Patent Application
20060163049
1. Field of the Invention
The present invention relates generally to electrical switching apparatus and, more particularly, to an auxiliary switch actuator mechanism for a circuit breaker. The invention also relates to circuit breakers employing an auxiliary switch actuator mechanism.
2. Background Information
Circuit breakers having auxiliary switches are generally old and well known in the art. Typically, the auxiliary switch is electrically connected with a circuit including a status indicator (e.g., an audible alarm, such as a bell, or a visual indicator, such as a light) for providing a remote indication of the condition of the circuit breaker. Some auxiliary switches provide different outputs for each of the three general circuit breaker conditions, OFF, ON, and tripped. Other auxiliary switches only provide an indication when the circuit breaker has tripped.
The design and configuration of auxiliary switches, which will be discussed in further detail herein, is substantially uniform and unchanging throughout the industry. While this is advantageous from the standpoint of establishing an industry standard, it is disadvantageous in that there is a lack of variation in switch design making it difficult to accommodate the differing requirements of various switching applications. For example, the microswitch or internal contacts of most known auxiliary switches are not actuated unless the circuit breaker is tripped. In certain applications, it is desirable to have the opposite situation, with the microswitch being activated until the breaker trips. Known auxiliary switch designs, alone, cannot accommodate these circumstances. Therefore, in order to achieve the desired auxiliary switch operation, it has been necessary to make modifications to the internal components of the circuit breaker. Accordingly, known circuit breaker designs have begun to incorporate auxiliary switch actuating mechanisms.
For example, U.S. Pat. No. 4,707,674 discloses a representative auxiliary switch actuator mechanism of the type shown in
Generally, when the circuit breaker handle 6 is moved from the OFF position (not shown) to the ON position, as shown in
A spring 34 biases the locking member 32 counterclockwise (with respect to
Typically, the auxiliary switch 26 has three contact terminals including a common (“C”) terminal 48 proximate the line side of the circuit breaker 2, a normally closed (“NC”) terminal 50 proximate the opposite or load side of the circuit breaker 2, and a generally central normally open (“NO”) terminal 52. Current flows through the auxiliary switch 26 between the C terminal 48 and one of the NC and NO terminals 50, 52. When the circuit breaker 2 is turned ON (
When the circuit breaker handle 6 is manually moved between the ON and OFF positions, a sear pin 54 engages the link members of the breaker mechanism 8 in order to prevent them from collapsing. The breaker mechanism 8 remains engaged and locked by the sear pin 54 as the handle 6 pivots counterclockwise (with respect to
Conversely, when a trip condition causes the circuit breaker 2 to trip, the armature 58 (
Despite the foregoing advancements in the art, significant disadvantageous remain. For example, the aforementioned auxiliary switch actuating mechanism is complex, requires numerous separate components and demands that all of the components interact precisely in order to function properly. For example, the shoulder and slot features and multiple interacting components previously discussed, could slip, become misaligned, or otherwise fail to interact correctly. Additionally, such an actuating mechanism requires the auxiliary switch to be modified, for example, to include a molded projection (
There is a need, therefore, for a simplified auxiliary switch actuating mechanism which is capable of reversing the operation of a standard auxiliary switch, without requiring the auxiliary switch to be modified.
There is, therefore, room for improvement in auxiliary switch actuating mechanisms and in circuit breakers employing an auxiliary switch actuating mechanism.
These needs and others are satisfied by the present invention, which is directed to a reverse-action auxiliary switch actuating mechanism for a circuit breaker. The circuit breaker includes a spring-biased actuating assembly in order to normally actuate the auxiliary switch when the circuit breaker is ON or OFF. The spring-bias is overcome when the breaker trips resulting in operation (e.g., actuation of a status indication such as an audible alarm or visual light) which is opposite the normal operation of a standard auxiliary switch. In other words, the present invention, through the design of an actuating mechanism for the circuit breaker, reverses the operation of the auxiliary switch.
As one aspect of the invention, an auxiliary switch actuating mechanism is for an electrical switching apparatus including a housing enclosing separable contacts, an operating mechanism including an operating handle protruding from the housing and structured to open and close the separable contacts, a linkage assembly interconnecting the operating handle and the separable contacts and moving between a set position corresponding to the separable contacts not being tripped open, and a collapsed position corresponding to the separable contacts being tripped open, an actuator structured to collapse the linkage assembly in response to a trip condition, and an auxiliary switch having a contact member. The auxiliary switch actuating mechanism comprises: an actuating lever including a first end and a second end, the actuating lever structured to be pivotally coupled within the housing proximate the auxiliary switch; and a bias member structured to bias the actuating lever towards engaging the contact member of the auxiliary switch, wherein the first end of the actuating lever is structured to engage and actuate the contact member of the auxiliary switch in accordance with the bias when the separable contacts are not tripped open and the linkage assembly is in the set position, and wherein the second end of the actuating lever is structured to be engaged and pivoted by the linkage assembly when the separable contacts are tripped open in response to the tripping condition and the linkage assembly is in the collapsed position, in order that the actuating lever overcomes the bias and disengages and deactivates the contact member of the auxiliary switch.
