Rotary lockout tagout latch system

A latch system for an electrical equipment enclosure includes a chassis and a latch arm, engaged with a circuit breaker, that moves between first, second, and intermediate arm positions. A handle operatively connected to the circuit breaker is movable between ON, TRIP, OFF, and RESET handle positions. The handle is operatively connected to the latch arm such that the latch arm is positioned in the second arm position when the handle is located in said RESET handle position. The latch arm spring biases the latch arm into the first or intermediate positions when the handle is in the ON, TRIP, or OFF handle position. A lockout plunger is connected to the handle to rotate with the handle and is movable between disengaged and engaged positions. The lockout plunger prevents movement of the handle from the OFF to the ON handle position when the lockout plunger is in its engaged position.

BACKGROUND INFORMATION

During maintenance of industrial equipment, it is often necessary for service personnel to work on machinery which could pose a hazard if not fully deenergized, or if accidentally reenergized, during the maintenance operation. For this reason, it is known to use lockout-tagout (LOTO) procedures to ensure disconnection of operative electrical power to such equipment for maintenance and to prevent accidental premature reconnection of electrical power to the equipment. In particular, it is known to equip the access door of cabinets/enclosures that house equipment with a rotating or pivoting latch that both latches and unlatches the door and also controls a circuit breaker or electrical contactor to prevent service personnel from unknowingly opening the access door while the equipment is energized and to prevent the equipment from being inadvertently energized when the door is open.

BRIEF DESCRIPTION

In accordance with one aspect of the present development, a latch system for an electrical equipment enclosure includes a latch arm receiver adapted to be connected to an associated enclosure door. A latch arm assembly is adapted to be connected in operative engagement with an associated circuit breaker. The latch arm assembly includes a chassis and a latch arm that moves relative to the chassis between: (i) a first arm position; (ii) a second arm position; and (iii) an intermediate arm position between the first arm position and the second arm position. A latch arm spring biases the latch arm toward its first arm position. A handle is rotatably connected to the chassis and operatively connected to the toggle of the circuit breaker. The handle is movable to and between an ON handle position, a TRIP handle position, an OFF handle position, and a RESET handle position. The handle is operatively connected to the latch arm such that the latch arm is positioned in the second arm position when the handle is located in said RESET handle position. The latch arm spring biases the latch arm into one of the first position and the intermediate position when the handle is in any one of said ON handle position, said TRIP handle position, and said OFF handle position. A lockout plunger is connected to the handle to rotate with the handle and is movable between a disengaged position and an engaged position, wherein the lockout plunger prevents movement of the handle from the OFF handle position to the ON handle position when the lockout plunger is in its engaged position.

In accordance with another aspect of the present development, an enclosure includes a body including an internal space and an enclosure opening that provides access to the internal space. A door is movable between a closed position and an opened position, wherein the door covers the enclosure opening and blocks access to the internal space in the closed position, the door including a door opening defined therein. A latch system is connected to the body in the internal space and includes a latch arm receiver connected to door. A circuit breaker controls connection of electrical power to associated equipment located in the internal space of the body. The circuit breaker includes a toggle that moves between a first toggle position, a second toggle position, a third toggle position, and a fourth toggle position corresponding respectively to ON, TRIPPED, OFF, and RESET operative states of the circuit breaker. A latch arm assembly is connected to the circuit breaker in operative engagement with the circuit breaker toggle to move the toggle between said first, second, third, and fourth toggle positions. The latch arm assembly includes a chassis and a latch arm that moves relative to the chassis between: (i) a first arm position; (ii) a second arm position; and (iii) an intermediate arm position between the first arm position and the second arm position. A latch arm spring biases the latch arm toward its first arm position. A handle is rotatably connected to the chassis and operatively connected to the toggle of the circuit breaker. The handle is movable to and between an ON handle position, a TRIP handle position, an OFF handle position, and a RESET handle position. The handle is operatively connected to the latch arm such that the latch arm is positioned in the second arm position when the handle is located in said RESET handle position. The latch arm spring biases the latch arm into one of the first position and the intermediate position when the handle is in any one of said ON handle position, said TRIP handle position, and said OFF handle position. A lockout plunger is connected to the handle to rotate with the handle and is movable between a disengaged position and an engaged position, wherein the lockout plunger prevents movement of the handle from the OFF handle position to the ON handle position when the lockout plunger is in its engaged position.

