This application is related to commonly assigned, concurrently filed:
U.S. patent application Ser. No. 11/696,810, filed Apr. 5, 2007, entitled “ELECTRICAL SWITCHING APPARATUS AND TRIP ACTUATOR ASSEMBLY THEREFOR”; and
U.S. patent application Ser. No. 11/696,812, filed Apr. 5, 2007, entitled “ELECTRICAL SWITCHING APPARATUS AND TRIP ACTUATOR RESET ASSEMBLY THEREFOR”, which are hereby incorporated herein by reference.
1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to trip actuator assemblies for electrical switching apparatus, such as circuit breakers. The invention also relates to reset assemblies for circuit breaker trip actuator assemblies.
2. Background Information
Electrical switching apparatus, such as circuit breakers, provide protection for electrical systems from electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions. Typically, circuit breakers include an operating mechanism which opens electrical contact assemblies to interrupt the flow of current through the conductors of an electrical system in response to such fault conditions as detected, for example, by a trip unit.
Among other components, the operating mechanisms of some low-voltage circuit breakers, for example, typically include a pole shaft and a trip actuator assembly. The pole shaft pivots during opening and closing operations of the circuit breaker, which operations respectively correspond to electrical contact assemblies being opened (e.g., contacts separated) and closed (e.g., contacts electrically connected). The trip actuator assembly typically includes a trip bar, a trip actuator such as, for example, a solenoid, and a cradle assembly. The cradle assembly is coupled to and is cooperable with the pole shaft. The trip actuator (e.g., solenoid) has a spring, a coil which is energized by the trip unit in response to the electrical fault condition, and an actuating element such as, for example, a plunger. Normally (e.g., in the absence of the electrical fault condition), the plunger is latched (e.g., by a magnet) in a retracted position. When the coil is energized, in response to the electrical fault condition, the magnetic force that holds the plunger in the retracted position is overcome and the spring biases the plunger to an extended position and maintains it there. When the plunger extends, it causes the trip bar to pivot and trip open the electrical contact assemblies.
Subsequently, both the electrical contact assemblies and the trip actuator must be reset. The trip actuator assembly operates in conjunction with the pole shaft to perform the resetting operation. Specifically, when the circuit breaker operating mechanism is reset, the pole shaft pivots, thereby moving the cradle assembly. The cradle assembly then pivots a reset arm which, in turn, depresses the actuating element (e.g., plunger) and resets the trip actuator (e.g., solenoid).
The travel and actuating force of the plunger are relatively limited. Therefore, to ensure that the trip actuator assembly consistently performs properly, the trip actuator assembly must be well designed, and the trip actuator of this assembly must be accurately installed and maintained in a precise predetermined position within the circuit breaker.
In the above regard, known trip actuator assemblies suffer from a number of disadvantages. Among them is the fact that at least one component of the trip actuator assembly and, in particular, the trip actuator, is typically fastened to a portion of the circuit breaker that has no correlation to the tripping and/or resetting function(s) of the circuit breaker. This, alone or in combination with the fact that the trip actuator is typically fastened to such portion using hardware (e.g., brackets) and a plurality of fasteners, can result in misalignment of the trip actuator. In other words, misalignment of the trip actuator can result not only from the positioning of the hardware and trip actuator during its installation, but also from the fact that each component of the circuit breaker tends to vary in precise dimension due, for example, to manufacturing tolerances. When the circuit breaker is assembled, the tolerance variations from one part of the circuit breaker to the next can undesirably accumulate or “stack” up. Consequently, the accuracy with which the trip actuator is installed can be compromised, adversely affecting circuit breaker performance.
The aforementioned misalignment between circuit breaker components can also adversely affect the reset operation of the trip actuator assembly of known circuit breakers. For example, because the pole shaft, the cradle assembly, and the reset lever are coupled together, dimensional variations and/or assembly errors can result in imprecise interaction among these components. By way of example, the pole shaft and the cradle assembly may, for example, move in a manner which tends to over-rotate the reset lever of the trip actuator reset assembly. More specifically, over-rotation occurs when the reset lever has completely depressed the plunger, thus resetting the trip actuator, but the pole shaft and/or the cradle assembly continue to move causing the reset lever to continue to apply pressure to the plunger. It is desirable, therefore, to provide a trip actuator reset assembly that is capable of accommodating such over-rotation.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in trip actuator reset assemblies therefor.
