CLIAMS:We claim –
1. A selectable contact device for modular protection devices configured to function as an auxiliary contact or a trip alarm contact, the device comprising:
at least one moving contact configured to toggle between an ON position and an OPEN position;
a bridge incorporating at least one pair of arms, wherein the at least one moving contact is configured between the at least one pair of arms such that the movement of the at least one moving contact is delayed due to a gap between the at least one moving contact and the at least one pair of arms; further wherein the toggling of the at least one moving contact provides the at least one moving contact a closing speed that is independent of the speed of the bridge.
2. The device of claim 1, wherein the device further comprises a knob that is configured to engage with an actuator of the modular protection device and receive movement caused by actuation of the actuator between ON and OFF position and movement of the actuator due to tripping of the modular protection device.
3. The device of claim 2, wherein the device further comprises a link assembly that is operatively coupled to the knob, wherein the link assembly moves when the knob receives movement caused by actuation of the actuator between ON and OFF position and movement of the actuator due to tripping of the modular protection device, wherein the link assembly is operatively coupled to the bridge to transfer the movement to the bridge.
4. The device of claim 3, wherein the link assembly comprises a small latch and a big latch, wherein the small latch is coupled to the knob through a knob pin to transfer the movement of the knob to the link assembly.
5. The device of claim 4, wherein the small latch and the big latch are normally latched together to transfer the movement from the knob.
6. The device of claim 5, wherein the big latch is configured to directly receive a trip signal from the modular protection device and delatch from the small latch to move the link assembly independent of the small latch.
7. The device of claim 2, wherein the device further comprises a selection mechanism to help switch over between auxiliary contact mode and trip alarm contact mode.
8. The device of claim 7, wherein the selection mechanism incorporates a contact selector lever that configured to allow full movement of the bridge when the selection mechanism is in auxiliary contact mode; and block the movement of the bridge during ON-OFF movement of the knob when the selection mechanism is in trip alarm contact mode.
9. The device of claim 8, wherein the knob incorporates a cam to which the contact selector lever is operatively coupled to block the movement of the bridge in trip alarm contact mode.
10. The device of claim 8, wherein, in trip situation, the contact selector lever is unable to block the movement of the bridge as the bridge moves faster under trip signal received by the big latch before the contact selector lever is moved by the cam for blocking the movement of the bridge.
,TagSPECI:TECHNICAL FIELD
[0001] The present disclosure relates generally to the field of low voltage power distribution control devices. In particular it pertains to architecture of a selectable, auxiliary and trip alarm contact for modular protection devices.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art
[0003] Low voltage power distribution systems use control devices such as MCBs, RCCBs, RCBOs or Switch Disconnectors (collectively referred to as main device hereinafter) to make or break the circuits depending on necessity or in the event of occurrence of abnormal conditions such as short circuit. In large power distribution systems, status of these devices needs to be monitored and the requirement is met by auxiliary contacts and trip alarm contacts.
[0004] Auxiliary contacts are accessories which provide appropriate signal of the functional status of the main device to which it is couple mechanically via a set of normally open / normally closed (NO / NC) contacts. (Also referred to as AUX device hereinafter).
[0005] Trip contacts are accessories which provide signal when the main device undergoes tripping due to a fault situation, to which it is couple mechanically via a set of normally open / normally closed (NO / NC) contacts. (Also referred to as TAC Device hereinafter).
[0006] A selectable auxiliary and trip alarm contact allows users to select any of the two functionality using an external mechanical selector. (Referred to as Selectable Device hereinafter).
[0007] Various auxiliary, trip and selectable devices that are available in market follow their own philosophy of mechanical coupling with the main device and mechanism that converts mechanical signal from main device into motion of NO / NC contacts. They typically employ different mechanisms for AUX, TAC and Selectable Device. Different mechanisms for these devices require different production set up and corresponding set of tools adding to cost of production. This also implies a complex storehouse management and therefore substantial cost reduction is not possible
[0008] Indian patent application 240/MUM/2012 teaches versions of AUX, TAC and Selectable Device that employ a common operating mechanism with small variations. Moreover the operating mechanism disclosed therein is replication of mechanism of a main device. Common mechanism architecture results in ease of manufacturing by employing common production set up and tooling resulting in substantial cost savings.
