DESC:TECHNICAL FIELD
[0001] The present disclosure relates generally to circuit breakers (MCCB) that incorporate arc runner profile for arc quenching. In particular it pertains to moving contact that incorporates a runner profile and a contact button and method of manufacturing the same.

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] A circuit Breaker is an electro-mechanical switching device capable of making, carrying and breaking currents. Under normal circuit conditions, it closes the circuit, carries current and breaks the circuit under specified abnormal circuit conditions. Circuit Breakers reemployed for current interruption. More particularly MCCBs are utilized to protect downstream equipment from damage during adverse conditions that may prevail during operation of the circuit in which the 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 parts downstream of the breaker from damages that may be caused by high currents.
[0004] A standard circuit breaker is placed between a line and a load. Generally, the line is the incoming electricity supply, most often from a power distributor company. This can sometimes be referred to as the input to the circuit breaker. The load, sometimes referred to as the output, feeds out of the circuit breaker and connects to the electrical components being fed from the circuit breaker. There may be an individual component connected directly to a circuit breaker, for example only an air conditioner, or a circuit breaker may be connected to multiple components through a power wire which terminates at electrical outlets.
[0005] A circuit breaker can be used as a replacement for a fuse. Unlike fuses, which operate once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Fuses performs the same duty as circuit breakers, however, CBs are safer to use than fuses and easier to fix. When the power to an area shuts down, the operator can look in the electrical panel and see which breaker has tripped to the “off” position. The breaker can then be made to “on” position and power will resume again.
[0006] A typical circuit-breaking device has an outer housing containing, for each pole, at least one current carrying fixed contact and at least one current carrying moving contact suitable for being mutually coupled and uncoupled. The device also has a control mechanism with a supporting frame that supports a kinematic chain operatively connected to the moving contact so as to enable the latter to be coupled to or uncoupled from the fixed contact to make or break the circuit. During the process of separation of the two contacts an ‘arc’ develops between the two which can damage the breaker and contact system.
[0007] A contact arc in a circuit breaker is an extremely complex electro-thermo-hydro-dynamic process whose detailed physics cannot be fully described mathematically. During normal circuit breaker operation, the arc is in a continual state of change. It is dynamically lengthened by parting contacts and by electromagnetic forces which push it away from its original trajectory. It is dynamically heated by its current. It is dynamically cooled by its environment and, perhaps, by other auxiliary means such as forced gas flow, cool containment walls, etc.; and depending on the net rate of energy absorption (heating minus cooling), it dynamically grows in cross-sectional area. As the arc changes physically and thermally, it also changes electrically. A change in the electrical characteristics of the arc, in turn, changes the amount of through current that the external electrical circuit can supply.
[0008] A common arc control scheme used in many circuit breaker designs is to increase the total arc voltage across the main contacts by forcing the arc into an arc baffle or splitter structure. Arc baffles act to break a single arc into several shorter arcs connected in series and consists of stack of de-ionizing plates made up of magnetic material to attract, split-up & cool the arcs. The de-ionizing splitter plates are stacked in between two electrically insulating material plates known as lining or stacked inside a chamber. The function of de-ionizing plates is to split the arc in several arcs of approximately equal length which results in higher arc voltage and distinctly greater dielectric strength after current zero thus precluding any possibility of reappearance of the arc.
[0009] Another method used for arc control is magnetic blow-out to force arc movement onto arc “runners”, which are attached to the contact structures. Use of arc runners preserves the more expensive silver alloy contact material by moving the cathode/anode “feet” of the arc off the contacts, and onto the less expensive runner material. In addition, the arc runners present a longer arc path for the arc to traverse, and can act as the transfer medium between the inter-contact region and any arc baffle or arc chamber region. Arc runners can be enhanced with the addition of staged electromagnetic drive coils to further strengthen the magnetic blow-out force along the runner length.