These needs and others are met by embodiments of the invention, which are directed to a trip actuator reset assembly for the trip actuator of electrical switching apparatus such as, for example, circuit breakers, wherein the cradle assembly of the trip actuator reset assembly can accommodate dimensional and/or assembly imperfections and conditions (e.g., over-rotation of the pole shaft, cradle assembly and/or reset lever) caused thereby, in order to avoid damage to the circuit breaker and to accurately and consistently reset the trip actuator.
As one aspect of the invention, a trip actuator reset assembly is provided for an electrical switching apparatus including a housing, separable contacts enclosed by the housing, and an operating mechanism structured to open and close the separable contacts. The operating mechanism includes a pole shaft. The trip actuator reset assembly comprises: a cradle assembly including a first end structured to be pivotably coupled to the pole shaft, a second end disposed opposite and distal from the first end, and a number of springs disposed between the first end and the second end, the cradle assembly being structured to be movable among a first position corresponding to the separable contacts being closed, and a second position corresponding to the separable contacts being open; a reset lever including a first end, a second end disposed opposite and distal from the first end of the reset lever, and a pivot structured to pivotably couple the reset lever to the housing; a trip actuator including an actuating element which, in response to a trip condition, is structured to move the first end of the reset lever; a rigid element structured to be pivotably coupled to the housing proximate the second end of the reset lever; and a guide member. After the trip condition, the actuating element of the trip actuator is structured to be reset. When the cradle assembly moves from the first position toward the second position, the guide member guides the cradle assembly into engagement with the rigid element which pivots the reset lever. When the rigid element pivots the reset lever, the first end of the reset lever moves the actuating element of the trip actuator, thereby resetting the trip actuator. After the trip actuator has been reset, if the cradle assembly continues to move beyond the second position, then the number of springs of the cradle assembly accommodate any additional motion of the cradle assembly.
The housing of the electrical switching apparatus may include a mounting surface, a first side plate extending outwardly from the mounting surface, and a second side plate extending outwardly from the mounting surface. The guide member may include a first end, a second end disposed opposite and distal from the first end of the guide member, and an elongated body extending between the first end of the guide member and the second end of the guide member, wherein the elongated body is structured to extend between the first side plate and the second side plate. The first side plate may include a first side and a second side, wherein the actuating element of the trip actuator is structured to be disposed on the first side of the first side plate, and wherein the pivot of the reset lever is structured to be pivotably coupled to the first end of the guide member at or about the first side of the first side plate. The reset lever may further include a bias element, and the first side plate may further include a hole wherein the second end of the reset lever is structured to extend from the first side of the first side plate through the hole of the first side plate and beyond the second side of the first side plate, and wherein the bias element is structured to be disposed within the hole of the first side plate, in order to bias the second end of the reset lever away from the actuating element of the trip actuator.
The cradle assembly may comprise a first side structured to extend from the pole shaft toward the second end of the cradle assembly, a second side disposed opposite and spaced from the first side of the cradle assembly, a first cross member disposed proximate the first end of the cradle assembly, a second cross member disposed at or about the second end of the cradle assembly, and at least one elongated member fixedly coupled to the second cross member and extending through the first cross member. The first cross member may extend between the first side of the cradle assembly and the second side of the cradle assembly, wherein the first cross member does not move independently with respect to the first side of the cradle assembly and the second side of the cradle assembly. The second cross member may be structured to extend between and be pivotably coupled to the first side plate and the second side plate, thereby providing a fixed pivot point for the cradle assembly with respect to the first side plate and the second side plate. When the cradle assembly is moved toward the second position, the first side of the cradle assembly, the second side of the cradle assembly, and the first cross member extending therebetween may be movable with respect to the second cross member and the at least one elongated member fixedly coupled to the second cross member.
