Patent Publication Number: US-9899166-B1

Title: High voltage folding disconnect switch with locking device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 62/187,876 filed Jul. 2, 2015, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a disconnect switch for high voltage electrical applications and, more particularly, to a folding disconnect switch having a switch blade that folds as it opens and is folded as it begins to close to lower the force necessary to disengage or re-engage the contacts of the switch. One example of such a switch is a folding side break electric disconnect switch such as manufactured and sold by Cleaveland/Price, Inc. of Trafford, Pa., the present assignee, as Model RL-C, a copper side break switch rated at 115 kV, 1200 A. The folding of the switch blade also aids in breaking ice on outdoor disconnect switches as the switch opens or closes. The typical folding blade has two switch blade portions, i.e., a fixed blade portion and a folding blade portion, that are operatively joined by a current carrying joint that is often spring biased to keep the blade in the folded state. The spring at the joint causes the switch blade to fold as it opens which sets up the blade to be in a folded condition prior to re-engaging, for example, reengaging with a notch in the break jaw contact as the switch closes. 
     In electric utility power systems, high voltage disconnect switches are employed to isolate substation conductors and transmission lines and high voltage electrical apparatus to permit the inspection or repair of such apparatus or redirect power or other reasons. When a switch is called on to close and the break jaw and/or blade is covered with a build-up of ice, the blade must be closed rapidly to impart a chopping action to break through the ice. In the case where the switch has no ice shield or is mounted in an orientation where an ice shield cannot be used to keep the switch contacts free of ice, the conventional folding blade will often malfunction by prematurely straightening, since the joint spring has limited force to keep the blade folded, often resulting in misalignment, for example, of a break jaw contact pin on the blade tip with a notch within the switch jaw contacts. This situation requires opening and refolding the switch blade using a hot stick and attempting to close the switch again, possibly repeatedly. 
     It is therefore an object of the present invention to provide a high voltage folding disconnect switch, such as a side break electric disconnect switch, with a simple reliable apparatus for preventing premature straightening of the blade during closing; to aid the switch in breaking ice build-up on the switch blade and break jaw contacts during switch opening or closing; and, to cause proper alignment of the folding switch blade with the break jaw contact during closing, for example, by proper alignment of the break jaw contact pin on the blade tip with the notch within the switch jaw contacts. 
     SUMMARY OF THE INVENTION 
     The present invention solves the malfunction problem due to ice build-up on the break jaw contacts and blade of a folding high voltage disconnect switch by locking the switch blade from straightening until most of any ice build-up has been chopped or broken away and the folding switch blade is in proper alignment with the break jaw contact, so that, for example, the break jaw contact pin on the blade is in position to enter the break jaw notch within the break jaw contacts during closing of the switch. At this point in the closing stroke of the switch, a trigger mechanism will release a lock which allows the blade to straighten and the blade pin to enter the notch in the break jaw and the switch contacts to be fully made closed electrically. 
     Such a folding high voltage disconnect switch is mounted at one end to a rotating insulator. To open or close the switch the rotating insulator is caused to rotate, for example, counter clockwise, causing the switch blade to fold at the current carrying joint. The switch blade, as mentioned, is divided into a fixed blade portion and a folding blade portion connected by a joint that enables folding of the switch blade. Typically mounted to the distal end of the folding blade portion is a blade pin or break jaw contact pin. A joint spring is provided and is attached at one end to a pin on the fixed blade portion and at the other end to a pin on the folding blade portion. The joint spring is known from the prior art, for example, side break switch, and keeps the blade folded as the switch blade opens and as the switch begins to close, the break jaw contact pin re-enters the notch in the break jaw contact as the folding blade straightens. 