[0009] In the above prior art, the actuating knob of the AUX, TAC or Selectable Device (collectively referred to as accessary hereinafter) is directly connected to actuating knob of a main device. The motion from the main device is transferred without any motion delay to the accessory knob. The motion of the actuating knob of the accessary is directly transferred to a bridge that operates a set of NO / NC contacts. In the mechanism architecture it is not possible to provide a delay in operation of the moving contacts after the bridge starts moving. It is because of limited sliding motion of the bridge and requirement of over travel for contacts. The over travel for contacts is required to generate sufficient contact pressure.
[0010] Lack of delay in operation of the moving contacts after the bridge starts moving creates problem in fault conditions where actuating knob of main device rotates partially during OFF operation due to situation of contact welding. In that case the state of the main device will be ON however since there is partial rotation of actuating knob of accessory, the accessory will change its state via toggle of NO / NC contact no account of no delay between motion of mechanism and motion of bridge and in turn between motion of bridge and motion of moving contacts. Thus accessory will show wrong indication of status of main device which could be detrimental from safety point of view.
[0011] Another disadvantage of the mechanism architecture of the prior art is that speed of operation of flexible moving contacts and is directly dependent on velocity of bridge which in turn is dependent on velocity of operation of knob of main device. If the knob of main device is operated manually at very slow speed then contact of the auxiliary device will also operate at very slow speed. This can have a negative impact on life of the compacts because of increased erosion due to extended arcing.
[0012] There is therefore need in the art of architecture for a common mechanism for AUX, TAC and Selectable Devices that mitigates the above disadvantages.
[0013] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0014] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0015] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0016] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0017] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

OBJECTS OF THE INVENTION
[0018] An object of the present disclosure is to provide a common mechanism for AUX, TAC and Selectable Devices that overcomes the short comings of the prior art.
[0019] Another object of the present disclosure is to provide a mechanism for Selectable Device that with minor modifications can be used for AUX and TAC devices.
[0020] Another object of the present disclosure is to provide a mechanism that eliminates the drawback of wrong indication in fault situations such as contact welding in the main device which results in only partial rotation of its actuator.
[0021] Another object of the present disclosure is to provide a common mechanism for AUX, TAC and Selectable Devices that can be housed in restricted space of ½ module.
[0022] Yet another object of the present disclosure is to provide a mechanism where the moving contacts have velocity independent of manual operating speed of the knob of the main device and speed of the bridge and in turn has improved life of contacts by avoiding excessive erosion due to extended arcing.

SUMMARY
[0023] Aspects of present disclosure relate to architecture of a selectable contact device for modular protection devices that besides being used as a selectable contact device can also be used as an auxiliary contact or trip alarm contact after minor modifications. In an aspect the disclosed architecture overcomes the shortcomings of such devices in the prior art.
[0024] In an embodiment the disclosed selectable contact device can incorporate a knob, a link assembly, a contact bridge (also referred to as bridge and the two terms used interchangeably hereinafter), at least one set of moving contacts (also referred to as contacts and the two terms used interchangeably hereinafter) and a selection mechanism. The knob can be configure for coupling with actuator of a main device with which the selectable contact device is coupled for use such that movement of the actuator of the main device during ON to OFF, OFF to ON or ON to TRIP is transferred to the selectable contact device.
[0025] In an embodiment the link assembly can be configured to transfer the movement of the knob to the contact bridge and can comprise a small latch, a big latch and a link. The big latch is also configured to receive a trip signal directly from the main device. The small latch and the big latch are latched together in regular ON and OFF operations transferring movement of the knob to the link via latched small latch and big latch. The small latch and the big latch disengage when a trip signal is received by the big latch in which case the movement of the big latch due to the trip signal is directly transferred to the link. Disengagement of the small latch and the big latch causes the device to trip independent of knob motion transferred from the main device.