DETAILED DESCRIPTION

FIGS.1&2provide front isometric views of electrical enclosure or electrical cabinet E including a rotary latch system10in accordance with an embodiment of the present disclosure. As shown inFIG.2, the enclosure E includes a body B that defines an interior space S. At least one of the walls of the enclosure include an opening O that provides access to the interior space S. The enclosure E includes a door D that is selectively movable to and from: (i) a closed position as shown inFIG.1where the door D is located adjacent the body B in covering relation with the access opening O to seal the space S from the environment external to the cabinet and to prevent access to the space S via opening O; and (ii) an opened position as shown inFIG.2where the door D is moved to a position wherein it is spaced outwardly away from the body B and away from the access opening O to allow user access to the interior space S via opening O. In the illustrated embodiment, the door is pivotally connected to the body B and pivots between its closed and opened positions, but it can be slidably or otherwise movably connected to the enclosure B or can be completely removable and removed from the body B in the opened position without departing from the overall scope and intent of the present development.

With continuing reference toFIGS.1&2, the rotary latch system10selectively captures the door D in its closed position when the latch system10is in a first or latched condition or state. The latch system10includes a handle H that is selectively rotated by a user to reconfigure the latch system10from a latched condition to an unlatched condition or state in which the latch system10is disengaged from the door D and allows movement of the door D from its closed position to its opened position.

Referring also toFIGS.3-5, the latch system10includes a manually rotatable latch handle H that is manually rotatable by a user about an axis of rotation that is typically but not necessarily a horizontal axis of rotation. The door D includes a latch handle opening DO that allows access to the latch handle H when the door D is in its closed position. As shown herein, the latch handle H projects outwardly through the latch handle door opening DO beyond the door D when the door is closed, but the latch handle H can remain entirely within the space S and be recessed relative to the door opening DO when the door D is closed so that the user can access and rotate the handle H through the opening DO.

With continuing reference toFIGS.3-5, the latch system10is located adjacent and operatively associated with a circuit breaker CB that controls the flow or conduction of electrical power to electrical equipment or electrical components located within the interior space S of the enclosure E. The illustrated circuit breaker CB has four functional positions or states: ON, TRIPPED, OFF, RESET, but other suitable circuit breakers can be used. The ON state is a conductive state as manually set by a user, the TRIPPED state is a non-conductive state resulting from the circuit breaker automatically tripping (becoming non-conductive) due to electrical or other operative conditions, the OFF state is a non-conductive state as manually set by a user to interrupt electrical power, and the RESET state is manually set by a user to reset the contacts of the circuit breaker after the circuit breaker has entered the TRIPPED state. The circuit breaker CB can be provided by any other electrical power conduction control component such as contactor, switch, circuit breaker or the like. As described in more detail below, the latch system10is operatively associated with the circuit breaker CB to ensure that: (i) when the door D is latched in its closed position, the door D cannot be moved from its closed position to an opened position when the circuit breaker CB is in its ON (conductive) state unless the latch system10is intentionally bypassed by a defeater system as described below; and (ii) when the door D is in an opened position and the circuit breaker handle CB is in its OFF (non-conductive) state, the handle H cannot be operated to set the circuit breaker CB to its ON (conductive) state unless the latch system10is intentionally bypassed by a user as described below.

As shown inFIG.5, the latch system10comprises a first group of latch system components10A that are operatively connected to the door D including an exterior bezel20connected adjacent an exterior surface of the door D around the door opening DO, a resilient door seal22located adjacent an interior surface of the door D around the door opening DO, and an interior bezel24located adjacent the interior surface of the door D around the door opening DO and over the door seal22. A plurality of fasteners F1are used to connect the exterior and interior bezels20,24together with the door D and door seal22sandwiched therebetween. The interior door bezel24comprises a latch arm receiver26that projects outwardly therefrom. The latch arm receiver26comprises an inclined ramp26athat extends from a leading (low) end26a1to a trailing (high) end26a2. The latch arm receiver26further comprises a lock face26bwith a first end that transversely intersects the trailing end26a2of the inclined ramp26aand with an opposite second end that connects to a latch arm recess26c.