The first side of the cradle assembly may further comprise a protrusion extending outwardly from the first side of the cradle assembly toward the first side plate, and the rigid element may be pivotably coupled to the second side of the first side plate wherein, when the cradle assembly moves toward the second position, the protrusion engages and moves the rigid element. The operating mechanism of the electrical switching apparatus may further include a trip lever wherein, when the protrusion engages and moves the rigid element and the cradle assembly continues to move toward the second position, the rigid element engages the second end of the reset lever and pivots the reset lever about the pivot, in order that the first end of the reset lever moves the actuating element of the trip actuator.
In response to the trip condition, the actuating element of the trip actuator may be structured to extend in order to pivot the reset lever and the trip lever. After the trip condition, the actuating element may remain extended until it is depressed by the reset lever in order to reset the trip actuator and the trip lever.
As another aspect of the invention, an electrical switching apparatus comprises: a housing; separable contacts enclosed by the housing; an operating mechanism structured to open and close the separable contacts, the operating mechanism including a pole shaft; and a trip actuator reset assembly comprising: a cradle assembly including a first end pivotably coupled to the pole shaft, a second end disposed opposite and distal from the first end, and a number of springs disposed between the first end and the second end, the cradle assembly being movable among a first position corresponding to the separable contacts being closed, and a second position corresponding to the separable contacts being open, a reset lever including a first end, a second end disposed opposite and distal from the first end of the reset lever, and a pivot pivotably couple the reset lever to the housing, a trip actuator including an actuating element which, in response to a trip condition, moves the first end of the reset lever, a rigid element pivotably coupled to the housing proximate the second end of the reset lever, and a guide member. After the trip condition, the actuating element of the trip actuator must be reset. When the cradle assembly moves from the first position toward the second position, the guide member guides the cradle assembly into engagement with the rigid element which pivots the reset lever. When the rigid element pivots the reset lever, the first end of the reset lever moves the actuating element of the trip actuator, thereby resetting the trip actuator. After the trip actuator has been reset, if the cradle assembly continues to move beyond the second position, then the number of springs of the cradle assembly accommodate any additional motion of the cradle assembly.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
For purposes of illustration, embodiments of the invention will be described as applied to low-voltage circuit breakers, although it will become apparent that they could also be applied to a wide variety of electrical switching apparatus (e.g., without limitation, circuit switching devices and other circuit interrupters, such as contactors, motor starters, motor controllers and other load controllers) other than low-voltage circuit breakers and other than low-voltage electrical switching apparatus.
Directional phrases used herein, such as, for example, left, right, top, bottom, upper, lower, front, back, clockwise and counterclockwise and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.
As employed herein, the terms “actuator” and “actuating element” refer to any known or suitable output mechanism (e.g., without limitation, trip actuator; solenoid) for an electrical switching apparatus (e.g., without limitation, circuit switching devices, circuit breakers and other circuit interrupters, such as contactors, motor starters, motor controllers and other load controllers) and/or the element (e.g., without limitation, stem; plunger; lever; paddle; arm) of such mechanism which moves in order to manipulate another component of the electrical switching apparatus.
As employed herein, the term “fastener” shall mean a separate element or elements which is/are employed to connect or tighten two or more components together, and expressly includes, without limitation, rivets, pins, screws, bolts and the combinations of bolts and nuts (e.g., without limitation, lock nuts) and bolts, washers and nuts.
As employed herein, the term “aperture” refers to any known or suitable passageway into or through a component and expressly includes, but is not limited to, openings, holes, gaps, slots, slits, recesses, and cut-outs.
As employed herein, the term “trip condition” refers to any electrical event that results in the initiation of a circuit breaker operation in which the separable contacts of the circuit breaker are tripped open, and expressly includes, but is not limited to, electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions, receipt of an input trip signal, and a trip coil being energized.
As employed herein, the statement that two or more parts are “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts.
As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality).
