Claims:1. An improved circuit breaker comprising:
at least one electrical conductor assembly wherein at least contact button with rectangular vertical slots or rectangular serrated detail on the back and at least one conductor arm or contact carrying arm with rectangular vertical slots rectangular serrated detail to facilitate the brazing process.

2. The improved circuit breaker as claimed in claim 1, wherein the one or more rectangular vertical slots or serrations on back of the contact button and the one or more rectangular vertical slots or serrations on the contact arm are adapted to bond for making and carrying the electrical current.

3. The improved circuit breaker as claimed in claim 1, wherein the rectangular vertical slots or serrations provided on a back surface of the at least one contact button are adapted to fit into the rectangular vertical slots or serrations of the contact arm.

4. The improved circuit breaker as claimed in claim 1, wherein the one or more serration slots on the back of the contact button provides small areas at and around which a considerable heat is generated when the second contact arm is urged against the first contact arm and a welding current is applied for binding the second contact arm to the first contact arm.

5. An improved electrical conductor arm assembly for a circuit breaker, comprising:
a contact button having a rectangular vertical slots provide on the back of the contact button with a pre-determined pitch and having a peak and a grove of the rectangular vertical slots in an alternate position on the contact button; and
a contact carrying arm having a rectangular vertical slots with a same pitch as that of the pre-determined pitch with a single pitch length offset, wherein the rectangular vertical slots of the first contact carrying arm provided at an alternate positions are adapted to make a lock-fit arrangement or assembly and prevents the sidewise sliding of the contact button for making, carrying and breaking an electrical current.

6. The improved electrical conductor arm assembly as claimed in claim 5, wherein the lock-fit arrangement or assembly is solidly brazed with no air gap.

7. The improved electrical conductor arm assembly as claimed in claim 5, wherein a fitment between the serrated surfaces or between the peak and grove or valleys of the slots of contact button and contact carrying arm is solidly brazed with no air gap.

8. The improved electrical conductor arm assembly as claimed in claim 5, wherein contact carrying arm includes a horizontal slot and wherein the peak and the grooves or valleys are of rectangular shape.

9. The improved electrical conductor arm assembly as claimed in claim 5, wherein the height of the peaks and the depth of the grooves are such that they provide a lock-fit arrangement or assembly of the contact button and contact carrying arm and prevents the sidewise sliding of the button on the contact carrying arm.

10. The improved electrical conductor arm assembly as claimed in claim 5, wherein rectangular vertical slots are provided on the back of the contact button with some certain pitch and the rectangular vertical slots with same pitch on the contact carrying arm with single pitch length offset, having the peak and grove of the slot in the alternate position in the contact button and in the contact carrying arm are provided so that the serration or slots can make a lock-fit kind arrangement or assembly.

11. The improved electrical conductor arm assembly as claimed in claim 5, wherein:
the rectangular slots having either peaks or ribs or grooves or valleys are provided at the two ends thickness wise of the conductor arm or the button; or
the rectangular slots having one peak or ribs at one end (thickness wise) and one grove or valley at the other end (thickness wise) of the conductor arm or button; and
wherein the slots are provided so that the peaks or ribs on the conductor arm and the groves or valleys on the contact button are in alternate position, when assembled and forms a lock fit assembly when assembled, and also the slots are provided so that the peaks or ribs on the contact button and the groves or valleys on the conductor arm are in alternate position, when assembled and make a lock fit assembly.
, Description:TECHNICAL FIELD
[0001] The present disclosure generally relates to the field of electrical conductor arm assembly for a circuit breaker. In particular, it pertains to, but not by way of limitation, an improved electrical conductor arm assembly for a circuit breaker.

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] Contact arm assemblies having electrical contacts for making, carrying and breaking an electrical current are not only employed in electrical circuit breakers, but also in other electrical devices, such as rotary double break circuit breakers, contactors, relays, switches, and disconnectors. The method of making an electrical contact by mixing silver and a refractory metal powder, such as molybdenum, tungsten, or their carbides, pressing them to form a porous metal with or without a serrated back, sintering and impregnating this contact with silver is well known in the art. Many variations of this procedure are in present use. One procedure is to serrate the electrical contact in the pill pressing operation. After the contacts are made by powder presses in pill form with a serrated back, they are sintered and then impregnated with silver. Subsequent to this each contact may go through a punch press operation to press the silver which has been formed in between the serrations into- a form corresponding to that of the serrations. A second procedure in use is to form a flat contact in a powder pill press, sinter this contact, impregnate it with enough silver so that an excess of silver will manifest itself as a layer of pure silver on one surface of the contact, and then by a coining process form the serrations of the pure silver surface of the contact.
[0004] Each procedure is objectionable from at least one of the following standpoints: 1. it requires an extra and comparatively expensive punch press operation. 2. The pyramidal serrations are rather delicate and brittle and a forming or punching press operation tends to crack the serrations. 3. In circular contacts it is almost impossible to make the serrations of the electrical contact line up with the serrations in the punch press coining plunger with the result that there is a definite distortion or breakage at the serrated points. 4. During the impregnation process the molten silver is not fully contained by the truncated pyramidal protrusions and, therefore, runs over the sides of the contact.