[0010] A typical structure of arc runner of circuit breakers is disclosed in US Patent 4885441and has a triangular shaped protrusion on the runner where portion near the button is narrow and portion away from the button is wider, requiring the arc to travel from narrow to wider zone and stabilize over there and never come back between moving and fixed contact buttons.
[0011] Another exemplary structure has been disclosed in US20140131317, which discloses an arc runner construction that is fitted with fixed conductor by means of a screw for rapidly extinguishing the electrical arc, making the arc not to come back between moving and fixed conductors.
[0012] In existing technologies, current carrying paths and arc runner components are made from separate materials or processes and then joined together, which increases the cost and assembly time of the finished product. Furthermore, existing structures need additional components to be developed for the circuit breaker. Also, the contact button brazing area available in the current carrying conductor is less, which results in improper contact button welding. All of these and other disadvantages of the existing arc runner configurations reduce the life of the circuit breaker if brazing is not done properly. For instance, existing structures also face a high joint resistance as joining is poor, which leads to higher product temperature and higher erosion on contact buttons in short circuit.
[0013] There is therefore a need in art for an improved arc runner configuration for circuit breakers.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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
[0019] An object of the present disclosure is to eliminate joint between current carrying paths/conductor and the arc runner of a moving contact of an air circuit breaker.
[0020] Another object of the present disclosure is to make current carrying paths/conductor and the arc runner of the moving contact from same material.
[0021] Another object of the present disclosure is to reduce number of components needed for the circuit breaker.
[0022] Another object of the present disclosure is to increase life of the circuit breaker.
[0023] Another object of the present disclosure is to increase life of the circuit breaker by improving the brazing joint between the current carrying conductor and contact button of the moving contact.
[0024] Another object of the present disclosure is to increase brazing area between the contact button and the current carrying conductor to improve the brazing joint between them.

SUMMARY
[0025] Aspects of present disclosure relate to a moving contact that incorporates an arc runner surface and a contact button. In particular it pertains to design and method of manufacturing the moving contact. In an aspect, the disclosure provides a method of manufacturing the moving contact that eliminates joint between current carrying conductor and the arc runner thus improving the current path, reducing number of components with corresponding cost benefits.
[0026] In an aspect, the disclosure provides a moving contact that incorporates an integrated arc runner profile. This integrated arc runner can help in moving the arc away from contact button of the moving contact at a faster rate which can help to reduce contact button erosion during arc quenching.
[0027] In an aspect, the integrated arc runner is formed on the moving contact by cold forming (or forging and the two terms are used interchangeably hereinafter) the conducting material of the contact. An integrated arc runner formed by cold forming process. Forming the arc runner on the moving contact by cold forming eliminates the requirement of an additional component which in conventional method is made separately and fixed to the conducting material of the moving contact.
[0028] In an aspect, during the cold forming process, width of the moving contact is also increased to increase landing area of the contact button. This eliminates unsupported & overhanging of the contact button and the contact button gets seating/landing area on the moving contact across its full width thereby improving joint between the contact button and conducting material of the moving contact.
[0029] In an aspect, forming of contact button seating/landing area on the moving contact by cold forming process ensures a good flatness and surface finish on the seating/landing surface of the contact button thereby eliminating the need for shaving process for ensuring flatness and surface finish of the seating/landing area of the moving contact in conventional methods/designs.
[0030] 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
[0031] 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.
[0032] FIG. 1 illustrates an exemplary side view of the moving contact with cold formed/forged arc runner and contact button area in accordance with an embodiment of the present disclosure.
[0033] FIG. 2 illustrates an exemplary enlarged view of the arc runner area of the moving contact before and after cold forging/forming in accordance with an embodiment of the present disclosure.
[0034] FIG. 3 illustrates an exemplary representation of moving contact button location on forged surface of moving contact in accordance with an embodiment of the present disclosure.
[0035] FIG. 4 illustrates an exemplary enlarged view of the contact button location on the forged surface of the moving contact in accordance with an embodiment of the present disclosure.
