Patent Publication Number: US-6217370-B1

Title: Circuit breaker accessory module terminal plug

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to electric circuit breakers and more particularly to the indication of the status of a circuit breaker and the remote control of a circuit breaker. 
     2. Description of the Related Art 
     Circuit breakers are commonly used for temporary interruption of electrical power to electrically powered devices. Various circuit breaker mechanisms have evolved and have been perfected over time on the basis of application-specific factors such as current capacity, response time, and the type of reset (manual or remote) function desired of the breaker. 
     One type of circuit breaker mechanism employs a thermo-magnetic tripping device to trip a latch in response to a specific range of over-current conditions. In another type of circuit breaker, referred to as a double-break circuit breaker, two sets of current breaking contacts are included to accommodate a higher level of over-current conditions than can be handled by one set of contacts. U.S. Pat. No. 5,430,419 describes a typical mechanical and electrical assembly that is utilized in circuit breakers according to the present invention and is incorporated herein by reference in its entirety. 
     A circuit breaker has typically three possible statuses: off, where the contacts are open; on, where the contacts are closed for completing a circuit path; and tripped, where the contacts are open because of an abnormal condition. It is desirable to monitor and control a circuit breaker&#39;s status from a remote location, such as in a control center. Systems are known, such as disclosed in U.S. Pat. No. 4,794,356, which provide in the form of a modular accessory a position-indicating switch coupled directly to the movement of an electrical circuit breaker contacter. The systems provide sensing conditions indicative of the contact condition of the circuit breaker and can indicate whether the contacts have become fused together. 
     U.S. Pat. No. 4,794,356 describes a combined trip actuator mechanism and accessory unit for articulating the circuit breaker operating mechanism and interfacing with the accessory unit for remote trip as well as trip indication function. U.S. Pat. Nos. 4,831,221 and 4,912,439 describe auxiliary switch accessories used within industrial-grade circuit breakers. The auxiliary switch accessories interact with the circuit breaker operating mechanism to provide remote indication of the condition of the circuit breaker contacts. U.S. Pat. No. 4,864,263 describes a crossbar unit that carries the movable contact arm and provides an accurate indication as to the actual condition of the contacts. In some instances the auxiliary switch accessory unit operates directly off the circuit breaker operating mechanism crossbar unit to provide an indication of the status of the circuit breaker. 
     U.S. Pat. No. 5,003,139 describes a circuit breaker housing modified to provide an access passage exposing a portion of the circuit breaker blade mechanism to external access and a bolt-on accessory module containing a rotor coupled to a movable coupling member configured to extend through the circuit breaker passage to engage a portion of the blade mechanism. A member carried with the blade mechanism mounted on a trip arm carried with the blade extends toward the passage to engage with the coupling member. A sensing switch is engaged by a camming surface on the rotor so that the rotor will be moved responsively to tripping and resetting of the circuit breaker blade to indicate the true position of the circuit breaker contacts. Rotation of the rotor will trip the circuit breaker when the circuit breaker is in the reset position. A solenoid is provided to engagingly rotate the rotor in the tripping direction. A single coupling element senses the state of the circuit breaker and provides means for remotely tripping it. 
     In general, the present invention pertains to monitoring and control of a circuit breaker from a remote location. Although devices exist for this general purpose, it is believed that a need exists for a circuit breaker accessory module capable of sensing the position of components in the circuit breaker and capable of initiating a change in the status of a circuit breaker. Such an accessory module is preferably reliable and durable and preferably incorporates advances in circuit board and switch technology when such advances improve the accessory module. Practical concerns regarding field installation are preferably addressed, and parts are preferably interchangeable so as to minimize the number of parts required. 
     SUMMARY OF THE INVENTION 
     The present invention provides a device for use with a circuit breaker having at least two positions therein that indicate different statuses of the circuit breaker. The device comprises an apparatus coupled to the circuit breaker for detecting the status of the circuit breaker, a status indicator having a separate state that corresponds to each of the statuses detected by the apparatus, and an actuator associated with the apparatus and the status indicator for communicating the status detected by the apparatus to the status indicator. 
