Claims:1. A top plate for an arc chute assembly, said top plate comprises:
one or more ribs running across opposite edges of the top plate;
wherein each rib further comprises of a cavity or groove;
wherein the ribs are situated on upper side of the top plate and the cavity or groove is situated on lower side of the top plate;
a plurality of vents;
means for securing the top plate on the arc chute;
wherein the top plate is a ferromagnetic sheet metal; and
wherein the top plate is power coated for insulation.

2. The top plate as claimed in claim 1, wherein the plate is substantially of any shape.

3. The top plate as claimed in claim 2, wherein the plate is preferably rectangular in shape.

4. The top plate as claimed in claim 1, wherein the cavity or grove is formed by punched operation.

5. The top plate as claimed in claim 1, wherein the cavity groove fits upper portion of a side plate with interference fit or with no gap at all.

6. The top plate as claimed in claim 1, wherein depth of the cavity depends on the length of the side plate inserted into the top plate.

7. The top plate as claimed in claim 1, wherein distance between two side plates of the arc chute assembly determines the position of ribs and cavities.

8. The top plate as claimed in claim 1, wherein the ribs are situated in opposite side of the arc chamber and the cavities are situated facing towards the arc chamber.

9. The top plate as claimed in claim 1, wherein thickness of the top plate is less than 4mm.

10. The top plate as claimed in claim 1, wherein the ribs run across the entire length of the top plate.

11. The top plate as claimed in claim 1, wherein optionally the ribs run across the partial length of the top plate.

12. An arc chute assembly comprising the top plate as claimed in claims 1 to 11, wherein upper portion of each side plate is groove fit into each rib of the top plate; and wherein the top plate is secured on top of the arch chute assembly by nut and bolt arrangement.
, Description:FIELD OF THE INVENTION

[001] The subject matter of the present invention, in general, relates to switchgears and circuit breakers, and more particularly, pertains to breaking current and clearing fault currents in switchgears in any switching device or circuit breaker using arc quenching technologies.

BACKGROUND OF INVENTION

[002] In an electric power system, a switchgear is the combination of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgears are used both to de-energize equipment to allow work to be done and to clear faults downstream. It is directly linked to the reliability of an electricity supply. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt the flow of current along with making, carrying and breaking of rated current.

[003] Opening of a live contact in an electrical circuit results in development of an electrical arc. An electric arc or an arc discharge is electrical breakdown of a gas that produces an ongoing electrical discharge. It is a form of electric discharge with comparatively highest current density. The maximum current through an arc is limited only by the external circuit, not by the arc itself. The current through a normally non-conductive medium such as air produces a plasma that may produce visible light. It relies on thermionic emission and field emissions of electrons from the electrodes supporting the arc.

[004] Electrical switching devices such as switchgears, circuit breakers and the like typically include a set of stationary electrical contacts and a set of moveable electrical contacts. The stationary and moveable contacts are in physical contact with one another when it is desired that the circuit breaker provide electrical current to a load. However, when it becomes necessary to interrupt the circuit the moveable contacts are moved away from the stationary contacts, thereby removing the moveable contacts from physical contact with the stationary contacts and creating a space there between.

[005] A circuit breaker is also used to break rated current and clear a fault current. In case of breaking rated current or in case of a fault, whenever fault current flows in the system, the circuit breaker used is expected to clear this fault with minimal damage to itself also along with the downstream devices, so that the breaker can be used for further operations. The contacts of the circuit breaker experience arcing during its opening i.e. an arc is formed between the contacts when they separate while interrupting a live circuit. As long as this arc is sustained in between the contacts the current through the circuit breaker will not be interrupted because the arc in itself is a conductive path of electricity. For total interruption of current, it is essential to quench the arc as quick as possible. Part of the energy of an electrical arc forms new chemical compounds from the air surrounding the arc that are corrosive to nearby metal surfaces. Arcing also erodes the surfaces of the contacts, wearing them down and creating high contact resistance when closed. The electrical arc erodes the contacts thereby reducing the life of the circuit breaker. Therefore, the design of an arcing chamber needs to be as effective as possible and arc chutes play an important role in it.

[006] Arc suppression/quenching aims to reduce or eliminate the electrical arc. The technology used in switchgears for arc quenching makes use of an arc quenching chamber for lengthening and splitting of arc. The faster the arc is quenched the better is the electrical life of the breaker. An arc chute assembly is designed with specific intention for efficient and quick arc quenching.

