Abstract:
Switchgear comprising: an air-insulated earthing disconnecting switch switchable among the closing position, disconnecting position, and earthing position; a vacuum interrupter electrically connected to the air-insulated earthing disconnecting switch; an operating device of the air-insulated earthing disconnecting switch having a motor; and an operating-force transmission unit transmitting driving force from the motor to a movable electrode of the air-insulated earthing disconnecting switch, wherein the operating-force transmission unit includes an operation rod fixedly coupled to the movable electrode, a shaft rotatably driven by the motor, a lever fixed to the shaft and making an arc motion with the shaft rotatably driven, a coupling pin coupling the lever and the operation rod, and limit switches detecting that the air-insulated earthing disconnecting switch is in the closing position, disconnecting position, or earthing position by means of the coupling pin driven by the operation of the rod operating with an arc motion of the lever.

Description:
CLAIM OF PRIORITY  
       [0001]    The present application claims priority from Japanese Patent application serial no. 2013-150235, filed on Jul. 19, 2013, the content of which is hereby incorporated by reference into this application. 
       TECHNICAL FIELD  
       [0002]    This invention relates to switchgears and is particularly suitable for switchgears having an air-insulated earthing disconnecting switch that performs closing, disconnecting, and earthing operations with air insulation. 
       BACKGROUND ART  
       [0003]    Japanese Unexamined Patent Application Publication No. 2011-41407 (Patent Literature 1) discloses an example of typical switchgears that include an air-insulated earthing disconnecting switch performing closing, disconnecting, and earthing operations with air insulation, but are still compact even though employing air insulation. 
         [0004]    This switchgear disclosed in the Patent Literature 1 includes an air-insulated earthing disconnecting switch that linearly moves and is switchable among three positions, i.e., a closing position, a disconnecting position, and an earthing position, a vacuum interrupter that applies or interrupts voltage and current in a vacuum chamber maintained under vacuum, and a solid insulator that encloses the air-insulated earthing disconnecting switch and the vacuum interrupter. The switchgear is also characterized in that the air-insulated earthing disconnecting switch is electrically connected to the vacuum interrupter, and application and interruption of voltage and current are performed inside the vacuum interrupter. 
         [0005]    In addition, the switchgear described in the Patent Literature 1 is operated as follows: application of voltage and current to a high-voltage circuit, such as a cable, is made by closing the vacuum interrupter after the air-insulated earthing disconnecting switch is brought into conduction; interruption of voltage and current is made by opening the vacuum interrupter while the air-insulated earthing disconnecting switch is in conduction; disconnection of the high-voltage circuit is made by switching the air-insulated earthing disconnecting switch to the disconnecting position after voltage and current are interrupted; and earthing of the high-voltage circuit is made by switching the air-insulated earthing disconnecting switch to the earthing position after the high-voltage circuit is disconnected, and then closing the vacuum interrupter. 
       CITATION LIST  
     Patent Literature  
       [0006]    [Patent Literature 1] JP-A No. 2011-41407 
       SUMMARY OF INVENTION  
     Technical Problem  
       [0007]    However, the switchgear as disclosed in the aforementioned Patent Literature 1 is configured so that the accuracy of three positions for closing, disconnecting, and earthing, more specifically, the dimensional accuracy of a gap between contacts at the closing, disconnecting, and earthing positions, affects insulation performance. Thus, further study on control is needed to improve the dimensional accuracy of a gap between the contacts. 
         [0008]    The present invention has been made in view of the above points and provides a switchgear that has improved stopping accuracy at three positions, i.e., a closing position, a disconnecting position, and an earthing position, thereby stabilizing insulation performance. 