     In another aspect the present invention provides an accessory module for a circuit breaker. The accessory module comprises a base, a mechanism in the base, the mechanism having at least two positions, a circuit board in the base, a position indicator mounted on the circuit board, and an actuator for communicating the position of the mechanism to the position indicator. Preferably, the accessory module further comprises a connector mounted on the board. The accessory module may include a terminal plug engaged with the connector. Preferably the actuator has a pivot, and the circuit board may have a hole for receiving the pivot. 
     In another aspect the invention provides a method for indicating the status of a circuit breaker. The method comprises coupling a mechanism to the circuit breaker, positioning the mechanism in different positions, each position corresponding to a status of the circuit breaker, detecting the position of the mechanism, and indicating the detected position. Preferably the method further comprises sending the indicated position to a remote location. 
     In another aspect the invention provides a printed circuit board for an accessory module for a circuit breaker, wherein the circuit breaker has a status. The printed circuit board comprising a board and a status indicator mounted on the board for indicating the status of the circuit breaker. Preferably, the status indicator is a switch. In a preferred embodiment the circuit board has a hole for receiving a pivot of an actuator cooperating with a switch on the circuit board. 
     In another aspect the invention provides an actuator for an accessory module for a circuit breaker, wherein the circuit breaker has a status. The actuator communicates the status of the circuit breaker and has a body. The body has a shape of a generally rectangular plate with at least one bend, first and second ends, and a pivot proximate to the first end. 
     In another aspect the invention provides a terminal plug having a pull tab, and a pull tab for a terminal plug so that an inaccessible plug can be removed from a connector. Preferably, a pull tab comprises a flexible sheet having adhesive on one side and a paper covering the adhesive. A pull tab is preferably secured to a terminal plug during assembly and preferably extends from an enclosure housing the terminal plug. 
     In another aspect the invention provides a dual-function base for holding and enclosing components of an accessory module attached to a circuit breaker and for spacing. The base has an inside surface for receiving components of an accessory module and for connection to an inside surface of a cover for enclosing the components, and an outside surface for connection to the circuit breaker, wherein the outside surface of the base is designed to also matingly engage an outside surface of the cover so that a second base can be used as a spacer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a detailed understanding of the present invention, references should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein: 
     FIG. 1 shows an isometric view of an accessory module of the present invention without its cover. 
     FIG. 2 shows a plan view of the accessory module of FIG. 1 with its mechanism in a first position. 
     FIG. 2A shows the accessory module of FIG. 1 with its internal mechanism in a second position. 
     FIG. 3 shows an isometric view of the top side of a circuit board, switches, and actuators according to the present invention. 
     FIG. 4 shows the actuators of the present invention. 
     FIG. 5 shows a plan view of a circuit board, according to the present invention. 
     FIG. 6 shows a terminal plug engaged with an accessory module, according to the present invention. 
     FIG. 7 shows the terminal plug of FIG. 6 removed from the accessory module. 
     FIG. 8 shows an isometric view of a connector, according to the present invention. 
     FIG. 9 shows an end view of the connector of FIG.  8 . 
     FIG. 10 shows an accessory module connected to a circuit breaker, and illustrates the use of a base as a spacer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An accessory module is attached to the side of a circuit breaker, and as will be discussed in more detail below, the accessory module has a mechanism for interacting with a circuit breaker. The mechanism can both detect the status of a circuit breaker and change that status, based on input from an outside source, i.e. a signal. In general, the accessory module completes certain circuits based on the status of the circuit breaker and thus serves as an indicator. Such indications can be sent to a remote site by electronic signals. On the other hand the accessory module can receive electronic signals from a remote site and change the status of a circuit breaker based on those signals. The mechanism cooperates with a printed circuit board having switches to perform various functions. Actuators transmit the mechanical motion of the mechanism to the switches. A coil and associated circuitry transform an electronic signal into mechanical motion of the mechanism in the accessory module, which is in turn transmitted to the circuit breaker. 
     In general, the mechanism used in the accessory module is a part-for-part duplication of the mechanism used in a circuit breaker. The design of the mechanism reflects a method of relaying the position of specific parts to a set of switch actuators that initiate circuit opening or closing based on the relationship between part position and circuit breaker condition. The accessory mechanism is controlled by handle keys and crossbars in a similar manner as control and/or manipulation is performed between circuit breaker poles. By using the same combination of crossbars, handle keys, and mechanisms between the circuit breaker and the accessory module as is used between poles in a circuit breaker, an accessory module is created that performs with the excellence expected of a circuit breaker. 
