Patent Publication Number: US-9852866-B2

Title: Panel device

Description:
TECHNICAL FIELD 
     The present invention relates to panel devices, such as breaker panels and control panels, incorporating an interlocking mechanism that provides protection against electric shock from any live part in conjunction with ON/OFF movement of a molded case circuit breaker knob. 
     BACKGROUND ART 
     A device is known as a conventional breaker panel, in which protective covers of molded case circuit breakers (hereinafter referred to as breakers) are attached to an inner door in the housing side, the inner door is locked by a tool-operating knob but can be opened by releasing the tool-operating knob, and when the inner door is opened, all of the protective covers of the breakers are brought into an open state regardless of the ON/OFF state of the breakers. Moreover, a control center has been known which is configured in such a way that breakers are provided with a handle for interlocking linked with a safety door, the safety door is prohibited from opening when the breakers are in the ON state, but when in the OFF state, the safety door can be opened with the internal interlock released (see Patent document 1, for example). 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent document 1: Japanese laid-open Patent Publication No. S61-236312 (see pp. 2-3, FIGS. 1-4) 
     DISCLOSURE OF THE INVENTION 
     Problem to be Solved by the Invention 
     In a device using conventional technology as described above, the door in the housing side can be opened regardless of the ON/OFF state of the breakers, if the lock of the tool-operating knob is released; therefore, there has been a danger that live parts of the breakers in the ON state can be touched in maintenance. Moreover, the interlocking mechanism of the conventional control center as described above is configured in such a way that the door cannot be opened when the breakers are in the ON state, but can be opened with the internal interlock released when the breakers are in the OFF state; therefore, the handle for interlocking is necessary for each breaker, and some extra parts for constituting the interlock are required in the housing door side, thereby causing a problem in that the number of parts increases and its configuration also becomes complicated. 
     The present invention has been made to solve the foregoing problem, and aims at providing a panel device that has a simple configuration and in addition can avoid such a danger as its live parts being mistakenly touched, thereby enabling maintenance to be carried out in safe. 
     Means for Solving the Problem 
     A panel device according to the present invention comprises a protective cover that has an insertion hole for an ON/OFF knob of a molded case circuit breaker and is formed to cover an exposed live part of the molded case circuit breaker and provided with an engaging part at a predetermined portion thereof; a cover support member that openably and closably supports this protective cover; and a cover locking member that engages with the engaging part when the protective cover is closed, so as to restrict turning of the protective cover; wherein either one of the protective cover and the cover support member is movably provided in conjunction with movement of the ON/OFF knob, and the engaging part and the cover locking member are engaged with each other or released from each other by the movement of the any one of those. 
     Advantage of the Invention 
     According to the present invention, since the interlock of the protective cover provided for each molded case circuit breaker can be released one by one; therefore, the danger of mistakenly touching live parts of other breakers can be avoided, so that maintenance can be carried out in safe. In addition, any one of the protective cover, the cover support member and the cover locking member is movably provided in conjunction with the movement of the ON/OFF knob, and the engaging part and the cover locking member can be engaged with each other or released from each other by the movement of the any one of those, so that the configuration of the device becomes simple and the number of parts can be decreased. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are views showing the entire configuration of a panel device according to Embodiment 1 of the present invention; 
         FIGS. 2A, 2B, and 2C  are views for explaining an interlocking mechanism of a protective cover of the panel device according to Embodiment 1 of the present invention; 
         FIGS. 3A, 3B, 3C, and 3D  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 2A, 2B, and 2C ; 
         FIGS. 4A, 4B, and 4C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 2 of the present invention; 
         FIGS. 5A, 5B, 5C, and 5D  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 4A, 4B, and 4C ; 
         FIGS. 6A, 6B, and 6C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 3 of the present invention; 
         FIGS. 7A, 7B, and 7C  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 6A, 6B, and 6C ; 
         FIGS. 8A, 8B, and 8C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 4 of the present invention; 
         FIGS. 9A and 9B  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 8A, 8B, and 8C ; 
         FIGS. 10A and 10B  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 5 of the present invention; 
         FIGS. 11A and 11B  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 10A and 10B ; 
         FIGS. 12A and 12B  are another views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 10A and 10B ; 
         FIGS. 13A and 13B  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 6 of the present invention; 
         FIGS. 14A and 14B  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 13A and 13B ; 
         FIGS. 15A, 15B, 15C, and 15D  are another views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 13A and 13B ; 
         FIGS. 16A, 16B, and 16C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 7 of the present invention; 
         FIGS. 17A and 17B  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 16A, 16B, and 16C ; 
         FIGS. 18A and 18B  are another views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 16A, 16B, and 16C ; 
         FIGS. 19A, 19B, and 19C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 8 of the present invention; 
         FIGS. 20A and 20B  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 19A, 19B, and 19C ; and 
         FIGS. 21A and 21B  are another views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 19A, 19B, and 19C . 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiment 1 
       FIGS. 1A and 1B  are views showing the entire configuration of a panel device according to Embodiment 1 of the present invention;  FIG. 1A  is a plan view and  FIG. 1B  is a perspective view.  FIGS. 2A, 2B, and 2C  are views for explaining an interlocking mechanism of a protective cover of the panel device according to Embodiment 1 of the present invention;  FIG. 2A  is a perspective view showing a state of a breaker being ON and a protective cover closing;  FIG. 2B  is a perspective view showing a state of the breaker being OFF and the protective cover sliding outward; and  FIG. 2C  is a perspective view showing a state of the breaker being OFF and the protective cover opening. In  FIGS. 1A and 1B , a breaker panel  1  as the panel device is configured using a housing  11  with an opening/closing door  11   a  at its front part, breakers  2 , which are a plurality of molded case circuit breakers housed inside the housing  11 , and a protective cover  3  that individually covers an exposed live part of each of the breakers  2 . 
     Additionally, the paired breakers  2  arranged right and left are disposed in this example point-symmetrically to each other in such a way that one of the breakers becomes ON when its ON/OFF knob  21  is moved inward (toward the other breaker of the breakers  2  arranged right and left) and becomes OFF when the ON/OFF knob  21  is moved outward of the breaker panel  1 . Additionally, for the sake of convenience, when the paired breakers  2  are arranged right and left so that ON/OFF directions of the ON/OFF knob  21  become the right and left directions, a direction toward the other breaker viewed from any one of the breakers is referred to as the “inward” direction and the opposite direction of that is referred to as the “outward” direction in this document. 