[0036] FIG. 5 illustrates an exemplary representation of arc movement in a circuit breaker in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] Embodiments of present disclosure relate to a moving contact that incorporates an arc runner surface and a contact button. In particular it pertains to design and method of manufacturing the moving contact.
[0042] In an embodiment, the disclosure provides a moving contact with an integrated arc runner wherein the integrated arc runner is formed by cold forging the conducting material (copper) of the moving contact. In an aspect, the integrated arc runner can help in moving the arc away from contact button of the moving contact at a faster rate which can help to reduce contact button erosion during arc quenching. In another aspect, forming the arc runner on the moving contact by cold forming does away with requirement of an additional component which in conventional method is made separately and fixed to the conducting material of the moving contact.
[0043] In an embodiment, during the cold forming process, width of the moving contact is also increased to increase landing area of the contact button. This eliminates unsupported & overhanging of the contact button and the contact button gets seating/landing area on the moving contact across its full width thereby improving joint between the contact button and conducting material of the moving contact. In an aspect, forming of contact button seating/landing area on the moving contact by cold forming process ensures a good flatness and surface finish on the seating/landing surface of the contact button thereby eliminating the need for shaving process for ensuring flatness and surface finish of the seating/landing area of the moving contact in conventional methods/designs.
[0044] In an aspect, the disclosed moving contact and method of manufacture improves the current path, reduces number of components with corresponding improvement in life of the circuit breaker and cost benefits.
[0045] Referring now to FIG. 1 wherein an exemplary moving contact 102 in accordance with embodiments of the present disclosure is disclosed. The moving contact 102 can incorporate an integrated arc runner 106, wherein the integrated arc runner106 can be configured to take the arc away from contact button at a faster rate thereby helping to reduce the button erosion during arc quenching.
[0046] In an embodiment, the disclosure provides for making the integrated arc runner 106 on the moving contact by cold forging process. FIG. 2 illustrates an exemplary enlarged view200 of the arc runner area of the moving contact before and after cold forging/forming in accordance with an embodiment of the present disclosure. As shown in the enlarged view200, a narrow section 202 of conducting material of the moving contact 102 can be cold forged to form a wider integrated arc runner 106. The arc runner 106 can have a suitable profile to move the arc off the contact button during tripping and prevent erosion of the contact button on account of arc.
[0047] In an aspect, an integrated arc runner 106 eliminates the need of a separate component that in conventional methods is fixed to the conducting material of the moving contact, can bring corresponding cost benefits besides improving the current conduction path for the arc current.
[0048] In an embodiment, the present disclosure provides for an improvement in fixing the contact button on the moving contact. In existing/conventional designs, the contact button fixed on the moving contact has a higher width than the width/thickness of the moving contact, because of which the joining area between the two is limited to the thickness of conducting material (copper)of the moving contact. This reduced area makes improper joining between the contact button and the conducting material. Furthermore, the unsupported and overhanging of the contact button on sides erodes at a faster rate due to arcing during fault protection.
[0049] In an embodiment, the above-mentioned limitation is overcome by increasing width of the moving contact by cold forging to increase landing area of the contact button. As shown in FIG. 2, the conducting material 204 is forged to provide a wider seating area 104 for the contact button. In an aspect the landing area 104 can be of same shape and size as the contact button. This eliminates unsupported & overhanging of the contact button and the contact button gets seating/landing area on the moving contact across its full width thereby improving joint between the contact button and conducting material of the moving contact.
[0050] In an embodiment, the contact button can also be supported and joined with the conducting material at vertical face 108 formed next to the arc runner 106 during the cold forging process. The additional vertical support can further strengthen the joint between the contact button and the conducting material and reduce joint resistance.
[0051] In an aspect, forming of contact button seating/landing area on the moving contact by cold forming process ensures a good flatness and surface finish on the seating/landing surface of the contact button thereby eliminating the need for any finishing operation such as shaving process for ensuring flatness and surface finish of the seating/landing area of the moving contact in conventional methods/designs.