     The present invention provides an additional return spring, i.e., a second spring, attached at one end in predetermined position to the fixed blade portion and the other end to a locking device. The fixed blade portion is fixed to the rotating insulator. A trigger lever-locking bar, i.e., the locking device, is mounted near its proximal end to the fixed blade portion, such that the trigger lever-locking bar is pivotal near its proximal end. The second return spring is attached at its other end to the proximal end of the trigger lever-locking bar. At the distal end of the trigger lever-locking bar is a trigger finger which contacts an opposing permanently mounted trigger surface which is attached to a plate at the top of a stationary insulator which the break jaw is also mounted to. Near the distal end of the trigger lever-locking bar, adjacent the trigger finger, is a cam slot that accommodates and cooperates with a cam follower pin that is attached to the folding blade portion in predetermined position. At the distal end of the folding blade portion is the break jaw contact pin that engages the notch in the break jaw upon the switch closing. When the switch is fully closed, the contact pin within the notch keeps the switch blade from opening due to short circuit magnetic forces. 
     The cam slot has two sections. The cam follower pin, when the switch blade is in the open position, that is, when the switch blade is folded, rides in the first section of the cam slot and the trigger lever-locking bar prevents the blade from straightening. As the switch blade is closed, the trigger finger contacts the trigger surface, which after a predetermined distance of contact between the trigger finger and the trigger surface, the cam follower pin is caused to move into the second section of the cam slot, whereupon the switch blade is unlocked and allows the blade to fully straighten. Upon the switch blade straightening, the break jaw contact pin continues to break any ice build-up at the break jaw, and enters the notch within the break jaw contacts to fully electrically close the switch. Thus, any malfunction by premature straightening of the switch blade when contacting ice build-up on the switch parts and the resultant misalignment of the of the break jaw contact pin with the notch in the breakjaw is prevented by the trigger-lever locking bar. By locking the folding blade from premature straightening any ice build-up may be chopped or broken away and the blade and contact pin may be properly aligned to enter the notch, thus, the malfunction problem of the prior art switch is eliminated with the present invention. 
     These and other aspects of the present invention will be further understood from the entirety of the description, drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the invention reference may be made to the accompanying drawings exemplary of the invention, in which: 
         FIG. 1A  is a perspective view of a prior art folding side break disconnect switch in the full closed position, and also shown in dotted line in the partially open position; 
         FIG. 1B  is an enlarged perspective view of area  1 B- 1 B of  FIG. 1A  with the upper blade of the folding blade portion cut away to show the break jaw; 
         FIG. 2A  is a perspective view of a folding side break disconnect switch of the present invention in the full closed position; 
         FIG. 2B  is an enlarged perspective view of area  2 B- 2 B of  FIG. 2A  with the upper blade of the fixed blade portion partially cut away to show the proximal end of the trigger lever-locking bar; 
         FIG. 3  is a perspective view of a folding side break disconnect switch of the present invention in the full open position with the upper blade of the folding blade portion cut away to show the cam slot of the locking bar; 
         FIG. 4A  is a perspective view of a folding side break disconnect switch of the present invention where the trigger finger is just beginning to contact the trigger surface upon closing prior to full straightening of the blade while the cam follower pin is still in the first section of the cam slot, which is the locking section of the slot; 
         FIG. 4B  is an enlarged perspective view taken along the line  4 B- 4 B of  FIG. 4A , also with the upper blade of the folding blade portion cut away to show part details; 
         FIG. 5A  is a perspective view of the folding side break disconnect switch of the present invention where the trigger finger has moved farther along the trigger surface than as shown in  FIG. 4A , and the cam follower pin is just entering the second section of the cam slot to initiate unlocking of the folding blade; 
         FIG. 5B  is an enlarged perspective view taken along the line  5 B- 5 B of  FIG. 5A , with the upper blade of the folding blade portion cut away to show part details; 
         FIG. 6A  is a perspective view of the folding side break disconnect switch of the present invention where the trigger finger has moved further along the trigger surface, then as shown in  FIG. 5A , and the cam follower pin is now at the far end of the second section of the cam slot and the blade has fully straightened and the break jaw contact pin has fully entered the notch within the break jaw contacts; and, 