       FIGS. 3A, 3B, 3C, and 3D  are views for explaining in more detail the interlocking mechanism shown in  FIGS. 2A, 2B, and 2C ; the protective cover  3  is formed in a U-shape in cross section as shown in  FIG. 3C ; elongated holes  3   a  through which the turning central axis for opening and closing the protective cover passes are made vertically symmetrically in the upper side and lower side sections shown in  FIG. 3C ; in addition, round holes  3   b  (holes for circling screws, hereinafter referred to as the same) are similarly made vertically symmetrically, through which sems screw  92   a  that engages with a cover support member  4  described later is inserted; and in the front section of the cover is provided an insertion hole  3   c  through which the ON/OFF knob, an ON/OFF lever of the breakers  2 , is inserted. Furthermore, engaging parts  31 , which are tongue-shaped protrusions, are formed as shown in  FIG. 3C  symmetrically facing each other at upper and lower end portions in the opposite side of the elongated holes  3   a  (outer side of the panel) in the upper side and lower side sections of the protective cover  3 ; a monitoring window  32  for monitoring the live part is formed in the front section in the side of the elongated holes  3   a  (inner side). The engaging parts  31  can be provided in predetermined portions decided at suitable required locations distant from the turning center of the protective cover  3  so as to match with the location and shape of locking parts  51  of a cover locking member  5  described later. 
     Additionally, the insertion hole  3   c  is shaped in a rectangular elongated in the moving directions of the ON/OFF knob  21  (right and left directions here). Taking the left-hand side breaker of the breakers  2  in the figure, for example, the insertion hole is formed in such a way that when the ON/OFF knob  21  is brought into the ON state (turned on) after the protective cover  3  is slid to the inner end portion (in the right direction) and closed, the right end portion of the insertion hole nearly touches the right lateral face of the ON/OFF knob  21 . Thereby, the protective cover  3  is restricted not to slide outward (in the left direction) when the ON/OFF knob  21  is in the ON state. Additionally, the insertion hole  3   c  is formed to have a length in the right and left directions in such a way that the left end portion thereof touches the left lateral face of the ON/OFF knob  21  even when the ON/OFF knob  21  is brought down in the OFF direction from the foregoing state, thereby prohibiting the protective cover  3  from moving outward. 
     The cover support member  4  made of a sheet metal is fixed to the housing  11  together with the breakers  2 , and screw holes  4   a  for supporting the protective cover  3  and arc-shaped grooves  4   b  centering at these screw holes  4   a  are provided vertically symmetrically in upper and lower bent sections protruding frontward as shown in  FIG. 3D . The cover locking member  5  that is made of a sheet metal and U-shaped in a size capable of fitting inside the protective cover  3  formed in the U-shape in cross section is fixed to suitable fixing portions of the breakers  2 , the housing  11  or the like as shown in  FIGS. 2A, 2B, and 2C , and provided with the locking parts  51 , such as notches or grooves, which are formed at upper and lower two locations by cutting away portions thereof from the outer side toward the inner side, and engage with their respective engaging parts  31  of the protective cover  3  when the cover is closed, so as to restrict turning of the protective cover  3 . 
     As shown in  FIGS. 3A, 3B, 3C, and 3D , a cylindrical spacer  91  is inserted through each of the elongated holes  3   a  of the protective cover  3 , furthermore a sems screw  92 O, which is a screw assembled with a washer, is inserted through the center of the spacer  91 , and fastened and fixed via a nylon washer  93  to the screw holes  4   a  made in the cover support member  4 . Thereby, the protective cover  3  becomes able to slide along the elongated holes  3   a  and also turn around the sems screw  92 O. On the other hand, sems screw  92   a  inserted through each of the round holes  3   b  of the protective cover  3  from the front side is fitted with the cylindrical spacer  91  and a washer  94  from the back side and then fastened and fixed by a nut  96  as shown in  FIG. 3B . 
     Additionally, in order to distinguish two sems screws numbered with  92  from each other for the sake of convenience in explaining operation, the screw that serves as the turning central axis when the protective cover  3  is opened/closed is referred to as the “sems screw  92 O” and the screw that circles around the sems screw  92 O together with the protective cover  3  is referred to as the “sems screw  92   a ” in this Embodiment 1. Since configurations other than the above-described interlocking mechanism are the same as those of the conventional device, their explanation will be omitted. 
     Next, the operation of Embodiment 1 configured as described above will be explained. First, when the breakers  2  are in the ON state, the spacer  91  fixed at the round holes  3   b  part of the protective cover  3  lies at the position A shown in  FIG. 2A  and  FIG. 3A , and the sems screw  92 O part that is inserted through the elongated holes  3   a  of the protective cover  3  and slidably and turnably fixes the protective cover  3  lies at the position in the outer side of the elongated holes  3   a  (left side in  FIG. 3A ). The engaging parts  31 , which are protrusions formed at the upper and lower portions in the back side of the protective cover  3 , are fitted into the locking parts  51  of the cover locking member  5  and locked in this state as shown in  FIG. 2A ; therefore, the protective cover  3  cannot be opened. 
     The ON/OFF knob  21  is brought down inward when the breakers  2  are in the ON state, the inner side end portion (right end portion in  FIG. 3C ) of the insertion hole  3   c  that is made in the front section of the protective cover  3  and through which the ON/OFF knob  21  is inserted touches the ON/OFF knob  21  and is restrained, whereby the protective cover  3  cannot be slid outward, and as a result, the protective cover is brought into a state of being unable to open. Therefore, the not-shown live part of the breakers  2  is covered by the protective cover  3 . 
     Next, when the breakers  2  are brought into the OFF state, the ON/OFF knob  21  is brought down outward as shown in  FIG. 2B , whereby the protective cover  3  becomes ready to slide outward by the same distance as the ON/OFF knob  21  has moved from the inner side to the outer side. When the protective cover  3  is manually slid outward as shown by the arrow in  FIG. 2B , the spacer  91  and the sems screw  92   a  that are fixed at the round holes  3   b  come to the position B; meanwhile, the sems screw  92 O that is inserted through the elongated holes  3   a  and serves as the turning central axis of the protective cover  3  moves to the inner position of the elongated holes  3   a . The engaging parts  31 , which are protrusions formed at the upper and lower portions in the back side of the protective cover  3 , are released from the locking parts  51  of the cover locking member  5 , so that the protective cover  3  becomes able to be opened. 
     When the end portion in the outer side of the protective cover  3  is pulled frontward (front side), the protective cover  3  turns around the sems screw  92 O that has moved to the position in the inner side of the elongated holes  3   a , and the spacer  91  inserted through the round holes  3   b  of the protective cover  3  moves to the position C along the arc-shaped grooves  4   b  of the cover support member  4 , thereby enabling the protective cover  3  to open. The spacer  91  and the sems screw  92   a  at the round holes  3   b  part of the protective cover  3  stop at the position C that is the end portion of the grooves  4   b , whereby the opening angle of the protective cover  3  is restricted, and also the sems screw  92 O part inserted through the elongated holes  3   a  of the protective cover  3  serves as a fulcrum; therefore, when the protective cover  3  is in the open state, the protective cover  3  becomes unable to move inward, so as to avoid interfering with its neighboring protective cover. 
     If the breakers  2  are mistakenly turned on when the protective cover  3  is in the open state and then the protective cover is intended to be closed in that state, the ON/OFF knob  21  hits the back of the protective cover  3  and the cover cannot be closed. Furthermore, if the protective cover  3  is intended to be closed with the cover slid inward, the engaging parts  31  provided at the upper and lower portions in the back side of the protective cover  3  hit the cover locking member  5 ; the protective cover  3  is structurally made unable to be closed even in either case. Moreover, by providing the protective cover  3  with the monitoring window  32 , change in color and the like of terminals of the internal live part can be inspected in safe from the outside. 
