Patent Publication Number: US-9431185-B2

Title: Spring operation device for switchgear

Description:
FIELD 
     The present invention relates to a spring operation device for use in a switchgear such as a breaker provided in a substation or a switching station. 
     BACKGROUND 
     In FIG. 31 of Patent Literature 1, a spring operation device for use in a switchgear is depicted in which the device includes two springs: an opening coil spring and a closing coil spring. In this conventional spring operation device, when the biased closing coil spring is released during a closing operation, a switch-on lever rotates about a main shaft under a condition where a guide engages with a first tripping latch, the first tripping latch engages with a tripping trigger, and the tripping trigger engages with a lock plate. In response to this rotation, a four-joint link (a first link, a second link, and a second blocking lever) rotates about the main shaft, while being supported by the guide. Further, a first blocking lever rotates about the main shaft and then compresses and biases the opening spring so as to close the breaker. 
     In the spring operation device described in Patent Literature 1 mentioned above, a first lock member and the lock plate are provided, and the lock plate locks the tripping trigger during a closing operation. Consequently, even when an opening command is improperly input and a tripping electromagnet is thus energized, the tripping trigger is configured so as not to rotate and perform an opening operation. The lock plate is configured so as to be pushed out by the first lock member and to disengage from the tripping trigger when the closing operation has been completed. Therefore, the spring operation device is in a state where it is capable of performing an opening operation. 
     In the spring operation device described in Patent Literature 2, a switch-on stopping device is provided, as illustrated in FIG. 3 of the Patent Literature, in order to prevent a closing operation from being performed immediately after an opening operation. Engagement of a trigger lever with a switch-on trigger is controlled by using an interlocking electromagnet. In this conventional spring operation device, even when a switch-on electromagnet is energized during an opening operation, the switch-on trigger is not driven and therefore a switch-on operation is prevented from being performed. 
     CITATION LIST 
     Patent Literatures 
     Patent Literature 1: Japanese Patent No. 3808328 
     Patent Literature 2: Japanese Patent Application Laid-open No. 2002-157946 
     SUMMARY 
     Technical Problem 
     As described above, the spring operation device described in Patent Literature 1 has a structure in which upon performing a closing operation, the opening coil spring is compressed such that the guide, the first tripping latch, the tripping trigger, and the lock plate engage with each other. However, over the course of an opening operation for example, the guide, the first tripping latch, the tripping trigger, and the lock plate disengage from each other, so that, in this state, a closing command is improperly input and the four-joint link cannot be supported by the guide and is thus brought into a non-rotatable state. Consequently, the opening coil spring is not biased and its load decreases accordingly and therefore the closing speed increases. This leads to a problem where the spring operation device may be damaged. 
     In the spring operation device described in Patent Literature 2, the switch-on stopping device is provided with an additional electromagnet in order to prevent a closing operation from being performed during an opening operation. With this technique, it is necessary to modify the control circuit so that a command also is transmitted to the electromagnet used for the switch-on stopping device (the interlocking electromagnet). This leads to problems such as the control circuit becoming more complicated, the spring operation device becoming a more complicated structure, and size of the spring operation device increasing. 
     The present invention has been achieved to solve the above problems, and an objective of the present invention is to provide a spring operation device for use in a switchgear that has a simple structure and is capable of preventing a closing operation from being performed during an opening operation. 
