Claims:
1. A circuit breaker comprising:
an operating mechanism 1 configured to switch contact system 2 by engaging and disengaging a moving contact 5c with fixed contact 8 to open and close the circuit,
wherein during normal switching operations, one or more stopper plates 4 mounted on a moving contact shaft 5 do not interfere with stopper pins 3a that are riveted on a fork lever 3, and wherein when the moving contact 5c is welded with the fixed contact 8 during overcurrent, the stopper pins 3a interfere with the one or more stopper plates 4 as the fork lever 3 is rotated so as to prevent the fork lever 3 from reaching the OFF position.

2. The circuit breaker of claim 1, wherein the fork lever 3 is configured such that even an application of three times the force required to switch off the circuit breaker during normal operation does not take the fork lever 3 to OFF position.

3. The circuit breaker of claim 2, wherein upon releasing the force to rotate the fork lever 3, said fork lever 3 returns to ON position and indicates true state of the circuit, and wherein the fork lever 3 is rotated anti-clockwise when in OFF state so as to switch ON the circuit breaker, and rotated clockwise when in ON state so as to switch OFF the circuit breaker.

4. The circuit breaker of claim 1, wherein said circuit breaker further comprises an extension spring 10 that is loaded onto the fork lever 3, and wherein as the spring loaded fork lever 3 is rotated, it reaches a toggle point 6a of an upper link 6 on to which the other end of extension spring 10 is loaded.

5. The circuit breaker of claim 4, wherein as the spring loaded fork lever 3 is rotated, said upper link 6 is rotated such that when the upper link 6 crosses toggle point 3b of the fork lever, it toggles the fork lever 3 to indicate the state of contact system 2, and wherein the upper link 6 is connected to lower link 9 on either side, and wherein the lower link 9 is connected to the moving shaft 5, enabling motion of the upper link 6 being able to rotate the moving contact shaft 5 to open and close the circuit.

6. The circuit breaker of claim 5, wherein when trip command is issued, latch link 7 is disengaged causing it to rotate anti-clockwise, said rotation causing the upper link 6 and lower link 9 to rotate and disengage the moving contact 5c from the fixed contact 8, and wherein as the upper link 6 rotates during trip, it crosses the toggle point 3b of the fork lever 3 so as to bring the fork lever 3 to trip position.

7. The circuit breaker of claim 6, wherein the stopper plates 4 are mounted on shaft pin 5b, said pin connecting the lower link 9 with the moving contact shaft through pin 5a, said pin 5a connecting RYB poles of the contact system 2 to each other on either side, and wherein said stopper plates 4 rotate as the moving contact shaft 5 rotates to open and close the circuit.

8. The circuit breaker of claim 7, wherein during overcurrent if the moving contact 5c gets welded to the fixed contact 8, said moving contact 5c restricts rotation of the moving contact shaft 5 beyond just-touch position when trip command is issued, and wherein, during tripping, rotation of the latch link 7 exerts a force on the moving contact shaft 5 through the upper link 6 and the lower link 9 so as to rotate the moving contact shaft 5 from over-travel position to just-touch position and then attempt to break the weld such that if the weld is strong and does not break with the force applied by the latch link 7, the weld restricts further motion of the moving contact shaft 5, in which case, as the upper link 6 does not rotate enough to cross the toggle point 3b of the fork lever 3, the fork lever 3 remains in ON position and indicates that the circuit is still closed.

9. The circuit breaker of claim 8, wherein if the upper link 6 does not rotate enough to cross the toggle point 3b of the fork lever 3, if a user tries to switch off the circuit breaker by applying a force to rotate fork lever 3 in clockwise direction, it will rotate a few degrees, and after said rotation, the stopper pins 3a on the fork lever 3 interfere with the stopper plates 4 mounted on the moving contact shaft 5 through the shaft pin 5b and through the pin 5a, which prevents further rotation of the fork lever 3 and does not allow it to reach the off position, and wherein on releasing the force applied to rotate the fork lever 3, said lever 3 returns to ON position as it’s toggle point 3b was not crossed on account of the upper link 6 not being able to rotate beyond the toggle point 3b of the fork lever 3.

10. The circuit breaker of claim 9, wherein, during normal operating conditions, when the fork lever 3 is rotated from On to OFF, it will first cross the toggle point 6a of the upper link 6 causing it to rotate and disengage the moving contact 5c and the fixed contact 8, and take the moving contact shaft 5 and stopper plates 4 to OFF position, which rotation of the upper link 6 makes the extension spring 10 to cross the toggle point 3b of the fork lever 3 and take the fork lever 3 to OFF position.