The linkage assembly may include a U-shaped link and the second end of the actuating lever may include a paddle. The paddle may be structured to be engaged by the U-shaped link when the separable contacts are tripped open and the linkage assembly collapses, in order to pivot the actuating lever and overcome the bias causing the second end of the actuating lever to disengage and deactivate the contact member of the auxiliary switch.
The actuating lever may be a single-piece molded member. The housing may be a two-piece molded housing having a first half and a second half, the actuating lever may include a pivot portion, and the first and second halves of the molded housing may include a receptacle wherein the pivot portion is structured to pivotally engage the receptacle.
As another aspect of the invention, a circuit breaker comprises: a housing; separable contacts enclosed within the housing; an operating mechanism including an operating handle for opening and closing the separable contacts, the operating handle protruding from the housing, a linkage assembly interconnecting the operating handle and the separable contacts, the linkage assembly moving between a set position corresponding to the separable contacts not being tripped open and a collapsed position corresponding to the separable contacts being tripped open, and an actuator structured to collapse the linkage assembly in response to a trip condition; an auxiliary switch having a contact member; and an auxiliary switch actuating mechanism comprising: an actuating lever including a first end and a second end, the actuating lever pivotally coupled within the housing proximate the auxiliary switch, and a bias member biasing the actuating lever towards engaging the contact member of the auxiliary switch, wherein the first end of the actuating lever engages and actuates the contact member in accordance with the bias when the separable contacts are not tripped open and the linkage assembly is in the set position, and wherein the second end of the actuating lever is engaged and pivoted by the linkage assembly when the separable contacts are tripped open in response to the tripping condition and the linkage assembly is in the collapsed position, in order that the actuating lever overcomes the bias and disengages and deactivates the contact member of the auxiliary switch.
The housing may further include a pivot securing the bias member, which may be a torsion spring, thereto.
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, the invention will be described as applied to a hydraulic-magnetic circuit breaker, although it will become apparent that it could also be applied to other types of circuit breakers (e.g., hydraulic circuit breakers; non-hydraulic circuit breakers) and other electrical switching apparatus, generally (e.g., without limitation, circuit switching devices and other circuit interrupters such as contactors, motor starters, motor controllers and other load controllers).
Directional phrases used herein, such as, for example, top, bottom, left, right, clockwise, counterclockwise and derivatives thereof, relate to the orientation of the elements in the drawings and are not limiting upon the claims unless expressly recited therein.
As employed herein, the term “fastener” refers to any suitable connecting or tightening mechanism expressly including, but not limited to, screws, bolts and the combinations of bolts and nuts (e.g., without limitation, lock nuts) and bolts, washers and nuts.
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 “trip condition” refers to any abnormal electrical condition causing a circuit breaker to trip and expressly includes, without limitation, an overcurrent condition, an overload condition, an arc fault condition, a ground fault condition, an undervoltage condition, or a relatively high level short circuit or fault condition.
The example operating mechanism 208 is similar in configuration and function to breaker mechanism 8 illustrated and discussed previously with respect to
In operation, when the linkage assembly 212 collapses, the U-shaped link 213 engages and pivots the exemplary auxiliary switch actuating mechanism 104, as will be discussed in further detail below. Specifically, the linkage assembly 212 moves between a set position (see, e.g.,
As shown in
A bias member, such as the torsion spring 112 shown in
In operation, when the separable contacts 206 are not tripped open and the linkage assembly 218 is in the set position (
As shown in
It will also be appreciated that the auxiliary switch actuating mechanism 104 illustrated and discussed herein is but one representative embodiment contemplated by the present invention. Alternative shapes, sizes and configurations of the components of the mechanism such as, for example, the actuating lever 106, could be employed. For example, without limitation, the actuating lever 106 has been illustrated and discussed herein as being a single-piece molded member which is substantially rigid. While the exemplary molded member is made from, for example, plastic, it could alternatively be made from any known or suitable material (e.g., without limitation, metal). Additionally, this member is not required to be molded, but could alternatively be made from a different suitable manufacturing process. In summary, the shape, configuration and composition of the lever 106, which is shown and discussed herein, do not limit the scope of the invention.
Accordingly, the auxiliary switch actuating mechanism 104 of the present invention provides a mechanism for use with, for example, circuit breakers, in order to achieve desired auxiliary switch operating characteristics. Specifically, the invention provides a relatively simple method of operating an auxiliary switch and associated electrical circuits in a manner reversed from its standard operation (e.g., with the auxiliary switch being actuated when the circuit breaker is not tripped and non-actuated when the circuit breaker is tripped). The present invention accomplishes all of the foregoing without requiring modification to the auxiliary switch and through use of a minimal number of relatively simple components.
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.