     Solution to Problem 
     To solve the problem and achieve the objective, the present invention relates to a spring operation device for use in a switchgear. The spring operation device includes: a main shaft that is rotatably supported by a casing; an output lever that is fixed to the main shaft, is rotatable about the main axis, and is coupled to a switching contact; an opening biasing unit that biases the output lever so as to rotate the output lever in a predetermined direction; a four-joint link that is fixed at one end to the main shaft, is rotatably coupled at the other end to the output lever, and is flexible and extendable; a guide that is rotatably supported by the casing, and includes a guide surface that is capable of guiding the four-joint link, while coming into contact with the four-joint link; a tripping latch that is rotatably supported by the casing and is capable of locking the guide; a tripping trigger that is rotatably supported by the casing and is capable of locking the tripping latch; a tripping electromagnet that has a plunger capable of moving back and forth toward the tripping trigger, and moves the plunger forward to rotate the tripping trigger when an opening command is input so as to make it possible to disengage the tripping latch from the tripping trigger; a switch-on lever that is fixed to the main shaft and is rotatable about the main shaft; a closing bias unit that biases the switch-on lever so as to rotate the switch-on lever in a reverse direction to the predetermined direction; a switch-on latch that is rotatably supported by the casing and is capable of locking the switch-on lever; a switch-on trigger that is rotatably supported by the casing and is capable of locking the switch-on latch; a switch-on electromagnet that has a plunger capable of moving back and forth toward the switch-on trigger, and moves the plunger forward to rotate the switch-on trigger when a closing command is input so as to make it possible to disengage the switch-on latch from the switch-on trigger; an opening-operation prevention unit that operates in conjunction with the output lever, stops the tripping trigger from rotating when the switching contact is in a closing operation, and allows the tripping trigger to rotate when the switching contact is in an opening operation; and a closing-operation prevention unit that operates in conjunction with the output lever, stops the switch-on trigger from rotating when the switching contact is in an opening operation, and allows the switch-on trigger to rotate when the switching contact is in a closing operation. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to prevent a closing operation from being performed during an opening operation with a simple structure and without any additional circuitry being provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram of the relevant parts of a spring operation device for use in a switchgear according to a first embodiment. The specific state illustrated is that before starting a closing operation. 
         FIG. 2  illustrates the shape of an interlock bar  41 . 
         FIG. 3  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the first embodiment. The specific state illustrated is a state when a closing operation has been completed. 
         FIG. 4  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the first embodiment. The specific state illustrated is at the start of an opening operation. 
         FIG. 5  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the first embodiment. The specific state illustrated is when the opening operation has been completed. 
         FIG. 6  is a configuration diagram of the relevant parts of a spring operation device for use in a switchgear according to an example used for comparison. The specific state illustrated is when an opening operation has been completed. 
         FIG. 7  is a configuration diagram of the relevant parts of a spring operation device for use in a switchgear according to a second embodiment. The specific state illustrated is that before starting a closing operation. 
         FIG. 8  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the second embodiment. The specific state illustrated is when the closing operation has been completed. 
         FIG. 9  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the second embodiment. The specific state illustrated is at the start of an opening operation. 
         FIG. 10  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the second embodiment. The specific state illustrated is when the opening operation has been completed. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Exemplary embodiments of a spring operation device for use in a switchgear according to the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments. 
     First Embodiment 
       FIG. 1  is a configuration diagram of the relevant parts of a spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is the state before starting a closing operation. The switchgear, for example, is a breaker. 
     A main shaft  51  is rotatably supported by a casing (not illustrated) that serves as a support structure. An output lever  52  is attached to and fixed to the main shaft  51 . The output lever  52  is rotatable about the main shaft  51 . The output lever  52  is coupled to an opening coil spring  60  and a buffer  42  via a blocking link  61 . The opening coil spring  60  is an example of an opening biasing unit. In  FIG. 1 , the opening coil spring  60  is in a released state. 
     A bar-shaped lock member  30  is attached to a four-joint link  43 . The lock member  30  moves in conjunction with the rotation of the output lever  52 . The distal end of the lock member  30  comes into and out of contact with a lock plate  32 . In  FIG. 1 , the distal end of the lock member  30  is in contact with the lock plate  32 . 
     A movable contact  22   a  is connected to the output lever  52 . The movable contact  22   a  is capable of coming into and out of contact with a fixed contact  22   b  according to the rotation of the output lever  52 . The movable contact  22   a  and the fixed contact  22   b  constitute a switching contact  22  of the breaker. The output lever  52  is coupled to the switching contact  22  via a link mechanism  95 . 