, Description:
TECHNICAL FIELD
[0001] The present disclosure relates to the field of circuit breaker, and more specifically relates to, a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.

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] 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 trough the conductors of an electrical system in response to such fault conditions. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overcurrent, typically resulting from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
[0004] Circuit breaker is a switching device designed to make, carry and break the circuit. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overcurrent, typically resulting from an overload or short circuit. Circuit breakers are generally installed to protect equipment from overcurrent (than its rated current) situations, for example, when a short circuit or ground fault occurs in an electrical supply conductor. Upon the occurrence of any such overcurrent condition, electrical contacts inside circuit breaker get opened, and stop supply of electrical current to equipment. Designs for circuit breakers generally include accommodations for both high quiescent currents and high withstand currents. To maintain a high withstand current rating, the contacts must be locked closed at the current withstand rating and be able to withstand the large electrodynamics repulsion forces generated by the current flow. With the increase of industry size and automation, the requirement of protection devices has also increased.
[0005] Circuit Breaker is a mechanical switching device capable of making, carrying and breaking currents. Under normal circuit conditions it will make the circuit, carry current for a specified time and break the circuit under specified abnormal circuit conditions. Circuit Breakers are employed for current interruption. More particularly Circuit Breakers are utilized to protect instruments from damage during adverse conditions prevailing during the operation of the circuit in which circuit breaker is employed. During adverse conditions like short circuit, the current rises to an alarmingly high level. This high current may cause damage to the parts in the electrical system. Hence during these conditions, the circuit has to be opened to protect the system. When release senses abnormal conditions, it gives Trip command to the mechanism so that the latter opens the circuit. This current interruption happens when a set of movable electrical contacts are separated from their respective fixed contacts by means of an operating mechanism. During certain abnormal conditions like overcurrent it is possible that one or many from the set of electrical contacts get welded to each other i.e. movable contacts get welded to their respective fixed contacts. Under such conditions when the release issues the trip command, it is required that the operating mechanism either break the weld and indicate trip via its indication means or if the weld is strong and cannot be broken then the indicator means should indicate “ON” even though the release has issued the trip command. Also under such circumstances if a user tries to switch off the MCCB by operating the mechanism, either manually or other operating mechanisms, he should not be able to take the lever to its “OFF” position provided the weld is still not broken.
[0006] Efforts have been made in related art to address above stated problem by using a circuit breaker. An example of such of the circuit breaker is recited in a United States Patent 5296664A, entitled “Circuit breaker with positive off protection”. The patent discloses a positive off mechanism for a circuit breaker includes a pair of positive off levers slidable in slots in the side plates and extendable into the path of the operating handle to prevent movement of the handle to the off position when the contacts are welded closed. The positive off levers are actuated by positive off links pivotally mounted to the side plates and coupled to the positive off levers by "dog bone" connections. The positive off links in turn are actuated by the toggle mechanism of the circuit breaker which collapses to open the contacts during normal circuit breaker operation, but which remains erect when the contacts are welded closed. This patent talks about an arrangement of links such that during contact welded conditions the links will prevent the lever from moving to the OFF position.
[0007] However in the prior- art, which uses an indirect method of stopping the lever wherein a complicated arrangement of some links sense the contact condition and then interfere with the lever. Such indirect method is less reliable owing to its complexity. Also any misalignment of the links can lead to malfunction and prevent the intended function from happening. Further, in the conventional method it uses a number of components as part of building the link work between the contacts and the lever. Furthermore, in the conventional system there is no mechanism or arrangement available that indicates positive indication when electrical contacts of a circuit breaker get welded due to overcurrent.
[0008] Whereas there is certainly nothing wrong with existing circuit breaker, nonetheless, there still exist a need to provide an efficient, effective, reliable, and improved a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, due to overcurrent. Further, there is a need of an arrangement that achieves all the requisite functions in a more simplistic way and by using fewer components. Furthermore, there is a need of a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.
[0009] 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.
[00010] 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.
[00011] 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.
[00012] 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.
[00013] 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 groups used in the appended claims.

OBJECTS OF THE INVENTION
[00014] An object of the present disclosure is to provide a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.