         FIG. 6B  is an enlarged perspective view taken along the line  6 B- 6 B of  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1A , there is shown a prior art folding high voltage electric disconnect switch  10  in a so-called side break configuration. The complete folding disconnect switch  10  includes a switch blade structure  18  that is mounted at one end  12   a  to rotating insulator  14  that has a lever  16  mounted thereto to permit turning of the insulator  14  to cause opening and closing of the switch  10 . At the top of rotating insulator  14  is electric terminal  39   a  which has an electric pivot contact to allow rotation of the fixed blade portion  20  while the terminal  39   a  is stationary. The switch  10  includes a switch blade structure  18  divided into the fixed blade portion  20  including upper fixed blade  20   a  and lower fixed blade  20   b  and a folding blade portion  24  including an upper folding blade  24   a  and a lower folding blade  24   b . The fixed blade portion  20  is attached at one end  22   a  to the rotating insulator  14  such that rotation of the insulator via lever  16  also rotates the fixed blade portion  20 , as well as the folding blade portion  24 . The other end  22   b  of the fixed blade portion  20  is rotatably attached to the folding blade portion  24  via an electrically conductive joining with pin  26  that permits folding of the switch blade structure  18 . Mounted to the distal end  28   a  of the folding blade portion  24  is a break jaw contact pin  30  that has an electric contact spring  30   a  that provides pressure to make electric contact between the distal end  28   a  of the folding blade portion  24 , i.e., the ends of upper folding blade  24   a  and lower folding blade  24   b , and the break jaw contacts  42   a  and  42   b , as shown in  FIGS. 1A and 1B . A joint return spring  32  within housing  38  is attached at the moving end  34   a  thereof to joint spring pin  27   b  which moves within housing  38  at slot  41 , the other stationary end  34   b  of the joint spring  32  is attached to joint spring pin  27   a . The joint spring  32  applies a force between pins  27   a  and  27   b  to bias the folding blade portion  24  in the folded position—pivoting about electric joint pin  26 . The joint spring  32  as mentioned keeps the blade folded as the blade opens and as the blade begins to close, but has only enough bias force to keep the blade folded but not enough force to prevent premature straightening during ice breaking. The joint return spring  32  within housing  38  is typically housed in a spring box  38  which keeps ice from binding the moving spring. The switch  10  also includes a stationary insulator  15  which is mounted to a base  17  opposite the rotating insulator  14 . Attached at the top  19  of the stationary insulator  14  is a break jaw electric terminal  39  which has electrically attached thereto the break jaw  40 . The break jaw  40  includes a pair of oppositely disposed break jaw contacts  42   a ,  42   b , better shown in  FIG. 1B . Between the two break jaw contacts  42   a ,  42   b  is notch  44 . The notch  44  as mentioned is for receiving the break jaw contact pin  30  upon the closing of switch  10 . The switch  10  described thus far as shown in  FIGS. 1A and 1B  is the prior art switch. 
     The present invention utilizes the prior art folding disconnect switch  10  as described thus far and makes improvements including the following. With reference to  FIGS. 2A, 2B and 3 , a second return spring  46  is attached at one end  48   a  to return spring pin  50  which is attached to fixed blade portion  20  and the other end  48   b  of the second return spring  46  is attached to a trigger lever-locking bar  52  at its proximal end  56   a . The trigger lever-locking bar  52  has a central elongated offset section  53  that is offset from the center line ‘L’ of the switch blade  18  in the closed position. The offset section  53  is offset structured to avoid interfering with a trigger lever pivot pin  54  that extends transversely to the center line ‘L’ between opposite upper and lower fixed blade pairs  20   a ,  20   b  of the fixed blade portion  20  as better shown in  FIG. 2B . Also, the offset section  53  avoids interfering with electric joint pin  26 , joint return spring  32 , housing  38 , joint spring pins  27   a ,  27   b  and folding blade portion pin  25 . The central elongated offset section  53  of the trigger lever-locking bar  52  is offset a distance such as, as two inches, from the center line ‘L’ of the switch blade structure  18 . The trigger lever-locking bar  52  has a trigger lever pivot pin engagement portion  55  at the proximal end  56   a  thereof. The trigger lever pivot pin engagement portion  55  having a pivot point hole  57  therethrough aligned with the center line ‘L’ of the switch blade  18  in the closed position, as shown in  FIG. 2A . The trigger lever pivot pin  54  engages the pivot point hole  57  to secure the trigger lever-locking bar  52  so that it is pivotally mounted near its proximal end  56   a  and attached to fixed blade portion  20 . 