     In Embodiment 1 as described above, the elongated holes  3   a  are made in the protective cover  3  so as to provide the cover slidably with respect to the cover support member  4 , and also the insertion hole  3   c  of the protective cover  3  interferes with the ON/OFF knob  21  when the breakers  2  are in the ON position, thereby making the protective cover  3  unable to slide. Furthermore, the engaging parts  31 , which are protrusions formed at the upper and lower portions in the back side of the protective cover  3 , are fitted into the locking parts  51  of the cover locking member  5 , thereby making the protective cover  3  unable to open. 
     By doing in this way, opening/closing conditions of the protective cover  3  can be set, without providing the breaker  2  with a handle for interlocking, using only ON/OFF movement of the ON/OFF knob  21 ; the protective cover  3  cannot be opened when the breakers are in the ON state, but can be opened only when the breakers in the OFF state. Since the interlocking mechanism for the protective cover  3  provided on each of the breakers  2  can be released breaker by breaker, there is no danger such as mistakenly touching live parts of other breakers during maintenance, so that maintenance can be carried out in safe. Moreover, every member necessary for the above can be easily formed by, for example, metal pressing and the configuration can be simplified, so that the number of parts can be decreased. Furthermore, the breakers can use regular standardized parts, so that an effect of providing breakers at low cost can be also produced. 
     Embodiment 2 
       FIGS. 4A, 4B, and 4C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 2 of the present invention;  FIG. 4A  is a perspective view showing a state of the breaker being ON and the protective cover closing;  FIG. 4B  is a perspective view showing a state of the breaker being OFF and the protective cover sliding outward; and  FIG. 4C  is a perspective view showing a state of the breaker being OFF and the protective cover opening.  FIGS. 5A, 5B, 5C, and 5D  are views for explaining in more detail the interlocking mechanism shown in  FIGS. 4A, 4B, and 4C ;  FIG. 5A  is a detailed perspective view of the interlocking mechanism;  FIG. 5B  is an arrow view taken in the X direction of  FIG. 5A ;  FIG. 5C  is a detailed view of the portion A encircled in  FIG. 5B ; and  FIG. 5D  is a detailed view of the portion B encircled in  FIG. 5B . Additionally, the protective cover  3  in Embodiment 1 is made to be manually slid outward after the breakers  2  are brought into the OFF state; however, in this Embodiment 2, when the breakers  2  are brought into the OFF state, the protective cover  3 A also slides at the same time so as to be able to open. 
     As shown in  FIGS. 4A, 4B, and 4C , a cover support member  4 A is provided with a rectangular hole  4   c  that is formed to engage with the ON/OFF knob  21  so that the cover support member  4 A itself can slide in the right and left directions of the figure in conjunction with the ON/OFF knob  21 , the screw holes  4   a  (shown in  FIG. 5A ,  FIG. 5C ) at which the protective cover  3 A is screwed by a screw  97  that turnably supports the cover at upper and lower two locations as shown in  FIG. 5B , and elongated holes  4   d  made at two locations through which the sems screw  92  that slidably supports the cover support member  4 A with respect to the breakers  2  is inserted. The insertion hole  3   c  (shown in  FIG. 4C ), which is the same as that of Embodiment 1, is made in the front section of the protective cover  3 A; at the upper and lower sections thereof are provided round holes  3   d  each of which the screw  97  that turnably supports the protective cover  3 A is inserted. The cylindrical spacer  91  is inserted through each of the round holes  3   d  at the upper and lower sections of the protective cover  3 A as shown in  FIG. 5C , furthermore the screw  97  is inserted through the spacer  91 , and the protective cover is fixed to the upper and lower screw holes  4   a  of the cover support member  4 A by the screw  97  via the nylon washer  93 , thereby enabling the protective cover  3 A to turn with the spacer  91  (screw  97 ) serving as the axis. 
     The ON/OFF knob  21  of the breakers  2  is inserted through the rectangular hole  4   c  of the cover support member  4 A, and the elongated holes  4   d  made at the two locations are fixed as shown in  FIG. 5D . First, a large washer  94 L that is larger than the washer  94  in diameter, the cylindrical spacer  91  and the washer  94  are stacked up in this order at each of fixing holes  22  of the breakers  2 , on which another spacer  91  is placed, and this spacer  91  is made to pass through the elongated holes  4   d  of the cover support member  4 A. Then, another washer  94  is placed on this spacer  91  and these are fastened together with the breakers  2  by the sems screw  92 . By doing in this way, the cover support member  4 A becomes able to slide right and left in conjunction with ON/OFF movement of the breakers  2 . Since the protective cover  3 A is fixed to the cover support member  4 A, the cover slides right and left in  FIGS. 4A, 4B, and 4C  together with the cover support member  4 A. Other configurations, such as the cover locking member  5 , are the same as those of Embodiment 1, so their explanation will be omitted. 
     In Embodiment 2 as configured above, the ON/OFF knob is brought down inward when the breakers  2  are in the ON state, and at the same time, the cover support member  4 A and the protective cover  3 A also slide inward. In this state, the engaging parts  31 , which are tongue-shaped protrusions provided at the upper and lower portions in the back side of the protective cover  3 A, are fitted into the locking parts  51  of the cover locking member  5 , thereby making the protective cover  3 A unable to open. When the breakers  2  are brought into the OFF state, the ON/OFF knob is brought down outward, and the cover support member  4 A and the protective cover  3 A also slide outward at the same time. When these slide outward, the engaging parts  31  provided at the upper and lower portions in the back side of the protective cover  3 A are released from the locking parts  51  of the cover locking member  5 , thereby enabling the protective cover  3 A to open by pulling it frontward. 
     If the breakers  2  are mistakenly turned on when the protective cover  3 A is in the open state and then the protective cover  3 A is intended to be closed in this state, the ON/OFF knob  21  is brought down inward, and at the same time, both of the cover support member  4 A and the protective cover  3 A come into a state of sliding inward. Even if the protective cover  3 A is intended to be closed in this state, the engaging parts  31  provided at the upper and lower portions in the back side of the protective cover  3 A hit an upper end portion of the cover locking member  5 , thereby making the protective cover  3 A unable to close. Additionally, the same as Embodiment 1, change in color and the like of internal terminals can be inspected in safe, without opening the protective cover  3 A, from the outside through the monitoring window  32  provided in this protective cover  3 A. 
     According to Embodiment 2 as described above, opening/closing conditions of the protective cover  3  can be set, without providing a handle for interlocking on the breakers  2 , by only the ON/OFF movement of the ON/OFF knob  21 ; the protective cover  3 A cannot be opened when the breakers  2  are in the ON state, but can be opened only when the breakers  2  in the OFF state. Since the interlocking mechanism for the protective cover  3 A provided on each of the breakers  2  can be released breaker by breaker, there is no danger such as mistakenly touching live parts of other breakers during maintenance, so that maintenance can be carried out in safe. Moreover, the configuration of the device becomes simple, the number of parts can be decreased, and the breakers  2  can use regular standardized parts, which will also produce an effect capable of providing breakers at low cost. 