The latch system10further comprises a second group of latch system components10B (FIG.5) including a rotary handle latch assembly30connected to the enclosure body B inside the space S. The latch assembly30, shown by itself inFIG.6, is operatively engaged with the circuit breaker CB. The latch assembly30includes a chassis32that contains and/or supports the components described below. The latch assembly30further comprises a latch arm40that projects outwardly therefrom and that moves between a first (down) arm position (shown inFIGS.6&12) and a second (up or unlatched) arm position as shown inFIG.13. The latch assembly30further comprises the rotatable handle H described above by which a user manually controls and changes the position of the latch arm40and by which the user manually controls and changes the state of the circuit breaker CB.FIG.3shows the latch arm40located in an intermediate (latched) arm position between the first (down) and second (up/unlatched) positions where it is engaged with and captured by the latch arm receiver26when the door D is located in its closed position such that the latch arm40is captured in the latch arm recess26cbehind and adjacent the lock face26bwhereby engagement between the latch arm40and lock face26bprevents movement of the door D from its closed position to its opened position. The latch arm40is operatively connected to the handle H of the latch assembly30such that when the handle H is rotated fully in a first or counter-clockwise direction to a reset position, the latch arm40is moved by the latch assembly30from this intermediate position engaged with the latch arm receiver26to its second (up) position (FIG.4) so that the latch arm40is lifted out of the latch arm recess26cover the lock face26bso that the latch arm receiver26is disengaged from the latch arm40to allow the door D to be moved from its closed position to its opened position. As described in more detail below, that the latch assembly30includes a spring that continuously spring-biases the latch arm40toward and into its first (down) position but that allows the latch arm40to be moved from its first (down) position or intermediate position to its second (up/unlatched) position. In this manner, the when the door is in its opened position and the latch arm40is in its first (down) position, the door D can be moved to its closed position because the latch arm40will contact the inclined ramp26aof the latch arm receiver26after which further movement of the door D toward its closed position will cause the latch arm40to move up the inclined ramp26asuch that the ramp26amoves the latch arm40resiliently against the spring-biasing force from its first (down) position toward its second (up) position so that the latch arm40moves over the ramp26aand seats in the lock arm recess26cadjacent the lock face26bto once again latch the door D in its closed position.

As shown inFIGS.3&5, the latch assembly30can be fixedly and operatively secured to the circuit breaker CB using one or more fasteners F2that extend through a body of the circuit breaker and that engage a mounting bracket MB that is connected to the body B of the enclosure E inside the space S. An insulator made from any suitable electrically insulative (electrically non-conductive) material can be located between the circuit breaker CB and the mounting bracket and enclosure body B to electrically insulate the circuit breaker CB from the bracket MB and enclosure body B. In one example, the fasteners F2can be screws that are threaded into mounting bracket MB. As shown inFIG.5, first and second phase separators PS can be located over opposite ends of the circuit breaker to redirect any plasma blast. The circuit breaker CB includes a toggle T that moves between a first or “on” toggle position, a second or “off” toggle position, a third or “tripped” position, and a fourth or “reset” toggle position corresponding respectively to the ON, OFF, TRIPPED, and RESET operative states of the circuit breaker CB. In the illustrated embodiment, the toggle T pivots about a pivot axis. When the latch assembly30is operatively connected to the circuit breaker CB as shown inFIG.3, the toggle T of the circuit breaker CB is operatively engaged with the latch assembly30to be moved by the latch assembly as described in further detail below.

FIG.6shows an isometric view of the latch assembly30, whileFIG.7provides an exploded isometric view of the latch assembly30. The chassis32can be defined as a one-piece molded polymeric component. A rear isometric view of the chassis32is shown inFIG.8. The chassis32comprises a circular mounting opening52, and a handle crank subassembly60is rotatably mounted in the chassis opening52. The handle crank subassembly60includes the handle H described above, and a lockout plunger P that rotates with the handle and that is slidably connected to the handle H. The handle H projects outwardly from a first or external side of the chassis32. The handle crank subassembly60further includes a crank60clocated on a second or rear side of the chassis32that is secured to the handle by fasteners F3or otherwise such that the crank60cand handle H rotate together as a unit. A resilient, elastomeric dynamic seal62is located between the handle H and crank60cto provide environmental sealing as described further below. A resilient annular seal64such as a foam or other elastomeric seal externally surrounds the chassis opening52on the first (external) side of the chassis32and sealingly engages the inner door bezel24when the door D is in the closed position to inhibit ingress of environmental contaminants into the enclosure space S through the door opening DO (the annular seal54can alternatively be secured to the interior door bezel24surrounding the door opening DO). The chassis32further comprises an indicia ring50ithat externally surrounds the chassis opening52and handle H and includes visual indicia to provide a user with an indication of the operative position of the handle H and operative state of the circuit breaker CB. As indicated on the indicia ring50i, the handle H comprises four operative positions ON, TRIP, OFF, and RESET that correspond respectively to the ON, TRIPPED, OFF, and RESET states of the circuit breaker CB such that the operative state of the circuit breaker CB and any time will correspond to the position of the handle H as indicated on the indicia ring50i. As described below, the handle H can also be moved to a lockout position LO (that can be indicated by a padlock or other icon on the indicia ring50i) that is adjacent the OFF position of the handle H but is at least 15 degrees angularly offset by an angle theta θ from the OFF position corresponding to the circuit breaker CB being in its OFF operative state but where the latch assembly30can be locked-out for safety as described below.