     A switch-on lever  76  is attached to and fixed to the main shaft  51 . The switch-on lever  76  is rotatable about the main shaft  51 . The switch-on lever  76  is coupled to a switch-on link  11 . The switch-on link  11  is coupled to a closing coil spring  77 . The closing coil spring  77  is compressed by a motor, which is not illustrated, when it is biased. The closing coil spring  77  is an example of a closing bias unit. In  FIG. 1 , the closing coil spring  77  is in a biased state. 
     One end of the four-joint link  43  is attached to the main shaft  51 , and the other end thereof is rotatably attached to the output lever  52  via a pin  26 . Specifically, the four-joint link  43  is constituted by a link  43   a  that is fixed at its one end to the main shaft  51 , a link  43   b  that is rotatably coupled to the link  43   a  via a pin  24 , and a link  43   c  that is rotatably coupled to the link  43   b  via a pin  25 . The link  43   c  is rotatably attached to a lever portion  52  of the output lever  52  via the pin  26 . The four-joint link  43  has joints at four positions that are the main shaft  51  and the pins  24  to  26 . The entirety of the four-joint link  43  is configured to be flexible and extendable. The lock member  30  is fixed to the output lever  52  via the pin  26 . 
     A guide  62  is supported at its one end by a rotational shaft  63  provided in the casing so as to be rotatable about the rotational shaft  63 . At the other end of the guide  62 , a pin  66  is provided. The pin  66  is engageable with a tripping latch  69  (a first tripping latch). In  FIG. 1 , the pin  66  is engaged with the tripping latch  69 . The guide  62  is biased by a return spring  68  so as to rotate clockwise. The guide  62  includes a substantially-arc-shaped guide surface  62   a  on the side that is opposed to the main shaft  51 . In  FIG. 1 , a portion of the four-joint link  43  comes into contact with the guide surface  62   a . A pin  62   b  is provided on one-end side of the guide  62  and is engageable with a tripping latch  64  (a second tripping latch), which is attached to and is rotatable about the rotational shaft  63 . In  FIG. 1 , the pin  62   b  is engaged with the tripping latch  64 . The tripping latch  64  is engageable, at its distal end, with the pin  24   aa  that is provided in the link  43   a . In  FIG. 1 , the tripping latch  64  is not engaged with the pin  24 . A spring  75  biases the tripping latch  64  so as to rotate the tripping latch  64  about the rotational shaft  63  clockwise. 
     The tripping latch  69  is attached to and is rotatable about a rotational shaft  70 . The rotational shaft  70  is rotatably supported by the casing. In the tripping latch  69 , a notch is provided, with which the pin  66  of the guide  62  is engageable, and also a pin  71  is provided. The pin  71  is engageable with a tripping trigger  73 . In  FIG. 1 , the pin  71  is engaged with the tripping trigger  73 . A spring  96  biases the tripping latch  69  so as to rotate the tripping latch  69  about the rotational shaft  70  clockwise. 
     The tripping trigger  73  is attached to and is rotatable about a rotational shaft  74 . In the tripping trigger  73 , a notch is provided, with which the pin  71  of the tripping latch  69  is engageable. A spring  97  biases the tripping trigger  73  so as to rotate the tripping trigger  73  about the rotational shaft  74  counterclockwise. 
     The lock plate  32  is attached to and is rotatable about a rotational shaft  31 . The distal end of the lock plate  32  is engageable with the distal end of the tripping trigger  73 . In  FIG. 1 , the lock plate  32  engages with the tripping trigger  73 . A spring  98  biases the lock plate  32  so as to rotate the lock plate  32  about the rotational shaft  31  counterclockwise. 
     One end of an interlock bar  41  is fixed to the lock plate  32 . The interlock bar  41  is attached to the lock plate  32  on the side opposite to the side where the lock member  30  is capable of coming into contact with the lock plate  32 . 
