Title of Invention

A PROTECTIVE GUARD SYSTEM FOR INSULATING SUPPORT STRUCTURES OF CONTACTORS AND THE LIKE

Abstract

A PROTECTIVE GUARD SYSTEMJ FOR INSULATING SUPPORT STRUCTURES OF CONTACTORS AND THE LIKE A protective guard for insulating suport structures for contactors and the like which would effectively protect thesupport structure from damages due to extreme heat/ionized hot gases usually generated by electric arcs during switching operations by way of a selective guard profile and configuration adapted for faster arc quenching and better heat dissipation and in the process enchance the life of contactors. The protective guard comprises a guard profile adapted to atleast partly and effecvtively surrounding the current carring parts of the contactor and adapted to be selectively disposed with respect to the support structure. The guard profile is also adapted to stretch the arc in mulitiple directions for faster arc quenching. The protective guard also comprises atleasdt one horn configuration adapted to attract the arce to itself for effective arc quenching and protection of the support structure.

Full Text

FORM -2 THE PATENTS ACT, 1970 (39 OF 1970) COMPLETE SPECIFICATION (See Section 10 ; rule 13) 1. TITLE OF INVENTION A PROTECTIVE GUARD SYSTEM FOR INSULATING SUPPORT STRUCTURES OF CONTACTORS AND THE LIKE 2. (a) LARSEN & TOUBRO LIMITED, (b) L & T House, Ballard Estate, Mumbai 400 001, State of Maharashtra, India, (c) an Indian company. The following specification particularly describes the nature of the invention and the manner in which it is to be performed. 1 6 FEB 2004 Field of the invention The present invention relates to a protective guard for insulating support structures for contactors and the like and, in particular, to a protective guard system for support structures of contactors which would effectively protect the support structure from damages due to extreme heat /ionized hot gases usually generated by electric arcs during switching operations by way of a selective guard profile and configuration adapted for faster arc quenching and better heat dissipation and in the process enhance the life of contactors. Back Ground Art It is known to provide arc chute in contactors and the like to protect the supporting structures of the current carrying components housed in the support structures. US 4,256,937 discloses an arc chute for clapper - type electromagnetic DC contactor having a closed off top wall with tapered and angled holes therethrough directing jets of air caused by the arc when the contact tips separate, to the front of the arc chute thereby preventing the arc from moving directly above the contactor and as a result decreasing overhead clearance between contactors and further imputing the upper limit of fault current interruption. Use of absorbing members in electromagnetic contactors to absorb molten metal particles formed by arcing is also known. In US 4,616,203 an absorbing member of porous metal is provided on the inner surface of a partition wall to absorb molten metal particles, which are formed by arcing at the time of disengagement of the contacts. A sheet plate of electrically insulating material is provided on the inner surface of the absorbing member and through holes are formed in the partition wall of the arc extinguishing chamber and the sheet plates in such a manner that the through holes of the partition wall are non-coincident in position with those of the sheet plate, so that the absorbing member is further protected from damage. US 5,014,027 discloses yet another -improvement irv arc-extinguishing performance in electromagnetic contactors. For the purpose the electro magnetic 2 contactor comprise a fixed iron core, a flat portion of the fixed iron core disposed along a moving direction of movable contacts to come close to each gap between fixed contacts and the moveable contacts with a shielding sheet of an insulation material put thereon. US 5,359,174 discloses a thermally conductive insulating arc quenching coating composition for current interrupters The coating proposed comprise urethane, melamine and acrylic based resin compositions containing inorganic nitrides such boron nitrides, aluminium nitride and silicon nitride. The prior art also discloses other coating compositions including high nitrogen organic compounds such urea, guanine etc. US 6,417,749 proposes a unitary housing structure preferably made of thermoplastic material to effectively limit the anticipated temperature rise during opening and closing cycles of electrically switching devices such as three-phase contactors. In case of multi-phase contactor, the housing also provides integral partitions between phase sections to avoid exchanges between gases within the housing which can lead to short circuit problems. It would be apparent from the above that several varieties of protective structures / units for contactors including arc quenching compositions / coatings have been proposed in the art to facilitate protecting the contactors from damage due to arcing. It would be also appreciated that most of the proposed / available structures / units to protect the contactors in general are either complex to manufacture/install or are cost extensive. Importantly also, conventionally all protecting devices used in contactors to protect the insulating support structure are usually known to be shaped to have a uniform "U" profile. However, such "U"" profiles necessarily provide for contact of the entire outer surface of the protectorwith the support structures which in some manner or other thus transmit the high temperature faced by the protective guard to the support structure risking the; latter to consequential damages and operational problems. - -3 It is also noted that due to such uniform "U" profile of the protective guards which usually remain in contact with the insulated support, the support structures is exposed to high temperatures which can lead to melting of the support unit which can be hazardous and dangerous. Also, it is experienced that the usual "U" shaped profiles of the protective guards for the support structure are usually not of sufficient strength and the same again lead to problems of collapse of the structure and failure in its purpose. Objects of the Invention It is thus the basic object of the invention to provide for protective guards for the insulated support structures of contactors and the like which would on one hand provide for the desired functions of the protective