Abstract:
An operation counter arrangement is provided for a circuit interrupter for opening a high-voltage circuit-isolating device. The operation counter arrangement responds to actual operations via response to a moving contact arrangement of the circuit interrupter. The operation counter arrangement is capable of retrofit to existing circuit interrupters via replacement of an exhaust control device of the circuit interrupter. In a preferred arrangement, a count of both the total number of operations and the number of operations since the most recent maintenance is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of Provisional Application No. 60/128,711 filed on Apr. 8, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to circuit interrupters and more particularly to an operation counter for a load-current interrupting tool, commonly known as a loadbreak tool, that is utilized for opening medium and high-voltage circuit-isolating devices such as disconnecting fuses, disconnecting switches, cutouts, or the like. 
     2. Description of the Related Art 
     It is common practice in the electrical power distribution field to utilize a load-current interrupting tool, commonly known as a loadbreak tool, to open circuit-isolating devices such as disconnecting fuses, disconnecting switches, cutouts, or the like. In this manner, the circuit. isolating devices do not require load-interrupting capabilities. The loadbreak tool is carried on an insulating pole and manipulated by an operator via the pole. A load current interrupting tool of this type is the Loadbuster R  Portable Loadbreak Tool available from the S&amp;C Electric Company, Chicago, Ill. Reference may also be made to the following U.S. patents for a detailed description of a portable loadbreak tool of this general type: 2,816,978, 2,816,980, 2,816,985 and 5,650,602. A typical circuit-isolating device with which the portable loadbreak tool is utilized is illustrated in U.S. Pat. Nos. 4,414,527 and 5,502,427 and in the aforementioned U.S. Pat. No. 2,816,980. A circuit-isolating device of this type is the S&amp;C Type XS Fuse Cutouts. When the cutout or other device, is connected in a circuit and is carrying a load current, the contacts of a movable portion (fuse tube) are in conductive engagement with respective upper and lower stationary terminals of the mounting. 
     The loadbreak tool includes two external, conductive attachment arrangements. A first of the conductive arrangements is arranged to selectively engage a hook-shaped anchor (commonly referred to as a Loadbuster R  hook) carried by the mounting of the cutout and connected electrically to the upper stationary terminal of the mounting. The second conductive arrangement is a detachable latch member that is utilized to engage a pull ring or the like provided on the fuse tube of the cutout. The pull ring is electrically connected to the upper contact of the fuse tube. The loadbreak tool includes internal arc-interrupting facilities having separable arc-interrupting contacts which are in a closed position when the loadbreak tool is connected to the cutout. Each of the separable arc-interrupting contacts is connected to a respective one of the attachment arrangements. 
     The loadbreak tool provides for relative movement between the two attachment arrangements while also providing a conductive path between the stationary terminal of the mounting and the upper terminal of the fuse tube via the pull ring. When the operator pulls downward on the pole, the fuse tube pivots away from the cutout mounting and in the initial stages of opening the fuse tube, the load current path is maintained through the separable contacts of the loadbreak tool. After the continued opening of the fuse tube of the cutout has caused appropriate relative motion between the two attachment arrangements of the loadbreak tool, the arc-interrupting contacts are opened such that load interruption takes place internally of the loadbreak tool. Next, the loadbreak tool is detached from the cutout and removed from the vicinity of the cutout. A manually operable resetting latch arrangement is then manipulated by the operator to permit resetting of the loadbreak tool for subsequent use. The resetting of the loadbreak tool closes and resets the separable arc-interrupting contacts, returns the conductive attachment arrangements to their initial positions, and resets an internal trigger mechanism. 
     The operating life of the loadbreak tool depends upon the number of operations and the severity of the switching duties. Based on typical usage, involving an intermixture of varied switching duties, 500-1000 operations may normally be expected between required inspections. During such periodic inspections, various internal parts are inspected. Based on such inspection, reconditioning is accomplished as required including the replacement of various parts. Since the number of operations between typical inspections is large and there are no audible or visual signals that indicate the need for replacement of worn component parts, the number of operations should be accumulated and kept track of. However, since it is difficult to accurately keep track of the actual number of operations, the scheduling of maintenance is not always accurate, i.e. maintenance may be more frequent than typically required or may be unintentionally delayed until a problem is noticed. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a principal object of the present invention to provide an operation counter for a load-current interrupting tool to improve the scheduling of maintenance and inspection. 