     A tripping electromagnet  20  is arranged near the tripping trigger  73 . The tripping electromagnet  20  has a plunger  19  that is capable of moving back and forth relative to the tripping trigger  73 . The plunger  19  has a bar shape. When the tripping electromagnet  20  is energized by an opening command that is input from outside, the plunger  19  operates and moves forward toward the tripping trigger  73 . The distal end of the plunger  19  is capable of coming into contact with the distal end of the tripping trigger  73 . In  FIG. 1 , even if the plunger  19  is to be pushed out by energizing the tripping electromagnet  20  and is to rotate the tripping trigger  73  clockwise, the lock plate  32  stops this movement and thus the opening operation is forced to stop. 
     A pin  23  provided on the switch-on lever  76  is engageable with a switch-on latch  79 . The switch-on latch  79  is attached to and is rotatable about a rotational shaft  80 . The rotational shaft  80  is rotatably supported by the casing. On the switch-on latch  79 , a notch is provided, with which the pin  23  of the switch-on lever  76  is engageable, and also a pin  82  is provided. The pin  82  is engageable with a switch-on trigger  83 . In  FIG. 1 , the pin  82  engages with the switch-on trigger  83 . A spring  100  biases the switch-on latch  79  so as to rotate the switch-on latch  79  about the rotational shaft  80  counterclockwise. 
     The switch-on trigger  83  is attached to and is rotatable about a rotational shaft  84 . The rotational shaft  84  is rotatably supported by the casing. In the switch-on trigger  83 , a notch is provided, with which the pin  82  of the switch-on latch  79  is engageable. A spring  101  biases the switch-on trigger  83  so as to rotate the switch-on trigger  83  about the rotational shaft  84  clockwise. 
     A switch-on electromagnet  16  is arranged near the switch-on trigger  83 . The switch-on electromagnet  16  has a plunger  17  that is capable of moving back and forth relative to the switch-on trigger  83 . The plunger  17  has substantially a bar shape and includes a flange portion  17   a . When the switch-on electromagnet  16  is energized by a closing command that is input from outside, the plunger  17  operates and moves forward to the switch-on trigger  83 . The distal end of the plunger  17  is capable of coming into contact with the distal end of the switch-on trigger  83 . The flange portion  17   a  is provided on at least a portion of the body of the plunger  17  in its circumferential direction. Particularly, the flange portion  17   a  is provided on the opposite side to the switch-on trigger  83 . In  FIG. 1 , the other end of the interlock bar  41  is in a non-contact state with the flange portion  17   a.    
     An example of the shape of the interlock bar  41  is described below.  FIG. 2  illustrates a shape of the interlock bar  41  when viewed from the front side of the flange portion  17   a . Besides the interlock bar  41 ,  FIG. 2  only illustrates the lock plate  32 , the switch-on electromagnet  16 , the plunger  17 , and the flange portion  17   a . As illustrated in  FIG. 2 , the interlock bar  41  has, for example, substantially a crank shape. As described above, one end of the interlock bar  41  is attached to the lock plate  32 . The lock plate  32  is rotatable about the rotational shaft  31  clockwise by being pushed by the lock member  30 . When the lock plate  32  rotates in this manner, the one end of the interlock bar  41  moves clockwise, and in conjunction with this movement, the other end of the interlock bar  41  also rotates clockwise. 
     Next, an operation performed by the present embodiment will be described. First, a closing operation is described with reference to  FIGS. 1 and 3 .  FIG. 3  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is when a closing operation has been completed. The closing operation in which the state in  FIG. 1  is shifted to the state in  FIG. 3  is described below. 
     First, in  FIG. 1 , the switching contact  22  is in an open state, the closing coil spring  77  is in a biased state, and the opening coil spring  60  is in a released state. The switch-on lever  76  has a clockwise rotational force applied to it by the closing coil spring  77  via the switch-on link  11 . However, the switch-on lever  76  is locked by the pin  23 , which engages with the switch-on latch  79 , and the switch-on latch  79  is locked by the pin  82 , which engages with the switch-on trigger  83 . The guide  62  is locked by the pin  66 , which engages with the tripping latch  69 . The tripping latch  69  is locked by the pin  71 , which engages with the tripping trigger  73 . The tripping trigger  73  is locked by its distal end engaging with the distal end of the lock plate  32 . The four-joint link  43  comes into contact with the guide surface  62   a  and is supported by the guide  62 . Because the lock plate  32  is not inclined with respect to the axial line of the plunger  19 , one end of the interlock bar  41  (one end on the side of the switch-on trigger  83 ) is arranged at a position where it does not overlap with the flange portion  17   a  when viewed from the axial direction of the plunger  17  in plan view; therefore, even when the plunger  17  operates, there is no interference with the operation. 