     Shunt tripping energizes a coil that is linked to an accessory armature, which delatches a trip lever conveying that information to an adjoining circuit breaker via action of a crossbar. A bell alarm or alarm switch activates when the trip lever in the accessory module is delatched by shunt tripping or by rotation of the crossbar. A clearing switch provides an energy drain for the shunt. Contacts in the clearing switch are normally closed and open after the coil is energized. When the coil is energized, the trip lever is delatched, which changes the status of the clearing switch. An activation switch for the accessory module itself is switched by a blade position, which is controlled by the switch handle position of the associated circuit breaker. A shunt trip circuit is activated when the circuit breaker switch handle is in the “on” position and deactivated when the handle is in the “off” position. The mechanism in the accessory module has its own stored energy for initiating the required mechanical motion. Energy is stored in a spring during assembly of the mechanism. 
     Turning now to the drawings, FIG. 1 shows an isometric view of an accessory module  10  without its cover. FIG. 2 shows a plan view of the accessory module  10  of FIG.  1 . FIG. 2A shows the accessory module  10  with its internal mechanism in a second position. The accessory module  10  having its cover (not shown) is attached to the side of a circuit breaker (not shown) by screws, rivets or similar means through holes  12 . A shaft or crossbar (not shown) extends from the switch handle of the circuit breaker into a hole  14  in a dummy handle  16  of the accessory module  10 . By this shaft the position of the switch handle in the circuit breaker is imitated by the dummy handle  16  in the accessory module  10 . The hole  14  is illustrated as square in shape, although other shapes may be used. However, the shaft should not pivot in the hole  14 , but rather should rotate the dummy handle about a pair of pivots  18 . (The second pivot is not shown, but is located on the opposite face of the dummy handle  16 .) 
     The dummy handle  16  has a forked projection  20  which has a bearing surface  22 . The bearing surface  22  is a cam with respect to the dummy handle  16 . An actuator blade  24  pivots in the bearing surface  22 . The actuator blade  24  has a pivot end  26  that pivots in the bearing surface  22  and a free end  28 . A trip lever  30  rotates on a pivot  32  that is molded into a base  34 . A mechanism spring  36  is attached at one end to a hook  38  on the actuator blade  24  and at its other end to a hook  40  on the trip lever  30 . The hook  40  is shown as a hidden line below the forked projection  20  in FIG.  2 . Rotation of the dummy handle  16  causes the free end  28  of the actuator blade  24  to move from a first position illustrated in FIG. 2 laterally to a second position illustrated in FIG.  2 A. 
     The first position of the free end  28  of the actuator blade  24 , which is illustrated in FIG. 2, occurs when the switch handle of the attached circuit breaker is in its “on” position, meaning that a circuit path is established between a source and a load through the circuit breaker. The second position of the free end  28  of the actuator blade  24 , which is illustrated in FIG. 2A, occurs when the switch handle of the attached circuit breaker is in its “off” or “trip” position, meaning that a circuit path between the source and the load through the circuit breaker is open. Tension can be put on the mechanism spring  36  to store energy in the spring  36 . This stored energy will be discussed more fully below, but it is used to drive the mechanical action that occurs when the circuit breaker switch handle moves to the “trip” position. 
     A force is transmitted from the circuit breaker switch handle through a shaft or crossbar (not shown) which is normally positioned in the hole  14  of the dummy handle  16 . The circuit breaker switch handle is similar to the dummy handle  16 , but has a lever that extends outward from the body of the handle for manual operation. The crossbar has one end in the hole  14  and an opposing end in a similar hole in the switch handle. Rotation of the switch handle in the circuit breaker causes the dummy handle  16  to rotate, since the two are linked by the crossbar. 
     The bearing surface  22  on the forked projections  20  moves in a cam-like motion, which is both lateral and reciprocating. The pivot end  26  of the actuator blade  24  is pressed into the bearing surface  22  by the tension on the mechanism spring  36 . With the dummy handle  16  in the position shown in FIGS. 1 and 2, the tension on the spring  36  tends to pull the free end  28  of the actuator bar  24  toward the left side  42  of the base  34 . A stop  44  is molded into the base  34 , which stops the free end  28  of the actuator bar  24  from moving further to a left  42 . Rotation of the handle  16  moves the bearing surface  22  and the pivot end  26  of the actuator blade  24 . Rotation causes a realignment of the spring  36  which causes the end  28  of the actuator blade  24  to swing to the second position illustrated in FIG.  2 A. This realignment of the spring  36  is called over-toggling. 