[0005] Current technology trend in modern circuit breakers uses multiple fingers moving contact assembly, where fingers of same cross section, to carry the rated current, to withstand the fault current and to break the fault current. To minimize the high repulsive force, current sharing technology using multiple finger or multiple conductor assembly is being used in the modern day switchgear, especially in circuit breakers. Due to proximity effect of intra phase and inter phase current carrying fingers, this current sharing by the multiple fingers in a single phase is not uniformly distributed. Thus for each finger for an alternating current cycle the maximum instantaneous current magnitude is different so each finger carries a maximum current of different magnitude. Also for each finger at a particular time instant the instantaneous current magnitude is different so each finger carries a current of different magnitude in a multiphase alternating current circuit breaker. In other terms the rms value and the peak value of current flown through each finger for a full cycle of current waveform is different and at a particular time instant the instantaneous value of the current flown through each finger is also different. This non-uniform distribution of current limits and decreases the current carrying capability, fault current withstand capability and fault current breaking capability and performance of a circuit breaker. This uneven instantaneous current distribution among the multiple fingers of multiphase circuit breaker also decreases the temperature rise performance and electrical life as well.
[0006] The electromagnetic torque acting on the movable conductors can be divided into Repulsion torque, Tilting torque, and Sliding torque according to the direction. Compared with the torque of the contact spring force, Repulsion torque decides whether the movable contact would be repulsed away from the fixed one. Tilting torque may tilt the movable conductor, and increase the contact resistance. As for Sliding torque, it may make the movable contact slide along the fixed contact. It can be seen that the contact reliability is significantly affected with the existence of tilting torque and sliding torque, especially under the high short-circuit current.
[0007] It is found that the electromagnetic torque due to the flowing current tilts and slides each fingers. It is also found that the peak tilting torque and peak sliding torque values of outer movable finger are considerably larger than those of the inner. It tilts the outer movable finger towards the middle of each phase and the sliding torque slides the head of outer moving finger or outer movable conductors toward the middle of each phase too. So due to these torques all the fingers are having less dynamic stability and the dynamic stability the side most or outer most fingers of each phase is comparatively lesser. The movable conductors of B phase perform the worst in case of a balanced 3 phase current in the aspect of dynamic stability as due to proximity effect and for a balanced 3 phase current the side most fingers of B phase carries the maximum shared current.
[0008] So the drawback of current technology is that it does not ensure the dynamic stability of the moving fingers against the electromagnetic tilting and sliding torque. In case of a little large tolerance or gap in between the fingers and the finger spacer or separator or in case of lower thickness of the finger separator or finger spacer, the finger and hence the contact button tilts and slides in case of high current electromagnetic torque. This decreases the dynamic stability of the contact finger and hence contact button. So the contact area of the contact buttons get varied and in case of lower contact area due to high repulsion force at contact button area micro opening happens, which leads to finger repulsion and ultimately total contact finger or pole opening due to cascading effect, so it deteriorates the Icw (Icw is the fault current the circuit-breaker will withstand for the maximum short-time) and fault clearing or breaking performance of circuit breaker. In case of more sliding of fingers and hence contact buttons, contact area varies and hence the contact resistance varies. In case of higher contact resistance temperature increases and contacts get more eroded and the erosion surface gets increased due to material transfer while sliding of the contacts. It also increases the temperature rise of the contacts and hence it deteriorates the thermal performance of circuit breaker. So the higher sliding of fingers and contacts, higher contact resistance, high current density, high temperature, high repulsive force, higher erosion of contacts, higher erosion surface of contacts, all have interconnected and cascaded and chained effect and this cascading and interconnected effects decreases the circuit breakers’ Icw, current breaking and current carrying performance.
[0009] As the capacity rating of the contact carrying arm assembly increases, the cross-sectional areas of the contact, conductor arm, and bond area between contact and conductor arm, typically increases in order to accommodate thermal limitations within an electrical device. While the cross-sectional areas of the contact and conductor arm or contact carrying arm are readily determined by geometric measurements, the cross-sectional area of the bond surface between contact and contact carrying arm is not so readily determined. Factors such as brazing electrode geometry variations, surface oxidation, brazing temperature, brazing time and braze alloy geometry variations can affect the quality of bonding and more precisely the percentage of bond area that is actually brazed, thereby effecting the ability of the brazed joint to withstand adiabatic heating at short circuit and in Icw, Icm and Icu performances, to withstand the sliding force at short circuit and in Icw, Icm and Icu performances and to withstand shear forces during mechanical opening and closing of the contacts. Thus, it would be beneficial to have an improved method of bonding an electrical contact to a contact carrier and an improved contact carrying arm assembly resulting therefrom.
[0010] Also in normal contact-to-contact-carrying arm brazing operations, Where annealing of the copper contact carrying arm occurs, the softened copper of the contact arm can result in deformation of the contact arm after the contact arm experiences repeated mechanical on-off impact loads, thereby reducing the term of usability of the contact arm and host device.
[0011] Also current technology uses serration on conductor arm of specially pyramidal shape or saw tooth shape where excess braze flow expels around the outer edge of the bond region due to lack of proper collector pocket for the braze flow. Also in absence of such serration also the excess braze flow expels around the outer edge of the bond region. Excessive braze flow that is expelled around the outer edge of the bond region during brazing can weep down to the contact surface and cause undesirable tack welding of the contacts.
[0012] Current technology mostly uses horizontal serration or slots on the conductor arm and/or on the back of the contact button. Where in case of rated or short circuit performance due to excess heat generated the brazing between contact button and conductor arm melts partially or completely and hence weakens the brazing bond strength. Under such circumstances due to the electromagnetic sliding force due to the rated or short circuit current the contact button gets dislocated often and easily and thus causing failure in rated and in short circuit performance and in mainly in Icw, Icm and in Icu performances. Also due to the shearing force and due to the impact load of mechanical on off operation, such a weak bonded button often gets dislocated. The horizontal serration thus decreases the life of the switching device or breaker in such cases.