The latch assembly30further comprises a lockout cup66non-rotatably connected to the chassis32adjacent the crank60cand that is selectively engaged by the lockout plunger P to prevent rotation of the handle H as described below. The lockout cup66can be a molded polymeric component. A torque converter68is located adjacent the lockout cup and is operatively engaged with the crank60cby a crank stud60s(FIGS.9&11) of the handle crank60c. The latch arm40is operatively engaged with the torque converter68such that rotational movement of the handle H is transmitted to the latch arm40through the crank60c, crank stud60s, and torque converter68to move the latch arm40between its first (down) and second (up) positions. The torque converter68and latch arm40can each be provided by one-piece steel components such as steel stampings but can alternatively be cast metal or molded polymeric components. The latch arm40includes a body42at its inner end comprising first and second transverse tabs40a,40bthat are selectively engaged with a projecting tooth68aof the torque converter68. The torque converter68includes a pivot aperture68bthat is pivotally seated on a pivot stud54(FIGS.8&18) of the chassis32. The torque converter68also includes a first contoured slot L1that is slidably engaged by the projecting stud60s(seeFIGS.9-11) of the handle crank60cas described below such that rotation of the handle H and crank60cinduces pivoting movement of the torque converter68about the pivot stud54which, in turn, causes the latch arm40to move between its first (down) and second (up) positions in response to rotation of the handle H. A latch arm spring40sis engaged with the latch arm40and the chassis32and continuously biases the latch arm40toward its first (down) position.

With reference also toFIGS.7A &8, a handle position spring60gis operatively engaged between first and second circumferentially spaced-apart tabs60t1,60t2of the handle crank60c. The spring60gis also positioned between circumferentially spaced-apart ribs32r1,32r2or similar features of the chassis32and/or of the lockout cup66that is fixed to the chassis32such that when the crank60crotates in a first direction, a first one of the crank tabs60t1compresses the spring60gin the first direction against a second one of the ribs32r2and when the crank60crotates in an opposite second direction, a second one of the crank tabs60t2compresses the spring60gin the second direction against a first one of the ribs32r1. Thus, the handle position spring is a dual-acting spring that acts between the handle crank60cand the chassis32in both first and second directions such that resilient engagement of the spring60gwith the chassis32exerts a biasing force on the handle crank60cin both the first and second rotational directions depending upon the rotational direction of the handle H such that the handle position spring60gprovides a two-way “snap-back functionality whereby: (i) upon partial or incomplete movement of the handle H in the first direction from its ON position toward its OFF position, the spring60gwill resilient return the handle H to the ON position when the handle H is released; and (ii) upon partial or incomplete movement of the handle H in the second direction from its OFF position toward its ON position, the spring60gwill resilient return the handle H to the OFF position when the handle H is released. This is a safety feature that ensures that the handle H only changes position from ON to OFF and vice versa in response to completed intentional inputs from a user to prevent unintended changes in the conductive state of the circuit breaker CB.

