FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
Title of the invention - INTEGRATED PROTECTIVE GUARD FOR ENHANCING THE PERFORMANCE OF A CONTACTOR
2. Applicant
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L &T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed :

FIELD OF INVENTION
The present invention relates to an integrated protective guard component for enhancing electrical performance of a contactor assembly. More particularly, the invention relates to an integrated protective guard component comprising a plate means adapted for effective arc quenching and providing flexibility for operation between a predetermined ampere domain thus enhancing the performance of the contactor. The invention also relates to a contactor assembly comprising the component.
BACKGROUND AND PRIOR ART
In a contactor, arcing takes place whenever circuit is broken. Severity of this arcing depends on the connected load, i.e basically current being broken. Severity of the arcing decides the life of the contactor since it causes erosion of contact materials used.
Normally, deion plates are used in contactors to reduce / minimize the effect of arcing and hence extend the useful life of the contactors. However, deion plates are generally not used in lower rating of the contactors due to space constrain and less severity of arcing, (e.g. 9A, 12A & 18A contactors).
Conventionally, in the smaller rated contactors, first frame of contactors in width 45 mm and 4 pole construction, space is a major constrain for the appropriate placement of the deion plates. All higher sized existing contactors have "U" shaped deion plates housed in the front housing. One of the major disadvantages is due to space constrain, it is not possible to
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place deion plates as per existing methods in 45 mm wide 4 pole contactor.
US4,393,287 discloses an arc suppressing means for current limiting circuit breakers wherein an arc generated between both movable and fixed contacts by an excess current at the time of short-circuiting is magnetically driven by a member extending from the contact part of fixed contactor to an arc running plate in the right angle relation to the plate with a shortened time of arc's staying at the contact part and a shortened time of arc's traveling from the member to a deion grid along the running plate to quickly obtain an elevated arc voltage and to thereby effectively elevate current limiting effect.
Normally, customers requiring a contactor rated more than 18A (ampere) and up to 22A (ampere) would choose a 25A (ampere) rated contactor for effective arc quenching. The 25 ampere rated contactor falls in next higher frame size and hence customer ends up paying higher cost.
Another disadvantage with the existing contactor (45 mm wide 4 pole contactors) is that due to the space constraints incorporation of deion plate is impossible.
Another disadvantage is that when moving contact breaks the circuit, arc gets struck between moving contacts and fixed contacts. This arc gets blown towards the arc shield walls by virtue of the blowout field. In the absence of the deion plate, arc strikes to the arc shield walls made of plastic material thereby damaging the same.
Thus there is a need to provide for an integrated protective guard component for effective arc quenching and providing
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flexibility for operation between a desired ampere domain thus enhancing the electrical performance of the contactor.
OBJECTS OF INVENTION
Thus one object of the present invention is to provide effective arc quenching in the contactors.
Another object of the present invention is to provide an ergonomically designed guard component to nullify all the above disadvantages of the existing contactors.
Yet another object of the present invention is to extract a 22A rated contactor out of 18A rated contactor.
Yet another object of the present invention is to provide a cost effective arc quenching operation in the contactors.
The other object of the present invention is providing a contactor assembly.
SUMMARY OF INVENTION
Thus according to one aspect of the present invention there is provided an integrated protective guard component for enhancing electrical performance of a contactor assembly, said component comprising :
plate means including
plurality of surfaces comprising surface I and surface II, wherein surface I being operatively juxtaposed to surface II
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such that a predetermined angle is established between said surface I and surface II,
wherein said surface II provides additional thermal mass so as to provide higher heat storing capacity by not increasing the temperature corresponding to the number of operations performed;
wherein said surface I and surface II being in operative fixation with a supporting means located where the surface I and surface II juxtaposed with each other;
adapted for extracting predetermined higher rated contactor from a lower rated contactor, thereby providing operational flexibility.
According to another aspect of the present invention there is provided a contactor assembly, said assembly comprising :
housing;
plural moving contacts and fixed contacts being operatively
provided inside the said housing and in operative connection
with plural integrated protective guard components;
said component comprising :
plate means including
plurality of surfaces comprising surface I and surface II,
wherein surface I being operatively juxtaposed to surface II
such that a predetermined angle is established between said
surface I and surface II,
wherein said surface II provides additional thermal mass so as
to provide higher heat storing capacity by not increasing the
temperature corresponding to the number of operations
performed;
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wherein said surface I and surface II being in operative fixation with a supporting means located where the surface I and surface II juxtaposed with each other;
adapted for extracting predetermined higher rated contactor from a lower rated contactor, thereby providing operational flexibility.
DETAILED DESCRIPTION OF INVENTION
In one embodiment of the present invention integrated protective guard component comprises deion plates adapted to suppress the arc produced between the contactors. The said plates are L - shaped and comprise of surface I and surface II having a predetermined angles between them so as to positively rests on the arc shield surface thus allowing heat dissipation by way of conduction and thus ensure reduction in deion plate temperature. This further improves the over all arc quenching efficiency by way of arc cooling. Surface II comprises an aperture so as to fix the deion plates in the arc shield by accommodating arc shield projections. Surface II of the deion plates provides additional thermal mass to the deion plates thus allowing it to store higher heat or not reaching high temperature for equal number of operations. Surface I drags/pulls the arc directed towards the arc shield due to breaking of moving contacts of the contactors towards the deion plates. Surface I and surface II are juxtaposed to each other at right angles for positive fixture on the arc shield, however, this angle does not restrict the scope of the present invention and can be varied proper fixing of the plate on the shield. Surface I and surface II comprises a supporting rib means located such that any angular deformation of the surfaces is prevented.