[0013] The aforementioned limitations of the contact arm assemblies are recognized by the inventors hereof and some or all of these limitations have been addressed by various embodiments of the current invention.
[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.

SUMMARY
[0019] The present invention relates in general to carrying current, short circuit withstand current Icw, clearing fault currents in switchgears in any switching device or circuit breaker using current sharing and current breaking technologies.
[0020] The aforementioned limitations of the contact assemblies are recognized by the inventors hereof and some or all of these limitations have been addressed by the current invention by providing rectangular vertical slots in the back of the silver contact button with some certain pitch and rectangular vertical slots with same pitch on the contact carrying arm with single pitch length offset, having the peak and grove of the slot in the alternate position in the contact button and in the contact carrying arm so that both serration or slots can make a lock-fit kind arrangement or assembly.
[0021] Aspect of the present disclosure provides an improved electrical conductor arm assembly for a circuit breaker. The improved electrical conductor arm assembly uses rectangular vertical slots in the back of the silver contact button with some certain pitch and rectangular vertical slots with same pitch on the contact carrying arm with single pitch length offset, having the peak and grove of the slot in the alternate position in the contact button and in the contact carrying arm so that both serration or slots can make a lock-fit kind arrangement or assembly.
[0022] An aspect of the present disclosure relates to an improved circuit breaker. The improved circuit breaker includes at least one electrical conductor assembly wherein at least contact button with rectangular vertical slots or rectangular serrated detail on the back and at least one conductor arm or contact carrying arm with rectangular vertical slots rectangular serrated detail to facilitate the brazing process.
[0023] An aspect of the present disclosure relates to an improved electrical conductor arm assembly for a circuit breaker. The improved electrical conductor arm assembly includes a contact button having a rectangular vertical slots provide on the back of the contact button with a pre-determined pitch and having a peak and a grove of the rectangular vertical slots in an alternate position on the contact button, and a contact carrying arm having a rectangular vertical slots with a same pitch as that of the pre-determined pitch with a single pitch length offset, wherein the rectangular vertical slots of the first contact carrying arm provided at an alternate positions are adapted to make a lock-fit arrangement or assembly and prevents the sidewise sliding of the contact button for making, carrying and breaking an electrical current.
[0024] In an aspect, the depth, length and width of the slot or serration, number of slots or serration can be varied as per requirement.
[0025] In an aspect, there can be slots, having either peaks or ribs or grooves or valleys at the two ends thickness wise of conductor arm or button or there can be slots having one peak or ribs at one end (thickness wise) and one grove or valley at the other end (thickness wise) of the conductor arm or button. The slots are so that the peaks or ribs on the conductor arm and the groves or valleys on the contact button are in alternate position, when assembled and make a lock fit assembly when assembled. Also the slots are so that the peaks or ribs on the contact button and the groves or valleys on the conductor arm are in alternate position, when assembled and make a lock fit assembly when assembled.
[0026] In an aspect, the fitment between the serrated surfaces or between the peak and grove or valleys of the slots of contact button and contact carrying arm is solidly brazed with no air gap.
[0027] In an aspect, there can be a horizontal slot for ease of manufacturing on the contact carrying arm at above or at bottom of the vertical slots. The peak and grooves or valleys are of rectangular shape.
[0028] In an aspect, the height of the peaks and the depth of the grooves is such that it can provide lock-fit arrangement or assembly of the contact button and contact carrying arm and it prevents the sidewise sliding of button on the contact carrying arm.
[0029] In an aspect, the bond surface of the contact carrying arm is provided with rectangular shaped slots or serrations that serve to more uniformly distribute the electrical current during brazing, provide multiple areas of localized current constriction during brazing, and provide collector pockets for accumulating the molten braze alloy during brazing. The uniform distribution of electrical current during brazing serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy. The multiple areas of localized current constriction during brazing serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact carrying arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminate the overflow of braze alloy onto the edges of the contact and contact carrying arm. A contact carrying arm assembly having uniform melting of braze alloy, reduced annealing of the contact carrying arm, and reduced overflow of braze alloy onto the edges of the contact and contact carrying arm results in an improved bond of contact to contact carrying arm. It increases the brazable surface on the contact button and conductor arm, hence increases bond strength.
[0030] In an aspect, the collector pockets created by the vertical rectangular shaped serration pattern or slots provide the molten braze alloy with flow regions, areas defining the groves or valleys of the collector pockets, across the entire bond area, thereby reducing the volume of excess braze flow that is expelled around the outer edge of the bond region. Excessive braze flow that is expelled around the outer edge of the bond region during brazing can weep down to the contact surface and cause undesirable tack welding of the contacts. The presence of rectangular collector pockets across the bond area of contact to contact carrying arm significantly reduces the volume of braze alloy that is available to weep down to the contact surface, thereby eliminating the need for post-braze cleaning.
[0031] In an aspect, for flame brazing, the brazing foil is used for brazing the silver contact button to the contact carrying arm, mainly copper. The molten brazing foil, when cooled, ensures the solid brazing with no air gap between the peaks and valleys of the contact button and contact carrying arm. The peak and valley of the serrated surface or slots ensures the increased surface area.
