 is in the closed state, with the movable electrode 56a and the fixed electrode 56b in contact. The cam mechanism 70 is configured to adjust the cam angle so that the movable electrode 56a of the vacuum valve 56 moves as the movable contact 54 moves between the closed and closed positions, thereby closing the vacuum valve 56. Because the contact of the driven joint member 556 is pressed against the cam plate 555 by the spring 558, during the closed operation, as soon as the movable contact 54 reaches the closed position, the vacuum valve 56 enters the closed state, with the movable electrode 56a and the fixed electrode 56b in contact. Similarly, during the closed operation, as soon as the movable contact 54 reaches the closed position, the vacuum valve 56 enters the closed state, with the movable electrode 56a and the fixed electrode 56b in contact.

[0023] The operation of the grounding switch 50a will now be explained. During normal operation of the gas-insulated switchgear 100, the grounding switch 50a is in the tripped state, and the movable contact 54 and the fixed contact 53 are separated. Therefore, for voltages during normal operation and voltages during faults such as lightning impulses, it is sufficient for the vacuum valve 56 to have the voltage withstand capability to maintain insulation between the movable contact 54 and the fixed contact 53, which are installed in the insulating gas, and the vacuum valve 56 does not require voltage withstand capability.

[0024] During maintenance of the gas-insulated switchgear 100, the circuit 10 on which the grounding switch 50a is installed is disconnected by the circuit breaker 30 and the disconnector 20. When the rotary output shaft 551 is rotated in a first direction, where the tip 552a of the lever 552 approaches the tank 51, the insulating rod 554 is moved in a direction that pushes it into the tank 51. Before the movable contact 54 contacts the fixed contact 53, the long diameter portion 555a of the cam plate 555 abuts against the contact of the driven joint member 556, pushing down one end 556a of the driven joint member 556. Figure 5 shows the state in which the cam plate of the grounding switch according to Embodiment 1 pushes down one end of the driven joint member. As shown in Figure 5, when one end 556a of the driven link member 556 is pushed down, the other end 556b of the driven link member 556 is lifted, and the second link member 557 fixed to the other end 556b of the driven link member 556 is also lifted. As a result, the movable electrode 56a of the vacuum valve 56 fixed to the other end 557b of the second link member 557 moves in a direction that pulls it out of the vacuum container 56c, and the vacuum valve 56 becomes closed. When the rotary output shaft 551 is further rotated in the first direction, and the insulating rod 554 is further moved in a direction that pushes it into the tank 51, the movable contact 54 comes into contact with the fixed contact 53, and the grounding switch 50a becomes closed. In the closed state, the circuit conductor 52 is connected to earth via the fixed contact 53, the movable contact 54, the electric wire 59, and the vacuum valve 56. Therefore, any charge remaining in the circuit conductor 52 is discharged to earth via the fixed contact 53, movable contact 54, wire 59, and vacuum valve 56. In addition, any induced current flowing through the circuit conductor 52 flows to earth via the fixed contact 53, movable contact 54, wire 59, and vacuum valve 56.

[0025] After maintenance and inspection of the gas-insulated switchgear 100 is completed, the rotary output shaft 551 is rotated in a second direction, where the tip 552a of the lever 552 moves away from the tank 51, thereby moving the insulating rod 554 in the direction of pulling it out of the tank 51. Before the movable contact 54 separates from the fixed contact 53, the long diameter portion 555a of the cam plate 555 comes into contact with the contact of the driven link member 556, pushing down one end 556a of the driven link member 556. When one end 556a of the driven link member 556 is pushed down, the other end 556b of the driven link member 556 rises, and the second link member 557 fixed to the other end 556b of the driven link member 556 also rises. As a result, the movable electrode 56a of the vacuum valve 56 fixed to the second link member 557 moves in the direction of being pulled out of the vacuum container 56c, and the vacuum valve 56 becomes closed. Therefore, the vacuum valve 56 is used to interrupt the residual current caused by the charge remaining in the circuit conductor 52 and the induced current caused by the current flowing through the adjacent circuit 10.