[00015] Another object of the present disclosure is to provide a method by which if the weld remains unbroken, the operating lever cannot be taken to “OFF” position.
[00016] Another object of the present disclosure is to provide a mechanism or arrangement for direct interaction of fork lever and contact system without any intermediate links.

SUMMARY
[00017] The present disclosure relates to the field of circuit breaker, and more specifically relates to, a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.
[00018] Embodiments of the present disclosure provide an efficient, effective, reliable, and improved circuit breaker. Further, a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.
[00019] Accordingly, an aspect of the present disclosure relates to a circuit breaker. In an aspect, the circuit breaker can include an operating mechanism. In another aspect, the operating mechanism can switch contact system by engaging and disengaging a moving contact with fixed contact to open and close the circuit. In another aspect, during normal switching operations, one or more stopper plates can be mounted on a moving contact shaft does not interfere with stopper pins that are riveted on a fork lever. In another aspect, when the moving contact can be welded with the fixed contact during overcurrent, the stopper pins interfere with the one or more stopper plates as the fork lever is rotated so as to prevent the the fork lever from reaching the OFF position.
[00020] In an aspect, the fork lever can be configured such that even an application of three times the force required to switch off the circuit breaker during normal operation does not take the fork lever to OFF position.
[00021] In an aspect, wherein upon releasing the force to rotate the fork lever, said fork lever returns to ON position and indicates true state of the circuit, and wherein the fork lever can be rotated anti-clockwise when in OFF state so as to switch ON the circuit breaker, and rotated clockwise when in ON state so as to switch OFF the circuit breaker.
[00022] In an aspect, circuit breaker further can include an extension spring 10 that is loaded onto the fork lever, and wherein as the spring loaded fork lever is rotated, it reaches a toggle point of an upper link on to which the other end of extension spring is loaded.
[00023] In an aspect, the spring loaded fork lever is rotated, said upper link is rotated such that when the upper link crosses toggle point of the fork lever, it toggles the fork lever to indicate the state of contact system, and wherein the upper link is connected to lower link on either side, and wherein the lower link is connected to the moving shaft, enabling motion of the upper link being able to rotate the moving contact shaft to open and close the circuit.
[00024] In an aspect, when trip command is issued, latch link can be disengaged causing it to rotate anti-clockwise, said rotation causing the upper link and lower link to rotate and disengage the moving contact from the fixed contact, and wherein as the upper link rotates during trip, it crosses the toggle point of the fork lever so as to bring the fork lever to trip position.
[00025] In an aspect, the stopper plates can be mounted on shaft pin, said pin connecting the lower link with the moving contact shaft through pin, said pin connecting RYB poles of the contact system to each other on either side, and wherein said stopper plates rotate as the moving contact shaft rotates to open and close the circuit.
[00026] In an aspect, during overcurrent if the moving contact gets welded to the fixed contact, said moving contact restricts rotation of the moving contact shaft beyond just-touch position when trip command is issued, and wherein, during tripping, rotation of the latch link exerts a force on the moving contact shaft through the upper link and the lower link so as to rotate the moving contact shaft from over-travel position to just-touch position and then attempt to break the weld such that if the weld is strong and does not break with the force applied by the latch link, the weld restricts further motion of the moving contact shaft, in which case, as the upper link does not rotate enough to cross the toggle point of the fork lever, the fork lever remains in ON position and indicates that the circuit is still closed.
[00027] In an aspect, the upper link does not rotate enough to cross the toggle point of the fork lever, if a user tries to switch off the circuit breaker by applying a force to rotate fork lever in clockwise direction, it will rotate a few degrees, and after said rotation, the stopper pins on the fork lever interfere with the stopper plates mounted on the moving contact shaft through the shaft pin and through the pin, which prevents further rotation of the fork lever and does not allow it to reach the off position, and wherein on releasing the force applied to rotate the fork lever, said lever returns to ON position as it’s toggle point was not crossed on account of the upper link not being able to rotate beyond the toggle point of the fork lever.
[00028] In an aspect, during normal operating conditions, when the fork lever is rotated from On to OFF, it will first cross the toggle point of the upper link causing it to rotate and disengage the moving contact and the fixed contact, and take the moving contact shaft and stopper plates to OFF position, which rotation of the upper link makes the extension spring to cross the toggle point of the fork lever and take the fork lever to OFF position.