[0032] In an aspect, the bond surface of the contact carrying arm is provided with rectangular shaped slots or serrations that serve to more uniformly distribute the heat during flame brazing due to increased brazing surface and provide collector pockets for accumulating the molten braze alloy during brazing. The distribution of heat during brazing and the increased surface area serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy. This serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact carrying arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminates the overflow of braze alloy either from one side or from both sides of the contact button and contact carrying arm onto the edges of the contact and contact carrying arm. A contact carrying arm assembly having uniform melting of braze alloy due to flame brazing, reduced annealing of the contact carrying arm, and reduced overflow of braze alloy onto the edges of the contact and contact carrying arm results in an improved bond of contact to contact carrying arm. It increases the brazable surface on the contact button and conductor arm, hence increases bond strength.
[0033] In an aspect, invention provides vertical rectangular slots that ensure assembly stability of the contact button to the contact carrying arm due to the locking fitment of contact button on the conductor arm against the sliding torque, a component of the electromagnetic torque. In case of high current and hence in case of high temperature the vertical slots and the locking fitment assembly of the contact button on the conductor arm ensures longer life before complete erosion or debrazing. This unique design thus improves the Icw performance of a circuit breaker, improves temperature rise performance of a circuit breaker, and improves fault current breaking capability and performance of a circuit breaker. This invention is of use in the switchgear industry.
[0034] In an aspect, depending upon the requirement the invention that is, the rectangular slots on the back of the contact button or on the contact carrying arm can be of horizontal type also and the peaks and grooves or valleys of the slots can be distributed or formed horizontal along the thickness of the contact carrying arm.
[0035] 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
[0036] 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.
[0037] FIG. 1A illustrates an isometric view of the pole assembly or contact assembly and the contact fingers or contact carrying arm or conductor having the propose invention, in accordance with an embodiment of the present disclosure.
[0038] FIG. 1B illustrates the side view of the pole assembly having the propose invention, in accordance with an embodiment of the present disclosure.
[0039] FIG. 1C illustrates the cross sectional side view of the pole assembly having the propose invention, in accordance with an embodiment of the present disclosure.
[0040] FIG. 1D illustrates the isometric view of the air circuit breaker having the propose invention, in accordance with an embodiment of the present disclosure.
[0041] FIG. 1E illustrates the side view (Partial) of the circuit breaker assembly having the propose invention, in accordance with an embodiment of the present disclosure.
[0042] FIG. 1F illustrates the top view and 1G, 1H and 1I shows the isometric views of the invention that is contact button with vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, in accordance with an embodiment of the present disclosure.
[0043] FIG. 1J illustrates the back view of the invention that is contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, in accordance with an embodiment of the present disclosure.
[0044] FIG. 2A illustrates the partial isometric view of the invention that is contact fingers or contact carrying arm or conductor, having vertical rectangular shaped slots or serration, where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, for assembling the contact button on it.
[0045] FIG. 2B illustrates the isometric assembly view of the invention that is contact fingers or contact carrying arm or conductor, having vertical rectangular shaped slots or serration, where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, for assembling the contact button on it, in accordance with an embodiment of the present disclosure..
[0046] FIG. 2C illustrates the top view and 2D shows the isometric view of the invention that is the conductor assembly, having vertical rectangular shaped slots or serration where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, with contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, assembled on the vertical rectangular shaped slots or serration of the conductor, in accordance with an embodiment of the present disclosure.
[0047] FIG. 3A illustrates the top view of the pole assembly and the invention, that is the conductor assembly, having vertical rectangular shaped slots or serration where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, with contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, assembled on the vertical rectangular shaped slots or serration of the conductor, having the proposed invention, in accordance with an embodiment of the present disclosure.
[0048] FIG. 3B and 3C illustrates the detailed top view of the pole assembly showing the invention that is the conductor assembly, having vertical rectangular shaped slots or serration where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor thickness, with contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, assembled on the vertical rectangular shaped slots or serration of the conductor, in accordance with an embodiment of the present disclosure.
[0049] FIG. 4A illustrates the top view and 4B shows the isometric view of the invention that is contact button with vertical rectangular shaped slots or serration in the back where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button, in accordance with an embodiment of the present disclosure.
[0050] FIG. 4B illustrates the isometric, 4C shows the front, 4D and 4E shows the detailed view of the invention that is contact fingers or contact carrying arm or conductor, having vertical rectangular shaped slots or serration, where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the conductor thickness, in accordance with an embodiment of the present disclosure.
[0051] FIG. 5A and 5B illustrates the isometric assembly view of the invention, that is the conductor assembly, having vertical rectangular shaped slots or serration, where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the conductor thickness, with contact button, having vertical rectangular shaped slots or serration in the back where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button, in accordance with an embodiment of the present disclosure.
[0052] FIG. 6A and 6B illustrates the side view and isometric view of the invention that is contact button, having horizontal rectangular shaped slots or serration in the back where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button height, in accordance with an embodiment of the present disclosure.
[0053] FIG. 6C illustrates the isometric view of the invention that is contact fingers or contact carrying arm or conductor, having horizontal rectangular shaped slots or serration, where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the serrated surface on the conductor, in accordance with an embodiment of the present disclosure.
[0054] FIG. 6D illustrates the side view, 6E shows the side view (Partial) and 6F illustrates the isometric detailed view of the invention, that is the conductor assembly, having horizontal rectangular shaped slots or serration, where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the serrated surface on the conductor, assembled with contact button, having horizontal rectangular shaped slots or serration in the back where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button height, in accordance with an embodiment of the present disclosure.