     It is another object of the present invention to provide a count of total operations and the number of operations since the most recent maintenance. 
     These and other objects of the present invention are efficiently achieved in a circuit interrupter through the provision of an operation counter. The operation counter responds to actual operations via response to a moving contact arrangement of the circuit interrupter. The operation counter arrangement is capable of retrofit to existing circuit interrupters via replacement of an exhaust control device of the circuit interrupter. In a preferred arrangement, a count of both the total number of operations and the number of operations since the most recent maintenance is provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in conjunction with the accompanying drawing in which like reference numerals refer to like elements and in which: 
     FIGS. 1-3 are elevational views, partly in section and with parts removed and cutaway for clarity, of an operation counter arrangement of the present invention assembled to a loadbreak tool and illustrating various operational modes; 
     FIG. 4 is a sectional view of a first subassembly of the operation counter arrangement of FIGS. 1-3 that incorporates the counter and associated circuit components; 
     FIG. 5 is a sectional view of a second subassembly of the operation counter arrangement of FIGS. 1-3 that incorporates an actuator assembly for the operation counter and also functions as an exhaust control device that is assembled onto the loadbreak tool; 
     FIGS. 6 and 7 are perspective views of the second subassembly of FIG. 5 illustrating various features thereof; 
     FIG. 8 is an elevational view of an actuator of the actuator assembly of the second subassembly of FIG. 5; 
     FIG. 9 is a perspective view of the overall operations counter arrangement of FIGS. 1-3; 
     FIG. 10 is an elevational view, partly in section and with parts removed and cutaway for clarity, of an alternate embodiment of an operation counter arrangement of the present invention; 
     FIG. 11 is an adapter component of the operation counter arrangement of FIG. 10; 
     FIG. 12 is a sectional view of a first subassembly of the operation counter arrangement of FIG. 10; 
     FIG. 13 is an elevational view, partly in section and with parts cut away for clarity of another embodiment of the operation counter arrangement of the present invention; and 
     FIG. 14 is an elevational view, partly in section and with parts removed for clarity of an exhaust control device of the type illustrated in FIGS. 1-3 and  10  as implemented for loadbreak tools without the operations counter feature of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1-3 and  9 , an operation counter arrangement  10  of the present invention is shown in conjunction with a trailer portion  14  of a movable contact assembly generally referred to at  16  of an illustrative circuit interrupter, hereafter loadbreak tool  18 , e.g. a portable load-current interrupting tool, e.g. the Loadbuster R  tool available from S&amp;C Electric Company as described in more detail in the Background section. During operation to interrupt a circuit and open a fuse cutout or the like, the trailer portion  14  moves to the left in FIG. 1 whereupon the loadbreak tool  18  internally opens the circuit and interrupts load current. In a specific arrangement, the trailer portion  14  is fabricated from arc-extinguishing material. The loadbreak tool  18  includes an exhaust control assembly  20  and a tube assembly  22  which are assembled via respective threaded portions  24 ,  26 . Accordingly, the operation counter arrangement  10  may be affixed to the loadbreak tool  18  as incorporated onto the exhaust control assembly  20  or via the assembly of the operation counter arrangement  10  onto the existing exhaust control device  20  as illustrated. The operation counter arrangement  10  responds to the movement of the trailer portion  14  during operation thereof in the loadbreak tool  18 . 