[0026] In an embodiment, the bridge can incorporate arms with gap and the contacts can be located between the gaps of the arms. In an aspect, the gap in arms allows some initial motion of bridge without moving the contacts and thus provides a delay in motion of contacts. Thus in the event of contacts of the main device getting welded in ON condition resulting in partial rotation of the knob from ON to OFF position and corresponding partial movement of the bridge, the contacts shall not change the state and maintain the status as in ON condition only.
[0027] In an embodiment, the bridge is biased to rotate in a direction such as clockwise direction by a bridge spring to remain in contact with the link to receive any movement of the link. The moving contacts can be configured to have bi-stable operation by providing moving contact spring one for each contact. The dead center of motion of moving contacts can lie between open and closed position so that the contact can move quickly to close or open position after crossing the dead center independent of the movement of the bridge. Thus the moving contacts have velocity independent of manual operating speed of the knob of the main device and speed of the bridge and this in turn leads to improved life of contacts by avoiding excessive erosion due to extended arcing.
[0028] In an embodiment, the selection mechanism can allow a user to select between AUX and TAC. The selection mechanism can incorporate a contact selector lever and when the selection mechanism is positioned to select AUX, the contact selector lever can occupy a position that does not create any obstacle in movement of the bridge in any state possible. This can allow the device to work as AUX contact device. Here the bridge can follow the motion of link assembly and the contacts can change state every time there is full motion of the bridge i.e., from ON-OFF and OFF-ON. Alternatively when the selection mechanism is positioned to select TAC, the contact selector lever can occupy a position in which a cam configured with the knob can engage with the contact selector lever to move it in a position such that the contact selector lever blocks the movement of the bridge during ON-OFF movement of the knob to meet the functional requirement of the TAC contact.
[0029] In an embodiment, when the link assembly moves under trip command received directly by the big latch, its movement is faster than the knob movement. Therefore the bridge moves before the contact selector lever is able to block its movement by change in its position because of the cam of the knob. Thus the bridge can complete full movement to toggle the contacts and change their state.
[0030] In an embodiment, the selectable contact device further incorporates a reset lever configured to test the health of the contacts without changing state of main device via a cam connection to the bridge.
[0031] In an embodiment, the selectable contact device can be configured to function as an AUX device or a TAC device with minor modifications such as deleting the selection mechanism for AUX device or providing the contact selector lever in a fixed position instead of on a selection mechanism for TAC device without any change in other parts such as the link assembly, bridge, contacts. This can enable cost effective production of the three devices without sacrificing other features such as true indication in fault situations such as contact welding in the main device or contacts having velocity independent of manual operating speed of the knob of the main device and speed of the bridge.
[0032] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components

BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0034] FIG. 1 illustrates an exemplary schematic diagram indicating connection of a AUX / TAC with a main device in accordance with embodiments of the present disclosure.
[0035] FIG. 2 illustrates an exemplary schematic diagram of the selectable contact device in AUX OFF condition in accordance with embodiments of the present disclosure.
[0036] FIG. 3 illustrates an exemplary exploded view of the link assembly in accordance with embodiments of the present disclosure.
[0037] FIG. 4 illustrates an exemplary schematic diagram of the contact bridge in accordance with embodiments of the present disclosure.
[0038] FIG. 5 illustrates an exemplary schematic diagram indicating features of the contact selector lever in accordance with embodiments of the present disclosure.
[0039] FIG. 6 illustrates an exemplary schematic diagram of the selectable contact device in AUX ON condition in accordance with embodiments of the present disclosure.
[0040] FIG. 7 illustrates an exemplary schematic diagram of the selectable contact device n TAC Tripped Condition in accordance with embodiments of the present disclosure.
[0041] FIG. 8 illustrates an exemplary schematic diagram of the selectable contact device in TAC ON condition in accordance with embodiments of the present disclosure.
[0042] FIG. 9 illustrates an exemplary schematic diagram of the selectable contact device in TAC OFF Condition in accordance with embodiments of the present disclosure.