[007] Generally, an arc chute assembly comprises of splitter plates that uses combination of ferromagnetic metallic plates to form the multiple arc lets to increase the arc voltage for quenching the arc effectively and efficiently, an insulating bottom plate above the splitter plates, an arc filter to cool and deionize the arc gases and an insulating or metallic top plate with vents to close the arc chamber and for the arc chute assembly and to let the arc gases out of the breaker through the vents.

[008] Reference is made to US 7705263 B2, wherein an arc chute assembly for a circuit breaker is disclosed. The arc chute assembly includes a housing having a lateral axis and a quenching portion disposed within the housing. The quenching portion includes at least two deion plates being spaced along the lateral axis of the housing and each having a cut portion wherein the cut portions are staggered along the lateral axis with respect to one another and are configured to mitigate an arc.

[009] Reference is also made to US 2011/0259852 A1, wherein a valve system for an arc extinguishing chamber and circuit breaker comprising same is disclosed. The system comprises of a first duct equipped with a set of filters able to support usual pressures caused by the gases arising from the switching arc, about 10 to 12 bars, and a second duct closed by a valve device enabling direct outlet of the exhaust gases when the pressure exceeds a threshold so as to prevent any explosion of the case. The outer wall of the extinguishing chamber is designed for the circuit breaker housing so as, including in case of opening of the valve device, to direct the gases and to prevent any arc-over on the frame. The valve device comprises a suitable membrane made from polymer, like aramide.

[0010] Reference is also made to US 5756951 A, wherein an arc chute having three barriers for the passage of arc gases is disclosed. The arc chute for a circuit-breaker has a chute member with an arc splitters and an end member that seals off the chute member to the top. The end member has three barriers for arc gases, the first and the second barrier have webs with a substantially square cross-sectional shape that are arranged in double the pitch of the arc splitters. Situated above the second barrier is a cooling chamber that is sealed off to the outside by the third barrier provided with outlet orifices.

[0011] The drawbacks of the existing state of art technologies is that the electrical arc quenching processes employed are not efficient. Notably, higher arcing times owing to insufficient pull force on arc results in higher contact erosion, while high arc chamber gas pressure results in breaking of arc chute top plate in case of insulating thermoset or thermoplastic material, and bending or deformation in case of metallic top plates.

[0012] Moreover, leaking of ionized arc gases from the side of an arc chute increases the risk of shorting or flashover. Often the breaking capacity gets limited by the structural or fitment features of the arc chute assembly as high energy and high current breaking involves handling of higher gas pressure, energy and forces. Thus, the use of thermoset and thermoplastic materials in the arc chute top plate limits their capability of handing high pressure, energy and force. Further, the life expectancy of the arc chute assemblies employing thermoset and thermoplastic material in the arc chute top plate is limited.

[0013] The state of art technologies mostly makes use of thermoset and thermoplastic material in the arc chute top plate that is manufactured, mostly, by tooling process resulting in any design iteration, update and improvement in the top plate vents and profile incur significant costs rendering them expensive.

[0014] Moreover, higher arcing time owing to insufficient pull force on the arc results in higher contact erosion. The state of art arc quenching assemblies employing metallic top plates employ comparatively thicker metallic plates (of about 4 mm to 7 mm) to withstand the higher arc chamber pressure or gas pressure. Certain arc chute assemblies employ rubber or a similar sealing material to decrease the gas leakage form the side of the arc chute assembly.

[0015] Therefore, there is a need for a comparatively slimmer top plate that not only improves the above stated short comings of state of the art arc chute top plate and increases the pull force on the arc, but also improves the arc quenching process by reducing the time required to extinguish the arc there improving the performance and life expectancy of the arc chute assembly.

SUMMARY OF THE INVENTION

[0016] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[0017] An object of the present invention is to overcome the drawbacks and to further improve the performance and life expectancy of an arc chute assembly.

[0018] Another object of the present invention is to improve the top plate to improve the arc quenching performance in arc chute assembly.

[0019] Another object of the present invention is to provide a metallic top plate with punched ribs for the arc chute assembly.

[0020] Another object of the present invention is to provide increased strength to an arc chute top plate for a comparatively lower thickness of the top plate.