     The trip lever  30  is in a latched position with the spring  36  in tension, while in the position shown in FIGS. 1, and  2 . An armature blade  48  has a slot  50  which receives a tip of a free end  46  of the trip lever  30 . A pin  51  in the trip lever  30  engages the projection  20  to latch the trip lever  30  when the handle  16  is rotated. A bearing bracket  52  is secured in the base  34  and has bearing notches  54 . One end of the armature blade  48  is notched to engage with and pivot on the bearing notches  54 . An armature spring  56  is normally under a compressive force which pushes a pivot end  58  of the armature blade  48  toward a right side  60  of the base  34 . Pushing the pivot end  58  to the right  60  causes a free end  62  of the armature blade  48  to move toward the left side  42 . Thus, the compressive force of the armature spring  56  presses the free end  62  to the left  42 . This force keeps the free end  46  of the trip lever  30  engaged in the slot  50  in the armature blade  48 . The trip lever  30  stays in this stable position until the free end  62  of the armature blade  48  is forced to the right  60 . 
     The armature blade  48  can be forced to the right  60  by a solenoid, a shunt trip coil  64 . The shunt trip coil  64  has a plunger  66  which is connected to the free end  62  of the armature blade  48  by a trip link  68 . The plunger  66  has a groove around its circumference and the trip link  68  has a cooperating slot that engages the groove, connecting the plunger  66  to the trip link  68  for lateral movement between left  42  and right  60 . The trip link  68  has an inverted “U” shape that cooperatively fits over the free end  62  of the armature blade  48 . The various mechanical parts that cooperate, including the dummy handle  16 , actuator blade  24 , trip lever  30 , mechanism spring  36 , armature blade  48 , and armature spring  56 , are referred to hereafter as a mechanism  69 . 
     When the shunt trip coil  64  is energized, the plunger  66  is pulled into the coil  64 . The movement of the plunger  66  to the right  60  pulls the free end  62  of the armature blade  48  to the right  60 . The movement of the armature blade  48  to the right  60  causes the free end  46  of the trip lever  30  to slide out of the slot  50  in the armature blade  48 . The stored tension energy in the mechanism spring  36  pulls the free end  46  of the trip lever  30  towards a bottom side  70  of the base  34 . The trip lever  30  rotates on its pivot  32 . The trip lever  30  is shaped such that the spring hook  40  moves toward the right  60  when the free end  46  is disengaged from the slot  50 . The lateral movement of the spring hook  40  toward the right  60  changes the alignment of the spring  36 , causing the free end  28  of the actuator blade  24  to move laterally to the right  60 . Thus, the actuator blade end  28  moves into its second position after the shunt trip coil  64  is energized. 
     The second position of the actuator blade  24  is illustrated in FIG. 2A, and the delatched position of the trip lever  30  is illustrated. The mechanism spring  36  has been omitted for clarity. The difference is that in the delatched position the end  46  of the trip lever  30  is moved toward the bottom side  70  and the end  46  is not engaged in the slot  50 . Near its pivot  32 , the trip lever  30  has a lateral movement to the right  60  when the end  46  is suddenly delatched. As discussed below, this movement is monitored and detected. 
     The shunt trip coil  64  can be energized by a remote electrical signal. This causes the response described above and trips the adjoined circuit breaker. The trip lever  30  has an ear  72  which contacts and rotates a trip cam  74  when the trip lever end  46  becomes disengaged from the slot  50 . The trip cam  74  has a hole  76 , similar to the hole  14  in the dummy handle  16 . A trip crossbar or shaft (not shown) extends from the hole  76  to a similar hole in a similar trip cam in the adjacent circuit breaker (not shown). To effect the rotation of the trip cam in the circuit breaker, the trip cam  74  and its crossbar are preferably square because this shape transmits torque to the adjoining trip cam rather than pivoting. A remote signal can be used to energize the shunt trip coil and, consequently, trip the circuit breaker. After such a trip the mechanism would remain in this state until the attached circuit breaker is reset to its “on” position. 