[0043] FIG. 10 illustrates an exemplary schematic diagram of the selectable contact device in state of getting locked in On-Off Operation in accordance with embodiments of the present disclosure.
[0044] FIG. 11 illustrates an exemplary schematic diagram of the selectable contact device under condition of partial rotation of the actuator of the main device due to contact welding in accordance with embodiments of the present disclosure.
[0045] FIG. 12 illustrates an exemplary schematic diagram of the selectable contact device in trip free condition in accordance with embodiments of the present disclosure.
DETAILED DESCRIPTION
[0046] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0047] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0048] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0049] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0050] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0051] Aspects of present disclosure relate to architecture of a selectable contact device for modular protection devices that besides being used as a selectable contact device can also be used as an auxiliary contact or trip alarm contact after minor modifications resulting in considerable cost advantage in their production on account of common production set up and tooling.
[0052] It is to be understood that though the embodiments of the present disclosure have been described with reference to a selectable contact device, they all are equally applicable to corresponding auxiliary contact or trip alarm contact that can be configured with these embodiments and all of them are well within the scope of the present disclosure.
[0053] In an aspect the disclosed architecture overcomes the shortcomings of such devices in the prior art such as the drawback of wrong indication in fault situations such as contact welding in the main device which results in only partial rotation of its actuator. Further, in the disclosed architecture, the moving contacts are configured to have velocity independent of manual operating speed of the knob of the main device and speed of the bridge and in turn have improved life of contacts by avoiding excessive erosion due to extended arcing.
[0054] In an embodiment the disclosed selectable contact device can incorporate a knob, a link assembly, a contact bridge, at least one set of moving contacts and a selection mechanism. The knob can be configure for coupling with knob of a main device with which the selectable contact device is coupled for use such that movement of the knob of the main device during ON to OFF, OFF to ON or ON to TRIP is transferred to the selectable contact device.
[0055] In an embodiment the link assembly can be configured to transfer the movement of the knob to the contact bridge and can comprise a small latch, a big latch and a link. The big latch is configured to directly receive a trip signal from the main device. The small latch and the big latch are latched together in regular ON and OFF operations transferring movement of the knob to the link via latched small latch and big latch. The small latch and the big latch disengage when a trip signal is received by the big latch in which case the movement of the big latch due to the trip signal is directly transferred to the link. Disengagement of the small latch and the big latch causes the device to trip independent of knob motion transferred from the main device.
[0056] In an embodiment, the bridge can incorporate arms with gap and the contacts can be located between the gaps of the arms. In an aspect, the gap in arms allows some initial motion of bridge without moving the contacts and thus provides a delay in motion of contacts. In the event of contacts of the main device getting welded in ON condition resulting in partial rotation of the knob from ON to OFF position and corresponding partial movement of the bridge, the contacts shall not change the state and maintain the status as in ON condition only.
[0057] In an embodiment, the bridge is biased to rotate in a direction such as clockwise direction by a bridge spring to remain in contact with the link to receive any movement of the link. The moving contacts can be configured to have bi-stable operation by providing moving contact spring one for each contact. The dead center of motion of moving contacts can lie between open and closed position so that the contact can move quickly to close or open position after crossing the dead center independent of the movement of the bridge. Thus the moving contacts have velocity independent of manual operating speed of the knob of the main device and speed of the bridge and this in turn leads to improved life of contacts by avoiding excessive erosion due to extended arcing.
[0058] In an embodiment, the selection mechanism can allow a user to select between AUX and TAC. The selection mechanism can incorporate a contact selector lever and when the selection mechanism is positioned to select AUX, the contact selector lever can occupy a position that does not create any obstacle in movement of the bridge in any state possible. This can allow the device to work as AUX contact device. Here the bridge can follow the motion of link assembly and the contacts can change state every time there is full motion of the bridge i.e., from ON-OFF and OFF-ON. Alternatively when the selection mechanism is positioned to select TAC, the contact selector lever can occupy a position in which a cam configured with the knob can engage with the contact selector lever to move it in a position such that the contact selector lever blocks the movement of the bridge during ON-OFF movement of the knob to meet the functional requirement of the TAC contact.