     After circuit-opening operation, the loadbreak tool  18  is reset for another operation by closing the loadbreak tool  18  whereupon the trailer portion  14  of the movable contact assembly  16  is moved to the right in FIG.  1  and through the positions illustrated in FIGS. 2 and 3. In a specific embodiment, the operation counter arrangement  10  includes an actuator  30  having an extending portion  32  that is contacted by the trailer portion  14 . For example, as the trailer portion  14  moves to the right from FIGS. 1-3, it moves the actuator  30  to the right from the position of FIG. 2 to the position of FIG. 3 as the trailer portion  14  moves as shown in FIG. 3 with the loadbreak tool  18  being in the closed position and reset for another operation. In a specific arrangement, as the actuator  30  moves to the position of FIG. 3, it actuates an operation counter switch  34  via contact with a switch actuator  36  to increment the operation count. When the loadbreak tool  18  is next operated, the trailer portion  14  moves to the left, from the closed, reset position of FIG. 3 to the position in FIG.  1 . Subsequent resetting of the loadbreak tool  18  results in an additional actuation of the operations counter switch  34 . In another specific arrangement, the operation counter switch  34  is actuated via the switch actuator  36  to increment the operation count as the trailer portion moves to the left from the position of FIG.  3  and through the positions of FIGS. 2 and I as the loadbreak tool is operated during a circuit-opening operation. 
     The actuator  30  is biased to the left in FIGS. 1-3 by a compression spring  37  that is arranged to act between the actuator  30  and a wall  38  that extends from a cap assembly  50  of the operations counter arrangement  10 . The spring  37  is arranged about a post  39  extending from the wall  38 . Thus, when the trailer portion  14  moves to the left from FIGS. 3 to  1 , the actuator  30  follows the portion  14  and stops in the position shown in FIG.  1 . With additional reference to FIG. 8, the spring  37  is received within a central cavity  44  of a widened portion  46  of the actuator  30 . The outer surface of the widened portion  46  includes a ramp surface  48  for actuating the switch actuator  36  of the operation counter switch  34 . The cap assembly  50  is affixed to a cover  60  of the operation counter arrangement  10 . The cover  60  is arranged to interfit with the exhaust control assembly  20 . The exhaust control assembly  20  houses a toroidal screen assembly  62  through which exhaust gases pass during circuit interruption to exit the exhaust control assembly  20  via openings  64  in the cover  60 . 
     The operation counter arrangement  10  includes a counter, associated electrical circuitry and a display assembly referred to generally at  40 , with display element at  41 . Electrical connections referred to at  42  connect the display assembly  40  to the operations counter switch  34  so as to provide a signal to the display assembly  40  to advance the operations count. 
     With additional reference now to FIG. 4, the cap assembly  50  is a generally hollow cylindrical shell. The top of the cap assembly  50  defines a cavity  52  for receiving the display assembly  40  of the counter, circuitry and display element. A circumferential recess  54  is also defined in the top of the cap assembly  50 . As shown in FIG. 1, a circular cover plate  56  of transparent material is affixed in the recess  54 , through which the display element  41  of the display assembly  40  may be viewed to ascertain the operations count, e.g. “0848” representing  848  total operations. In a preferred embodiment, an inside transparent cover  57  is also provided over the cavity  52  to provide additional sealing to and protection of the display assembly  40 . A passage  58  is provided through the top of the cap assembly  50 . As seen in FIGS. 1-3, in one specific embodiment, a reset switch  59  is provided that is accessible via the passage  58  and includes a reset actuator  61 . Actuation of the reset switch  59  via the reset actuator  61  provides a reset signal to the display assembly  40  over electrical connections  63 . In a preferred embodiment, the reset signal is utilized to reset a lap count representing the count since the last maintenance/overhaul or the like while the assembly also maintains an accumulated count of total operations. For example, the display  41  indicates both the total number of operations, e.g. “848” and the number of operations since the most recent maintenance/overhaul procedure, e.g. “348” corresponding to the loadbreak tool  18  having an overhaul at 500 operations. 
     With additional reference now to FIGS. 5-7, the cover  60  is a generally hollow cylindrical shell having a top portion  66  that defines a central opening  67  for passage of the extending portion  32  of the actuator  30 . A recess  68  is also provided around the opening  67  for receiving the widened portion  46  of the actuator  30 . As seen in FIGS. 1-3, in a preferred embodiment, the central opening  67  includes a sealing arrangement at  33  that cooperates with the extending portion  32  to seal the gases that may be generated in the exhaust control assembly  20  from passing into the interior  35  of the cap assembly  50 . In other embodiments, the sealing arrangement may be provided at the base of the recess  68  either alternatively or additionally to the sealing arrangement  33 . The cover  60  fits over the inner portions of the exhaust control assembly  20  and is affixed thereto. Projections  72  on the top  66  of the cover  60  are arranged to support the operations counter switch  34 . To provide electromagnetic shielding to the circuitry and components of the display assembly  40 , the cap assembly  50  and/or the cover  60  are molded from a conductive plastic or the like, or alternatively, coated with a conductive film. 