     The trip cam  74  also works to trip the accessory module  10  when the adjoining circuit breaker is tripped. If the circuit breaker experiences an abnormal condition that causes it to trip, then the trip crossbar rotates the trip cam  74 , which moves the armature blade to the right  60 . This delatches the end  46  from the slot  50  in the armature blade  48 . 
     The end  28  of the actuator blade  24  is moved toward the right  60  whenever the circuit breaker contacts are open. If the handle  16  is rotated to the “off” position, the spring  36  is over-toggled, and the end  28  is snapped to the right  60 . If the circuit breaker handle is in the “on” position, but is then moved to the “tripped” position, the trip lever  30  is delatched and the movement of the hook  40  on the trip lever  30  over-toggles the spring  36 , causing the end  28  to be snapped to the right  60 . The end  28  is toward the right whenever the circuit breaker contacts are open. 
     With the operation of the mechanism  69  thus explained, consider now how the physical position of the mechanism  69  is detected and that signal transmitted. As best seen in FIG. 2, the trip lever  30  contacts a first actuator  80  when the mechanism  69  is in the latched position illustrated in FIG.  2 . With reference to FIG. 3, the first actuator  80  has a pivot  82  that snaps into a hole  83  in a printed circuit board  84 . As best seen in FIG. 4, the pivot  82  is a pin with a longitudinal slot  86  and barbs  88 . The actuator  80  rotates about the pivot  82 . As best seen in FIG. 2A, the actuator  80  contacts a button  90  on an alarm switch  92 , sometimes referred to as a bell alarm switch. When the mechanism  69  is in the latched position illustrated in FIG. 2, the trip lever  30  presses on the actuator  80 , which rotates about its pivot  82 , and depresses the button  90 . When the trip lever end  46  is disengaged from the slot  50 , the trip lever  30  moves to the right  60 , which allows the button  90  to protrude to its fullest extent. In this manner the alarm switch  92  detects the position of the trip lever  30 , which indicates the status of the adjacent circuit breaker, i.e. whether the circuit breaker is tripped. Thus, the trip status of the adjacent circuit breaker can be inferred from the status of the alarm switch  92 . The status of the alarm switch  92  can be indicated in a remote control center. 
     A second actuator  94  is essentially identical to the first actuator  80 . The first and second actuators  80 ,  94  are designed to be interchangeable, thus reducing the number of parts required for the accessory module  10 . The second actuator  94  rotates about a pivot  96  which snaps into a hole  97 . The actuator  94  contacts a button  98  on a shunt clearing switch  100 . When the mechanism  69  is in the latched and “on” position illustrated in FIG. 2, the free end  28  of the actuator blade  24  presses or forces the actuator  94  to the left  42 . 
     A third actuator  102  is strategically located so that movement of the second actuator  94  is also transmitted to the third actuator  102 . The third actuator  102  rotates about a pivot  104  and engages a third button  106  in an auxiliary switch  108 . The buttons  98 ,  106  can be either depressed or extended while the button  90  is depressed. If the button  90  is extended outward, then the trip lever  30  is in its tripped or delatched position, which moves the end  28  to the right  60 , releasing the buttons  98 ,  106 . If the button  90  is out, then necessarily, the other two buttons are out. The buttons  98 ,  106  can be either in or out while the button  90  is in. As described above, when the trip lever  30  is disengaged from the armature blade  48 , the free end  28  of the actuator blade  24  moves laterally to the right  60 . This removes the force that was applied to the second actuator  94 , which, in turn, removes the force that the second actuator  94  applied to the third actuator  102 . The three buttons  90 ,  98 ,  106  are spring loaded so that when the force holding the actuators  80 ,  94 ,  102  is removed, the buttons  90 ,  98 ,  106  extend to their fullest outward position. 
     The clearing switch  100  normally completes a circuit path when the adjacent circuit breaker is not tripped and its contacts are closed, completing its circuit path. The clearing switch  100  is in a circuit path with the shunt trip coil  64 . If the shunt trip coil  64  is energized, the mechanism  69  and the adjacent circuit breaker are both tripped. This opens the clearing switch  100  and de-energizes the shunt trip coil  64 , since that circuit path is broken when the button  98  is released. The clearing switch allows the coil  64  to reset to its normal deactivated state. 