[0021] Another object of the present invention is to provide increased withstanding capability to an arc chute top plate for comparatively high arc chamber gas pressure for comparatively high energy and high current breaking without getting damaged, deformed or bent.

[0022] Another object of the present invention is to provide a powder coated ferromagnetic metallic top plate with punched ribs for arc chute assembly.

[0023] Yet another object of the present invention is to provide an arc chute assembly wherein a side plate is inserted into the punched cavity of the powder coated ferromagnetic metallic top plate.

[0024] Yet another object of the present invention is to provide a powder coated ferromagnetic metallic top plate wherein the punched ribs and cavities are spaced far apart (to a larger extent), to accommodate the side plate for higher frames, as per requirement.

[0025] Briefly, a powder coated ferromagnetic metallic top plate with punched ribs for an arc chute assembly is disclosed. The said arc chute top plate exhibits increased strength of the arc chute top plate for a comparatively lower thickness, and increased withstanding capability for a comparatively higher arc chamber gas pressure for comparatively higher energy and higher current breaking without suffering from damage, deformation or bending, thereby ensuring higher life expectancy for an arc chute assembly.

[0026] The present invention discloses a top plate for an arc chute assembly, said top plate comprises one or more of ribs running across opposite edges of the top plate; wherein each rib further comprises of a cavity or groove; wherein the ribs are situated on upper side of the top plate and the cavity or groove is situated on lower side of the top plate; a plurality of vents; means for securing the top plate on the arc chute; wherein the top plate is a ferromagnetic sheet metal; and wherein the top plate is power coated for insulation.

[0027] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0028] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0029] Figure 1 illustrates the isometric and top view of a circuit breaker assembly according to one implementation of the present invention.

[0030] Figure 2 illustrates the top, side and isometric views of a powder coated ferromagnetic metallic top plate with punched ribs and cavity according to one implementation of the present invention.

[0031] Figure 3 illustrates the side and isometric view of arc chute assembly wherein the powder coated ferromagnetic metallic top plate with punched ribs is mounted according to one implementation of the present invention.

[0032] Figure 4 illustrates the cross-sectional view of the arc chute assembly where the side plate is inserted into the punched cavity of the powder coated ferromagnetic metallic top plate according to one implementation of the present invention.

[0033] Figure 5 illustrates the isometric and top view of the top plate wherein the punched ribs and cavities are spaced far apart to accommodate the side plates according to another implementation of the present invention.

[0034] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0035] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0036] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0037] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0038] It is to be understood that the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0039] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0040] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0041] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or component but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0042] The subject invention lies in providing powder coated ferromagnetic metallic top plate with punched ribs for arc chute assembly

[0043] The present invention pertains to a powder coated ferromagnetic metallic top plate with punched ribs for an arc chute assembly that increase the strength of the arc chute top plate for a comparatively lower thickness, and increases the withstand capability for comparatively high arc chamber gas pressure for comparatively high energy and high current breaking without getting damaged, deformed or bent, thereby ensuring higher life expectancy for arc chute assembly. The ferromagnetic top plate also increases the pull force on arc and hence improves the arc quenching process by reducing the time to extinguish the arc. It also aids with fixing the side plates of arc chute thereby ensuring greater structural fitment and comparatively greater sealing of upward arc chamber gases and helps in decreasing the leaking of gases side wise. Moreover, easy machining on sheet metal makes the top plate profile and vent design to be simple and changes in the design to be easily accommodated without drastically increasing the overhead costs.

[0044] In one implementation, an arc chute top plate that overcomes the drawbacks and improves upon the performance and life expectancy of an arc chute assembly, is provided for.

[0045] In another implementation, an arch chute top plate to improve the arc quenching performance of an arc chute assembly, is provided for.

[0046] In another implementation, a metallic top plate with punched ribs for the arc chute assembly, is provided for.

[0047] In another implementation, increased strength for an arc chute top plate at a comparatively lower thickness of the top plate, is provided for.

[0048] In another implementation, increased withstanding capability for an arc chute top plate at a comparatively high arc chamber gas pressure for comparatively high energy and high current breaking without getting damaged, deformed or bent, is provided for.

[0049] In another implementation, a powder coated ferromagnetic metallic top plate with punched ribs for arc chute assembly, is provided for.