     Considering now an alternate embodiment of the operations counter of the present invention and referring now additionally to FIGS. 10-12, an operations counter arrangement  80  is shown that includes an actuator switch assembly  82  having a switch actuator  84  that is biased outwardly toward the trailer portion  14  so as to be driven thereby. In operation, the actuator switch assembly  82  is actuated when the trailer portion  14  and the switch actuator  84  moves from the phantom position in FIG. 10 to the solid position as shown in FIG. 10, similarly to the discussion in conjunction with FIGS. 1-3. Accordingly, the switch actuator assembly  82  at output leads  86  provides input signals to the electrical circuit and display assembly  40  to increment the display  41 . The actuator switch assembly  82  is carried by a base plate or member  88  at the base of a cap assembly  100 . The base plate  88  is affixed to a cover  92  of the operation counter arrangement  80  that is arranged to interfit with an exhaust control assembly  90  (the details of the base plate  88  being illustrated in FIG.  11 ). Alternatively, the base plate  88  and the cover  92  are molded integrally. The cover  92  includes a central opening  91  which cooperates and interfits with a shoulder portion  93  (FIG. 11) of the base plate  88 . The exhaust control assembly  90 , as discussed hereinbefore in connection with the exhaust control assembly  20  houses a toroidal screen assembly  62  through which exhaust gases pass during circuit interruption to exit the exhaust control assembly  20  via openings  64  in the cover  92 . The base plate  88  supports an affixed cap assembly  100 , the cap assembly  100  housing the actuator switch assembly  82  and the electrical circuit and display assembly  40  (the details of the cap assembly  100  being illustrated in FIG.  12 ). As best seen in FIG. 11, the base plate  88  includes a central opening at  89  for receiving the actuator switch assembly  82 . As best seen in FIG. 12, cap assembly  100  includes a cavity  52  for receiving the display assembly of the counter, circuitry and display element. A circumferential recess  54  is also defined in the top of the cap assembly  100 . A passage  58  is provided through the top of the cap assembly  100  for resetting the reset switch  59  (FIG. 10) via the reset actuator  61 . 
     In accordance with another embodiment of the present invention and with additional reference now to FIG. 13, an operation counter arrangement  110  includes a mechanical counter/display device  112  that is actuated via actuator arm  114  by the trailer portion  14  and provides a display at  116 . 
     Referring now additionally to FIG. 14, an exhaust control assembly  120  is illustrated that is suitable for use with a loadbreak tool as discussed hereinbefore without the provisions of the operation counter arrangements  10 ,  80  and  110 . For example, the exhaust control assembly  120  is similar in internal construction to the exhaust control assemblies  20  and  90  but includes a cover  122  with a solid top surface  124 . In order to retrofit loadbreak tools  18  that are not equipped with the operation counter arrangement  10 ,  80  or  110 , the existing exhaust control assembly such as  120  or prior available assembly is removed and the exhaust control assembly  20  or  90  with the operations counter arrangement  10 ,  80  or  110  is assembled onto the loadbreak tool. Alternatively, the cover  122  is removed from the exhaust control assembly  120 , and the operation counter arrangement  10 ,  80  or  110  is assembled onto the exhaust control assembly  120  with the cover  60  or  92  being affixed to the exhaust control assembly  120 . 
     While there have been illustrated and described various embodiments of the present invention, it will be apparent that various changes and modifications will occur to those skilled in the art. For example, in other specific embodiments, instead of being actuated by direct contact of the trailer portion, the operation counter arrangement  10  is arranged to sense the movement or proximity of the movable contact assembly  16  or the like. It is intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the present invention.