guard to protect and enhance the life of the contactor and on the other hand avoid the problems and limitation of the usually "U" shaped protector guard profiles presently used in the art as discussed above. Another object of the present invention is to effectively protect the insulated structure supporting the uninstalling live parts in the contactor from electric arc by providing for faster arc quenching and better heat dissipation during switching operations of a contactor which is a known challenge to development of protective guards for such contactors. Yet another object of the present inventions to enable maintaining the insulating support structure free of the extreme heat faced by the protective guards to the extent possible thereby favoring avoiding problems of melting / damage to the support structure. Yet another object of the present inventions is to provide for a protector guard profile which would facilitate better stretching of the arc in multiple directions to favour faster arc quenching and thereby ensure better protection of the support structure. ; Yet further object is directed to take care of problems experienced in the art of the arcs merging at the top and generation of hot ionized gases which is found to "4 cause further problems associated with failures of existing protector guards of insulating structures. Yet further object is directed to provide protective guard for support structures free from pre mature failure and favour substantial increase in the product life. Yet another object is to provide for selective material in combination with selectively profile of the protective guard for support structure and the like which would further facilitate effective heat dissipation and faster arc quenching in protection of the support structures. Summary of the Invention Thus according to the basic aspects of the present invention there is provided a protective guard system for insulating support structures of contactors and the like comprising: - a guard profile adapted to atleast partly and effectively surrounding the current carrying parts of the contactor and adapted to be selectively disposed with respect to the support structure free of continuous body contact therebetween the guard and the support structure ; said guard profile also adapted to stretch the arc in multiple directions for faster arc quenching and atleast one horn configuration adapted to attract the arcs to itself for effective arc quenching and protection of the support structure. In accordance with an aspect of the invention there is provided a protective guard for insulating support structure of contactors and the life comprising :- a guard profile adapted to atleast partly and effectively surround the current carrying parts of the contactor andjadapted to be selectively disposed with respect to the support structure free Of continuous body contact therebetween ;5 the guard and the support structure comprising a stepped profile further adapted to stretch the arc in multiple directions and atleast one horn configuration adapted to attract the arcs and avoid merging of arcs for faster dissipation of heat and protection of the support structure. In accordance with a preferred aspect of the present invention there is provided a protective guard system for insulating support structure of contactors and the-life-comprising :- a guard profile adapted to selectively surround the current carrying parts comprising two side walls and an intermediate contiguous top; each said side walls having stepped profile adapted to provide substantial clearance therebetween the outer surface of the guard and the inner surface of said support and also adapted to stretch the arc in multiple directions and said top having atleast one protruding horn means selectively disposed and adapted to attract the arcs to itself and avoia merging of arcs to favour faster dissipation of heat and protection of the support structure. It is thus possible by way above selective profile of the protective guard adapted to avoid the continuous contact of the entire outer surface of the guard with the support structure preferably by involving the stepped side walls configuration and also the provision of the horn to on one hand avoid contact throughout the outer surface of the guard and the inner surface of the support and also enable stretching of the arc in multiple directions for faster arc quenching and further attract the arcs towards the horn at the top to take care of problems of arc merging to effectively protect the support structure from the arc and /or problems of associated heat and ionized gas generation. In accordance "with "a further preferred aspect of the protective guard in accordance with*the present invention, the protective guard for insulating support structures of contactors and the like corpprise ,6 additional means provided in said profile to facilitate maintaining clearance of a substantial portion of the protective guard from said support structure in its assembled form. In accordance with yet further aspect of the present invention there is provided a contactor assembly comprising protective guard disposed around the current carrying parts housed in a support structure, said protective guard profile adapted to atleast partly and effectively surrounding the current carrying parts of the contactor and adapted to be selectively disposed with respect to the support structure free of continuous body contact therebetween the guard and the support structure ; said guard profile also adapted to stretch the arc in multiple directions for faster arc quenching and atleast one horn configuration adapted to attract the arcs to itself for effective arc quenching and protection of the support structure. Importantly apart from the stepped configuration of the profile the protective guard is further provided with atleast one dimple in the profile just below the horn in the top to further facilitate maintaining the desired clearance the top of the protective guard with the adjacent support structure of the contactor. Importantly, the steps are provided in the sides of the protective guard which enable attracting the arc and the splitting in multiple directions. This clearly avoids the problems of traditional "U" shaped profiles where the entire outer surface remain in contact with the support structures exposing the latter to the high temperature and possible consequential melting and break down. In particular the stepped configuration