[0050] In another implementation, a powder coated ferromagnetic top plate with punched ribs for an arc chute assembly having a thickness lower than 4 mm, is provided for.

[0051] In another implementation, arc chute assembly wherein a side plate is inserted into the punched cavity of the powder coated ferromagnetic metallic top plate, is provided for.

[0052] In another implementation, a powder coated ferromagnetic metallic top plate wherein the punched ribs and cavities are spaced far apart to accommodate the side plate for higher frame dimensions, is provided for.

[0053] In another implementation, punching of a cavity or groove is such that it can grove fit the upper portion of the side plates.

[0054] In another implementation, at least two such punched ribs are used, though as per requirements, the number of the punched ribs can be increased or altered.

[0055] In another implementation, the dimension of the cavity formed after the punching operation is such that it can groove fit the upper portion of the side plate with interference fit or with no gap at all.

[0056] In another implementation, the depth of the cavity decides the portion length of the side plate that can be inserted into the metallic top plate.

[0057] In another implementation, the distance between the side plates of the arc chute assembly decides the position of the punched ribs and cavity.

[0058] In another implementation, the punched rib is on the upper side of the plate or in the opposite side of the arc chamber while the cavity is on the lower side of the metallic top plate or facing towards the arc chamber.

[0059] In another implementation, fixing of the side plates of arc chute into the cavity of the punched metal top plate ensures greater structural fitment and comparatively greater sealing for upward arc chamber gases thereby reducing side wise leakage of gases.

[0060] In another implementation, easy machining on sheet metals enables the top plate profile and vent manufacturing to be simple and changes in vent size, number of vents, top plate profile for fitment in the arc chamber etc. can be easily accommodated thereby avoiding comparatively expensive tooling processes.

[0061] In another implementation, the ferromagnetic metal top plate is powder coated for insulation. However, it is to be noted that the top plate can be insulated by any other suitable means which may be known to a person skilled in the art.

[0062] In another implementation, the ferromagnetic metallic top plate increases the magnetic pull on the arc thereby ensuring comparatively lower total arcing time.

[0063] In another implementation, the combination of insulating arc chute bottom plate and ferromagnetic metallic punched top plate ensures that there is no combining of arcs above the splitter plates.

[0064] Conventional arc chute assemblies comprise of splitter plates that uses a combination of ferromagnetic metallic plates to form the multiple arc to increase the arc voltage for quenching the arc, an insulating bottom plate above the splitter plates, an arc filter to cool and deionize the arc gases and an insulating or metallic top plate with vents to close the arc chamber and for the arc chute assembly and to let the arc gases out of the breaker through the vents.

[0065] The present invention is directed to an arc chute top plate for an arc chute assembly, as illustrated in Figures 1a, 1b, 1c, which by the virtue of its design, withstands comparatively higher arc gas pressure for higher current breaking and ensuring better arc quenching of an electrical arc by reducing the time required to extinguish the arc. Figures 1a (arc chute is in partially lifted position) and 1b illustrate the isometric view of a circuit breaker assembly, and Figure 1c illustrates the top view of the circuit breaker assembly.

[0066] The powder coated ferromagnetic top plate (2) with punched ribs (3) for arc chute assembly (1) is made from sheet metal with thickness <4mm. Figures 2a and 2b illustrate the top view and side view of a powder coated ferromagnetic metallic top plate (2) with punched ribs (3), and Figures 2c and 2d illustrate the isometric view of the powder coated ferromagnetic metallic top plate (2) with punched ribs (3) and cavity (4). The top plate also comprises a plurality of vents (5) for circulation of hot air.

[0067] The cavity or groove (4) formed after punching operation is such that it can grove fit the upper portion of the side plates (6) as illustrated in claims 4a, 4b and 4c. In particular, Figure 4a illustrates the cross section view of arc chute assembly where a side plate is inserted into the punched cavity (4) of the powder coated ferromagnetic metallic top plate (2) with punched ribs (3), Figures 4b illustrates the detail view of the cross section of arc chute assembly (1) where the side plate (6) is inserted into the punched cavity of the powder coated ferromagnetic metallic top plate (2) with punched ribs (3), and Figures 4c illustrates the exploded view of arc chute assembly showing all its components.

