CLIAMS:1. A switching device comprising a contact system (100), said contact system (100) comprising:
a moving contact (106) detachably joined with a fixed contact (102); and
a slot motor (108) configured adjacent to the moving contact (106), wherein the slot motor (108) comprises a plurality of laminations that enable application of magnetic force opposite to the electrodynamic repulsive force acting on the moving contact (106) to ensure that the moving contact (106) and the fixed contact (102) remain joined.

2. The switching device of claim 1, wherein the laminated slot motor (108) enhances flux density by minimizing eddy currents.

3. The switching device of claim 1, wherein magnetic force provided by the slot motor (108) increases with increasing current in fault condition, enabling higher magnetic force to counter increasing electrodynamic repulsive force and further ensuring that threshold force required to separate the moving contact (106) and the fixed contact (102) is not achieved.

4. The switching device of claim 1, wherein the slot motor (108) provides the magnetic force in favor of the contact pressure on the moving contact (106) under any or a combination of steady state current, normal overload condition, and extreme fault condition.

5. The switching device of claim 1, wherein the contact system (100) further comprises a moving contact button (104) operatively coupled with the moving contact (106), wherein the contact system (100) further comprises a fixed contact button (110) operatively coupled with the fixed contact (102), wherein the moving contact button (104) and the fixed contact button (110) are detachably joined.
6. The switching device of claim 5, wherein the fixed contact button (110) is brazed to the fixed contact (102) and the moving contact button (104) is brazed to the moving contact (106).

7. A contact system (100) comprising:
a moving contact (106) detachably joined with a fixed contact (102); and
a slot motor (108) configured adjacent to the moving contact (106), wherein the slot motor (108) comprises a plurality of laminations that enable application of magnetic force opposite to the electrodynamic repulsive force acting on the moving contact (106) to ensure that the moving contact (106) and the fixed contact (102) remain joined.
,TagSPECI:TECHNICAL FIELD
[0001] The present invention relates to a switching device, particularly to a contact system of a switching device. The present disclosure further relates to a contact system that uses a flux concentrator/slot motor to generate magnetic force to counter electrodynamic repulsive force to keep contacts of the contact system detachable fixed to each other.

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] Switching devices are typically used in electrical power distribution circuits for switching ON/OFF a live or an off loaded circuit by isolating a part of the circuit from the system, as and when required. Such switching devices should be able to withstand high current during a fault condition for a particular time period as during inrush or a short circuit fault, high current flows through the circuit and through the switching apparatus, which the switching apparatus should be able to withstand in order to keep the circuit healthy. Existing switching apparatuses/devices use a set of separable contacts to make and break the circuit, wherein when two current flowing conductors/contacts are detachably joined to carry current, they experience electrodynamic repulsive forces. Contacts of existing switching devices are made in a way to minimize such repulsive force by eliminating reversely directed parallel current paths. Elimination of repulsive force increases the current withstand capacity of the switching apparatus. However, separable contacts of the switching apparatus separate from each other sooner the electrodynamic repulsive force exceeds the contact pressure.
[0004] In few existing switching devices, a strong contact spring is used to increase the contact pressure and to increase the current withstand capacity. In few other switching devices, profile of a contact is designed in such a way as to minimize the electrodynamic repulsive forces. US5694098 is an exemplary prior art that discloses a current limiting contact arrangement incorporating a flux concentrator device, commonly known as a slot motor, wherein an additional slot motor is used to augment the contact spring pressure under steady state current conditions and to reduce the force under high rate of current rise conditions to enhance dynamic separation of the movable conductor from a stationary conductor, reducing the strength requirement of the contact pressure spring. Furthermore, in this reference, a separable contact profile is designed with current reversal loop to increase the repulsive electrodynamic forces on the moving contact. As the magnitude of the current increases, the current generates electromagnetic forces which dynamically repel the conductor members. In the present invention, there is no reversely directed parallel path. The repel force between the separable contacts due to the reversely directed parallel current path does not exists in this contact arrangement. Withstand capacity or the repulsion threshold for this contact system is higher due to its inherent structure. In the same reference, A second slot motor, relatively thick piece of steel is also incorporates to generate a magnetic contact pressure force under steady state current conditions to augment the contact pressure spring force. The second slot motor is made particularly receptive to eddy currents. Under fault conditions, the rate of change of current is high and the force generated by the second slot motor reduces to near zero. Thus, for steady state current and normal conditions of overload current and inrush current, the second slot motor augments the contact pressure spring, enabling a lighter spring to be used as a contact pressure spring, enabling a lighter springs in the circuit breaker operating mechanism. However, under extreme fault current having a sharp rate of rise, the force generated by the second slot motor reduces to zero or near zero, or may even reverse.
[0005] There is therefore a need in the art for an improved contact system that is able to withstand high fault currents with a high rate of rise.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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
[0011] It is an object of the present disclosure to provide an improved contact system that is able to withstand high fault currents.
[0012] It is another object of the present disclosure to provide a single flux concentrator that is disposed adjacent to movable contact of the proposed contact system to apply a magnetic force on the movable contact.
[0013] It is another object of the present disclosure to provide a single flux concentrator (slot motor) that is used to withstand current by providing a magnetic force opposite to electrodynamic repulsive force (constriction force).

