Shutter locking mechanism for circuit breaker assembly

In one embodiment, a shutter lock assembly for a circuit breaker cassette having a shutter coupled to a shutter rod is provided. The shutter lock assembly includes a lock plate assembly configured to couple to the circuit breaker cassette and an actuation mechanism having a first end coupled the lock plate assembly. The actuation mechanism is configured to actuate the lock plate assembly to lock the shutter of the circuit breaker cassette in a closed position.

BACKGROUND OF THE INVENTION

The field of the invention relates generally to circuit breakers and more particularly, to a circuit breaker assembly having a shutter locking mechanism.

Generally, known circuit breakers include mechanical operating components that are mainly exposed to the environment. The circuit breaker includes main contacts, which are either opened to interrupt a path for electrical power traveling from an electrical power source to a load or closed to provide a path for the power to travel from the source to the load. Arc chambers are disposed in the housing and are used for extinguishing an arc generated while opening the contacts. A draw out type circuit breaker is movable to be separated from the power source and the load circuit in order to facilitate maintenance.

A cassette is a mounting accessory into which a circuit breaker may be installed. The cassette includes terminals that are connected to the main electrical supply lines. The cassette also includes shutters configured to cover the terminals, preventing contact with live terminals when the circuit breaker is withdrawn. The shutters move to allow the circuit breaker to be easily and rapidly connected to the terminals in the cassette. The cassette further includes a circuit breaker trip-free mechanism that sets the circuit breaker in a trip-free condition and a padlock that locks the shutters. However, setting the circuit breaker to a trip-free condition and locking the shutters requires actuating two separate assemblies.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a shutter lock assembly for a circuit breaker cassette having a shutter coupled to a shutter rod is provided. The shutter lock assembly includes a lock plate assembly configured to couple to the circuit breaker cassette and an actuation mechanism having a first end coupled the lock plate assembly. The actuation mechanism is configured to actuate the lock plate assembly to lock the shutter of the circuit breaker cassette in a closed position.

In another embodiment, a circuit breaker assembly configured to receive a circuit breaker is provided. The circuit breaker assembly includes a cassette, a shutter, and an actuator assembly coupled to the cassette. The actuator assembly is configured to substantially simultaneously lock the shutter in a closed position and set the circuit breaker in a trip-free condition.

In yet another embodiment, a circuit breaker assembly is provided. The circuit breaker assembly includes a cassette and a circuit breaker removably coupled to the cassette. The circuit breaker assembly further includes a shutter coupled to the cassette and configured to move between an open position enabling electrical contact with the circuit breaker and a closed position preventing electrical contact with the circuit breaker. The circuit breaker assembly further includes a trip-free actuator assembly configured to selectively set the circuit breaker in a trip-free condition and a shutter lock assembly configured to selectively lock the shutter in the closed position.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure provides an exemplary circuit breaker assembly that is operable to substantially simultaneously actuate two mechanical control systems. More particularly, a single user-actuated assembly locks the circuit breaker shutters in the closed position and simultaneously sets the circuit breaker trip-free condition. Thus, the single actuation assembly provides a quick and easy way to control two mechanical system operations with one action.

FIG. 1illustrates an exemplary circuit breaker assembly10that includes a circuit breaker cassette12with a draw out circuit breaker removed. Circuit breaker cassette12includes a base panel14, a rear panel16, a rear shutter18, a front shutter20, a top panel22, a front panel24and opposed side panels26and28. Line terminals (not shown) are disposed within rear panel16and provide an electrical connection to main electrical supply lines (not shown). The line terminals are in physical and electrical connection with the circuit breaker when installed in cassette12. Shutters18and20are disposed within rear panel16, in front of the line terminals, and rear shutter18is configured to translate vertically or horizontally to either open or close, exposing or covering the line terminals, as described further below.FIG. 1depicts a CLOSED shutter position in which the line terminals are not accessible by the circuit breaker.

In the exemplary embodiment, cassette12further includes a padlock assembly30and a shutter rod assembly32, an actuator assembly34, a trip-free assembly36, and a shutter lock assembly38. Padlock assembly30actuates shutter rod assembly32to control the locking and unlocking of shutters18and20. Actuator assembly34substantially simultaneously actuates trip-free assembly36to set the circuit breaker in a trip-free condition and actuates shutter lock assembly38to lock shutters18and20in the CLOSED shutter position.

FIG. 2illustrates an enlarged view of cassette base panel14. Padlock assembly30includes a first padlock lever50slidably coupled to base panel14and a second padlock lever52rotatably coupled to base panel14. First padlock lever50includes a first portion54, which extends through front panel24, and a second portion56. Second padlock lever52includes a first portion58rotatably coupled to base panel14, a second portion60rotatably coupled to first padlock lever second portion56, and a U-shaped third portion62operatively associated with shutter rod assembly32.

In the exemplary embodiment, shutter rod assembly32includes a shutter rod66, a sleeve68coupled to shutter rod66, and a front bracket70coupled to base panel14. Front bracket70includes apertures72configured to receive and guide shutter rod66. Shutter rod66includes a first portion74operatively associated with U-shaped portion62and a second portion76operatively associated with shutters18and20. A spring78is positioned at second portion76to bias shutter rod66towards front panel24.