     Embodiment 3 
       FIGS. 6A, 6B, and 6C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 3 of the present invention;  FIG. 6A  is a perspective view showing a state of the breaker being ON and the protective cover closing;  FIG. 6B  is a perspective view showing a state of the breaker being OFF and the protective cover opening; and  FIG. 6C  is a perspective view showing in detail the interlocking mechanism.  FIGS. 7A, 7B, and 7C  are views for explaining in detail the essential part of the interlocking mechanism shown in  FIGS. 6A, 6B, and 6C ;  FIG. 7A  is a detailed view of the portion A encircled in  FIG. 6A ; and  FIG. 7B  is an arrow view taken in the Y direction of  FIG. 6B . Additionally, the main difference between Embodiment 3 and Embodiments 1 and 2 described above is that a protective cover  3 B does not slide but is made to open from the upper side toward the lower side, and a cover locking member  5 B is configured to be able to slide in conjunction with the ON/OFF knob  21 , thereby controlling opening/closing of the protective cover  3 B. 
     In  FIGS. 6A, 6B, and 6C , the cover locking member  5 B is provided with in the front section thereof a rectangular hole  5   a  that is formed to engage with the ON/OFF knob  21  so as to be able to move right and left in conjunction with movement of the knob, and at two locations thereof elongated holes  5   b  that support the cover locking member  5 B slidably with respect to the breakers  2 , and furthermore locking parts  51 T, which are tongue-shaped protrusions projecting upward, are provided at two locations. The protective cover  3 B is provided with in the right and left lower sections thereof round holes  3   d  (not shown) for turning, in the front section thereof the insertion hole  3   c  through which the ON/OFF knob  21  shown in  FIG. 6C  is inserted (see  FIG. 6B ), and at right and left two locations in the upper section thereof engaging parts  31 B, which are L-shaped notches for receiving and engaging with the locking parts  51 T, as well as the monitoring window  32 . As shown in  FIG. 6C , a support member that turnably supports the protective cover  3 B includes a cover support member  4 B 1  that is attached to both outer side portions of the paired breakers  2  arranged side by side and a cover support member  4 B 2  that is attached to the central portion thereof; both are rigidly fixed to the breakers  2  and cannot be moved. Additionally, the nearly T-shaped cover support member  4 B 2  is shared between the breakers  2  in the right and left sides. 
     In assembling, the spacer  91  and the washer  94  are placed at first on a fixing part of the breakers  2  as shown in  FIG. 7B , furthermore another spacer  91  is placed on that, and this spacer  91  is inserted through one of the elongated holes  5   b  of the cover locking member  5 B. Then, another washer  94  is placed on this spacer  91 , and these are fixed together with the breakers  2  by the sems screw  92 . The ON/OFF knob  21  of the breakers  2  is inserted through the rectangular hole  5   a  in the front section of the cover locking member  5 B. Thereby, the cover locking member  5 B becomes able to slide right and left in conjunction with the movement of the ON/OFF knob  21 . 
     An internally-threaded screw hole  4   a  (not shown) is made in the cover support member  4 B 1  attached to both sides of the breakers, and the cover support member  4 B 2  attached to the central part is provided with a round hole  4   e . (Additionally, none of round hole, spacer, washer, nut, etc are not given reference numerals in the drawings in this paragraph.) In both sides of the protective cover  3 B, the spacer  91  is inserted through the round holes  3   d  made in the protective cover  3 B, and the sems screw  92  is inserted through the spacer  91  and screwed to the screw hole  4   a  of the cover support member  4 B 1 . In the central side of the protective cover  3 B, the spacer  91  is inserted through the round holes  3   d  in the central side of the right-hand side and the left-hand side protective cover  3 B and the round hole  4   e  of the cover support member  4 B 2  at the same time so as to fix these using the sems screw  92 , the washer  94  and the nut  96 . By doing in this way, the right-hand side and the left-hand side protective cover  3 B become able to open from the upper side toward the lower side. 
     In Embodiment 3 as configured above, the ON/OFF knob is brought down inward when the breakers  2  are in the ON state, and accordingly the cover locking member  5 B also slides inward at the same time. In this state, the locking parts  51 T provided at the two locations in the upper side of the cover locking member  5 B are fitted into the engaging parts  31 B provided at the two locations in the upper side of the protective cover  3 B, thereby making the protective cover  3 B unable to open (see  FIG. 6C ). 
     When the breakers  2  are brought into the OFF state, the ON/OFF knob  21  of the breakers  2  is brought down outward, and accordingly the cover locking member  5 B slides outward at the same time. When the cover locking member  5 B slides outward, the locking parts  51 T provided at the two locations in the upper side of the cover locking member  5 B are released from the engaging parts  31 B provided at the two locations in the upper side of the protective cover  3 B, thereby making the protective covers  3 B able to open. 
     If the breakers  2  are mistakenly turned on when the protective cover  3 B is in the open state and then the protective cover  3 B is intended to be closed in this state, the ON/OFF knob  21  is brought down inward by the turn-on operation, and accordingly the cover locking member  5 B is also brought into a state of sliding inward. Therefore, if the protective cover  3 B is intended to be closed in this state, the locking parts  51 T provided at the two locations in the upper side of the cover locking member  5 B are brought into a state of not engaging with the engaging parts  31 B provided at the two locations in the upper side of the protective cover  3 B, thereby making the protective cover  3 B unable to close. In addition, change in color and the like of internal terminals can be inspected in safe, without opening the protective cover  3 B, from the outside through the monitoring window  32 . 
     According to Embodiment 3 as described above, opening/closing conditions of the protective cover  3  can be set, without providing a handle for interlocking on the breakers  2 , by only the ON/OFF movement of the ON/OFF knob  21 ; the protective cover  3 B cannot be opened when the breakers  2  are in the ON state, but can be opened only when the breakers  2  are in the OFF state. Since the interlocking mechanism for the protective cover  3 B provided on each of the breakers  2  can be released breaker by breaker, there is no danger such as mistakenly touching live parts of other breakers during maintenance, so that maintenance can be carried out in safe. Moreover, the configuration of the device becomes simple, the number of parts can be decreased, and the breakers  2  can use regular standardized parts, thereby also producing an effect of providing breakers at low cost. 