The latch assembly30further comprises a slide plate70connected to said chassis30, a rear cover74connected to said chassis adjacent the slide plate, and a toggle plate72that is located between the slide plate70and rear cover74that slides in a reciprocal linear manner relative to the chassis30between the slide plate70and rear cover74. The rear cover74can include a spaced-apart pair of linear rails74rthat are slidably engaged by mating recesses72r(see alsoFIG.10) of the toggle plate72to guide the reciprocal sliding movement of the toggle plate72. The rear cover74can be connected to the chassis32by fasteners F4. The toggle plate72include a projecting toggle plate stud72sthat is slidably located in a second contoured slot L2of the torque converter68(see alsoFIGS.9-11) such that pivoting movement of the torque converter68in response to rotation of the handle H induces linear movement of the toggle plate72between first (down) and second (up) positions. As shown inFIG.11, the toggle plate72includes a recess73rthat is engaged with the toggle T of the circuit breaker CB such that linear sliding movement of the toggle plate72controls the operative position of the circuit breaker toggle T. A toggle plate spring72gis operatively engaged between the toggle plate72and the rear cover74and biases the toggle plate72and the circuit breaker toggle T engaged therewith toward the OFF position of the circuit breaker toggle T.

FIG.7also shows that the latch assembly30comprises a defeater80including a defeater shaft82sthat pivotally supports the latch arm40relative to the chassis32such that the latch arm40pivots in first and second opposite directions relative to the chassis32as limited in each direction by opposite ends32s1,32s2of a slot32sdefined by the chassis32. With reference also toFIGS.17&18, the defeater shaft82sis non-rotatably engaged with the latch arm40such that rotation of the defeater80in a first direction induces movement of the latch arm40from its first (down) position or intermediate (latched) position toward and into its second (up) position to disengage the latch arm40from the latch arm receiver26, even when the circuit breaker CB is in its on (conductive) state as required for certain maintenance and testing procedures. In the illustrated example, the defeater80includes a non-circular portion84(FIGS.17&18) that is closely located and keyed in a correspondingly non-circular opening44of the latch arm body42such that the defeater shaft82spivotally supports the latch arm40on the chassis32and such that rotation of the defeater causes rotation of the latch arm40. The defeater shaft82sis rotatably supported on the chassis32and comprises a head82that is exposed on the first/outer side of the chassis as shown inFIGS.12&13. The defeater head82is slotted or otherwise configured to be engaged by a screwdriver or other tool for rotating the defeater to move the latch arm40from its first position to its second position to disengage the latch arm40from the latch arm receiver26to allow the door D to be opened when the circuit breaker CB is in its on/conductive state.

The latch assembly30further comprises a test button86slidably engaged with the chassis32. The test button86is spring biased to an extended position by a spring88engaged with the rear cover74. As shown inFIGS.12&13, the test button86is accessible on the first/outer side of the chassis32and can be selectively moved from its normal, extended position to a depressed position in which the test button86engages a corresponding test switch or test button86tlocated on the circuit breaker CB to trip the circuit breaker CB such that it changes from the ON (conductive) state to the TRIPPED state (non-conductive state) and must be reset.

FIG.9shows the operative engagement between the handle crank60cand the torque converter68. As noted above, the torque converter68includes a pivot aperture68bthat is pivotally seated on a pivot stud54(FIGS.8&18) of the chassis32. The torque converter68also includes a first contoured slot L1that is slidably engaged by a projecting stud60sof the handle crank60cwhereby rotation of the handle H and handle crank60cresults in sliding movement of the handle crank stud60sin the first contoured slot L1which induces pivoting movement of the torque converter68about the pivot stud54as indicated by the arrow R which, in turn, causes the latch arm40to move with the torque converter68between the first (down) and second (up) positions of the latch arm40in response to rotation of the handle H. More particularly, as shown inFIG.18, rotation of the handle H and handle crank60cin a first direction toward the RESET position causes the torque converter to pivot in a first direction T1where the projecting tooth68awill contact the second tab40bof the latch arm40induce rotation of the latch arm40(and defeater shaft82s) in a first direction A1from the illustrated first (down) position toward and into its second (up) position until the latch arm40contacts the first or upper edge32s1of the chassis slot32s. Rotation of the handle H and crank60cin the opposite direction toward the ON position pivots the torque converter68in an opposite, second direction T2which allows the latch arm spring40sto resiliently pivot the latch arm40in a second direction A2toward its intermediate position. It should be noted, however, that the latch assembly30is structured such that when the door D is open and the handle H is in the OFF position, the latch arm40is biased by the latch arm spring40sbeyond its intermediate (latched) position (where it engages the latch arm receiver26) farther away from the second (unlatched) position fully to the first (down) position shown inFIGS.6&12and also inFIG.18where the latch arm40abuts the second edge32s2of the chassis slot32s. When the latch arm40is allowed to pivot fully to its first (down) position in contact with the second edge32s2of the chassis slot32s, the handle H cannot be rotated past the OFF position toward the ON position until the latch arm40is lifted out of the first (down) position by either: (i) closing the door D such that the latch arm40is lifted by latch arm receiver26to its intermediate (latched) position; or (ii) a user manually lifting and holding the latch arm40out of the first (down) position. When the latch arm40is lifted and held out of the first (down) position, the handle H can then be rotated from the OFF position toward and into the ON position to set the circuit breaker CB in its conductive state. As shown inFIG.18, this safety feature results from the fact that when the latch arm40is in the illustrated first (down) position, the first tab40aof the latch arm40will be contacted by the torque converter tooth68aand will block movement of the torque converter68in the second direction T2because the latch arm cannot pivot farther in the second direction A2due to its engagement with the chassis slot edge32s2. However, when the latch arm40is pivoted in the first direction A1, the first tab40athereof is moved out of the path of the torque converter tooth68asuch that the handle H can be rotated fully to the ON position.