ft the side and the dimple near the horn provide for the required adequate clearance between the protective guard of the support structure which favour extending the life of the contactor. The horn at the top of the profile as stated above, takes care of problems of flash over between phase & with arcs merging at the top because of hot ionized gasses. -7 The horn favours attracting the arcs itself without problems of merging and consequential generation of hot ionized gasses. It is advantageously found that the above selective profile of the protective guard of the invention favours protecting the support structures from pre matured failure and substantially increase the product life. It is also possible to maintain the above inventive feature of the stepped profile and horn configuration of the protective guard by way of varied forms of such stepped and horn configuration of the profile. In particular alternate forms are possible, wherein the disposition and number of the steps can be altered. Also it is possible to vary the depth of the steps constituting the stepped profile depending upon the specific end use/ application and in particular the extent of protection required for the support structure of the contactor. It is also possible to have variety of horn configuration depending upon the application and used such as providing of the horn split into two small ones. Brief descriptions of the figures The protective guard profile, its objects and advantages are explained here under in grater detail in relation to non limiting exemplary illustration of the protective guard of the invention as per the accompanying figures wherein: - Figure 1 is a schematic illustration of the protective guard profile of the present invention having the stepped configuration and the horn. Figure 2 illustrate in perspective view the disposition of the innovative guard profile assembled with respect to the $upport structures in a contactor assembly. Reference is first invited to accompanying figure 1, which clearly illustrates in greater detail the selective profile of the protective guard in accordance with the present invention. 8 As shown in said figure the protective guard (1) is shaped to have a profile having side walls (SW1) with stepped configuration. The top portion (TP1) of the protective guard serves as a contiguous connection for the stepped side walls (SW1). The top part (TP1) is further shown to be provided with horn (HR1) which facilitate attracting the arcs towards the horn at the iop avoiding problems of arc merging and problems associated with generation of hot ionized gas. The aforesaid stepped and horn configuration together provide for the stretching of the arc in multiple directions for faster arc quenching and maintaining desired clearance between the protective guard and the support structure. As also shown in figure 1 a dimple (DM1) is provided near the horn in the top (TP1) portion which further facilitates maintaining the desired clearance between the support structure and the protective guard to avoid subjecting the support structures to the extreme heat generated by the arcs and thereby enhance the life of the contactor. Reference is now invited to figure 2 which illustrates the disposition of the protective guard (1) having the stepped side wall and the horn at the top installed with respect to the support structure in the contactor assembly. As shown in figure 2, the protective guard (1) is having the stepped side wall configuration and the horn top profile and is preferably made of a high heat conducting material. The above protective guard (1) is shown disposed around the current carrying parts (2&3) which are housed in the support structures (4). The above selectively profiled protective guard and its disposition around the current carrying parts (2&3) in the support structure (4) provide for stretching the arc in multiple direction resulting in faster arc quenching and at the same time protects the insulating support structure from direct exposure to arc. The special materials conventional high heat conducting materials favour dissipation of heat at a faster rate resulting in lesser heat transfer to the supporting structure and reducing the hot spot temperature. ,; 9 WE CLAIM: 1. A protective guard system for insulating support structures of contactors and the like comprising: - a guard profile adapted to atleast partly and effectively surrounding the current carrying parts of the contactor and adapted to be selectively disposed with respect to the support structure free of continuous body contact there between the guard and the support structure ; said guard profile also adapted to stretch the arc in multiple directions for faster arc quenching; and atleast one horn configuration adapted to attract the arcs to itself for effective arc quenching and protection of the support structure. 2. A protective guard for insulating support structure of contactors and the life comprising :- a guard profile adapted to atleast partly and effectively surround the current carrying parts of the contactor and adapted to be selectively disposed with respect to the support structure free of continuous body contact there between the guard and the support structure comprising a stepped profile further adapted to stretch the arc in multiple directions and atleast one horn configuration selectively provided and adapted to attract the arcs and avoid merging of arcs for faster dissipation of heat and protection of the support structure. 3. A protective guard system as claimed in anyone of claims 1 or 2 comprising :- a guard profile adapted to selectively surround the current carrying parts comprising two side walls and an intermediate contiguous top; each said side walls having stepped profile adapted to provide substantial clearance therebetween the outer surface of the guard and the inner surface of said support and also adapted to"stretch the arc in mujtiple directipns.and 11

Documents:

171-mum-2004-claims(granted)-(15-6-2004).doc

171-mum-2004-claims(granted)-(15-6-2004).pdf

171-mum-2004-correspondence(31-1-2005).pdf

171-mum-2004-correspondence(ipo)-(31-3-2004).pdf

171-mum-2004-drawing(16-2-2004).pdf

171-mum-2004-form 1(16-2-2004).pdf

171-mum-2004-form 19(24-2-2004).pdf

171-mum-2004-form 2(granted)-(15-6-2004).doc

171-mum-2004-form 2(granted)-(15-6-2004).pdf

171-mum-2004-form 3(16-2-2004).pdf

171-mum-2004-power of attorney(16-2-2004).pdf

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