[0055] FIG. 7A, 7B and 7C illustrates the isometric view of the invention, that is the conductor assembly, having vertical rectangular shaped slots or serration, where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the conductor thickness, where a horizontal slot is there at the bottom of the vertical slots for ease of manufacturing, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0056] The following is a detailed description of embodiments of the disclosure illustrated 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.
[0057] 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.
[0058] The primary function of a conductor arm or contact carrying arm assembly is enabling the making, carrying and breaking of an electrical current in an electric circuit. Conductor or contact carrying arm assemblies having electrical contacts for making, carrying and breaking an electrical current are not only employed in electrical circuit breakers, but also in other electrical devices, such as rotary double break circuit breakers, contactors, relays, switches, and disconnects. The applications that these electrical devices are used in are vast, and include, but are not limited to, the utility, industrial, commercial, residential, and automotive industries. The contact must be bonded to the conductor arm, which is typically, but not necessarily, a copper alloy, in such a manner that the assembly will not disassemble during operation of the device. The bonding method that is generally employed is brazing electrical contacts suitable for the noted applications are typically made of a silver impregnated material, such as, but not limited to; silver-nickel-carbon, silver-tungsten, silver-tungsten-carbide, silver-nickel, silver-tin oxide, silver-cadmium oxide, silver graphite, silver-molybdenum, silver-nickel-graphite, and silver-iron. However, the use of copper in place of silver may also be suitable for some lower current applications.
[0059] As the capacity rating of the contact carrying arm assembly increases, the cross-sectional areas of the contact, conductor arm, and bond area between contact and conductor arm, typically increases In order to accommodate thermal limitations within an electrical device. While the cross-sectional areas of the contact and conductor arm or contact carrying arm are readily determined by geometric measurements, the cross-sectional area of the bond surface between contact and contact carrying arm is not so readily determined. Factors such as brazing electrode geometry variations, surface oxidation, brazing temperature, brazing time and braze alloy geometry variations can affect the quality of bonding and more precisely the percentage of bond area that is actually brazed, thereby effecting the ability of the brazed joint to withstand adiabatic heating at short circuit and in Icw, Icm and Icu performances, to withstand the sliding force at short circuit and in Icw, Icm and Icu performances and to withstand shear forces during mechanical opening and closing of the contacts. Thus, it would be beneficial to have an improved method of bonding an electrical contact to a contact carrier and an improved contact carrying arm assembly resulting therefrom.
[0060] A finger assembly or electrical conductor assembly or contact carrying arm assembly is provided having an electrical contact or contact button for making, carrying and breaking an electrical rated current, a conductor arm for supporting the electrical contact button, and bond surface on the conductor arm and on back of the contact button, that is conditioned for improving the bond between the electrical contact button and conductor arm after brazing. Also provided is an electrical circuit breaker that utilizes the improved contact carrying arm assembly. The bond surface of the contact carrying arm is provided with rectangular shaped serrations that serve to more uniformly distribute the electrical current during brazing, provide multiple areas of localized current constriction during brazing, and provide collector pockets for accumulating the molten braze alloy during brazing. The uniform distribution of electrical current during brazing serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy. The multiple areas of localized current constriction during brazing serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact carrying arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminate the overflow of braze alloy onto the edges of the contact and contact carrying arm. A contact carrying arm assembly having uniform melting of braze alloy due to current or flame brazing, reduced annealing of the contact carrying arm, and reduced overflow of braze alloy onto the edges of the contact and contact carrying arm results in an improved bond of contact to contact carrying arm. It increases the brazable surface on the contact button and conductor arm, hence increases bond strength. The invention also provides vertical rectangular slots that ensure the locking fitment of contact button on the conductor arm against the sliding torque, a component of the electromagnetic torque. In case of high current and hence in case of high temperature the vertical slots and the locking fitment assembly of the contact button on the conductor arm ensures longer life before complete erosion or debrazing. This unique design thus improves the ICW performance of a circuit breaker, improves temperature rise performance of a circuit breaker, and improves fault current breaking capability and performance of a circuit breaker. This invention is of use in the switchgear industry.
[0061] The bond surface of the contact carrying arm is provided with rectangular shaped slots or serrations that serve to more uniformly distribute the electrical current during brazing, provide multiple areas of localized current constriction during brazing, and provide collector pockets for accumulating the molten braze alloy during brazing. The uniform distribution of electrical current during brazing serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy. The multiple areas of localized current constriction during brazing serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact carrying arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminates the overflow of braze alloy onto the edges of the contact and contact carrying arm. A contact carrying arm assembly having uniform melting of braze alloy due to current or flame brazing, reduced annealing of the contact carrying arm, and reduced overflow of braze alloy onto the edges of the contact and contact carrying arm results in an improved bond of contact to contact carrying arm. It increases the brazable surface on the contact button and conductor arm, hence increases bond strength. The invention provides vertical rectangular slots that ensure assembly stability of the contact button to the contact carrying arm due to the locking fitment of contact button on the conductor arm against the sliding torque, a component of the electromagnetic torque. In case of high current and hence in case of high temperature the vertical slots and the locking fitment assembly of the contact button on the conductor arm ensures longer life before complete erosion or debrazing. This unique design thus improves the Icw performance of a circuit breaker, improves temperature rise performance of a circuit breaker, and improves fault current breaking capability and performance of a circuit breaker. This invention is of use in the switchgear industry.