     Embodiment 4 
       FIGS. 8A, 8B, and 8C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 4 of the present invention;  FIG. 8A  is a perspective view showing a state of the breaker being ON and the protective cover closing;  FIG. 8B  is a perspective view showing a state of the breaker being OFF and the protective cover sliding outward; and  FIG. 8C  is a perspective view showing a state of the breaker being OFF and the protective cover opening.  FIGS. 9A and 9B  are views for explaining in more detail the interlocking mechanism shown in  FIGS. 8A, 8B, and 8C ;  FIG. 9A  is a detailed perspective view of the interlocking mechanism; and  FIG. 9B  is an arrow view of the essential part thereof taken in the Z direction in  FIG. 9A . Additionally, in this Embodiment 4, a protective cover  3 C and its turning central axis are made movable in conjunction with movement of the ON/OFF knob  21 , and an engaging part  31 C is configured using an engaging pin disposed in parallel to the turning central axis at a radially predetermined distance from the axis. On the other hand, a cover locking member  5 C is configured using a sheet guide member having a locking part  51 S made of a slit guide groove formed including a straight section that is parallel to the directions to guide to slide the engaging pin and has the same length as the sliding distance of the engaging pin and an arc section that continuously connects to the straight section. 
     As shown in  FIG. 9A , the protective cover  3 C with a U-shaped cross section is provided with round holes  3   d  each located in the upper side and lower side sections thereof and an engaging part  31 C that is the engaging pin and erected at the radially predetermined distance from the round holes  3   d ; in the front section thereof is provided the insertion hole  3   c , the same as that of Embodiment 1 (shown in  FIG. 8C ), through which the ON/OFF knob  21  is inserted. A cover support member  4 C is provided with the elongated holes  4   d  that are elongated in the right and left directions and each located in the upper and lower sections thereof. As shown in  FIG. 9B , the round holes  3   d  of the protective cover  3 C are laid on their respective elongated holes  4   d  (not shown) via the nylon washer  93 , the cylindrical spacer  91  is inserted from the back side, and these are fixed together by the sems screw  92 , the washer  94  and the nut  96 . The cover support member  4 C is fixed to the breakers  2  and does not move. The cover locking member  5 C is made of a sheet material having the locking part  51 S provided with the guide groove that engages with the engaging part  31 C and is formed including the straight section  51   a  that is parallel to the elongated directions of the holes  4   d , that is, the sliding directions of the protective cover  3 C, and has the same length as the sliding distance of the cover, and the arc section  51   b  that continuously connects to the straight section  51   a . The cover locking member  5 C is fixed to the housing  11  (shown in  FIGS. 1A and 1B ) by a not-shown fixing member. 
     Then, the engaging part  31 C erected on the protective cover  3 C is fitted into the locking part  51 S of the cover locking member  5 C as shown in  FIG. 9A . Additionally, let one end portion of the straight section  51   a  of the locking part  51 S be a position A, the connecting point of the straight section  51   a  with the arc section  51   b , a position B, the other end portion of the arc section  51   b , a position C, the inner end portion of the elongated holes  4   d , a position E, and the outer end portion thereof, a position F. In a state of the protective cover  3 C sliding inward and closing, the turning central axis of the protective cover  3 C lies at the position E and the engaging part  31 C, which is the engaging pin, lies at the position A. The turning central axis of the protective cover  3 C moves to the position F and the engaging part  31 C to the position B when the protective cover  3 C is slid outward. The curvature center of the arc section  51   b  is formed to coincide with the turning center when the turning central axis is at the position F. By doing in this way, the protective cover  3 C becomes able to move along the elongated holes  4   d  of the cover support member  4 C and the locking part  51 S of the cover locking member  5 C. The ON/OFF knob  21  of the breakers  2  is inserted through the insertion hole  3   c  in the front face of the protective cover  3 C. The protective cover  3 C is provided with the monitoring window  32 . 
     In Embodiment 4 as configured above, when the breakers  2  are in the ON state, the ON/OFF knob  21  is brought down inward, and the protective cover  3 C is also in a state of having moved inward, the turning central axis of the protective cover  3 C lies at the position E in the inner side of the elongated holes  4   d , and as a result, the engaging part  31 C of the protective cover  3 C comes to the position A. At this moment, the inner side end portion of the insertion hole  3   c  of the protective cover  3 C touches the ON/OFF knob  21 , so that the protective cover  3 C is in a state of being unable to slide outward. If the protective cover  3  is intended to be opened frontward in this state, the engaging part  31 C of the protective cover  3 C interferes with a face D of the locking part  51 S of the cover locking member  5 C, in the turning central axis side of the straight section  51   a , thereby making the protective cover  3 C unable to open. In this example, the straight section  51   a  of the locking part  51 S serves as a practical locking part. 
     When the breakers  2  are brought into the OFF state, the ON/OFF knob  21  is brought down outward, thereby making the protective cover  3 C ready to slide outward. Then, when the protective cover  3 C is manually slid outward, the position of the turning central axis of the protective cover  3 C comes to the position F in the outer side of the elongated holes  4   d  of the cover support member  4 C, and the engaging part  31 C of the protective cover  3 C comes to the position B. If the protective cover  3 C is opened frontward in this state, the sems screw  92 , which is the turning central axis of the protective cover  3 C, serves as a fulcrum, the engaging part  31 C moves from the position B to the position C along the arc section  51   b  of the locking part  51 S, thereby making the protective cover  3 C able to open. Then, the engaging part  31 C of the protective cover  3 C stops at the position C, whereby the opening angle of the protective cover  3 C can be restricted. Even if the protective cover  3 C is pulled inward when in the open state, the engaging part  31 C at the position C is restrained by the locking part  51 S of the cover locking member  5 C, and the protective cover  3 C cannot move inward; therefore, the protective cover  3 C can be prevented from interfering with that of the neighboring breaker of the breakers  2  arranged side by side. 
     If the breakers  2  are mistakenly turned on when the protective cover  3 C is in the open state and then the protective cover  3 C is intended to be closed in this state, the ON/OFF knob  21  hits the back of the protective cover  3 C, and as a result, the cover is brought into a state of being unable to completely close. The engaging part  31 C of the protective cover  3 C stops on the arc section of the locking part  51 S of the cover locking member  5 C; therefore, the engaging part  31 C cannot move to the position B, and the protective cover  3 C cannot slide inward, thereby making the protective cover  3 C unable to close. 
     According to Embodiment 4 as described above, the same effects as those of Embodiments 1 to 3 can be produced, such as the protective cover  3 C cannot be opened when the breakers  2  are in the ON state, but can be opened only when the breakers  2  are in the OFF state. 
     Additionally, the engaging part  31 C of the protective cover  3 C is made of an engaging pin, and the locking part  51 S of the cover locking member  5 C is made of a slit guide groove formed of the straight section and the arc section continuously connecting to the straight section; however, it is also possible to provide a guide groove in the protective cover  3 C side and configure the locking part  51 S of the cover locking member  5 C using a locking pin. 