SUMMARY
[0014] The present disclosure relates to a switching device, particularly to a contact system of a switching device. The present disclosure further relates to a contact system that uses a flux concentrator/slot motor to generate magnetic force to counter electrodynamic repulsive force to keep contacts of the contact system detachable fixed to each other.
[0015] According to one embodiment, the present disclosure relates to a switching device that includes a contact system having a moving contact that is detachably joined with a fixed contact; and a slot motor configured adjacent to the moving contact, wherein the slot motor includes a plurality of laminations that enable application of magnetic force opposite to the electrodynamic repulsive force acting on the moving contact to ensure that the moving contact and the fixed contact remain joined.
[0016] In an aspect, the laminated slot motor enhances flux density by minimizing eddy currents. In yet another aspect, magnetic force provided by the slot motor can increase with increasing current in fault condition, enabling higher magnetic force to counter increasing electrodynamic repulsive force and further ensuring that threshold force required to separate the moving contact and the fixed contact is not achieved. In another embodiment, the slot motor can provide the magnetic force in favor of the contact pressure on the moving contact under any or a combination of steady state current, normal overload condition, and extreme fault condition.
[0017] In an aspect, the contact system can further include a moving contact button that is operatively coupled with the moving contact, wherein the contact system can further include a fixed contact button that is operatively coupled with the fixed contact, wherein the moving contact button and the fixed contact button are detachably joined. In an aspect, the fixed contact button can be brazed to the fixed contact and the moving contact button can be brazed to the moving contact.
[0018] 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
[0019] 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.
[0020] FIG. 1 illustrates an exemplary isometric view of the proposed contact system in accordance with an embodiment of the present disclosure.
[0021] FIG. 2 illustrates an exemplary front view of the proposed contact system without slot motor in accordance with an embodiment of the present disclosure.
[0022] FIG. 3 illustrates a schematic representation showing current path and flux linkages through components of the proposed contact system in accordance with an embodiment of the present disclosure.
[0023] FIG. 4 illustrates a schematic representation showing force distribution on the moving contact of the proposed contact system in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] The present disclosure relates to a switching device, particularly to a contact system of a switching device. The present disclosure further relates to a contact system that uses a flux concentrator/slot motor to generate magnetic force to counter electrodynamic repulsive force to keep contacts of the contact system detachable fixed to each other.
[0030] According to one embodiment, the present disclosure relates to a switching device that includes a contact system having a moving contact that is detachably joined with a fixed contact, and a slot motor configured adjacent to the moving contact, wherein the slot motor includes a plurality of laminations that enable application of magnetic force opposite to the electrodynamic repulsive force acting on the moving contact to ensure that the moving contact and the fixed contact remain joined.
[0031] In an aspect, the laminated slot motor enhances flux density by minimizing eddy currents. In yet another aspect, magnetic force provided by the slot motor can increase with increasing current in fault condition, enabling higher magnetic force to counter increasing electrodynamic repulsive force and further ensuring that threshold force required to separate the moving contact and the fixed contact is not achieved. In another embodiment, the slot motor can provide the magnetic force in favor of the contact pressure on the moving contact under any or a combination of steady state current, normal overload condition, and extreme fault condition.
[0032] In an aspect, the contact system can further include a moving contact button that is operatively coupled with the moving contact, wherein the contact system can further include a fixed contact button that is operatively coupled with the fixed contact, wherein the moving contact button and the fixed contact button are detachably joined. In an aspect, the fixed contact button can be brazed to the fixed contact and the moving contact button can be brazed to the moving contact.
[0033] With reference to FIGs. 1-4, in an embodiment, the present disclosure provides a switching device comprising a contact system (100), wherein the contact system (100) can include a moving contact (106) that is detachably joined with a fixed contact (102). The contact system can further include a slot motor (108) that is configured adjacent to the moving contact (106), wherein the slot motor (108) can include a plurality of laminations that enable application of magnetic force opposite to the electrodynamic repulsive force acting on the moving contact (106) to ensure that the moving contact (106) and the fixed contact (102) remain joined.
[0034] In an aspect, the slot motor (108) enhances flux density by minimizing eddy currents. In another aspect, magnetic force provided by the slot motor (108) increases with increasing current in fault condition, enabling higher magnetic force to counter increasing electrodynamic repulsive force and further ensuring that threshold force required to separate the moving contact (106) and the fixed contact (102) is not achieved. In yet another aspect, the slot motor (108) can provide the magnetic force in favor of the contact pressure on the moving contact (106) under any or a combination of steady state current, normal overload condition, and extreme fault condition.
[0035] According to one embodiment, the contact system (100) can further include a moving contact button (104) that is operatively coupled with the moving contact (106), and a fixed contact button (110) that is operatively coupled with the fixed contact (102), wherein the moving contact button (104) and the fixed contact button (110) are detachably joined. In yet another embodiment, the fixed contact button (110) can be brazed to the fixed contact (102) and the moving contact button (104) can be brazed to the moving contact (106).