       FIG. 3  shows at the distal end  56   b  of the trigger lever-locking bar  52  operatively positioned is the trigger finger  58 . Also mounted to the break jaw terminal  39  is a trigger finger contact member  60  having a trigger surface  65 . The trigger finger  58  during closing of the switch blade  18  contacts the trigger surface  65  as hereinafter described in further detail. The trigger lever-locking bar  52  adjacent to the trigger finger  58  includes a cam slot  62  operatively positioned therethrough. The cam slot  62  as can be seen also, for example, in  FIGS. 4A and 4B , has a somewhat reverse “S” shape. The cam slot  62  as mentioned has a first section  64   a  and a second section  64   b  more clearly shown in  FIG. 4B . The first section  64   a , when the switch blade  18  is in the closed position as shown in  FIGS. 6A and 6B , is offset from the center line ‘L’ and is further away from the trigger finger  58  then the second section  64   b . The second section  64   b , when the switch blade  18  is in the closed position, is in substantial alignment with the center line ‘L’ of the switch blade  18  and is closer to the trigger finger  58  then the first section  64   a . The cam follower pin  66  is attached to upper and lower folding blade pairs  24   a ,  24   b  of the folding blade portion  24  as shown in  FIG. 2 ,  FIG. 3 ,  FIGS. 6A and 6B , and rides in the cam slot  62  of the trigger lever-locking bar  52 . As mentioned the cam slot  62  cooperates with the cam follower pin  66 . 
     The cam follower pin  66 , when the switch  10  of the present invention is in the open position, rides in the first section  64   a  of the reverse “S” shaped cam slot  62  and the trigger lever-locking bar, as shown in  FIG. 3 , prevents the blade  18  from straightening. As the switch blade  18  is closed, the trigger finger  58  now begins to contact the trigger surface  65 , as shown in  FIGS. 4A and 4B . The cam follower pin  66 , as shown in  FIGS. 5A and 5B , at the same time begins to leave the first section  64   a , i.e., at the middle part of the reverse “S” of the cam slot  62 , and enters the second section  64   b  of the cam slot  62  allowing the blade  18  to straighten by permitting the cam follower pin  66  to become aligned with the center line ‘L’ of the straightened switch blade  18 . As the trigger finger  58  slides further along the trigger surface  65  the pin  66  moves along the cam surface  67  of the cam slot  62  as shown in  FIG. 4B . When the cam follower pin  66  is in the  64   a  section of the cam slot  62 , i.e., the first section of the slot, the folding blade  18  remains folded and is locked from straightening and when pin  66  is located in the  64   b  section of the cam slot  62 , i.e., the second section of the slot  62 , the folding blade  18  is unlocked as the cam follower pin  66  moves along the cam surface  67  and is allowed to straighten. The trigger surface  65  for the side break switch  10 , as shown in the drawings, may be preferably vertical and flat. As the trigger finger  58  is caused, by the closing of the switch blade  18 , to move further along the trigger surface  65 , as shown in  FIGS. 6A and 6B , the cam follower pin  66  reaches the second section  64   b  of the slot  62  in substantial alignment with center line ‘L’ and the switch blade may be fully straightened. At that point, the break jaw contact pin  30  is caused to be in full electrical closed position within the notch  44  within the break jaw contacts  42   a ,  42   b . Of course, when the switch  10  is opened the opposite procedure takes place. 
     The present locking mechanism as described can also be applied, for example, to folding ground switch blades, or any type of switch with a folding blade. 
     Of course variations from the foregoing embodiments are possible without departing from the scope of the invention. Other switch types such as ground blades and double break switch with folding blades can also utilize the present invention of this locking device to improve performance during ice breaking.