FIG. 3illustrates an exploded view of exemplary actuator assembly34. Actuator assembly34includes a rotational device80and a cam82coupled to rotational device80. In the exemplary embodiment, rotational device80is a lock84. Alternatively, rotational device80may be any device that enables rotational movement of cam82as described herein. Lock84is positioned at least partially within front panel24against a spacer86. Cam82, a first nut88, a cam spacer90and a second nut92are coupled to lock84, as illustrated inFIG. 4. Cam82includes a first leg94operatively associated with trip-free assembly36and a second leg96operatively associated with shutter lock assembly38and trip-free assembly36.

FIG. 4illustrates a top view of exemplary trip-free assembly36that includes a slider100slidably coupled to base panel14, and a mid-drive assembly104rotatably coupled to front panel24. Slider100includes a first pin106operatively associated with cam first leg94, and a raised portion108operatively associated with mid-drive assembly104, which is operatively connected with the circuit breaker. Actuation of trip-free assembly36sets the circuit breaker in a trip-free condition. The trip-free condition prevents the circuit breaker main contact assembly (not shown) from closing following a tripping of the circuit breaker until the circuit breaker has been reset.

FIGS. 2-4illustrate exemplary shutter lock assembly38that includes a retainer assembly200, an actuation mechanism such as cable202, and a lock plate assembly204. Retainer assembly200is coupled to front panel24, and lock plate assembly204is coupled to base panel14. Alternatively, retainer assembly200and lock plate assembly204are coupled to any portion of cassette12that enables shutter lock assembly38to function as described herein. Cable202includes a first end206coupled to retainer assembly200and a second end208(FIG. 5) coupled to lock plate assembly204.

In the exemplary embodiment, retainer assembly200includes a connector210extending through front panel24, a retainer212, and a fastener214. In the exemplary embodiment, fastener214extends through connector210and couples retainer212to connector210and front panel24. Retainer212includes a body216and a projection218that includes an aperture220configured to receive cable202. Alternatively, retainer212is coupled to front panel24by welding, adhesive, or any other fastening means that enables retainer212to function as described herein.

In the exemplary embodiment, cable202is a Bowden cable that transmits mechanical force through an inner cable (not shown) inside an outer cable230. Cable first end206includes a threaded portion232and a piston234coupled to the inner cable. Cable first end206extends through retainer aperture220and is secured to retainer212by nuts236and238. Actuation of piston234transfers mechanical force to cable second end208, as further described below.

FIGS. 5-7illustrate exemplary lock plate assembly204that includes a fixing bracket240and a blocking plate242. Fixing bracket240is coupled to base panel14with a fastener (not shown) inserted through apertures241. A pin244rotatably couples blocking plate242to fixing bracket240. A sleeve246provides a surface248between blocking plate242and pin end250to receive a biasing mechanism252that biases blocking plate242in a first position (seeFIG. 6). In the exemplary embodiment, biasing mechanism252is a spring such as a torsion spring. Alternatively, biasing mechanism252is any device that enables lock plate assembly204to function as described herein. Fixing bracket240includes a threaded inner edge254defining an aperture256configured to receive cable second end208.

In the exemplary embodiment, cable second end208includes a threaded portion260and a piston262coupled to the inner cable (not shown). Threaded portion260is coupled to fixing bracket threaded inner edge254such that piston262is positioned for engagement with blocking plate242. Actuation of piston234of cable first end206transfers mechanical force to piston262of cable second end208.

During operation, first portion54of first padlock lever50is pulled away from front panel24, causing first padlock lever50to translate along base panel14and rotate second padlock lever52about first portion58. Rotation of second padlock lever52causes U-shaped third portion62to engage and translate shutter rod66to translate towards and into rear panel16. In the exemplary embodiment, translation of shutter rod66towards and into rear panel16causes shutters18and20lock in the CLOSED position. Thus, actuation of padlock assembly30and shutter rod assembly32translates shutter rod66and sleeve68from a first position (seeFIG. 6) to a second position (seeFIG. 7).

Actuator assembly34actuates both trip-free assembly36and shutter lock assembly38. In the exemplary embodiment, lock84is rotated counter-clockwise by a key85, causing cam82to rotate counterclockwise. During rotation of lock84, cam first leg94engages first pin106causing slider100to translate along base panel14. Slider raised portion108moves into contact with mid-drive assembly104and causes mid-drive assembly104to rotate and set the circuit breaker (not shown) in a trip-free condition. Also during rotation of lock84, cam second leg96engages piston234of cable202, which transfers mechanical force to piston262. Actuation of piston234causes piston262to engage and rotate blocking plate242from a first position, where blocking plate242does not engage sleeve68(seeFIG. 6), to a second position, where blocking plate242engages and blocks sleeve68from translating towards front panel24(seeFIG. 7). Thus, blocking plate242is rotated within the translation path of shutter rod66and sleeve68to maintain the shutter rod66in its second position and lock shutters18and20in the CLOSED position.

As described, an operator actuates padlock assembly30causing shutter rod assembly to lock shutters18and20. Subsequently, the operator actuates actuator assembly34with key85to simultaneously actuate trip-free assembly36and shutter lock assembly38. Actuation of trip-free assembly sets the circuit breaker in a trip-free condition and actuation of shutter lock assembly38locks shutter rod assembly32in position to maintain shutters18and20in a CLOSED position. The operator may then release padlock assembly30and remove key85to leave shutters18and20locked in a CLOSED position and the circuit breaker in a trip-free condition. Accordingly, the circuit breaker cassette described herein combines locking of the shutters and setting the circuit breaker trip-free condition with a single actuation assembly.