       Solution to Problem  
       [0009]    The switchgear according to the invention includes an air-insulated earthing disconnecting switch that linearly moves and is switchable among a closing position, a disconnecting position, and an earthing position, a vacuum interrupter that is electrically connected to the air-insulated earthing disconnecting switch and makes and breaks current flow in a vacuum chamber maintained under vacuum, and an operating device that provides driving force to movable electrodes of the air-insulated earthing disconnecting switch and the vacuum interrupter. The air-insulated earthing disconnecting switch and the vacuum interrupter are integrally covered with a solid insulation. The operating device of the air-insulated earthing disconnecting switch transmits driving force from a motor to the air-insulated earthing disconnecting switch via an operating-force transmission unit. The operating-force transmission unit includes an operation rod fixedly coupled to the movable electrode of the air-insulated earthing disconnecting switch, a lever making an arc motion with a shaft rotatably driven by the motor, a coupling pin coupling the lever and the operation rod, and limit switches detecting that the air-insulated earthing disconnecting switch is in the closing position, disconnecting position, or earthing position by means of the coupling pin driven by the operation of the rod operating with an arc motion of the lever. 
       Advantageous Effects of Invention  
       [0010]    The present invention can provide a switchgear that has improved stopping accuracy at three positions, i.e., a closing position, a disconnecting position, and an earthing position, thereby stabilizing insulation performance. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS  
         [0011]      FIG. 1  is a schematic diagram showing the configuration of a switchgear according to an embodiment of the present invention; 
           [0012]      FIG. 2  is a schematic diagram showing details of an operating-force transmission unit of an air-insulated earthing disconnecting switch of the switchgear according to the embodiment of the invention; 
           [0013]      FIG. 3  is a perspective view showing details of the operating-force transmission unit of the air-insulated earthing disconnecting switch of the switchgear according to the embodiment of the invention; and 
           [0014]      FIG. 4  is a front view of  FIG. 3 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS  
       [0015]    With reference to an illustrated embodiment, a switchgear according to the embodiment of the present invention will be described below. 
       Embodiment  
       [0016]      FIGS. 1 to 4  show a vacuum insulated switchgear which is a switchgear according to the embodiment of the invention. 
         [0017]    As shown in  FIGS. 1 to 4 , the vacuum insulated switchgear  1  of the embodiment mainly includes a mold switch  2 , an operating device  3 , and an operating-force transmission unit  4 . The following are descriptions of those inclusions. 
         [0018]    The mold switch  2  includes a vacuum interrupter  5  having the functions of closing and breaking in vacuum insulation and a three-position air-insulated earthing disconnecting switch  6  having the functions of closing, disconnecting, and earthing. The interrupter  5  and switch  6  are covered with a solid insulator  27  of epoxy or the like. The vacuum interrupter  5  is electrically connected to the air-insulated earthing disconnecting switch  6  with a flexible conductor  13 . 
         [0019]    The air-insulated earthing disconnecting switch  6  has a first fixed electrode  7  that is connected to a busbar-side conductor (not shown) in a busbar mold bushing  10  connected to a busbar. The air-insulated earthing disconnecting switch  6  has a second fixed electrode  8  that is connected to a movable conductor  14  of the vacuum interrupter  5  through the flexible conductor  13  connected therebetween. Furthermore, the air-insulated earthing disconnecting switch  6  has a third fixed electrode  9  that is earthed. 
         [0020]    The inner circumferences of the first fixed electrode  7 , second fixed electrode  8 , and third fixed electrode  9  of the air-insulated earthing disconnecting switch  6  are aligned along the same cylinder. An air movable electrode  43  in a shape corresponding to the cylinder slides along the inner circumferences of the respective fixed electrodes. The air movable electrode  43  is connected to an air-insulated operation rod  62  made from an insulating member. This air-insulated operation rod  62  is connected to an operation rod  63  linked to the operating device  3 . 
         [0021]    The vacuum interrupter  5  includes a fixed electrode  11 , a movable electrode  12  facing the fixed electrode  11 , a fixed conductor  19  connected to the fixed electrode  11 , and a movable conductor  14  connected to the movable electrode  12 . The fixed electrode  11  and movable electrode  12  are surrounded by an arc shield  18  to prevent a vacuum chamber  20  from being damaged by arc vapor. 