[0036] In an aspect, the present disclosure provides a single flux concentrator (also referred to as slot motor 108) that is disposed adjacent to the movable contact (106) to apply a magnetic force on the movable contact (106). This magnetic force adds to the contact pressure of the switching apparatus and increases with the increasing current. The magnetic flux concentrator (108), commonly known as slot motor (108) can include a plurality of laminations to enhance the flux density by minimizing eddy currents even during high rate of rise of fault current. The increased contact pressure can help the separable contacts (106 and 102) not to separate in the influence of electrodynamic repulsive forces and to withstand high current.
[0037] In another aspect, the present disclosure provides only a single slot motor (108) to be is used to withstand current by providing a magnetic force that is opposite to the electrodynamic repulsive force (constriction force). In yet another aspect, due to the present disclosure and structure therein, there is no reversely directed parallel path. The repel force between the separable contacts (106 and 102) due to the reversely directed parallel current path does not exist in this contact arrangement. Withstand capacity or the repulsion threshold for this contact system is therefore higher due to its inherent structure. In yet another aspect, the slot motor (108) can include a plurality of laminations to enhance the flux density by minimizing the eddy currents. The force provided by the slot motor (108) increases with the increasing current even under extreme fault current having a sharp rate of rise as it is unreceptive to eddy current. The increasing force acts in favor of contact pressure and prevents the contacts from separate under high current.
[0038] In present invention, a single flux concentrator (108) can be disposed adjacent to the movable contact (106) to apply a magnetic force on the movable contact. This magnetic force adds to the contact pressure of the switching apparatus and increases with the increasing current. The magnetic flux concentrator, commonly known as slot motor (108) comprises a plurality of laminations to enhance the flux density by minimizing the eddy currents even during the high rate of rise of fault current. The increased contact pressure helps the separable contacts not to separate in the influence of electrodynamic repulsive forces and to withstand high current.
[0039] Using the proposed structure, flux concentration increases with the increase in current, and concentrated flux is maintained even under extreme fault current having a sharp rate of current rise. In an embodiment, the present disclosure provides a slot motor (108) that can include a plurality of laminations to enhance flux density by minimizing the eddy currents. The proposed slot motor (108) can provide magnetic force in favor of contact pressure under steady state current, normal conditions of overload and also under extreme fault condition. The proposed contact system (100) experiences least electrodynamic repulsive force due to absence of reversely directed current path. Furthermore, addition of a current sensitive force with the contact pressure helps the contacts to withstand high current and increases the repulsion threshold of the contact system.
[0040] According to one embodiment of the present disclosure, a contact structure (100) of a switching device is provided, wherein an aspect of the present disclosure relates to being able to withstand high current during a fault condition. FIG. 1 discloses the isometric view of the contact structure (100), wherein the contact system (100) can include a fixed contact (102), a moving contact button (104), a moving contact (106), a fixed contact button (110), and a plurality of laminations called as slot motor (108). FIG. 2 shows a view of contact system (100) without slot motor (108). In an aspect, the fixed contact button (110) can be made of a silver alloy that is is brazed to the fixed contact (102). Similarly, the moving contact button (106) can be brazed to the moving contact (106). In an aspect, the contact buttons can be made as separable joints between fixed moving (102) and the moving contact (106). A number of laminations can be assembled in a stack to make slot motor (108). FIG. 3 explains the current path through the contacts. The cross sectional view of the FIG. 3 shows flux linkage with moving contact (106) and the slot motor (108), wherein the flux lines (112) are shown in the cross sectional view in FIG. 3B, and FIG. 3A shows the current path. Force distribution on the moving contact (106) is shown in FIG. 4.
[0041] FIG. 3 further explains the working of the contact system. Fig. 3B shows the current direction through the contacts, wherein FIG. 3B is a cross sectional view of Fig. 3A. Current in the moving contact (106) in FIG. 3B has been represented as dot (.). The current will produce a magnetic field around the moving contact (106), wherein direction of the flux is as per right hand rule as shown in the Fig. 3B. The flux concentrator (108) can provide a low reluctance path to the flux. Upper half of the flux links with the moving contact (106) and lower half flows through the slot motor (108) as shown in the FIG. 3B. The current and flux in the moving contact (106) can interact with each other to produce a force on the moving contact, wherein direction of the force is as per Flemings left hand rule as shown in the FIG. 3. The force increases with the increasing current. The magnetic force (Fm) acts against the electrodynamic force (Fh) and in favor of contact pressure (Fcp) as shown in FIG. 4. The resultant force helps the moving contact to withstand high current. In an aspect, the slot motor (108) can be made of a plurality of laminations to make it less receptive to eddy current. As a result, the force does not reduce even under extreme fault current having a sharp rate of current rise.
[0042] 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
[0043] The present disclosure provides an improved contact system that is able to withstand high fault currents.
[0044] The present disclosure provides a single flux concentrator that is disposed adjacent to movable contact of the proposed contact system to apply a magnetic force on the movable contact.
[0045] The present disclosure provides a single flux concentrator (slot motor) that is used to withstand current by providing a magnetic force opposite to electrodynamic repulsive force (constriction force).