The trip actuator assembly 100 includes a trip actuator 102 (e.g., without limitation, a solenoid 102), which is structured to be cooperable with the circuit breaker operating mechanism 10 (
The first end 132 of the trip actuator enclosure 130 further includes a recess 140, as shown in
In view of the foregoing, it will be appreciated that disclosed trip actuator assembly 100 effectively maintains the trip actuator 102 in a desired position within the circuit breaker 2. Specifically, it will be appreciated that the trip actuator 102 is secured directly by the first side plate 104 to the mounting surface 6 of the circuit breaker housing 4. Additionally, the first side plate 104 is preferably substantially flat and devoid of deformations (e.g., without limitation, bends). It will, therefore, be appreciated that the trip actuator 102 is secured directly by the first side plate 104, without requiring any intermediate component (e.g., without limitation, a mounting bracket), or, for example, a mounting flange. Thus, it is the first side plate 104 that, by itself, functions as the mounting element for precisely mounting the trip actuator 102 within the circuit breaker 2. This, along with the fact that circuit breaker components which interact with the trip actuator 102 (e.g., without limitation, the cradle assembly 202 and the reset lever 204 of the trip actuator reset assembly 200 discussed hereinbelow with respect to
As an added benefit, the example trip actuator assembly 100 also reduces the number of components and/or fasteners required to accurately position the trip actuator 102 within the circuit breaker 2, and thereby further simplifies the installation, removal and/or maintenance of the trip actuator 102. Specifically, as will now be discussed, the first side plate 104 removably couples the trip actuator 102 to the circuit breaker housing 4, without a plurality of separate fasteners. In particular, as shown in
As will be described in greater detail hereinbelow, the example circuit breaker 2 further includes at least one linking member such as, for example and without limitation, the cradle assembly 202 of
In order to further secure the trip actuator 102 in the desired position with respect to the circuit breaker 2 and, in particular, the operating mechanism 10 (
The housing 4 of the example circuit breaker 2 also includes an accessory tray 40 which, for economy of disclosure, is shown in simplified form in phantom line drawing in
In view of the foregoing, it will be appreciated that the disclosed trip actuator assembly 100 functions to removably secure the trip actuator 102 in a precise orientation within the circuit breaker 2 (
The resilient element 220 is pivotally coupled to the circuit breaker housing 4 (
More specifically, as shown in
The aforementioned first side 216 (
In the example of
The operating mechanism 10 (shown in simplified form in
An operation of the trip actuator reset assembly 200 to reset the trip actuator 102 following a trip condition, will now be discussed with reference to
Unique to the disclosed trip actuator reset assembly 200 is that, after the trip actuator 102 is reset, if the cradle assembly 202 has a tendency to continue to move, for example, thereby having a tendency to over-rotate the reset lever 204 and potentially damage the plunger 138 and/or trip actuator 102 or a component (e.g., without limitation, cradle assembly 202) of the trip actuator reset assembly 200, the intermediate portion 226 of the resilient element 220 advantageously bends to absorb such movement, as previously discussed. The disclosed trip indicator reset assembly 200, therefore, resists undesirable consequences, for example, associated with over-rotation of the cradle assembly 202.
It will, however, be appreciated that the trip actuator reset assembly (e.g., 200) and components (e.g., without limitation cradle assembly 202; reset lever 204; resilient element 220) could comprise any known or suitable alternative configuration. For example,
In addition to the distinction of the rigid element 320 which, unlike the aforementioned resilient element 220 (e.g., without limitation, leaf spring) is not intended to bend or otherwise deflect, the trip actuator reset assembly 300 is further different from trip actuator reset assembly 200 in that the springs 348,349 or suitable equivalent resilient element(s) is/are required elements of the cradle assembly 302. This is because any additional movement (e.g., without limitation, over-rotation) of, for example, the cradle assembly 302, that is experienced during the reset operation, must be accommodated by the springs 348,349. In other words, after the trip actuator 102 has been reset, if the cradle assembly 302 continues to move beyond the second position, as shown in phantom line drawing in
It will, therefore, be appreciated that the disclosed trip actuator reset assemblies 200,300 can accommodate, for example and without limitation, misalignment and/or over-rotation associated therewith, in order to effectively, consistently reset the trip actuator 102 of the circuit breaker (
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
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Number | Date | Country | |
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20080246565 A1 | Oct 2008 | US |