     Next, a switch-on command is input to the switch-on electromagnet  16 , the switch-on electromagnet  16  is energized, and the plunger  17  operates and moves toward the switch-on trigger  83 . The plunger  17  pushes the switch-on trigger  83 , and the switch-on trigger  83  rotates about the rotational shaft  84  counterclockwise. Thus, the switch-on latch  79  disengages from the switch-on trigger  83 . At this point, because the lock plate  32  is not in an inclined state, the one end of the interlock bar  41  does not interfere with the operation of the plunger  17 . 
     Because the switch-on trigger  83  rotates counterclockwise, and therefore disengages from the pin  82 , the switch-on latch  79  then rotates about the rotational shaft  80  clockwise. Therefore, the switch-on latch  79  disengages from the switch-on lever  76 . 
     Because the switch-on latch  79  rotates clockwise and thus disengages from the pin  23  of the switch-on lever  76 , the closing coil spring  77  is then released, and the switch-on lever  76  rotates about the main shaft  51  clockwise via the switch-on link  11 . Along with this rotation of the main shaft  51 , the four-joint link  43  is driven so as to rotate clockwise, while being guided by the guide surface  62   a  of the guide  62  that is locked by the tripping latch  69 . Therefore, the output lever  52  connecting to the main shaft  51  also rotates clockwise. Accordingly, the movable contact  22   a , which is connected to the output lever  52 , is switched on to bring the switching contact  22  into an on-state, and the opening coil spring  60  is biased via the blocking link  61  that is coupled also with the output lever  52 . In this state, the tripping latch  64  engages with the pin  24   aa  provided in the link  43   a.    
     Along with the rotation of the output lever  52  and the four-joint link  43  clockwise, the lock member  30  moves toward the lock plate  32  and pushes the lock plate  32 . The lock plate  32  rotates about the rotational shaft  31  clockwise. Along with this rotation of the lock plate  32 , the interlock bar  41  also rotates clockwise. The one end of the interlock bar  41  moves to be above the flange portion  17   a  of the plunger  17 . That is, the one end of the interlock bar  41  becomes arranged at a position where it overlaps with the flange portion  17   a  when viewed from the axial direction of the plunger  17  in plan view. Thus as described above, the switching contact  22  is brought into a closed state in  FIG. 3 . 
     Because the four-joint link  43  is supported by the guide surface  62   a  of the guide  62 , which is locked by the tripping latch  69 , the opening coil spring  60  can maintain its biased state, and the switching contact  22  can maintain its closed state. 
     Next, an opening operation is described with reference to  FIGS. 4 and 5 .  FIG. 4  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is at the start of an opening operation.  FIG. 4  illustrates a state where the closing coil spring  77  is biased by a motor (not illustrated) after the state illustrated in  FIG. 3 .  FIG. 5  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is when the opening operation has been completed. The opening operation, in which the state in  FIG. 4  is shifted to the state in  FIG. 5 , is described below. 
     In the state in  FIG. 4 , an opening command is input to the tripping electromagnet  20 , the tripping electromagnet  20  is energized, and the plunger  19  operates and moves toward the tripping trigger  73  so as to push the tripping trigger  73 . Therefore, the tripping trigger  73  rotates about the rotational shaft  74  clockwise and disengages from the pin  71  of the tripping latch  69 . 