[0062] The present invention that is contact button with rectangular slots or rectangular serrated detail on the back and conductor arm or contact carrying arm with rectangular serrated slots facilitate the brazing process. The rectangular slots or serrated detail on the back of the contact serves to retain the excess silver infiltrate and braze alloy that results during contact manufacturing, thereby providing a silver rich layer and a layer of braze alloy on the back of the contact for brazing. The resulting finished contact is substantially void of any serration pockets on the back since the silver infiltrate and braze alloy have substantially filled them in. Also the contact buttons can come without the excess silver infiltrate and braze alloy layer on the back and can be made of only with the base metal like silver along with the refractory metal powder, such as molybdenum, tungsten, or their carbides or silver impregnated material, such as, but not limited to; silver-nickel-carbon, silver-tungsten, silver-tungsten-carbide, silver-nickel, silver-tin oxide, silver-cadmium oxide, silver graphite, silver-molybdenum, silver-nickel-graphite, and silver-iron. However, the use of copper in place of silver may also be suitable for some lower current applications. In case of flame brazing of contact buttons to conductor arm or contact carrying arm, the serrated detail on the contact button and on the conductor or contact carrying arm serves to increase the total surface area available for brazing, for distributing the brazing heat and for increasing the brazing area and thus bonding strength. The rectangular slots or serrated detail on the back of the contact serves to retain the excess silver infiltrate and braze alloy that is used for brazing the contact button on the contact carrying arm.
[0063] The invention has serrations or rectangular slots on the back of the contact button to provide small areas at and around which considerable heat is generated when the contact is urged against the contact carrying arm and the welding current is applied for binding the contact to the arm. The serrations of the contact will fit into the slot on the copper contact carrying arm to provide a “toe-in” or “dig-in” or “locked” weld. Prior to the welding process, a fusible bonding material, such as silver, is allowed to impregnate the electrical contact. This prevents oxidation of the contact, decreases electrical resistance and provides a material to assist in brazing or welding the contact to the contact carrying arm.
[0064] The method of making an electrical contact by mixing silver and a refractory metal powder, such as molybdenum, tungsten, or their carbides, pressing them to form a porous metal with or without a serrated back, sintering and impregnating this contact with silver is well known in the art. Many variations of this procedure are in present use. One procedure is to serrate the electrical contact in the pill pressing operation. After the contacts are made by powder presses in pill form with a serrated back, they are sintered and then impregnated with silver. Subsequent to this each contact may go through a punch press operation to press the silver which has been formed in between the serrations into- a form corresponding to that of the serrations. A second procedure in use is to form a flat contact in a powder pill press, sinter this contact, impregnate it with enough silver so that an excess of silver will manifest itself as a layer of pure silver on one surface of the contact, and then by a coining process form the serrations of the pure silver surface of the contact.
[0065] In order to facilitate the description of the invention, the two methods of preparing serrated impregnated contacts will be designated as 1 and 2. Method 1 is the procedure whereby the serrations are pressed in the electrical contact of silver and a refractory material while it is in the powder pill press, sintered and then impregnated.
[0066] Following these steps, the serrated electrical contact may or may not 'go through a punch press or restriking operation to press the silver which has been found in between the serrations into a form corresponding to that of the serrations. Method 2 consists of mixing silver and a refractory material, pressing them to form a porous contact similar to that of method 1, but without the serrated back. This double flat surface electrical contact is then sintered and impregnated. Following the impregnating step the contact is sent through a coining or punch pressing operation where the serrations are impressed on the back of the contact.
[0067] The invention uses rectangular vertical slots in the back of the silver contact button with some certain pitch and rectangular vertical slots with same pitch on the contact carrying arm with single pitch length offset, having the peak and grove of the slot in the alternate position in the contact button and in the contact carrying arm so that both serration or slots can make a lock-fit kind arrangement or assembly. There can be slots, having either peaks or ribs or grooves or valleys at the two ends thickness wise of conductor arm or button [FIG. 1F to 3C] or there can be slots having one peak or ribs at one end (thickness wise) and one grove or valley at the other end (thickness wise) of the conductor arm or button [FIG. 4A to 5B].
[0068] The slots are so that the peaks or ribs on the conductor arm and the groves or valleys on the contact button are in alternate position, when assembled and make a lock fit assembly when assembled [FIG. 1F to 5B]. Also the slots are so that the peaks or ribs on the contact button and the groves or valleys on the conductor arm are in alternate position, when assembled and make a lock fit assembly when assembled [FIG. 1F to 5B]. The depth, length and width of the slot or serration, number of slots or serration can be varied as per requirement. The fitment between the serrated surfaces or between the peak and grove or valleys of the slots of contact button and contact carrying arm is solidly brazed with no air gap. There can be a horizontal slot for ease of manufacturing on the contact carrying arm at above or at bottom of the vertical slots [FIG. 7A to 7C]. The peak and grooves or valleys are of rectangular shape. The height of the peaks and the depth of the grooves is such that it can provide lock-fit arrangement or assembly of the contact button and contact carrying arm and it prevents the sidewise sliding of button on the contact carrying arm.
[0069] The bond surface of the contact carrying arm is provided with rectangular shaped slots or serrations that serve to more uniformly distribute the electrical current during brazing, provide multiple areas of localized current constriction during brazing, and provide collector pockets for accumulating the molten braze alloy during brazing. The uniform distribution of electrical current during brazing serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy. The multiple areas of localized current constriction during brazing serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact carrying arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminate the overflow of braze alloy onto the edges of the contact and contact carrying arm. A contact carrying arm assembly having uniform melting of braze alloy, reduced annealing of the contact carrying arm, and reduced overflow of braze alloy onto the edges of the contact and contact carrying arm results in an improved bond of contact to contact carrying arm. It increases the brazable surface on the contact button and conductor arm, hence increases bond strength.