[0026] When the rotating output shaft 551 is rotated further in the second direction, and the insulating rod 554 is moved further in the direction of withdrawing it from the tank 51, the movable contact 54 separates from the fixed contact 53, and the earthing switch 50a is turned off. Since the residual current due to the charge remaining in the circuit conductor 52 and the induced current due to the current flowing through the adjacent circuit 10 have already been interrupted by the vacuum valve 56, no arc is generated between the movable contact 54 and the fixed contact 53 even when the movable contact 54 separates from the fixed contact 53.

[0027] By further rotating the rotary output shaft 551 in the second direction and moving the insulating rod 554 further in the direction of withdrawing it from the tank 51, the movable contact 54 reaches the interrupted position. In this state, by closing the circuit breaker 30 and the disconnector 20, the circuit 10 in which the grounding switch 50a is installed is connected to the rest of the circuit 10, and power transmission is started.

[0028] In the first embodiment, the grounding switch 50a does not require the vacuum valve 56 to have the voltage withstand capability to withstand the voltage during normal operation of the gas-insulated switchgear 100 and the voltage during faults such as lightning impulses, thus eliminating the need to enlarge the vacuum valve 56. Furthermore, since the vacuum valve 56 is installed outside the tank 51, there is no need to install a mechanism for transmitting driving force to the vacuum valve 56 inside the tank 51. For this reason, the first embodiment of the grounding switch 50a can interrupt induced currents while suppressing an increase in the number of parts inside the tank 51 filled with insulating gas and an increase in the size of the equipment.

[0029] The configurations shown in the above embodiments are merely examples of the content, and can be combined with other known technologies. It is also possible to omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of Symbols]

[0030] 10 Electrical circuit, 20 Disconnector, 30 Circuit breaker, 40 Lightning arrester, 50a, 50b Grounding switch, 51 Tank, 52 Electrical circuit conductor, 53 Fixed contact, 54 Movable contact, 55 Operating device, 56 Vacuum valve, 56a Movable side electrode, 56b Fixed side electrode, 56c Vacuum container, 59 Electric wire, 60 Slider crank mechanism, 70 Cam mechanism, 80 Transmission line, 100 Gas-insulated switchgear, 550 Power source, 551 Rotating output shaft, 552 Lever, 552a Tip, 553 First link member, 553a, 554a, 556a, 557a One end, 553b, 554b, 556b, 557b Other end, 554 Insulating rod, 555 Cam plate, 555a Long diameter section, 556 Driven joint member, 557 Second link member, 558 Springs, 581, 582, 583, 584 Conductive conductors, 587, 588 Insulating members.

Claims

1. A circuit conductor installed inside a tank filled with insulating gas, A fixed contact fixed to the aforementioned circuit conductor, A movable contact is installed in the tank so as to be movable between an insertion position in contact with the fixed contact and a blocking position where a gap exists between the fixed contact and the movable contact, The vacuum valve is installed outside the tank and in an environment where insulating gas is not sealed, the movable electrode is connected in series with the movable contact, and when the movable contact is in the inlet position or the shut-off position, the movable electrode contacts the fixed electrode. The device is installed outside the tank and in an environment where insulating gas is not sealed, and includes an operating device that causes the movable contact to perform an input operation, moving from the shut-off position to the input position, and a shut-off operation, moving from the input position to the shut-off position. The operating device comprises a power source for generating rotational force, a rotary output shaft for outputting the rotational force, a slider-crank mechanism for converting the rotational force into a force for linear movement of the movable contact, and a cam mechanism for converting the rotational force into a force for linear movement of the movable electrode of the vacuum valve. The cam mechanism is characterized in that, while the movable contact moves between the closed position and the closed position, the movable electrode is separated from the fixed electrode.

2. The earthing switch according to claim 1, characterized in that the slider crank mechanism comprises a lever installed on the rotating output shaft, a first link member with one end rotatably fixed to the lever, and an insulating rod with one end rotatably fixed to the other end of the first link member and the other end fixed to the movable contact.

3. The grounding switch according to claim 2, characterized in that the cam mechanism comprises a cam plate installed on the rotating output shaft, a driven link member having a contact element at one end that contacts the cam plate, a second link member having one end rotatably fixed to the other end of the driven link member and the other end fixed to the movable electrode, and a spring that biases one end of the driven link member in a direction that presses it against the cam plate.

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