     At this time, the lock plate  32  is pushed by the lock member  30  and is thus in an inclined state in the clockwise direction with respect to the axial direction of the plunger  19 . Therefore, the lock plate  32  does not interfere with the operation of the tripping trigger  73 . The interlock bar  41  is in a state where it has followed the lock plate  32  and rotated clockwise. One end of the interlock bar  41  is arranged above the flange portion  17   a  of the plunger  17 . Consequently, even if a switch-on command is input to the switch-on electromagnet  16  and then the plunger  17  tries to operate, the one end of the interlock bar  41  comes into contact with the flange portion  17   a  so as to stop the plunger  17  from operating. Consequently, the switch-on operation is prevented from being performed. 
     Because the pin  71  of the tripping latch  69  disengages from the tripping trigger  73 , the tripping latch  69  rotates about the rotational shaft  70  counterclockwise; therefore, the tripping latch  69  disengages from the pin  66  of the guide  62 . 
     Because the tripping latch  69  rotates counterclockwise and therefore disengages from the pin  66  of the guide  62 , the guide  62  is then rotated about the rotational shaft  63  counterclockwise by the opening coil spring  68 . 
     Because the guide  62  rotates counterclockwise, the four-joint link  43  is then lowered and the opening coil spring  60  is released. This releasing force is transmitted to the output lever  52  via the blocking link  61 . The output lever  52  rotates about the main shaft  51  counterclockwise, the movable contact  22   a  is opened to bring the switching contact  22  into an off-state, and thus the opening operation is completed. In this state, the tripping latch  64  disengages from the pin  24   aa  provided in the link  43   a . The output lever  52  rotates counterclockwise, so the distal end of the lock member  30  comes out of contact with the lock plate  32 . 
     Next, the effects of the present embodiment are described with reference to  FIGS. 4 to 6 .  FIG. 6  is a configuration diagram of the relevant parts of a spring operation device for use in a switchgear according to an example used here for comparison. The specific state illustrated is when an opening operation has been completed. 
     In  FIGS. 4 and 5 , the closing coil spring  77  is biased and the spring operation device is in a state of being capable of performing a closing operation. In this state, because the lock plate  32  is inclined clockwise with respect to the axial direction of the plunger  19 , one end of the interlock bar  41  is positioned to interfere with the operation of the plunger  17 . Even if a closing command is input to the switch-on electromagnet  16 , the flange portion  17   a  of the plunger  17  is blocked by the one end of the interlock bar  41 , and thus the operation of the plunger  17  is stopped. The plunger  17  cannot rotate the switch-on trigger  83 . This prevents the closing operation from being performed during the opening operation. 
     As described above, in the present embodiment, only in a state where the guide  62 , the tripping latch  69 , the tripping trigger  73 , and the lock plate  32  engage with each other, can the plunger  17 , having been interlocked by the interlock bar  41 , be brought into an unlocked state, which in turn makes it possible to perform a closing operation. In a state where the guide  62 , the tripping latch  69 , the tripping trigger  73 , and the lock plate  32  disengage from each other, the plunger  17  is interlocked by the interlock bar  41 , which makes it impossible to perform a closing operation. 
     In contrast, in  FIG. 6 , the lock plate  32  in  FIGS. 4 and 5  is replaced with a lock plate  102 , the plunger  17  in  FIGS. 4 and 5  is replaced with a plunger  117  that does not include a flange portion, and the interlock bar  41  in  FIGS. 4 and 5  is not provided. Aside from these points, the configuration illustrated in  FIG. 6  is identical to the configuration illustrated in  FIGS. 4 and 5 . 
     The spring operation device for use in a switchgear according to this example used for here comparison has a structure in which, at the closing operation, the opening coil spring  60  is compressed such that the guide  62 , the tripping latch  69 , the tripping trigger  73 , and the lock plate  102  engage with each other. However, while during an opening operation, the guide  62 , the tripping latch  69 , the tripping trigger  73 , and the lock plate  102  disengage from each other in the same manner as in the present embodiment, a unit that stops the operation of the plunger  117  (such as the interlock bar  41  in  FIGS. 4 and 5 ) is not provided. Therefore, when, in this state, a closing command is improperly input, the four-joint link  43  is not supported by the guide  62  and is thus brought into a non-rotatable state. Consequently, the opening coil spring  60  is not biased, and its load is reduced accordingly, which increases the closing speed of the movable contact  22   a . This leads to a problem in that the spring operation device may be damaged. 