[0059] In an embodiment, when the link assembly moves under trip command received directly by the big latch, its movement is faster than the knob movement. Therefore the bridge moves before the contact selector lever is able to block its movement by change in its position because of the cam of the knob. Thus the bridge can complete full movement to toggle the contacts and change their state.
[0060] In an embodiment, the selectable contact device further incorporates a reset lever configured to test the health of the contacts without changing state of main device via a cam connection to the bridge.
[0061] In an embodiment, the selectable contact device can be configured to function as an AUX device or a TAC device with minor modifications such as deleting the selection mechanism for AUX device or providing the contact selector lever in a fixed position instead of on a selection mechanism for TAC device without any change in other parts such as the link assembly, bridge, contacts. This can enable cost effective production of the three devices without sacrificing other features such as true indication in fault situations such as contact welding in the main device or contacts having velocity independent of manual operating speed of the knob of the main device and speed of the bridge.
[0062] FIG. 1 illustrates an exemplary schematic diagram 100 indicating connection of an AUX / TAC/selectable contact device 102 with a main device 104 in accordance with embodiments of the present disclosure. The view 100 indicates the two devices before they are coupled to each other. The actuator 106 of the main device 104 can be mechanically connected to knob 108 of AUX / TAC/selectable contact device 102. The connection can be via an arrangement such as but not limited to a knob bar 110. Once the knob 108 is coupled to the actuator 106 of the main device 104, movement of the actuator 106 of the main device 104 during ON to OFF, OFF to ON or ON to TRIP is transferred to the selectable contact device 102. In an embodiment, the tripping signal from the main device 104 can be directly transmitted to the device 102 through connection 112.
[0063] Referring now to FIG. 2, wherein a selectable contact device 200 is disclosed. The FIG. 2 indicates the device 200 set to function as an auxiliary contact and in its OFF position. As illustrated the exemplary device 200 can comprise a knob 108, a link assembly 202, a contact bridge 204, at least one set of moving contacts such as moving contact left 206 and moving contact right 208. In order to facilitate selection by a user of AUX or a TAC functionality, the device 200 can further incorporate a selection mechanism comprising a contact selector lever 210 and a selector 214. The contact selector lever 210 can be pivoted by a contact selector lever pin 216.
[0064] In an embodiment the link assembly 202 can be configured to transfer the movement of the knob 108 to the contact bridge 204 and as illustrated in FIG. 3 can comprise a small latch 302, a big latch 304, a link 306, a big latch spring 308, a knob pin 310, a link pivot pin 312 and a small latch pin 314. The small latch 302 can be connected to the knob 108 by the knob pin 310 and pivoted to the link 306 by the small latch pin 314. Under normal condition the small latch 302 can be in latched condition with the big latch 304 such that regular ON and OFF operations of the knob 108 can be transferred to the link 306 via latched small latch 302 and big latch 304.
[0065] In an embodiment, the big latch 304 is configured to directly receive a trip signal from the main device 104. When a trip signal is received by the big latch 304, the small latch 302 and the big latch 304 can disengage in which case the disengagement of small latch 302 and big latch 304 allows the link 306 to move independent of motion of knob 108. The motion of link is achieved due to force acting on it from the bridge 204 and its own biasing spring (which is not shown here) Thus disengagement of the small latch 302 and the big latch 304 causes the device 200 to trip independent of knob motion transferred from the main device 104. Thus in the event of the actuator 106 of the main device 104 getting stuck for some reason, the device 200 can still function to move contacts to give a trip signal.
[0066] FIG. 4 illustrates an exemplary schematic diagram 400 of the contact bridge 204 in accordance with embodiments of the present disclosure. In an embodiment, the contact bridge 204 can incorporate arms such as 402 and 404 for moving contact left 206 and another set of arms such as 406 and 408 for moving contact right 208. The contact bridge 204 can be pivoted about a pivot point 410 and also incorporate a latching point 412 where the contact selector lever 210 of the selection mechanism can latch to block movement of the can latch to contact bridge 204 to block its movement when desired (to be explained in succeeding paragraphs).