[0070] The multiple areas of localized current constriction across the contact-to-contact-arm interface serve to rapidly increase the interface temperature without excessively over heating the contact or contact arm, thereby resulting in rapid melting of the braze alloy while minimizing the degree of annealing experienced by the contact and contact arm. In normal contact-to-contact-carrying-arm brazing operations, where annealing of the copper contact arm occurs, the softened copper of the contact arm can result in deformation of the contact carrying arm after the contact carrying arm experiences repeated mechanical on-off impact loads, thereby reducing the term of usability of the contact carrying arm and the switching device. Minimizing the degree of annealing experienced by the copper contact arm will avoid premature deformation of the contact carrying arm, thereby enhancing the term of usability of the contact carrying arm and the switching device as compared to a normal contact-to-contact carrying arm assembly employing a less effective brazing technique. Collector pockets created by the vertical rectangular shaped serration pattern or slots provide the molten braze alloy with flow regions, areas defining the grooves or valleys of the collector pockets, across the entire bond area, thereby reducing the volume of excess braze flow that is expelled around the outer edge of the bond region. Excessive braze flow that is expelled around the outer edge of the bond region during brazing can weep down to the contact surface and cause undesirable tack welding of the contacts. The presence of rectangular collector pockets across the bond area of contact to contact carrying arm significantly reduces the volume of braze alloy that is available to weep down to the contact surface, thereby eliminating the need for post-braze cleaning.
[0071] Also the present invention can include a layer of nickel or material from same group between the serrated copper contact arm and the silver impregnated contact, which acts as a barrier to prevent the intermixing of copper and silver. By preventing the intermixing of copper and silver at the bond interface, the resulting bond interface is free of a copper silver eutectic alloy, which has a melting point lower than that of the copper and the silver. Thus, a contact carrying arm assembly having a serrated bond surface on the copper contact arm and a nickel layer between the copper contact carrying arm and silver impregnated contact provides a further improved bond by elevating the melt temperature of the bond interface above that of the copper-silver eutectic melt temperature.
[0072] For flame brazing, the brazing foil is used for brazing the silver contact button to the contact carrying arm, mainly copper. The molten brazing foil, when cooled, ensures the solid brazing with no air gap between the peaks and valleys of the contact button and contact carrying arm. The peak and valley of the serrated surface or slots ensures the increased surface area.
[0073] The bond surface of the contact carrying arm is provided with rectangular shaped slots or serrations that serve to more uniformly distribute the heat during flame brazing due to increased brazing surface and provide collector pockets for accumulating the molten braze alloy during brazing. The distribution of heat during brazing and the increased surface area serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy. This serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact carrying arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminates the overflow of braze alloy either from one side or from both sides of the contact button and contact carrying arm onto the edges of the contact and contact carrying arm. A contact carrying arm assembly having uniform melting of braze alloy due to flame brazing, reduced annealing of the contact carrying arm, and reduced overflow of braze alloy onto the edges of the contact and contact carrying arm results in an improved bond of contact to contact carrying arm. It increases the brazable surface on the contact button and conductor arm, hence increases bond strength.
[0074] The invention provides vertical rectangular slots that ensure assembly stability of the contact button to the contact carrying arm due to the locking fitment of contact button on the conductor arm against the sliding torque, a component of the electromagnetic torque. In case of high current and hence in case of high temperature the vertical slots and the locking fitment assembly of the contact button on the conductor arm ensures higher thermal withstand ability before debrazing (with higher debrazing temperature) and longer life before complete erosion or debrazing. This unique design thus improves the Icw performance of a circuit breaker, improves temperature rise performance of a circuit breaker, and improves fault current breaking capability and performance of a circuit breaker. This invention is of use in the switchgear industry.
[0075] Depending upon the requirement the invention that is, the rectangular slots on the back of the contact button or on the contact carrying arm can be of horizontal type also and the peaks and grooves or valleys of the slots can be distributed or formed horizontal along the thickness of the contact carrying arm [FIG. 6A to 6F].
[0076] FIG. 1A illustrates an isometric view of the pole assembly or contact assembly and the contact fingers or contact carrying arm or conductor having the propose invention, in accordance with an embodiment of the present disclosure.
[0077] FIG. 1B illustrates the side view of the pole assembly having the propose invention, in accordance with an embodiment of the present disclosure.
[0078] FIG. 1C illustrates the cross sectional side view of the pole assembly having the propose invention, in accordance with an embodiment of the present disclosure.
[0079] FIG. 1D illustrates the isometric view of the air circuit breaker having the propose invention, in accordance with an embodiment of the present disclosure.
[0080] FIG. 1E illustrates the side view (Partial) of the circuit breaker assembly having the propose invention, in accordance with an embodiment of the present disclosure.
[0081] FIG. 1F illustrates the top view and 1G, 1H and 1I shows the isometric views of the invention that is contact button with vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, in accordance with an embodiment of the present disclosure.
[0082] FIG. 1J illustrates the back view of the invention that is contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, in accordance with an embodiment of the present disclosure.
[0083] FIG. 2A illustrates the partial isometric view of the invention that is contact fingers or contact carrying arm or conductor, having vertical rectangular shaped slots or serration, where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, for assembling the contact button on it.