     The auxiliary switch  108  can be used to infer whether the adjoining circuit breaker is in its “on” or “off” or “tripped” position. The position of the end  28  mimics the position of a movable contact in the adjoining circuit breaker. When the movable contact in the adjoining circuit breaker is toward the left  42 , it contacts a stationary contact and establishes a circuit path. When the movable contact in the adjoining circuit breaker is toward the right  60 , it does not contact the stationary contact, which breaks its circuit path. Thus, from the position of the end  28 , the position of the movable contact in the adjoining circuit breaker can be inferred. The position of the end  28  is sensed by the auxiliary switch  108  through the actuators  94  and  102 . The state of the auxiliary switch  108  is therefore correlated to the status of the adjoining circuit breaker. The state or status of the auxiliary switch  108  can be monitored from a remote control center, and the status of the adjoining circuit breaker can be inferred therefrom. Further, the status of the alarm switch  92  and the status of the auxiliary switch  108  can be interpreted together to infer the status of the adjoining of the adjoining circuit breaker. 
     Consider now the actuators  80 ,  94 ,  102 , which are made of a flexible and resilient material, typically a thermoplastic. The design of the actuators offers many advantages. The material is sufficiently stiff to ensure activation, yet flexible enough to prevent over-actuation that would damage the switches  92 ,  100 ,  108 . Over-actuation could otherwise result because the mating parts are made of high strength material. The design of the pivots  82 ,  96 ,  104  with the slot  86  provides compressibility, allowing them to directly engage the circuit board  84 . Thus, a separate mechanical fastener is not needed to fasten the actuators  80 ,  94 ,  102  to the circuit board  84 . The ends of the pivots  82 ,  96 ,  104  are compressed during insertion of a pivot into the aligning hole in the circuit board. The barb or hook on the end of a pivot slides through the opening in the circuit board because the slot  86  allows it to be compressed. The resiliency of the material causes the pivot pin to expand back to its normal size. The barbs or hooks engage the circuit board and prevent the pivots from backing out. 
     The shape of the actuators  80 ,  94 ,  102  somewhat resembles an “L” shape. The shape, location of the pivots  82 ,  96 ,  104 , and point of contact with the mechanism  69  were all designed to transform or scale down the large movement of the mechanism parts, the trip lever  30  and the blade actuator  24 , to a small movement required for the for the switch buttons  90 ,  98 ,  106 . The circuit board  84  was particularly designed to fit in the base  34  and provide a surface for mounting the switches  92 ,  100 ,  108  and actuator pivots  82 ,  96 ,  104 . Utilizing two identical actuators  80 ,  94  in different locations in a confined space was accomplished in the design by strategically placing the switches  92 ,  100 ,  108  on the circuit board  84 . 
     The thermoplastic actuators  80 ,  94 ,  102  act as a link between the mechanism  69  and the switches  92 ,  100 ,  108 . The flexibility of the actuators eliminate the need to hold tight positional tolerances on the switches or the actuators. The snap-in feature of the pivots  82 ,  96 ,  104  eliminate the need for rivets or screws. When the mechanism  69  is latched, as shown in FIG. 2, one set of signals or information is conveyed to the switches  92 ,  100 ,  108  through the actuators  80 ,  94 ,  102 . When the mechanism  69  is tripped, a different set of signals or information is conveyed to the switches  92 ,  100 ,  108  through the actuators  80 ,  94 ,  102 . 
     Turning now to the accessory circuit board  84 , an isometric view of its top  110  is provided in FIG. 3 and a plan view of its bottom  112  is provided in FIG.  5 . The circuit board  84  serves as a locator of moving parts that pivot in the board and actuate the switches. Electrically conductive foil traces  114  are provided on both the top  110  and the bottom  112 . All current carrying aspects of the accessory module  10  are incorporated into the circuit board  84 , its traces  114 , the switches  92 ,  100 ,  108 , the coil  64 , and a mounted seven-pin connector  116 . The connector  116  provides a receptacle for a terminal plug  126  (discussed below) for communication of signals with a remote site. The traces  114  eliminate the need for wires connecting the switches  92 ,  100 ,  108 . Wires are typically hand soldered at their connections, while the traces  114  are machine made and tend to be of higher quality. The machine made traces  114  can be produced for lower cost than hand-soldered wiring. 