FIGS.10and11show the operative engagement of the toggle plate72with the torque converter68. The toggle plate72include a projecting stud72sthat is slidably located in a second contoured slot L2of the torque converter68such that pivoting movement of the torque converter68in response to rotation of the handle H induces sliding movement of the toggle plate stud72sin the second contoured slot L2which causes linear movement of the toggle plate72between first (down) and second (up) positions as indicated by the arrow Y. As shown inFIG.11, the toggle plate72includes a recess73rthat is engaged with the toggle T of the circuit breaker CB such that linear sliding movement of the toggle plate72controls the operative position of the circuit breaker toggle T and thus controls the operative state of the circuit breaker CB.

With reference toFIGS.12&13, the indicia ring50iindicates five different locations for the handle H: ON, TRIP, OFF, LOCKOUT (indicated by a padlock or other icon LO), and RESET. The handle H can be rotated to an ON handle position where its nose H1is aligned with the ON location on the indicia ring50iwhich places the latch arm40in the first (down) position (or intermediate (latched) position) and sets the circuit break CB to its on/conductive state. The handle H can be rotated such that its nose H1is aligned with the OFF handle position on the indicia ring50iwhich places the circuit breaker CB in its off/non-conductive state but leaves the latch arm40in the first (down) position or intermediate (latched) position. If the circuit breaker CB is tripped from its on/conductive state, movement of the toggle T will cause the handle H to rotate such that its nose H1is aligned with the TRIP handle location of the indicia ring50ito provide a visual indication to the user that the circuit breaker CB has been tripped. To reset the circuit breaker CB and to move the latch arm40from its first position or its intermediate position (FIG.3orFIG.12) to the second/up position (FIG.13) to allow the door D to be opened, the handle H must be rotated such that its nose H1is aligned with the RESET handle position on the indicia ring50ias shown inFIG.13.

FIG.12shows the handle H positioned in a LOCKOUT handle position with its nose H1aligned with lockout indicia (such as the padlock icon LO) of the indicia ring50i. As noted, the lockout plunger P rotates together with the handle H but is axially slidable relative to the handle H between its extended/disengaged position and its depressed/engaged position. When the handle H is located in the LOCKOUT handle position LO or when the handle H is located in any position between and including the lockout position LO and RESET position, the lockout plunger P can be depressed and locked in the depressed state or engaged state to activate a lockout function of the handle H which prevents movement of the handle H toward the ON position from the LOCKOUT handle position. Engagement of the lockout plunger P thus ensures that the circuit breaker CB cannot be placed in a conductive ON state when the handle H is located in the LOCKOUT handle position with the lockout plunger P engaged.