[0084] FIG. 2B illustrates the isometric assembly view of the invention that is contact fingers or contact carrying arm or conductor, having vertical rectangular shaped slots or serration, where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, for assembling the contact button on it, in accordance with an embodiment of the present disclosure..
[0085] FIG. 2C illustrates the top view and 2D shows the isometric view of the invention that is the conductor assembly, having vertical rectangular shaped slots or serration where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, with contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, assembled on the vertical rectangular shaped slots or serration of the conductor, in accordance with an embodiment of the present disclosure.
[0086] FIG. 3A illustrates the top view of the pole assembly and the invention, that is the conductor assembly, having vertical rectangular shaped slots or serration where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor, with contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, assembled on the vertical rectangular shaped slots or serration of the conductor, having the proposed invention, in accordance with an embodiment of the present disclosure.
[0087] FIG. 3B and 3C illustrates the detailed top view of the pole assembly showing the invention that is the conductor assembly, having vertical rectangular shaped slots or serration where two vertical rectangular shaped groves or valleys of the serrated or slotted surface are on both end of the conductor thickness, with contact button, having vertical rectangular shaped slots or serration in the back where two vertical rectangular shaped peaks or ribs of the serrated or slotted surface are on both end of the contact button, assembled on the vertical rectangular shaped slots or serration of the conductor, in accordance with an embodiment of the present disclosure.
[0088] FIG. 4A illustrates the top view and 4B shows the isometric view of the invention that is contact button with vertical rectangular shaped slots or serration in the back where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button, in accordance with an embodiment of the present disclosure.
[0089] FIG. 4B illustrates the isometric, 4C shows the front, 4D and 4E shows the detailed view of the invention that is contact fingers or contact carrying arm or conductor, having vertical rectangular shaped slots or serration, where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the conductor thickness, in accordance with an embodiment of the present disclosure.
[0090] FIG. 5A and 5B illustrates the isometric assembly view of the invention, that is the conductor assembly, having vertical rectangular shaped slots or serration, where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the conductor thickness, with contact button, having vertical rectangular shaped slots or serration in the back where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button, in accordance with an embodiment of the present disclosure.
[0091] FIG. 6A and 6B illustrates the side view and isometric view of the invention that is contact button, having horizontal rectangular shaped slots or serration in the back where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button height, in accordance with an embodiment of the present disclosure.
[0092] FIG. 6C illustrates the isometric view of the invention that is contact fingers or contact carrying arm or conductor, having horizontal rectangular shaped slots or serration, where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the serrated surface on the conductor, in accordance with an embodiment of the present disclosure.
[0093] FIG. 6D illustrates the side view, 6E shows the side view (Partial) and 6F illustrates the isometric detailed view of the invention, that is the conductor assembly, having horizontal rectangular shaped slots or serration, where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the serrated surface on the conductor, assembled with contact button, having horizontal rectangular shaped slots or serration in the back where one horizontal rectangular shaped peak or rib of the serrated or slotted surface is on one end and one horizontal rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the contact button height, in accordance with an embodiment of the present disclosure.
[0094] FIG. 7A, 7B and 7C illustrates the isometric view of the invention, that is the conductor assembly, having vertical rectangular shaped slots or serration, where one vertical rectangular shaped peak or rib of the serrated or slotted surface is on one end and one vertical rectangular shaped groove or valley of the serrated or slotted surface is on the other end of the conductor thickness, where a horizontal slot is there at the bottom of the vertical slots for ease of manufacturing, in accordance with an embodiment of the present disclosure.
[0095] Again to summarize the invention, a finger assembly or electrical conductor assembly or contact carrying arm assembly is provided having an electrical contact or contact button for making, carrying and breaking an electrical rated current, a conductor arm for supporting the electrical contact button, and a bond surface on the conductor arm that is conditioned for improving the bond between the electrical contact button and conductor arm after brazing. Also provided is an electrical circuit breaker that utilizes the improved contact carrying arm assembly.
[0096] The bond surface of the contact carrying arm is provided with rectangular shaped slots or serrations that serve to more uniformly distribute the electrical current during brazing, provide multiple areas of localized current constriction during brazing, and provide collector pockets for accumulating the molten braze alloy during brazing. The uniform distribution of electrical current during brazing serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy.
[0097] The multiple areas of localized current constriction during brazing serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact carrying arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminate the overflow of braze alloy onto the edges of the contact and contact carrying arm. A contact carrying arm assembly having uniform melting of braze alloy due to current or flame brazing, reduced annealing of the contact carrying arm, and reduced overflow of braze alloy onto the edges of the contact and contact carrying arm results in an improved bond of contact to contact carrying arm. It increases the brazable surface on the contact button and conductor arm, hence increases bond strength.
[0098] The invention also provides a vertical rectangular slot that ensures the locking fitment of contact button on the conductor arm against the sliding torque, a component of the electromagnetic torque. In case of high current and hence in case of high temperature the vertical slots and the locking fitment assembly of the contact button on the conductor arm ensures longer life before complete erosion or debrazing. This unique design thus improves the Icw performance of a circuit breaker, improves temperature rise performance of a circuit breaker, and improves fault current breaking capability and performance of a circuit breaker. This invention is of use in the switchgear industry.
[0099] Although the preferred embodiments have been described, it should be pointed out that changes are possible and attainable without departing from the scope of the present invention.
[00100] 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.
[00101] 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.