[0067] In an embodiment, and referring back to the FIG. 2, the gap in arms can allow some initial motion of the contact bridge 204 without moving the contacts 204 and 206. The respective arms 224 and 226 of the moving contacts 206 and 208 can be located between the gaps of the arms such the contact bridge 204 makes a contact with the respective arms 224 and 226 of the moving contacts 206 and 208 after some initial movement. Thus the gap provides a delay in motion of the moving contacts 204 and 206. In the event of contacts of the main device 104 getting welded in ON condition resulting in partial rotation of the knob from ON to OFF position and corresponding partial movement of the bridge, the contacts 204 and 206 shall not change the state and maintain the status as in ON condition only.
[0068] In an embodiment, the contact bridge 204 can be biased to rotate in a direction such as clockwise direction by a contact bridge spring 218 so that the contact bridge 204 remains in contact with the link assembly 202 at point 220. Therefore whenever there is a movement in the link assembly 202, the contact bridge 204 can make corresponding movement.
[0069] In an embodiment, the moving contacts 206 and 208 can be configured to have bi-stable operation by providing moving contact spring 222, one for each of the moving contacts 206 and 208. The dead center of motion of moving contacts 206 and 208 can lie between open and closed position so that the contacts can move quickly to close or open position after crossing the dead center independent of the movement of the bridge. Thus the moving contacts 206 and 208 can have closing velocity independent of manual operating speed of the knob 108 and speed of the contact bridge 204 and this in turn can lead to improved life of contacts by avoiding excessive erosion due to extended arcing.
[0070] In an embodiment, the selectable contact device 200 can further incorporate a reset lever 230 configured to test the health of the contacts 206 and 208 without changing state of main device via a cam connection to the bridge.
[0071] In an embodiment, the selection mechanism is configured to allow a user to select between AUX and TAC. FIG. 5 illustrates the features of the selection mechanism wherein 502 can be the bridge locking area configured to engage with the contact bridge 204 at its latching point 412 to block movement of the contact bridge 204. Further 504 can be the selector locking area and 508 can be the cam engagement area (there function is described in subsequent paragraphs).
[0072] When the selection mechanism is positioned to select AUX, as in FIG. 2 the contact selector lever 210 can occupy a position that does not create any obstacle in movement of the bridge 204 in any state possible. This can allow the device to work as AUX contact device. Here the bridge 204 can follow the motion of link assembly 202 and the contacts 206 and 208 can change state every time there is full motion of the bridge 204 i.e., from ON-OFF and OFF-ON. The FIG. 2 shows the device in AUX mode and in OFF condition wherein the moving contact left 206 is in OPEN condition and the moving contact right 208 is in ON condition.
[0073] FIG. 6 illustrates the device 200 working in AUX mode and in ON condition. This state is achieved when the actuator 106 of the main device 104 is moved from OFF to ON position upon which the coupling between the actuator 106 of the main device 104 and knob 108 of the device 200 can move the knob 108. This in turn rotates the link assembly 202 via the knob pin 310 and latching of the small latch 302 and the big latch 304. The link assembly 202 can rotate around its pivot 602. On complete motion of knob 108, the knob the knob pin 310 and knob 108 cross their dead center and can toggle to reach a stable ON condition. The bridge 204 thus rotates in clockwise direction. The rotation of bridge 204 can be sufficient for its respective arms 402, 404, 406 and 408 to drive arms 224 and 226 of the moving contacts 206 and 208 so that they can cross their dead centers and change the state. In an alternate situation when the main device 104 is turned from ON to OFF, the reverse happens. In the event of occurrence of a TRIP in the main device 104, the sequence of motion of ON-OFF operation is repeated that can in turn trip the device 200. Hence in AUX mode of the device 200 the state of contacts is same in OFF and TRIPPED state.