     In the present embodiment, there are provided the lock member  30  that operates in conjunction with the output lever  52  or the four-joint link  43 ; the lock plate  32  that is pushed by the lock member  30  to operate also in conjunction with the output lever  52  or the four-joint-link  43 ; the interlock bar  41  that operates in conjunction with the lock plate  32 ; and the flange portion  17   a  of the plunger  17  of the switch-on electromagnet  16 . It is possible to control the operation of the plunger  17  of the switch-on electromagnet  16  in accordance with the position of the lock plate  32 . 
     That is, when an opening operation is performed, the lock plate  32  is in a state where it has been pushed by the lock member  30  and rotated counterclockwise, and the tripping trigger  73  is allowed to rotate. Meanwhile, when the interlock bar  41  rotates clockwise, one end of which moves to be above the flange portion  17   a  of the plunger  17  of the switch-on electromagnet  16 . Therefore, the plunger  17  is brought into an interlocked state by the interlock bar  41 . Even if a closing operation command is transmitted to the switch-on electromagnet  16 , the operation of the plunger  17  is limited, and thus the switch-on trigger  83  is stopped from rotating. Consequently, a closing operation is not performed. 
     When performing a closing operation, the lock plate  32  is not pushed by the lock member  30  and is thus engaged with the tripping trigger  73 . The interlock bar  41  does not interfere with the operation of the plunger  17 , thereby allowing the switch-on trigger  83  to rotate. Meanwhile, even if an opening operation command is transmitted to the tripping electromagnet  20 , the lock plate  32  stops the rotational operation of the tripping trigger  73  resulting from the operation of the plunger  19 . Thus, an opening operation is not performed. 
     As described above, the interlock bar  41  and the flange portion  17   a  constitute a closing-operation prevention unit during the performance of an opening operation. The interlock bar  41  that constitutes the closing-operation prevention unit operates in conjunction with the output lever  52  or the four-joint link  43 . The closing-operation prevention unit stops the switch-on trigger  83  from rotating during the performance of an opening operation and allows the switch-on trigger  83  to rotate when a closing operation is performed. The lock plate  32  and the lock member  30  constitute an opening-operation prevention unit when a closing operation is performed. The lock plate  32  and the lock member  30 , which constitute the opening-operation prevention unit, operate in conjunction with the output lever  52  or the four-joint link  43 . The lock plate  32  and the lock member  30  stop the tripping trigger  73  from rotating when a closing operation is performed and allow the tripping trigger  73  to rotate when an opening operation is performed. 
     According to the present embodiment, there is no need to provide an additional control circuit, and a closing operation can be effectively prevented from being performed during an opening operation with a simple structure. 
     In the present embodiment, the closing coil spring  77  is used as a closing bias unit, and the opening coil spring  60  is used as an opening biasing unit. However, instead of using these coil springs, torsion bars can be used. For example, Patent Literature 1 describes a case in which a coil spring is used as a biasing unit and a case in which a torsion bar is used. In the present embodiment also, by applying the configurations described in Patent Literature 1, for example, a torsion bar can be used instead of a coil spring. 
     Second Embodiment 
       FIG. 7  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is before starting a closing operation.  FIG. 8  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is when the closing operation has been completed.  FIG. 9  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is at the start of an opening operation.  FIG. 10  is a configuration diagram of the relevant parts of the spring operation device for use in a switchgear according to the present embodiment. The specific state illustrated is when the opening operation has been completed.  FIGS. 7 to 10  respectively correspond to  FIG. 1  and  FIGS. 3 to 5 . In  FIGS. 7 to 10 , constituent elements identical to those illustrated in  FIG. 1  and  FIGS. 3 to 5  are denoted by like reference letters and numbers. 