[0052] FIG. 3 illustrates an exemplary representation 300 of the contact button located on the forged surface of moving contact in accordance with an embodiment of the present disclosure. As shown the contact button 110 gets fully supported on the bottom face as well as on vertical face.
[0053] FIG. 4 illustrates an exemplary enlarged view 400 of the contact button location on the forged surface of the moving contact along with the arc runner in accordance with an embodiment of the present disclosure. The cold formed support 104 for the contact button 110 allows the current to distribute through the entire moving contact button and prevent current concentration in small region that can result in local heating of contact button reducing its life.
[0054] FIG. 5 illustrates an exemplary representation of arc movement in a circuit breaker in accordance with an embodiment of the present disclosure. As shown the integrated arc runner profile helps the arc to move smoothly away from the button as the arc travels from point A to point B during short circuit. This helps the arc to remain at the top of the ion plates and reduce button erosion. With the integrated runner curved profile 106 in the moving contact, the arc moves on to the runner 106 and reduces the contact button erosion.
[0055] In an aspect, the present disclosure relates to method of production of moving contacts with integrated arc runner profiles to reduce the number of components and to reduce button erosion. The proposed construction requires no additional components as the arc runner profile 106 is a part of the moving contact 102.The proposed method provides a good surface and flatness for button brazing and ensuring low resistance and enhanced life.
[0056] In an aspect, the proposed method also provides making a forged rectangular or square surface by cold forming process for the contact button location. The proposed design also incorporates a forged curved arc runner surface to avoid heavy erosion of copper arc runner, and further incorporates a vertical surface for proper location and support for the contact button. Flatness of the moving contact flat surface for joining contact button is further achieved during the cold forging process to enable proper joining of the contact button to the rectangular or square shaped support area. In an embodiment, a cold formed surface is configured to behave as if the copper contact is of larger thickness
[0057] 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
[0058] The present disclosure eliminates joint between current carrying paths/conductor and the arc runner of a moving contact of a circuit breaker.
[0059] The present disclosure makes current carrying paths/conductor and the arc runner of the moving contact from same material.
[0060] The present disclosure reduces number of components needed for the circuit breaker.
[0061] The present disclosure increases life of the circuit breaker.
[0062] The present disclosure increases the life of the circuit breaker by improving the brazing joint between the current carrying conductor and contact button of the moving contact.
[0063] The present disclosure increases brazing area between the contact button and the current carrying conductor to improve the brazing joint between them.
,CLAIMS:1. A moving contact for a circuit breaker comprising:
a contact button fixed on a flat landing area of same size and shape as the contact button; and
an arc runner face configured to move an arc generated during separation of the moving contact from a fixed contact, away from the contact button;
wherein both the flat landing area and the arc runner face are formed by cold forging of conducting material of the moving contact.
2. The moving contact of the claim 1, wherein the landing area is of rectangular shape.
3. The moving contact of the claim 1, wherein the landing area is of square shape.
4. The moving contact of the claim 1, wherein the conducting material has thickness less than width of the contact button.
5. The moving contact of the claim 1, wherein the cold forging of conducting material of the moving contact further generates a vertical surface to locate and support the contact button along a vertical plane.
6. The moving contact of the claim 1, wherein no finishing operation is carried out on the cold forged flat landing area.
7. The moving contact of the claim 1, wherein the landing area is configured to prevent arcing between the contact button and the conducting material of the moving contact.
8. The moving contact of the claim 1, wherein the conducting material is of copper.
9. The moving contact of the claim 1, wherein the contact button is fixed to the landing area by brazing.
10. A circuit breaker comprising:
a fixed contact; and
a moving contact wherein the moving contact comprises:
a contact button fixed on a flat landing area of same size and shape as the contact button; and
an arc runner face configured to move an arc generated during separation of the moving contact and the fixed contact, away from the contact button;
wherein both the flat landing area and the arc runner face are formed by cold forging of conducting material of the moving contact.