[00029] In contrast to the conventional circuit breaker, the present disclosure provides a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken. Further, in contrast to the existing circuit breaker, the present invention provides an arrangement that achieves all the requisite functions in a more simplistic way and by using fewer components. Furthermore, in contrast to the existing circuit breaker, the present invention provides a method by which if the weld remains unbroken, the operating lever cannot be taken to “OFF” position. The lever can interfere with a component which cannot let the lever move further even with the application of three times the normal force required to switch off the MCCB. And on removal of this force the lever can return to the “ON” position thereby depicting the true condition of the contacts and the circuit.
[00030] 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
[00031] 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. The diagrams are for illustration only, which thus is not a limitation of the present disclosure, and wherein:
[00032] FIG. 1 illustrates an operating mechanism and contact system in ON condition, in accordance with an exemplary embodiment of the present disclosure.
[00033] FIG. 2 illustrates a section view of operating mechanism and contact system in ON condition, in accordance with an exemplary embodiment of the present disclosure.
[00034] FIG. 3 illustrates an operating mechanism and contact system in OFF condition, in accordance with another exemplary embodiment of the present disclosure.
[00035] FIG. 4 illustrates a section view of operating mechanism and contact system in OFF condition, in accordance with another exemplary embodiment of the present disclosure.
[00036] FIG. 5 illustrates an operating mechanism and contact system in TRIP condition, in accordance with another exemplary embodiment of the present disclosure.
[00037] FIG. 6 illustrates a section view of operating mechanism and contact system in TRIP condition, in accordance with another exemplary embodiment of the present disclosure.
[00038] FIG. 7 illustrates a partial section view of operating mechanism switching to OFF when contact system is in welded condition, in accordance with another exemplary embodiment of the present disclosure.
[00039] FIG. 8 illustrates a partial section view of operating mechanism when tripped and contact system is in welded condition, in accordance with another exemplary embodiment of the present disclosure.
[00040] FIG. 9 illustrates a partial section view of operating mechanism is tripped and fork lever moved to OFF when contact system is in welded condition, in accordance with another exemplary embodiment of the present disclosure.
[00041] FIG. 10 illustrates an exploded view of contact system, in accordance with another exemplary embodiment of the present disclosure.
[00042] FIG. 11 illustrates an isometric view of operating mechanism, in accordance with another exemplary embodiment of the present disclosure.
[00043] FIG. 12 illustrates an isometric view of stopper pins on fork lever interfering with stopper plates, in accordance with another exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION
[00044] 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 scope of the present disclosure as defined by the appended claims.
[00045] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[00046] 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.
[00047] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[00048] 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.
[00049] 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.
[00050] 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.
[00051] The present disclosure relates to the field of circuit breaker, and more specifically relates to, a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.
[00052] Embodiments of the present disclosure provide an efficient, effective, reliable, and improved circuit breaker. Further, a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.
[00053] Accordingly, an aspect of the present disclosure relates to a circuit breaker. In an aspect, the circuit breaker can include an operating mechanism. In another aspect, the operating mechanism can switch contact system by engaging and disengaging a moving contact with fixed contact to open and close the circuit. In another aspect, during normal switching operations, one or more stopper plates can be mounted on a moving contact shaft does not interfere with stopper pins that are riveted on a fork lever. In another aspect, when the moving contact can be welded with the fixed contact during overcurrent, the stopper pins interfere with the one or more stopper plates as the fork lever is rotated so as to prevent the fork lever from reaching the OFF position.
[00054] In an aspect, the fork lever can be configured such that even an application of three times the force required to switch off the circuit breaker during normal operation does not take the fork lever to OFF position.
[00055] In an aspect, wherein upon releasing the force to rotate the fork lever, said fork lever returns to ON position and indicates true state of the circuit, and wherein the fork lever can be rotated anti-clockwise when in OFF state so as to switch ON the circuit breaker, and rotated clockwise when in ON state so as to switch OFF the circuit breaker.
[00056] In an aspect, circuit breaker further can include an extension spring 10 that is loaded onto the fork lever, and wherein as the spring loaded fork lever is rotated, it reaches a toggle point of an upper link on to which the other end of extension spring is loaded.
[00057] In an aspect, the spring loaded fork lever is rotated, said upper link is rotated such that when the upper link crosses toggle point of the fork lever, it toggles the fork lever to indicate the state of contact system, and wherein the upper link is connected to lower link on either side, and wherein the lower link is connected to the moving shaft, enabling motion of the upper link being able to rotate the moving contact shaft to open and close the circuit.