     Embodiment 5 
       FIGS. 10A and 10B  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 5 of the present invention;  FIG. 10A  is a perspective view showing a state of the breaker being ON and the protective cover closing; and  FIG. 10B  is a perspective view showing a state of the breaker being OFF and the protective cover opening.  FIGS. 11A and 11B  are views for explaining in more detail the interlocking mechanism shown in  FIGS. 10A and 10B ;  FIG. 11A  is a detailed perspective view of the interlocking mechanism; and  FIG. 11B  is a detailed view of the portion G encircled in  FIG. 10A .  FIG. 12A  is an arrow view taken from the direction R of  FIG. 11A ;  FIG. 12B  is a detailed view of the portion E encircled in  FIG. 12A . Additionally, this Embodiment 5 is an example in which the arrangement of the breakers  2  in Embodiment 3 described above is turned by 180°. Although the breakers  2  in Embodiment 3 are arranged in such a way that they are in the ON state when the ON/OFF knob  21  is in the inner side and in the OFF state when the knob in the outer side, the breakers in this Embodiment 5 are in the ON state when the ON/OFF knob  21  is in the outer side and in the OFF state when the knob is in the inner side. 
     The interlocking mechanism is basically the same as that of Embodiment 3; a cover locking member  5 D is provided with in its front section the rectangular hole  5   a  that engages with the ON/OFF knob  21 , at two locations thereof the elongated holes  5   b  that slidably support the cover locking member  5 D with respect to the breakers  2 , and furthermore at two locations thereof the locking parts  51 T made of the tongue-shaped protrusions projecting upward. With ON/OFF directions of the ON/OFF knob  21  reversed with respect to those in Embodiment 3, the direction of grooves of the engaging parts  31 D, which are L-shaped notches and provided at two locations to receive and engage with the locking parts  51 T, is reversed as shown in  FIG. 11B  with respect to that in Embodiment 3 shown in  FIG. 6C . Other configurations, such as the opening direction of the protective cover  3 D and the monitoring window  32 , are the same as those of Embodiment 3, so their explanation will be omitted. 
     In Embodiment 5 as configured above, the locking parts  51 T provided at the two locations of the cover locking member  5 D that moves, when the breakers  2  are in the ON state, in conjunction with the ON/OFF knob  21  of the breakers  2  are fitted into the engaging parts  31 D provided at the two locations of the protective cover  3 D, thereby making the protective cover  3 D unable to open, so that the same effects as those in Embodiments 1 to 3 can be produced. 
     Embodiment 6 
       FIGS. 13A and 13B  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 6 of the present invention;  FIG. 13A  is a perspective view showing a state of the breaker being ON and the protective cover closing; and  FIG. 13B  is a perspective view showing a state of the breaker being OFF and the protective cover opening.  FIGS. 14A and 14B  are views for explaining in more detail the interlocking mechanism shown in  FIGS. 13A and 13B ;  FIG. 14A  is a detailed perspective view of the interlocking mechanism; and  FIG. 14B  is a detailed view of the portion H encircled in  FIG. 13A .  FIG. 15A  is an arrow view taken in the direction S in  FIG. 14A ;  FIG. 15B  is a detailed view of the portion F encircled in  FIG. 15A ;  FIG. 15C  is an arrow view taken in the direction T in  FIG. 14A ; and  FIG. 15D  is a detailed view of the portion I encircled in  FIG. 15C . Additionally, Embodiment 6 is, the same as Embodiment 5, an example in which the breakers  2  are arranged in such a way that they are in the ON state when the ON/OFF knob  21  is in the outer side; meanwhile in the OFF state when the knob is in the inner side. 
     A cover locking member  5 E is provided with in its front section the rectangular hole  5   a  that engages with the ON/OFF knob  21 , at two locations thereof the elongated holes  5   b  for sliding, and upper and lower portions thereof the locking parts  51 T, which are tongue-shaped protrusions. A protective cover  3 E is provided with in upper and lower sections thereof engaging parts  31 E, which are L-shaped notches, and the round holes  3   d  for turning (not shown in the figure), and in the front section thereof the insertion hole  3   c  for the ON/OFF knob  21  merely to pass therethrough. First, a cover support member  4 E is placed on each inner side fixing hole of the fixing holes  22  of the breakers  2  (shown in  FIG. 15B ), and on which are stacked up the cylindrical spacer  91  and the washer  94 . Furthermore, another spacer  91  is placed on that, and this spacer is inserted through one of the elongated holes  5   b  of the cover locking member  5 E. At this moment, the ON/OFF knob  21  is also kept inserted through the rectangular hole  5   a  of the cover locking member  5 E. After the insertion, the washer  94  is placed and these are collectively fastened by the sems screw  92 . 
     The large washer  94 L, which is larger than the washer  94 , is place on each outer side fixing hole of the fixing holes  22  of the breakers  2 , and on which are stacked up the cylindrical spacer  91  and the washer  94 . Furthermore, another spacer  91  is placed on that and this spacer is inserted through the other hole of the elongated holes  5   b  of the cover locking member  5 E. After the insertion, the washer  94  is placed and these are collectively fastened by the sems screw  92 . By doing in this way, the cover locking member  5 E becomes able to slide right and left in conjunction with ON/OFF movement of the ON/OFF knob  21 . Next, as shown in  FIG. 14A , the spacer  91  (not shown) is inserted through each of the round holes  3   d  (not shown) in the upper and lower sections of the protective cover  3 E, furthermore the sems screw  92  (not shown) is inserted through this spacer  91  (not shown), and then these are fastened to the upper and lower screw holes  4   a  of the cover support members  4 E. By doing so, the protective cover  3 E becomes able to turn. Additionally, configurations, such as the monitoring window, are the same as those of other embodiments. 
     In Embodiment 6 as configured above, the ON/OFF knob is brought down outward when the breakers  2  are in the ON state, and the cover locking member  5 E also slides outward accordingly. When the cover locking member  5 E slides outward, the locking parts  51 T in the upper and lower portions of the cover locking member  5 E are fitted into the upper and lower engaging parts  31 E of the protective cover  3 E, thereby making the protective cover unable to open. When the breakers  2  are brought into the OFF state, the ON/OFF knob  21  is brought down inward, and the cover locking member  55  slides inward accordingly. When the cover locking member  5 E slides inward, the locking parts  51 T in the upper and lower portions of the cover locking member  5 E are released from the upper and lower engaging parts  31 E of the protective cover  3 E, thereby enabling the protective cover to open. Then, when the protective cover  3 E is pulled frontward, the protective cover  3 E opens. 
     If the breakers  2  are mistakenly turned on when the protective cover  3 E is in the open state and then the protective cover  3 E is intended to be closed in this state, the ON/OFF knob  21  is brought down outward when the breakers  2  are in the ON state, and accordingly the cover locking member  5 E comes into the state of sliding outward at the same time. If the protective cover  3 E is intended to be closed in this state, the locking parts  51 T provided at the two locations in the upper and lower portions of the cover locking member  5 E are brought into a state of not engaging with the engaging parts  31 E provided at the two locations in the upper and lower sections of the protective cover  3 E, thereby making the protective cover  3 E unable to close. 
     According to Embodiment 6 as described above, opening/closing conditions of the protective cover  3  can be set by only the movement of the ON/OFF knob  21 ; the protective cover  3 E cannot be opened when the breakers  2  are in the ON state, but can be opened only when the breakers  2  are in the OFF state. Since the interlocking mechanism for the protective cover  3 E provided on each of the breakers  2  can be released breaker by breaker, maintenance can be carried out in safe, the configuration of the device becomes simple, the number of parts can be decreased, and regular standardized parts can be used for the breakers  2 , so that the same effects as those of Embodiment 1, such as providing breakers at low cost, can be produced. 