     Some of the foil traces  114  have been sized and positioned to attain an unusually high current rating for a printed circuit board, and the auxiliary switch  108  is also designed for an unusually high current rating as well. The traces  114  for the auxiliary switch  108  have a maximum 13 ampere rating. The traces  114  are located both on the top  110  and the bottom  112  of the circuit board  84 . The circuit board  84  is mounted in the base  34  and in the mating cover (not shown) with a clearance between the traces  114  and the interior surfaces of the base  34  and cover. The thickness of the board is sized for proper insulation between the top  110  and bottom  112  traces  114  and for proper positioning of cooperating parts between the mechanism  69  and the actuators  80 ,  94 ,  102 . 
     The circuit board  84  is positioned in the base  34  by the mating of a hole  118  in the circuit board  84  about a post  120  on the base  34 , as best illustrated in FIGS. 1 and 3. The edges  122  of the circuit board  84  are designed to act as limiters which orient the board  84  within walls  124  of the base  34 . In this manner the circuit board  84  is firmly positioned in the base  34  and sufficiently secured to detect movement of the mechanism  69 . 
     The switches  92 ,  100 ,  108  are mounted on the board  84  at a right angle to the board  84 . As best seen in FIG. 5, each switch  92 ,  100 ,  108  has three pin connectors, but all three are not necessarily used. The alarm switch  92  activates when the trip lever  30  is delatched from the armature blade  48  by shunt tripping or the rotation of the trip crossbar. The alarm switch  92  monitors whether the mechanism  69  is in a tripped position. Thus, it detects an abnormal condition, which may be due to a current overload. This status is communicated to a remote site by current through the traces  114  to the connector  116  which connects with a terminal plug. The alarm switch  92  can activate an alarm in a remote control center when the adjoining circuit breaker is tripped. 
     The clearing switch  100  deactivates the shunt trip coil  64  after its has been activated. A trace  114  connects one pin of the second switch  100  to a pin from the shunt trip coil  64 . Under normal conditions, the attached circuit breaker would have its contacts closed making a circuit. In this normal condition the mechanism  69  would be in the position illustrated in FIG. 2, and the button  98  on switch  100  would be depressed. With the button  98  depressed, a circuit is made with the shunt trip coil  64 , but in this normal condition, the circuit is deactivated. A remote signal can energize the coil  64  through this circuit, which causes the trip lever  30  to delatch, allowing the button  98  to open outward. When the button  98  projects outward, the circuit with the coil  64  is opened, deactivating the coil  64 . 
     The auxiliary switch  108  monitors whether the circuit breaker contacts are open or closed. The auxiliary switch  108  detects whether the associated circuit breaker is in its “on” or “off” position. This switch  108  is more than merely a toggle switch having two positions, and all three of its pins are used. The auxiliary switch  108  on/off status is based on the blade end  28  position which is controlled by the handle position of the circuit breaker. A shunt trip circuit is deactivated by the clearing switch  100  based on the blade end  28  position, where “on” indicates activation and “off”indicates deactivation. The traces  114  provide circuit paths between the switches  92 ,  100 ,  108 , the coil  64 , and the connector  116 . 
     With reference to FIGS. 6 and 7, a terminal plug  126  engages with the connector  116 . The terminal plug  126  has seven slots  128  for receiving wires from a remote site. The terminal plug  126  has a pull tab  130  adhered to it. An installer can grasp the pull tab  130  and pull the terminal plug  126  out of the accessory module  10 . This disconnects the terminal plug  126  from the connector  116 . The installer can insert wire ends into the slots  128  and tighten lugs  131  in the holes  132 . A cover  134  covers the base  34 , which makes the terminal plug inaccessible. Without the pull tab  130 , field installation of wires into the plug  126  would be impractical because the cover  134  would have to be taken off the base  34  in order to access the plug  126 . The pull tab  130  is a sheet of strong, flexible plastic material having an adhesive coating on one side and a removable paper sheet covering the adhesive. The paper is scored near one end for removal of a minor portion of the paper when assembling the pull tab  130  onto the terminal plug  126 . A major portion of the paper is left adhered to the plastic sheet. 