[00058] In an aspect, when trip command is issued, latch link can be disengaged causing it to rotate anti-clockwise, said rotation causing the upper link and lower link to rotate and disengage the moving contact from the fixed contact, and wherein as the upper link rotates during trip, it crosses the toggle point of the fork lever so as to bring the fork lever to trip position.
[00059] In an aspect, the stopper plates can be mounted on shaft pin, said pin connecting the lower link with the moving contact shaft through pin, said pin connecting RYB poles of the contact system to each other on either side, and wherein said stopper plates rotate as the moving contact shaft rotates to open and close the circuit.
[00060] In an aspect, during overcurrent if the moving contact gets welded to the fixed contact, said moving contact restricts rotation of the moving contact shaft beyond just-touch position when trip command is issued, and wherein, during tripping, rotation of the latch link exerts a force on the moving contact shaft through the upper link and the lower link so as to rotate the moving contact shaft from over-travel position to just-touch position and then attempt to break the weld such that if the weld is strong and does not break with the force applied by the latch link, the weld restricts further motion of the moving contact shaft, in which case, as the upper link does not rotate enough to cross the toggle point of the fork lever, the fork lever remains in ON position and indicates that the circuit is still closed.
[00061] In an aspect, the upper link does not rotate enough to cross the toggle point of the fork lever, if a user tries to switch off the circuit breaker by applying a force to rotate fork lever in clockwise direction, it will rotate a few degrees, and after said rotation, the stopper pins on the fork lever interfere with the stopper plates mounted on the moving contact shaft through the shaft pin and through the pin, which prevents further rotation of the fork lever and does not allow it to reach the off position, and wherein on releasing the force applied to rotate the fork lever, said lever returns to ON position as it’s toggle point was not crossed on account of the upper link not being able to rotate beyond the toggle point of the fork lever.
[00062] In an aspect, during normal operating conditions, when the fork lever is rotated from On to OFF, it will first cross the toggle point of the upper link causing it to rotate and disengage the moving contact and the fixed contact, and take the moving contact shaft and stopper plates to OFF position, which rotation of the upper link makes the extension spring to cross the toggle point of the fork lever and take the fork lever to OFF position.
[00063] In contrast to the conventional circuit breaker, the present disclosure provides a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken. Further, in contrast to the existing circuit breaker, the present invention provides an arrangement that achieves all the requisite functions in a more simplistic way and by using fewer components. Furthermore, in contrast to the existing circuit breaker, the present invention provides a method by which if the weld remains unbroken, the operating lever cannot be taken to “OFF” position. The lever can interfere with a component which cannot let the lever move further even with the application of three times the normal force required to switch off the MCCB. And on removal of this force the lever can return to the “ON” position thereby depicting the true condition of the contacts and the circuit.
[00064] For the simplicity of understanding of the subject matter, following reference numerals are used for associated/corresponding feature/elements of the proposed circuit breaker:
1. Operating mechanism
2. Contact system
3. Fork lever
3a. stopper pins
4. Stopper plates
5. Moving contact shaft
5c. moving contact
6. Upper link
3b/6a. Toggle point
7. Latch link
8. Fixed contact
9. Lower link
10. Extension spring
[00065] FIG. 1 illustrates an operating mechanism and contact system in ON condition, in accordance with an exemplary embodiment of the present disclosure.
[00066] As shown in FIG. 1, an operating mechanism 1 can be configured to switch contact system 2 by engaging and disengaging a moving contact 5c with fixed contact 8 to open and close the circuit. In an embodiment, during normal switching operations, one or more stopper plates 4 can be mounted on a moving contact shaft 5 do not interfere with stopper pins 3a that are riveted on a fork lever 3. In another embodiment, when the moving contact 5c can be welded with the fixed contact 8 during overcurrent, the stopper pins 3a can interfere with the one or more stopper plates 4 as the fork lever 3 is rotated so as to prevent the fork lever 3 from reaching the OFF position
[00067] In an embodiment, the fork lever 3 can be configured such that even an application of three times the force required to switch off the circuit breaker during normal operation does not take the fork lever 3 to OFF position.
[00068] FIG. 2 illustrates a section view of operating mechanism and contact system in ON condition, in accordance with an exemplary embodiment of the present disclosure.
[00069] As shown in FIG. 2, extension spring 10 can be loaded onto the fork lever 3, and wherein as the spring loaded fork lever 3 is rotated, it reaches a toggle point 6a of an upper link 6 on to which the other end of extension spring 10 is loaded.