According to one aspect of the present development, the LOCKOUT handle position illustrated inFIG.12, where the handle nose H1is aligned with the lockout icon LO, is adjacent but angularly separated the OFF position, where the handle H is ordinarily positioned to manually place the circuit breaker CB in its non-conductive OFF state. In particular, the handle H1must be rotated in the first, counter-clockwise direction away from the ON position by a safety angle theta θ of at least an additional 15 degrees beyond the indicated OFF position to be in the LOCKOUT handle position where the handle nose H1is aligned with the locket indicia LO and the plunger P can be depressed/engaged.FIG.14is a section view taken at14-14ofFIG.12, wherein the handle H is in the LOCKOUT handle position and the lockout plunger P is depressed into an engaged position.FIG.15is a section view that is similar toFIG.14but shows the handle H in the OFF position and shows the lockout plunger P in its extended, disengaged position. The lockout plunger P comprises a body Pa and at least one but preferably at least first and second legs Pb,Pc that extend axially outward from the body Pa toward the lockout cup66. A lockout plunger return spring Pg is located between the plunger body Pa and the handle crank60cand biases the lockout plunger P outwardly toward its extended, disengaged position (FIG.15). When the handle H is in the lockout position LO, which is distinct from the OFF position as noted above, the lockout plunger P can be manually moved/depressed into its engaged position as shown inFIG.14, where the first and second legs Pb,Pc extend through the handle H, through respective first and second apertures61b,61cdefined through the handle crank60c, and are moved axially into respective first and second lockout recesses66rin the lockout cup66. When the first and second legs Pb,Pc are located in the respective first and second lockout recesses66r, the handle H can be rotated only in a first (counter-clockwise) direction away from the ON position toward and into the RESET position to reset the circuit breaker CB, but the handle H cannot be rotated in the opposite second (clockwise) direction, from the lockout position toward or to the ON position such that the circuit breaker CB cannot be set to its ON or conductive state when the lockout plunger P is located in its depressed, engaged position. When the handle H is located in the OFF handle position, the TRIP handle position, or the ON handle position, the lockout recesses66rare not respectively registered or aligned with the first and second plunger legs Pb,Pc which prevent movement of the plunger to its depressed/engaged position.

When the lockout plunger P is depressed/engaged, an enclosed handle lockout space H2(FIG.14) is opened between the lockout plunger P and an outer, grasping portion H3of the handle H. When the handle lockout space H2is opened by depressing/engaging the lockout plunger P, a lockout padlock and/or tagout card and/or any other selectively applied lockout or tagout device LTD can be connected to the handle H such that a shackle LTD1portion of the lockout device extends through and is captured in the handle lockout space H2and blocks movement of the lockout plunger P from its depressed, engaged position to its extended, disengaged position. When the lockout padlock or other lockout device LTD is removed from the lockout space H2of the handle H, the lockout return spring Pg urges the plunger P back to its extended, disengaged position to allow rotation of the handle H in both the first and second directions.

The latch assembly30is sealed to at least inhibit ingress of environmental contaminants. Likewise, the interface between the latch arm assembly30and the door D of the enclosure E is also sealed to at least inhibit ingress of environmental contaminants. In one, non-limiting example, the sealing in both instances at least satisfies IP54 sealing standards. As noted above, a resilient, elastomeric dynamic seal62is located between the handle H and crank60cto provide environmental sealing for the latch arm assembly30, and a resilient annular seal64is connected to the latch assembly30or to the interior door bezel24to seal the interface between the inner door bezel24and the latch assembly chassis32. As shown in the partial, enlarged section view ofFIG.16, the dynamic seal62is closely fitted to the handle crank60cand comprises an annular peripheral sealing lip62athat sealingly engages the chassis32to provide an environmental seal between the handle crank60cand the chassis32where the handle crank60crotates relative to the chassis32. The dynamic seal62further comprises first and second seal apertures62b,62cthrough which the first and second plunger legs Pb,Pc of the lockout plunger P slidably extend. The dynamic seal62comprises first and second continuous, circumferentially extending sealing ribs62rthat project radially inward from the cylindrical wall defining each of the first and second seal apertures62b,62cand that sealingly engage the respective plunger legs Pb,Pc to inhibit flow of environmental contaminants into the handle crank subassembly60where the lockout plunger legs Pb,Pc extend through the handle crank60c.

FIG.17provides a section view through the defeater mechanism80of the latch arm assembly30and shows that a defeater shaft80sis rotatably located in a defeater shaft bore32bof the chassis32. The defeater shaft82scomprises an O-ring seal coaxially positioned thereon that is sealingly engaged with the cylindrical wall32wof the chassis32that defines the defeater bore32bto inhibit ingress of environmental contaminants into the handle crank subassembly60through the defeater shaft bore32bbetween the defeater shaft82sand the cylindrical wall32wof the defeater bore32b.