[0068] The top plate (2) comprises two such punched ribs (3), as illustrated in Figures 2a, 2b, 2c, 2d. Based on requirement, the number of the punched ribs can be increased or decreased. The dimension of the cavity (4) formed after the punching operation is such that it can groove fit the upper portion of the side plate (6) with interference fit or with no gap at all, as illustrated in Figures 4a, 4b, 4c. The depth of the cavity (4) decides the portion length of the side plate (6) that can be inserted into the metallic top plate (2). The distance between the side plates (6) of the arc chute assembly (1) decides the position of the punched ribs (3) and cavity (4), as illustrated in Figures 5a, 5b, 5c. Figures 5a, 5b and 5c illustrate the isometric views and top view of the powder coated ferromagnetic metallic top plate with punched ribs where the punched ribs and cavities are spaced far apart, to a larger extent, to accommodate the side plates for higher frames, as per requirements.

[0069] The punched rib (3) is on the upper side of the plate (2) or in the opposite side of the arc chamber (1) while the cavity (4) is on the lower side of the metallic top plate (2) or facing towards the arc chamber (1), as illustrated in Figures 3a, 3b and Figures 1a, 1b, 1c. Figures 3a and 3b illustrate the side and isometric view of arc chute assembly in which the powder coated ferromagnetic metallic top plate with punched ribs is mounted. These punched ribs increase the strength of the arc chute top plate for a comparatively lower thickness and increases the withstand capability for comparatively high arc chamber gas pressure for comparatively high energy and high current breaking without getting damaged, deformed or bent. This ensures in higher life of the arc chute assembly.

[0070] The fixing of the side plates (6) of arc chute (1) into the cavity (4) of the punched metal top plate (2), which ensures a greater structural fitment and comparatively greater sealing for upward arc chamber gases and helps in decreasing the leaking of gases side wise. Easy machining on sheet metal makes top plate profile and vent design simple and any change can be accommodated easily like vent size, number of vents (5), top plate profile for fitment in the arc chamber etc. This also avoids the comparatively expensive tooling process. The ferromagnetic metal top plate is also powder coated for required insulation. The use of ferromagnetic metallic top plate increases the magnetic pull on the arc, thus ensuring comparatively lower total arcing time. The combination of insulating arc chute bottom plate and ferromagnetic metallic punched top plate ensures that there is no combining of arc lets above splitter plates.

[0071] Thus, a powder coated ferromagnetic top plate with punched ribs for arc chute assembly made from sheet metal with thickness < 4 mm. The cavity or groove formed after punching operation is such that it can grove fit the upper portion of the side plates. Usually, two such punched ribs are used, though their numbers may be increased or decreased based on requirement. The dimensions of the cavity formed after the punching operation is such that it can groove fit the upper portion of the side plate with interference fit or with no gap at all while the depth of the cavity decides the portion length of the side plate that can be inserted into the metallic top plate. The distance between the side plates of the arc chute assembly decides the position of the punched ribs and cavity. The punched rib is on the upper side of the plate or in the opposite side of the arc chamber while the cavity is on the lower side of the metallic top plate or facing towards the arc chamber. These punched ribs increase the strength of the arc chute top plate for a comparatively lower thickness and increases the withstand capability for comparatively high arc chamber gas pressure for comparatively high energy and high current breaking without getting damaged, deformed or bent. This ensures in higher life of the arc chute assembly. The fixing of the side plates of arc chute into the cavity of the punched metal top plate ensures a greater structural fitment and comparatively greater sealing for upward arc chamber gases and helps in decreasing the leaking of gases side wise. Easy machining on sheet metal makes top plate profile and vent design simple and any change in vent size, number of vents, top plate profile for fitment in the arc chamber etc. can be easily and economically incorporated. The ferromagnetic metal top plate is also powder coated for required insulation. The use of this ferromagnetic metallic top plate increases the magnetic pull on the arc, thus ensuring comparatively lower total arcing time. Notably, the combination of insulating arc chute bottom plate and ferromagnetic metallic punched top plate ensures that there is no combining of arc lets above splitter plates.

[0072] Although a simple, economic and cost effective manner of improving the performance, reliability, durability and life expectancy of arc chute assembly by using a powder coated ferromagnetic metallic top plate with punched ribs has been described in language specific to structural features/methods indicated, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or components or devices or methods described therein. Rather, the specific features are disclosed as examples of implementations of a metallic top plate with ribs for use in an arc chute assembly.