         [0022]    In the vacuum interrupter  5 , a vacuum chamber  20  is maintained under vacuum. A bellows  15  provided between the vacuum chamber  20  and the movable conductor  14  allows the movable conductor  14  to operate while maintaining the vacuum chamber  20  under vacuum. The fixed conductor  19  is connected to a feeder conductor  33  that has an end provided with a mold bushing  16  molded with an insulation material. In addition, a voltage detector  17  is connected to a middle part of the feeder conductor  33  to make it possible to measure voltage to be applied to a load. Outside of the vacuum chamber  20 , the movable conductor  14  is connected to the flexible conductor  13 , which is connected to the second fixed electrode  8  of the air-insulated earthing disconnecting switch  6 , and also is connected to an air-insulated operation rod  52 , which is made from an insulating member and used with the vacuum interrupter  5 . The air-insulated operation rod  52  is connected to an operation rod  53  for the vacuum interrupter  5 , disposed on the side of the operating-force transmission unit  4 . 
         [0023]    The busbar-side conductor (not shown) in the busbar mold bushing  10 , the first fixed electrode  7  and the second fixed electrode  8  of the air-insulated earthing disconnecting switch  6 , the vacuum chamber  20  and the feeder conductor  33  are integrally molded with an insulation material of epoxy or the like, which forms the solid insulator  27 . Further, the solid insulator  27  is formed to surround the air-insulated operation rods  52 ,  62  with a space therebetween. However, the flexible conductor  13  is not molded with the insulation material to maintain its flexibility. The flexibility of the flexible conductor  13  permits the movable conductor  14  that is connected to the second fixed electrode  8  of the air-insulated earthing disconnecting switch  6  to move in an axis direction. 
         [0024]    The following describes the operating device  3 . The operating device  3  includes a motor  25  playing a role of an operating instrument for the air-insulated earthing disconnecting switch  6  and an operating instrument  26  for the vacuum interrupter  5 . The motor  25  provides driving force to the air movable electrode  43  in the air-insulated earthing disconnecting switch  6 , while the operating instrument  26  provides driving force to the movable electrode  12  in the vacuum interrupter  5 . 
         [0025]    Next, the operating-force transmission unit  4  will be described. The operating-force transmission unit  4  is broadly divided into a part on the vacuum interrupter  5  side and apart on the air-insulated earthing disconnecting switch  6  side. 
         [0026]    First, the operating-force transmission unit  4  on the vacuum interrupter  5  side includes an operating-instrument-side rod  55  connected to the operating instrument  26 , a main lever  50  connected to the operating-instrument-side rod  55 , a shaft (pivot)  51 A connected to the main lever  50 , three-phase levers  51  connected to the shaft  51 A, and three-phase operation rods  53  respectively connected to the three-phase levers  51 . Each operation rod  53  is connected to the air-insulated operation rod  52  on the vacuum interrupter  5  side. 
         [0027]    The operating-force transmission unit  4  on the air-insulated earthing disconnecting switch  6  side includes a first chain  65 A linked to a rotating shaft  25 A of the motor  25 , a first gear  66 A engaged with the first chain  65 A to transmit the rotational energy of the motor  25  to a shaft  61 A, a second chain  65 B linked to the shaft  61 A, a second gear  66 B engaged with the second chain  65 B to transmit the rotational energy from the shaft  61 A to an extended shaft  61 B, three-phase levers  61  connected to the extended shaft  61 B and performing an arc motion, three-phase operation rods  63  respectively connected to the three-phase levers  61 , and coupling pins  21  respectively coupling each of the three-phase operation rods  63  to the corresponding lever of the three-phase levers  61 . 