     Embodiment 7 
       FIGS. 16A, 16B, and 16C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 7 of the present invention;  FIG. 16A  is a perspective view showing a state of the breaker being ON and the protective cover closing;  FIG. 16B  is a perspective view showing a state of the breaker being OFF and the protective cover opening; and  FIG. 16C  is a detailed view of the portion J encircled in  FIG. 16A .  FIGS. 17A and 17B  are views for explaining in more detail the interlocking mechanism shown in  FIGS. 16A, 16B, and 16C ;  FIG. 17A  is a detailed perspective view of the interlocking mechanism; and  FIG. 17B  is a detailed view of the portion C encircled in  FIG. 16A .  FIG. 18A  is an arrow view of the essential part taken from the direction Q in  FIG. 17A ;  FIG. 18B  is a detailed view of the portion D encircled in  FIG. 18A . Additionally, Embodiment 7 is an example in which the breakers  2  are placed in portrait orientation and arranged right and left; the breakers are turned on when the ON/OFF knob  21  is brought down downward; meanwhile turned off when the knob is brought down upward; and a cover locking member  5 F slides in the up and down directions in conjunction with the ON/OFF knob  21 . When the breakers  2  are in the ON state, the tongue-shaped locking parts  51 T protruding right and left of the cover locking member  5 F are fitted into engaging parts  31 F, which are L-shaped notches formed in right and left sections of a protective cover  3 F, thereby making the protective cover  3 F unable to open. 
     The cover locking member  5 F is provided with in the front section thereof the rectangular hole  5   a  that engages with the ON/OFF knob  21 , at two locations thereof the elongated holes  5   b  for sliding, and in the right and left portions thereof the tongue-shaped locking parts  51 T that are fitted into the engaging parts  31 F of the protective cover  3 F. On the other hand, the protective cover  3 F is provided with in the front section thereof the insertion hole  3   c  through which the ON/OFF knob merely passes, and in the right and left sections thereof the engaging parts  31 F into which the locking parts  51 T of the cover locking member  5 F are fitted and the round holes  3   d  (not shown) for the protective cover  3 F to turn. In addition, the round holes  4   e  (not shown) for turnably fixing the protective cover  3 F are made in right and left sections of a cover support member  4 F. Additionally, configurations, such as the monitoring window, are the same as those of other embodiments. 
     In assembling, the large washer  94 L is placed at first on each of the fixing holes  22  of the breakers  2  (shown in  FIG. 18B ), and on which are stacked up the spacer  91  and the washer  94 . Furthermore, another spacer  91  is placed on that, and this spacer  91  is inserted through each of the elongated holes  5   b  of the cover locking member  5 F, and at the same time, the ON/OFF knob  21  is also inserted through the rectangular hole  5   a  of the cover locking member  5 F. Then, these are collectively fixed by the sems screw  92 . Thereby, the cover locking member  5 F becomes able to slide up and down in conjunction with ON/OFF movement of the ON/OFF knob  21 . Next as shown in  FIGS. 16A, 16B, and 16C , the spacer  91  (not shown) is inserted at the same time through each of the round holes  3   d  (not shown) in the right and left sides of the protective cover  3 F and the round holes  4   e  (not shown) for fixing the protective cover  3 F in the right and left sides of the cover support member  4 F, and these are fixed by the sems screw  92  and the nut  96 . By doing in this way, the protective cover  3 F becomes able to turn from the upper side toward the lower side of the breakers  2 . 
     In Embodiment 7 as configured above, the ON/OFF knob is brought down downward when the breakers are in the ON state, and the cover locking member  5 E also slides downward accordingly. When the cover locking member  5 F slides downward, the locking parts  51 T provided in the right and left sides of the cover locking member  5 F are fitted into the engaging parts  31 F provided in the right and left sides of the protective cover  3 F, thereby making the protective cover  3 F unable to open. When the breakers  2  are brought into the OFF state, the ON/OFF knob  21  is brought down upward, and the cover locking member  5 F also slides upward accordingly. When the cover locking member  5 F slides upward, the locking parts  51 T of the cover locking member  5 F are released from the engaging parts  31 F of the protective cover  3 F, and the protective cover  3 F thereby becomes able to open. When the protective cover is pulled frontward, the protective cover  3 F opens. 
     If the breakers  2  are mistakenly turned on when the protective cover  3 F is in the open state and then the protective cover  3 F is intended to be closed in this state, the ON/OFF knob  21  is brought down downward when the breakers  2  are in the ON state, and accordingly the cover locking member  5 F comes into the state of sliding downward at the same time. If the protective cover  3 F is intended to be closed in this state, the locking parts  51 T provided at the two locations in the right and left sides of the cover locking member  5 F are brought into a state of not engaging with the engaging parts  31 F provided at the two locations in the right and left sections of the protective cover  3 F, thereby making the protective cover  3 F unable to close. 
     According to Embodiment 7 as described above, opening/closing conditions of the protective cover  3 F can be set by only the ON/OFF movement of the ON/OFF knob  21 ; the protective cover  3 F cannot be opened when the breakers  2  are in the ON state, but can be opened only when the breakers  2  are in the OFF state. Since the interlocking mechanism for the protective cover  3 F provided on each of the breakers  2  can be released breaker by breaker, maintenance can be carried out in safe, the configuration of the device becomes simple, the number of parts can be decreased, and regular standardized parts can be used for the breakers  2 , thereby producing the same effects as those in Embodiment 1, such as enabling the provided breakers to be provided at low cost. 
     Embodiment 8 
       FIGS. 19A, 19B, and 19C  are views for explaining an interlocking mechanism of a protective cover of a panel device according to Embodiment 8 of the present invention;  FIG. 19A  is a perspective view showing a state of the breaker being ON and the protective cover closing;  FIG. 19B  is a perspective view showing a state of the breaker being OFF and the protective cover opening; and  FIG. 19C  is a detailed view of the portion K encircled in  FIG. 19A .  FIGS. 20A and 20B  are views for explaining in more detail the interlocking mechanism shown in  FIGS. 19A, 19B, and 19C ;  FIG. 20A  is a detailed perspective view of the interlocking mechanism; and  FIG. 20B  is a detailed view of the portion A encircled in  FIG. 19A .  FIG. 21A  is an arrow view of the essential part taken from the direction P in  FIG. 20A ;  FIG. 21B  is a detailed view of the portion B encircled in  FIG. 21A . Additionally, Embodiment 8 represents an interlocking mechanism in which the breakers  2 , the same as Embodiment 7, are placed in portrait orientation and arranged right and left; however, this is an example in which the breakers  2  are arranged such that the ON/OFF directions of the breakers are reversed, so the ON/OFF knob  21  is brought down upward when the breakers are in the ON state and the knob is brought down downward when in the OFF state. A cover locking member  5 G is made to move in conjunction with the ON/OFF knob  21 ; when the breakers  2  are in the ON state, a locking part  51 T, which is a tongue-shaped protrusion projecting upward of the cover locking member  5 G, is fitted into an engaging part  31 G, which is a slit hole provided in the upper side of a protective cover  3 G, thereby making the protective cover  3 G unable to open. 