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In another embodiment of the present invention contactor housing comprises moving contact and fixed contact being operatively located and inter related to each other. Deion plates are designed so as to be accommodated in 45 mm wide 4 pole contactors in spite of the space constraints.
Yet in another embodiment of the present invention each pole means of 4 pole contactor has 11.25 mm width including the thickness of insulating walls. Width of the moving contacts is 5 mm. The L-shaped deion plates as described provides basic criteria which requires that the addition of gap between moving contact to deion plates and deion plates to fixed contacts is higher than the contact gap to achieve the basic functions and providing flexibility in operation by way of extraction of 22 ampere rated contactor from 18 ampere rated contactor.
Presence of deion plate ensures faster cooling of the arc and hence improved electrical life thereby extracting 22 ampere rated contactor out of 18A rated contactor in spite of the space constrains.
The deion plates are fixed on the arc shield by using thermal flaring process. However, this does not restrict the scope of the present invention. Process like adhesive fixing, ultrasonic welding etc. can be used for deion plate fixing. However, adhesive fixing will be a unclean and inconsistent process. Also, any use of adhesive is to be minimized as per our environment policy. Ultrasonic welding process can be used but it requires costly fixtures to ensure consistent quality.
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Process of thermal flaring helps by way of using the existing material projections. It is possible to deform the thermoplastic material (arc shield material itself) and get the proper shape to ensure good holding of the deion plates thus avoiding need for any third material like adhesives.
BRIEF DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates an isometric view of the deion plate of the present invention.
Figure 2 illustrates an isometric view of arc shield without the deion plates.
Figure 3 illustrates an isometric view of arc shield with deion plates in the present invention.
Figure 4 illustrates cross sectional view of contactor with the deion plates in the present invention.
DETAILED DESCRIPTION OF ACCOMPANYING FIGURES
L - shaped deion plates (1) is illustrated in figure 1. Plate (1) comprises surface I (2) and surface II (3) having a predetermined angle between them. Surface II (3) comprises an aperture (4) being provided so as to fix the deion plates (1) in the arc shield (5) (shown in figures 2 and 3) . Rib (9) is fixed to surface I (2) and surface II (3) . Contactor housing (6) comprises moving contact (7) and fixed contact (8) being operatively located and inter related each other (as shown in figure 4) . The arc (10) is shown in figure 4. Deion plates (1) are designed so as to be accommodated in 45 mm wide 4 pole contactors in spite of the space constraints.
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Advantages of invention:
1. Protects the front housing and arc shield walls from direct exposure to arc by pulling the arc towards deion plates and hence improves overall performance.
2. Flexibility in deriving higher ampere range from a lower rated contactor.
3. Can be used in lower rating contactor such as 9A and 12A which will enhance the performance further.
4. Innovative fixing (by thermal flaring process) of the deion plates with the arc shield thereby providing easy inspection and maintainability at customer's end.
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WE CLAIM
1. An integrated protective guard component for enhancing
electrical performance of a contactor assembly, said
component comprising :
plate means including
plurality of surfaces comprising surface I and surface
II, wherein surface I being operatively juxtaposed to
surface II such that a predetermined angle is established
between said surface I and surface II,
wherein said surface II provides additional thermal mass so as to provide higher heat storing capacity by not increasing the temperature corresponding to the number of operations performed;
wherein said surface I and surface II being in operative fixation with a supporting means located where the surface I and surface II juxtaposed with each other;
adapted for extracting predetermined higher rated contactor from a lower rated contactor, thereby providing operational flexibility.
2. Component as claimed in claim 1, wherein the surface II further comprises fixing means which is an aperture such that it accommodates projections from the arc shield so as to hold the component intact on the shield.
3. Component as claimed in claim 1, wherein the plate means comprises deion plates.
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4. Component as claimed in any preceding claims is L-shaped.
5. Component as claimed in claim 1, wherein the surface I being adapted to drag the arc directed towards the arc shield towards the deion plates thereby quenching the arc.
6. Component as claimed in any preceding claims being fixed to a contactor arc shield by adopting thermal flaring process.
7. A contactor assembly comprising :
housing;
plural moving contacts and fixed contacts being
operatively provided inside the said housing and in
operative connection with plural integrated protective
guard components;
said component comprising :
plate means including
plurality of surfaces comprising surface I and surface
II, wherein surface I being operatively juxtaposed to
surface II such that a predetermined angle is established
between said surface I and surface II,
wherein said surface II provides additional thermal mass so as to provide higher heat storing capacity by not increasing the temperature corresponding to the number of operations performed;
wherein said surface I and surface II being in operative fixation with a supporting means located where the surface I and surface II juxtaposed with each other;
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adapted for extracting predetermined higher rated contactor from a lower rated contactor, thereby providing operational flexibility.
Assembly as claimed in claim 7, wherein the deion plates being L shaped such that the addition of gap between moving contact to deion plates and deion plates to fixed contacts is higher than the contact gap.
An integrated protective guard component and contactor assembly as herein described and illustrated with reference to the accompanying figures.


ed this the 29th day of May 2007

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Abhishek Sen
Of S. Majumdar & Co. Applicant's Agent

ABSTRACT
TITLE : INTEGRATED PROTECTIVE GUARD FOR ENHANCING THE PERFORMANCE OF A CONTACTOR
The present invention relates to an integrated protective guard component for enhancing electrical performance of a contactor assembly. The component comprises plate means including plurality of surfaces comprising surface I (2) being operatively juxtaposed to surface II (3) such that a predetermined angle is established between said surface I (2) and surface II (3), which provides additional thermal mass. Surface I (2) and surface II (3) are in operative fixation with a supporting means (9) adapted for extracting predetermined higher rated contactor from a lower rated contactor, thereby providing operational flexibility.
Figure 1