         [0028]    In addition, the operating-force transmission unit  4  on the air-insulated earthing disconnecting switch  6  side according to the embodiment includes a closing-position detecting limit switch  22 A, a disconnecting-position detecting limit switch  22 B, and an earthing-position detecting limit switch  22 C. The rotational motion generated by the motor  25  is transmitted to the extended shaft  61 B via the first chain  65 A, first gear  66 A, second chain  65 B, and second gear  66 B and causes the three-phase levers  61  coupled to the extended shaft  61 B to perform an arc motion. The arc motion actuates the operation rod  63  and resultantly drives the coupling pin  21  to allow the aforementioned limit switches to detect that the air-insulated earthing disconnecting switch  6  is in the closing position, disconnecting position, or earthing position. 
         [0029]    The closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C are attached to a U-shaped guide hardware  23  that is disposed so as to surround the coupling part where one of the three-phase levers  61  and one of the three-phase operation rods  63  is coupled by the coupling pin  21 . The U-shaped guide hardware  23  has first slotted holes  23 A extending in a vertical direction formed in the side walls opposite to each other. The coupling pin  21  moves in the first slotted holes  23 A in the vertical direction and comes into contact with the closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C, respectively arranged at positions corresponding to the closing position, disconnecting position, and earthing position of the air-insulated earthing disconnecting switch  6 , thereby detecting that the air-insulated earthing disconnecting switch  6  is in the closing position, disconnecting position, or earthing position. 
         [0030]    In addition, each of the three-phase levers  61  has an end with a second slotted hole  61 C extending in a longitudinal direction of each of the three-phase levers  61 . The coupling pin  21  moves in the second slotted hole  61 C operatively associated with the arc motion of each of the three-phase levers  61  and also moves in the first slotted holes  23 A in the vertical direction, thereby causing the operation rod  63  to move vertically. 
         [0031]    Furthermore, one closing-position detecting limit switch  22 A and one earthing-position detecting limit switch  22 C are disposed at positions corresponding to the closing position and earthing position of the air-insulated earthing disconnecting switch  6 , respectively, while two disconnecting-position detecting limit switches  22 B are disposed at positions corresponding to the disconnecting position of the air-insulated earthing disconnecting switch  6 . 
         [0032]    More specifically, the closing-position detecting limit switch  22 A disposed at a position corresponding to the closing position of the air-insulated earthing disconnecting switch  6  is arranged at an upper part of the U-shaped guide hardware  23 . The disconnecting-position detecting limit switches  22 B disposed at positions corresponding to the disconnecting position of the air-insulated earthing disconnecting switch  6  are arranged at the center of both the side walls of the U-shaped guide hardware  23 , respectively. The earthing-position detecting limit switch  22 C disposed at a position corresponding to the earthing position of the air-insulated earthing disconnecting switch  6  is arranged at a lower part of the U-shaped guide hardware  23 . 
         [0033]    In addition, in the vicinity of the first slotted holes  23 A around which the closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C for the air-insulated earthing disconnecting switch  6  are disposed, rollers  24 A,  24 B,  24 C are set as integral parts of the limit switches, respectively. When the coupling pin  2 l makes contact with the rollers  24 A,  24 B,  24 C, the rollers push to actuate the closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C disposed at positions corresponding to the closing, disconnecting, earthing positions of the air-insulated earthing disconnecting switch. 
         [0034]    According to the embodiment, the coupling pin  21  attached to the operation rod  63  pushes the closing-position detecting limit switch  22 A when the air-insulated earthing disconnecting switch  6  is in the closing position, pushes the disconnecting-position detecting limit switch  22 B when the air-insulated earthing disconnecting switch  6  is in the disconnecting position, and pushes the earthing-position detecting limit switch  22 C when the air-insulated earthing disconnecting switch  6  is in the earthing position, thereby detecting the each position of the air-insulated earthing disconnecting switch  6 . 