     In the front section of the cover locking member  5 G are provided the rectangular hole  5   a  that engages with the ON/OFF knob  21  and the elongated holes  5   b  that slidably support the cover locking member  5 G at two locations, and in the upper side thereof is provided the locking part  51 T that is fitted into the engaging part  31 G of the protective cover  3 G. In the protective cover  3 G are provided in the front section thereof the insertion hole  3   c  through which the ON/OFF knob merely passes, in the upper side thereof the engaging part  31 G into which the locking part  51 T of the cover locking member  5 G is fitted, and in right and left sections thereof round holes  3   d  (not shown) for the protective cover  3 G to turn. The round holes  4   e  (not shown) for fixing the protective cover  3 G are provided in right and left sections of a cover support member  4 G. 
     Additionally, structures enabling the cover locking member  5 G to slide up and down with respect to the breakers  2  in conjunction with ON/OFF movement of the ON/OFF knob  21  and the protective cover  3 G to turn from the upper side toward the lower side of the breakers  2  are the same as those in Embodiment 7, so their explanation will be omitted. Additionally, the difference other than the above between Embodiments 8 and 7 is whether the locking parts  51 T project in the right and left directions or the locking part  51 T projects in the upward direction, and whether the engaging part  31 G is formed of an L-shaped notch or of a slit hole in a bent section formed in the back side of the upper end face of the protective cover  3 G. 
     In Embodiment 8 as configured above, the ON/OFF knob is brought down upward when the breakers  2  are in the ON state, and the cover locking member  5 G also slides upward accordingly. When the cover locking member  5 G slides upward, the locking part  51 T provided in the upper side of the cover locking member  5 G is fitted into the engaging part  31 G provided in the upper side of the protective cover  3 G, thereby making the protective cover  3 G unable to open. When the breakers  2  are brought into the OFF state, the ON/OFF knob  21  is brought down downward, and the cover locking member  5 G also slides downward accordingly. When the cover locking member  5 G slides downward, the locking part  51 T of the cover locking member  5 G is released from the engaging part  31 G of the protective cover  3 G, thereby making the protective cover  3 G ready to open. Then, when the protective cover  3 E is pulled frontward, the protective cover  3 G opens. 
     If the breakers  2  are mistakenly turned on when the protective cover  3 G is in the open state and then the protective cover  3 G is intended to be closed in this state, the ON/OFF knob  21  is brought down upward when the breakers  2  are in the ON state, and accordingly the cover locking member  5 G slides upward at the same time. If the protective cover  3 G is intended to be closed in this state, the bent section in which the engaging part  31 G of the protective cover  3 G is provided interferes with the locking part  51 T of the cover locking member  5 G that has slid upward, thereby making the protective cover  3 G unable to close. 
     According to Embodiment 8 as described above, opening/closing conditions of the protective cover  3  can be set by only the ON/OFF movement of the ON/OFF knob  21 ; the protective cover  3 G cannot be opened when the breakers  2  are in the ON state, but can be opened only when the breakers  2  are in the OFF state. Since the interlocking mechanism for the protective cover  3 G provided on each of the breakers  2  can be released breaker by breaker, maintenance can be carried out in safe, the configuration of the device becomes simple, the number of parts can be decreased, and regular standardized parts can be used for the breakers  2 , thereby producing the same effects as those in Embodiment 1, such as providing breakers at low cost. 
     As described above, in each embodiment exemplifying a panel device related to the present invention, the interlocking mechanism for the protective cover  3  is configured in such a way that any one of the protective cover  3 , the cover support member  4  and the cover locking member  5  is slidably provided, in conjunction with the movement of the ON/OFF knob  21 , in parallel to the moving directions of the ON/OFF knob  21 , and in each of the foregoing cases, the engaging parts  31  of the protective cover  3  are locked by the cover locking member  5  when the ON/OFF knob  21  is in the turned-on position, thereby making the cover unable to open. In this connection, the device is configured as follows: the protective covers  3  and  3 C are made to slide in Embodiments 1 and 4, respectively, the cover support member  4 B is made to slide in Embodiment 2, and the cover locking members  5 B and  5 D to  5 G are made to slide in Embodiment 3 and Embodiments 5 to 8, respectively. The interlocking mechanism for the protective cover is provided for each breaker in all of the above cases, whereby danger of touching live parts of other breakers can be avoided, so that maintenance can be carried out in safe. Moreover, not only the configuration of the device becomes simple and the number of parts can be decreased, but also a remarkable effect of coping with various breaker layouts can be produced. 
     Additionally, it is possible without departing from the scope and spirit of this invention for those skilled in the art to freely combine part of or the whole of each embodiment, or amend or delete each embodiment as needed. For example, it goes without saying that the type and the shape of screws, such as the sems screw  92  and the screw  97 , materials for these screws, and how to fix these screws can be altered as needed. Explanations have been made on cases of the panel device being a breaker panel; however, the device will be preferably applied to panels such as control panels. Moreover, the breakers  2  are not necessarily arranged in a pair, and in addition, it goes without saying that the breakers can be operated independently of each other even when they are paired and arranged right and left. Furthermore, alterations, such as interchanging the shape of the engaging parts  31  ( 31 B to  31 F) with that of the locking parts  51  ( 51 T,  51 S), will be possible. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
           1 : breaker panel 
           11 : housing 
           11   a : opening/closing door 
           2 : breakers 
           21 : ON/OFF knob 
           22 : fixing holes 
           3 ,  3 A,  3 B,  3 C,  3 D,  3 E,  3 F,  3 G: protective cover 
           3   a ; elongated holes 
           3   b : round holes (for circling screw) 
           3   c : insertion hole 
           3   d : round holes (for turning) 
           31 ,  31 B,  31 C,  31 D,  31 E,  31 F,  31 G: engaging part/engaging parts 
           32 : monitoring window 
           4 ,  4 A,  4 C,  4 E,  4 F,  4 G: cover support member 
           4 B 1 : cover support member 
           4 B 2 : cover support member 
           4   a : screw hole/screw holes 
           4   b : grooves 
           4   c : rectangular hole 
           4   d : elongated holes 
           4   e : round hole/round holes 
           5 ,  5 B,  5 C,  5 D,  5 E,  5 F,  5 G: cover locking member 
           5   a : rectangular hole 
           5   b : elongated holes 
           51 : locking parts (groove) 
           51 T: locking part/locking parts (tongue-shaped protrusion) 
           51 S: locking part (slit) 
           51   a ; straight section 
           51   b : arc section 
           91 : spacer 
           92 ,  92   a ,  92 O: sems screw 
           93 : nylon washer 
           94 : washer 
           94 L: large washer 
           96 : nut 
           97 : screw