[0074] FIG. 7 to FIG. 10 illustrate exemplary diagrams of the device 200 in TAC mode and in different operating positions. When the selector 214 is rotated in the position as shown in these figures the selection lever 210 gets activated and can now act because of reset lever spring 228 and cam 802 (FIG. 8) provided on the knob 108 resulting in overall TAC functionality.
[0075] FIG. 8 illustrates an exemplary diagram of the device 200 in TAC mode and in ON condition. When Main device 104 is operated from OFF to ON condition the link assembly 202 can drive the bridge 204 to rotate in anti-clockwise direction so as to change state of contacts 206 and 208 to close and open conditions respectively. In the final ON condition the cam 802 provided on the knob 108 can lift the contact selector lever 210 slightly as shown in FIG. 8. This is normal condition of TAC.
[0076] FIG. 9 illustrates an exemplary diagram of the device 200 in TAC mode and in OFF condition. When Main device 104 is operated from ON to OFF condition the link assembly 202 rotates in anticlockwise direction and can drive the bridge 204. Initial rotation of a few degrees of the bridge 204 is not sufficient for the arms 402 and 406 of the bridge 204 to touch the moving contact arms 224 and 226. After a few degrees of rotation of the knob 108, the cam 802 provided on the knob 108 can rotate the contact selector lever 210 in anticlockwise direction until it touches the bridge 204 as shown in the FIG. 10. Further rotation of the bridge 204 can bring the bridge locking area 502 of the contact selector lever 210 in contact with the latching point 412 of the bridge 204 ( FIG. 9) that can prevent further movement of the bridge 204. After the bridge 204 is locked, the link assembly 202 can continue to move and lose contact with the bridge 204. The link assembly can finally go to its OFF condition as shown in FIG. 9.
[0077] In an embodiment, when the link assembly 202 moves under trip command received directly by the big latch 304, its movement is faster than movement of the knob 108. Therefore the bridge 204 can move before the contact selector lever 210 is able to block its movement by change in its position because of the cam 802 of the knob 108. Thus the bridge 204 can complete full movement to toggle the contacts 206 and 208 and change their state. FIG. 7 illustrates an exemplary diagram of TRIPPED condition of the device 200 in TAC mode.
[0078] FIG. 11 illustrates an exemplary schematic diagram 1100 of the selectable contact device 200 under condition of partial rotation of the actuator 106 of the main device 104 due to contact welding in accordance with embodiments of the present disclosure. Welding of the contacts of the main device 104 can result in only partial rotation of the knob 108, link assembly 202 and the bridge 204. Due to the gap between the arms of the bridge 402, 404, 406 and 408 the contacts 206 and 208 cannot change the state and maintain the status as in ON condition only.
[0079] FIG. 12 illustrates an exemplary schematic diagram of the selectable contact device in trip free condition in accordance with embodiments of the present disclosure. When the actuator 106 of the main device 104 gets locked either for a purpose or due to an external obstruction and the main device 104 trips, the trip signal is received by the big latch 304. Under this situation, the big latch 304 can get unlatched from the small latch 302 and rotate the link assembly 202 which can rotate completely. This will toggle the moving contacts 206 and 208 resulting in change of state as desired for the functionality in both AUX and TAC modes.
[0080] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0081] The present disclosure provides a common mechanism for AUX, TAC and Selectable Devices that overcomes the short comings of the prior art.
[0082] The present disclosure provides a mechanism for Selectable Device that with minor modifications can be used for AUX and TAC devices.
[0083] The present disclosure provides a mechanism that eliminates the drawback of wrong indication in fault situations such as contact welding in the main device which results in only partial rotation of its actuator.
[0084] The present disclosure provides a common mechanism for AUX, TAC and Selectable Devices that can be housed in restricted space of ½ module.
[0085] The present disclosure provides a mechanism where the moving contacts have velocity independent of manual operating speed of the knob of the main device and speed of the bridge and in turn has improved life of contacts by avoiding excessive erosion due to extended arcing.