[00070] FIG. 3 illustrates an operating mechanism and contact system in OFF condition, in accordance with another exemplary embodiment of the present disclosure.
[00071] As shown in FIG. 3, the fork lever 3 can be rotated anti-clockwise when in OFF state so as to switch ON the circuit breaker, and rotated clockwise when in ON state so as to switch OFF the circuit breaker.
[00072] FIG. 4 illustrates a section view of operating mechanism and contact system in OFF condition, in accordance with another exemplary embodiment of the present disclosure.
[00073] FIG. 5 illustrates an operating mechanism and contact system in TRIP condition, in accordance with another exemplary embodiment of the present disclosure.
[00074] As shown in FIG. 5, when trip command is issued, latch link 7 can be disengaged causing it to rotate anti-clockwise, said rotation causing the upper link 6 and lower link 9 to rotate and disengage the moving contact 5c from the fixed contact 8, and wherein as the upper link 6 rotates during trip, it crosses the toggle point 3b of the fork lever 3 so as to bring the fork lever 3 to trip position.
[00075] FIG. 6 illustrates a section view of operating mechanism and contact system in TRIP condition, in accordance with another exemplary embodiment of the present disclosure.
[00076] FIG. 7 illustrates a partial section view of operating mechanism switching to OFF when contact system is in welded condition, in accordance with another exemplary embodiment of the present disclosure.
[00077] FIG. 8 illustrates a partial section view of operating mechanism when tripped and contact system is in welded condition, in accordance with another exemplary embodiment of the present disclosure.
[00078] As shown in FIG. 8, during overcurrent if the moving contact 5c gets welded to the fixed contact 8, said moving contact 5c restricts rotation of the moving contact shaft 5 beyond just-touch position when trip command is issued, and wherein, during tripping, rotation of the latch link 7 exerts a force on the moving contact shaft 5 through the upper link 6 and the lower link 9 so as to rotate the moving contact shaft 5 from over-travel position to just-touch position and then attempt to break the weld such that if the weld is strong and does not break with the force applied by the latch link 7, the weld restricts further motion of the moving contact shaft 5, in which case, as the upper link 6 does not rotate enough to cross the toggle point 3b of the fork lever 3, the fork lever 3 remains in ON position and indicates that the circuit is still closed.
[00079] FIG. 9 illustrates a partial section view of operating mechanism is tripped and fork lever being moved to OFF when contact system is in welded condition, in accordance with another exemplary embodiment of the present disclosure.
[00080] As shown in FIG. 9, if the upper link 6 does not rotate enough to cross the toggle point 3b of the fork lever 3, if a user tries to switch off the circuit breaker by applying a force to rotate fork lever 3 in clockwise direction, it will rotate a few degrees, and after said rotation, the stopper pins 3a on the fork lever 3 interfere with the stopper plates 4 mounted on the moving contact shaft 5 through the shaft pin 5b and through the pin 5a, which prevents further rotation of the fork lever 3 and does not allow it to reach the off position, and wherein on releasing the force applied to rotate the fork lever 3, said lever 3 returns to ON position as it’s toggle point 3b was not crossed on account of the upper link 6 not being able to rotate beyond the toggle point 3b of the fork lever 3.
[00081] FIG. 10 illustrates an exploded view of contact system, in accordance with another exemplary embodiment of the present disclosure.
[00082] As shown in FIG. 10, the stopper plates 4 can be mounted on shaft pin 5b, said pin connecting the lower link 9 with the moving contact shaft through pin 5a, said pin 5a connecting RYB poles of the contact system 2 to each other on either side, and wherein said stopper plates 4 rotate as the moving contact shaft 5 rotates to open and close the circuit.
[00083] FIG. 11 illustrates an isometric view of operating mechanism, in accordance with another exemplary embodiment of the present disclosure.
[00084] FIG. 12 illustrates an isometric view of stopper pins on fork lever interfering with stopper plates, in accordance with another exemplary embodiment of the present disclosure.