     As seen best in FIG. 7, the plug  126  has female connectors  136  that mate with male connector pins in the connector  116 . With the wires installed, the plug  126  can be inserted into the connector  116 . The plug  126  cannot be inserted wrongly, because there is only one position where the connector  116  will engage with the plug  126 . This functionality is provided by raised surfaces  138  and a rounded or sculpted bottom portion  140  of the plug  126 . 
     FIG. 8 shows an isometric view of the connector  116 , and FIG. 9 shows an end view of the connector  116 . The connector  116  has receiving slots  142  for mating with the surfaces  138  in the plug  126 . The connector  116  also has a rounded or sculpted bottom  144  for mating with the rounded or sculpted bottom  140  of the plug  126 . As shown in FIG. 8, the connector  116  has a shoulder  146 , and the plug  126  has extending clips  148 . When the plug  126  is inserted into the connector  116 , the clips  148  engage the shoulder  146 , holding the plug  126  and the connector  116  together in a locked position. Connector pins  149  are also illustrated in FIGS. 8 and 9. 
     Thus, the accessory terminal plug  126  provides a means of connecting the internal accessory components with an external, user-defined circuit, and allows easy installation of wire leads by removal of the plug  126  from the accessory module  10 . The plug  126  and pull tab  130  eliminate the need for pigtails or wire leads to be shipped with the accessory module  10  and the cost and quality problems associated with soldering lead wires for later field connection. The combination of the connector  116 , terminal plug  126 , and pull tab  130  is adaptable to other devices or enclosures where the flexibility and convenience of removing the plug for wire installation is advantageous. 
     Turning now to another aspect of the present invention, FIG. 10 illustrates the multifunctionality of the base  34 . For some installations of an accessory module  10  (in an I-Line panelboard, for example), a spacer is required to adapt the width of the circuit breaker and the accessory module  10  to the requirements of the panel. The base  34  has been designed to function both as a casing for the mechanism  69 , circuit board  84 , etc. and as a spacer. The use of the base  34  as a casing has been illustrated throughout the discussion above. However, the base  34  can be flipped over and used as a spacer. As a spacer, the base  34  adapts the assembly to the requirements of the panel. 
     With reference to FIG. 10, a base  34 ′ can be mounted to the cover  134  of an accessory module  10 . The accessory module  10  comprises a base  34 , holding and locating the mechanism  69 , the circuit board  84 , and other internal accessories, and a cover  134 . The mounting holes in the base  34  are positioned to allow for a screw to fasten the cover  134  and base  34  to a circuit breaker  150  via through-holes in the base  34 ,  34 ′. The bottom side  70  of the base has one through-hole  152  countersunk for a screw to be used to attach the flipped-over base  34 ′ to the cover  134 . An additional countersunk through-hole  154  is required in the base  34 ,  34 ′ to complete the spacer installation. A total of three holes exist in the base  34 ,  34 ′. Two of the holes  152 ,  154  are countersunk on the flat bottom-side to allow for the dual functioning of the base  34 ,  34 ′. Use of the base  34  as a spacer  34 ′ reduces the overall number of parts required to furnish the circuit breaker  150  with an accessory module  10 . 
     In summary, the invention provides an accessory module  10  having an assembly  69  of various mechanical parts that cooperate to mimic the operation of similar parts in a circuit breaker. Like a circuit breaker, the accessory module  10  has a handle  16 , a trip lever  30 , a movable contact point  28  on an actuator blade  24 , a mechanism spring  36 , and an armature  48 . Actuators  80 ,  94 ,  102  sense, monitor, and detect the position of the trip lever  30  and the blade contact end  28 . The actuators transfer the motions of the mechanical assembly  69 , particularly the trip lever  30  and the blade contact end  28 , to switches  92 ,  100 ,  108  which transform the movement into electrical signals by either making or breaking a circuit. A circuit board  84  is especially designed to hold and locate the switches and provide tracings that can withstand high currents. A terminal plug  126  provides a convenient and useful means for field installation of wires for connection of the accessory module  10 . In some applications a spacer is required for the accessory module  10 , and the base  34  has been designed to function in a dual capacity as a base  34  and as a spacer  34 ′. 
     The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention. It is intended that the following claims be interpreted to embrace all such modifications and changes.