       FIGS. 7 to 10  illustrate a switch-on control line  91  that is connected to the switch-on electromagnet  16 . The switch-on control line  91  is used for transmitting a closing command, which is input from a switch-on control-line connection terminal  92 , to the switch-on electromagnet  16 . In the present embodiment, a limit switch  90  is provided at a certain location on the switch-on control line  91 . The limit switch  90  is turned on/off in conjunction with the operation of a lock plate  86 . That is, the lock plate  86  is rotatable about the rotational shaft  31 , and when the lock plate  86  is inclined with respect to the axial direction of a plunger  87  so as to disengage from the tripping trigger  73  ( FIGS. 8 to 10 ), the limit switch  90  enters an off-state; and when the lock plate  86  engages with the tripping trigger  73  ( FIG. 7 ), the limit switch  90  enters an on-state. A member  89 , which is connected to the lock plate  86 , moves according to the rotating position of the lock plate  86 , thereby turning on/off the limit switch  90 . In  FIGS. 7 to 10 , the member  89  is illustrated as a line for the sake of simplicity. 
     In the present embodiment, the interlock bar  41  provided in the first embodiment is not provided, and the plunger  87  of the switch-on electromagnet  16  does not include a flange portion. 
     In  FIG. 7 , the guide  62  engages with the tripping latch  69 ; the tripping latch  69  engages with the tripping trigger  73 ; and the tripping trigger  73  engages with the lock plate  86 . In this case, because the tripping trigger  73  engages with the lock plate  86 , the limit switch  90  is brought into an on-state. Therefore, a closing command that is input from the switch-on control-line connection terminal  92  is transmitted to the switch-on electromagnet  16  via the switch-on control line  91 . The switch-on electromagnet  16  receives the closing command and is energized, and the plunger  87  operates, pushes and rotates the switch-on trigger  83 , thus starting a closing operation. 
     In contrast, in  FIG. 9 , the lock plate  86  rotates about the rotational shaft  31  clockwise, and the tripping trigger  73  disengages from the lock plate  86 . Therefore, the limit switch  90  is brought into an off-state. A closing command cannot be transmitted to the switch-on electromagnet  16  via the switch-on control line  91 , so a closing operation is prevented from being performed. That is, also in the present embodiment, a closing operation during an opening operation is prevented from being performed. 
     As described above, in the present embodiment, the closing-operation prevention unit is configured to include the limit switch  90 , which is provided at a certain location on the switch-on control line  91  that is used for transmission of a closing command to the switch-on electromagnet  16  and which is turned on/off in conjunction with the rotating position of the lock plate  86 . Interlocking is achieved by electrically turning on/off instead of by using an interlock bar, which is what is described in the first embodiment. Note that the present invention has the same configuration, operation, and effects as those described in the first embodiment except in the way that the interlocking is performed. 
     INDUSTRIAL APPLICABILITY 
     As described above, the present invention is useful as a spring operation device for use in a switchgear. 
     REFERENCE SIGNS LIST 
       11  switch-on link,  16  switch-on electromagnet,  17 ,  19 ,  87 ,  117  plunger,  17   a  flange portion,  20  tripping electromagnet,  22  switching contact,  23 ,  24 ,  24   aa ,  25 ,  26 ,  62   b ,  66 ,  71 ,  82  pin,  30  lock member,  31 ,  63 ,  70 ,  74 ,  80 ,  84  rotational shaft,  32 ,  86 ,  102  lock plate,  41  interlock bar,  42  buffer,  43  four-joint link,  43   a  to  43   c  link,  51  main shaft,  52  output lever,  52  lever portion,  60  opening coil spring,  61  blocking link,  62  guide,  62   a  guide surface,  68  return spring,  64 ,  69  tripping latch,  73  tripping trigger,  75 ,  96  to  98 ,  100 ,  101  spring,  76  switch-on lever,  77  closing coil spring,  79  switch-on latch,  83  switch-on trigger,  90  limit switch,  91  switch-on control line,  92  switch-on control-line connection terminal,  95  link mechanism.