[00085] In an embodiment, the operating mechanism 1 can be used to switch the contact system 2 by engaging and disengaging the moving contact 5c with fixed contact 8 to close and open the circuit. The fork lever 3 can be rotated anti-clockwise, when in OFF as shown in FIG. 3 and 4, to switch ON the MCCB and clockwise, when in ON as shown in FIG. 1 and 2, to switch OFF the MCCB. As the extension spring 10 loaded fork lever 3 can be rotated it reaches the toggle point 6a of upper link 6 on to which the other end of extension spring 10 is loaded. This rotates the upper link 6 and when upper link 6 crosses the toggle point 3b of the fork lever 3 it toggles the fork lever 3 to indicate the state of contact system 2 viz. close or Open. The upper link 6 can be connected to lower links 9 on either side which in turn are connected to moving contact shaft 5. Hence the motion of upper link 6 rotates the moving contact shaft 5 to open and close the circuit.
[00086] When trip command is issued the latch link 7 can be disengaged causing it to rotate anti-clockwise, as shown in FIG. 5 and 6. This rotation causes upper link 6 and thereby lower links 9 to rotate and disengage the moving contact 5c from fixed contact 8. As the upper link 6 rotates during trip it crosses the toggle point 3b of fork lever 3 and brings it to trip position, as shown in FIG. 5 and 6.
[00087] Two stopper plates 4 can be mounted on shaft pin 5b, which is a connection between lower link 9 and moving contact shaft 5, and through pin 5a, which connects the R-Y-B poles of contact system 2 to each other, on either side as depicted in figure 10. These stopper plates 4 rotate as the moving contact shaft 5 rotate to open and close the circuit.
[00088] During overcurrent if moving contact 5c gets welded to fixed contact 8 it can restrict the rotation of moving contact shaft 5 beyond just-touch position, as shown in figure 8, when trip command is issued by the release and the mechanism trips. During tripping the rotation of latch link 7 will exert a force on moving contact shaft 5 through upper link 6 and lower links 9 to rotate the moving contact shaft 5 from over-travel position to just-touch position and then will try to break the weld. However, if the weld is strong and does not break with the force applied by latch link 7 then the weld will restrict further motion of moving contact shaft 5 and thereby of lower links 9, upper link 6 and latch link 7. As upper link 6 does not rotate enough to cross the toggle point 3b of fork lever 3, fork lever 3 will remain in ON position and indicate that the circuit is still closed.
[00089] In this condition if a user tries to switch off the breaker by applying a force to rotate fork lever 3 in clockwise direction, it will rotate a few degrees. After which the stopper pins 3a on fork lever 3 can interfere with the stopper plates 4 mounted on moving contact shaft 5 through shaft pin 5b and through pin 5a, as shown in FIG. 9. This interference can prevent further rotation of fork lever 3 and won’t allow it to reach the off position. On releasing the force applied to rotate the fork lever 3 it will return to ON position as it’s toggle point 3b was not crossed on account of upper link 6 not being able to rotate beyond the toggle point 3b of fork lever 3.
[00090] During normal operating conditions, when the fork lever 3 can be rotated from On to OFF, it can first cross the toggle point 6a of upper link 6 causing it to rotate and disengage the moving contact 5c and fixed contact 8 and take the moving contact shaft 5 and stopper plates 4 to OFF position. This rotation of upper link 6 can then make the extension spring 10 to cross the toggle point 3b of fork lever 3 and take the fork lever 3 to OFF position.
[00091] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the appended claims.
[00092] While embodiments of the present disclosure have been illustrated and described, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the scope of the disclosure, as described in the claims.
[00093] In the description of the present specification, reference to the term "one embodiment," "an embodiments", "an example", "an instance", or "some examples" and the description is meant in connection with the embodiment or example described The particular feature, structure, material, or characteristic included in the present invention, at least one embodiment or example. In the present specification, the term of the above schematic representation is not necessarily for the same embodiment or example. Furthermore, the particular features structures, materials, or characteristics described in any one or more embodiments or examples in proper manner. Moreover, those skilled in the art can be described in the specification of different embodiments or examples are joined and combinations thereof.
[00094] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
[00095] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
[00096] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
[00097] 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
[00098] The present disclosure provides a mechanism to indicate positive indication when electrical contacts of a circuit breaker get welded, when electrical contacts of circuit breakers get welded due to overcurrent it is imperative to either break the weld as the user tries to switch off the MCCB or prevent the indicator knob from reaching the “OFF” position when the weld cannot be broken.
[00099] The present disclosure provides a method by which if the weld remains unbroken, the operating lever cannot be taken to “OFF” position.
[000100] The present disclosure provides a mechanism or arrangement for direct interaction of fork lever and contact system without any intermediate links.