         [0035]    In addition, a brake command is issued to the motor  25  in synchronization with a press of one of the closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C for the air-insulated earthing disconnecting switch  6 , thereby stopping the motor  25 . 
         [0036]    During the time from the moment a limit switch is turned on until a brake command reaches the motor  25 , the motor  25  keeps running and also the coupling pin  21  keeps moving. By employing a reduction gear designed to rotate at a lower speed than the motor  25  to reduce the amount of movement of the coupling pin  21  from when the closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C are turned on to when the brake command reaches the motor  25 , the coupling pin  21  can be controlled to stop at positions for closing, disconnecting, and earthing with high accuracy. 
         [0037]    The coupling pin  21  is configured so as to be capable of moving downward at the closing position, both upward and downward at the disconnecting position, and upward at the earthing position. 
         [0038]    Since the disconnecting-position detecting limit switch  22 B adopts a roller mechanism that allows the coupling pin  21  to pass by both upwardly and downwardly, the coupling pin  21  presses in the disconnecting-position detecting limit switch  22 B at different positions between when the coupling pin  21  moves from above to below and from below to above. More specifically, the coupling pin  21  pressed down from above pushes the roller  24 B at a different position from the position at which the coupling pin  21  pressed up from below pushes the roller  24 B. Because of this, two disconnecting-position detecting limit switches  22 B are provided to separately detect the coupling pin  21  moving from above to below and from below to above in order to control the stop position of the coupling pin  21  to be the same in both directions. 
         [0039]    Although the timing of pressing the closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C varies depending on the lateral positional relationship between the coupling pin  21  and those limit switches, the U-shaped guide hardware  23  can improve the positioning accuracy between the coupling pin  21  and the closing-position detecting limit switch  22 A, disconnecting-position detecting limit switch  22 B, and earthing-position detecting limit switch  22 C. 
         [0040]    As described above, the switchgear according to this embodiment can improve stopping accuracy at three positions, i.e., a closing position, a disconnecting position, and an earthing position, thereby stabilizing insulation performance. 
         [0041]    The present invention should not be limited to the above embodiment, but includes various modifications. For example, the above embodiment is detailed descriptions for comprehensively explaining the present invention, and the invention should not necessarily be limited to include all the configurations described above. Furthermore, a part of a configuration in one embodiment can be replaced by a configuration in another embodiment, and a configuration in one embodiment can be added to a configuration in another embodiment. Apart of a configuration in each embodiment can also be added to, deleted from, or replaced by another configuration. 
       REFERENCE SIGNS LIST  
       [0042]      1 : vacuum insulated switchgear;  2 : mold switch;  3 : operating device;  4 : operating-force transmission unit;  5 : vacuum interrupter;  6 : air-insulated earthing disconnecting switch;  7 : first fixed electrode;  8 : second fixed electrode;  9 : third fixed electrode;  10 : busbar mold bushing;  11 : fixed electrode;  12 : movable electrode;  13  flexible conductor;  14 : movable conductor;  15 : bellows;  16 : mold bushing;  17 : voltage detector;  18 : arc shield;  19 : fixed conductor;  20 : vacuum chamber;  21 : coupling pin;  22 A: closing-position detecting limit switch;  22 B: disconnecting-position detecting limit switch;  22 C: earthing-position detecting limit switch;  23 : guide hardware;  23 A: first slotted hole;  24 A,  24 B,  24 C: roller;  25 : motor;  25 A: motor&#39;s rotating shaft;  26 : operating instrument;  27 : solid insulator;  33 : feeder conductor;  43 : air movable electrode;  50 : main lever;  51 ,  61 : three-phase levers;  51 A,  61 A: shaft;  52 ,  62 : air-insulated operation rod;  53 ,  63 : operation rod;  55 : operating-instrument-side rod;  61 B: extended shaft;  61 C: second slotted hole;  65 A: first chain;  65 B second chain;  66 A: first gear; and  66 B: second gear.