FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
A FUSE HOLDING ASSEMBLY;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA
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 switch disconnector fuses used in electrical switching industry. More particularly, the present invention relates to a fuse holding assembly.
BACKGROUND OF INVENTION
The fuses or fuse links form an integral part of a product. The fuses are installed on the product through various mechanisms. At present fuses are assembled on to the switch using two methods. One is by bolting them onto the fuse holders using a nut and bolt arrangement. Another arrangement is by inserting them into a spring loaded groove. This spring loaded groove expands itself on insertion of fuse knife and thereafter exerts constant pressure on it, thus providing sufficient electrical contact between the fuse holder and the fuse knife.
In a switch disconnector fuse, it is desirable to have a good electrical contact between the fuse holders and fuse knife. At the same time, for having higher contact pressure the spring action posed by fuse holder should be stiff enough. This limitation poses a problem of higher fuse insertion/withdrawal force. A higher fuse insertion force poses difficulty in inserting the fuse and often results into customer irritation and deterioration of product in case excessive unbalanced force is required.
It is therefore required to provide a mechanism which facilitates ease of operation.

SUMMARY OF THE INVENTION
it is an object of the present invention to provide an improvement in spring loaded type assembly of fuses which enables reduction in the insertion/withdrawal force and at the same time provides high contact pressure.
Accordingly, the present invention provides a fuse assembly comprising a pair of fuse holders, a fuse knife, a retention spring for providing contact pressure force to the fuse holders, and an actuation button adapted between the fuse holders, wherein when the fuse knife is pushed towards the actuation button, the actuation button enables the fuse holder to grip and un-grip the fuse knife, the actuation button being mounted on an actuation spring.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the Invention Is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1A shows a front view of a fuse assembly, in accordance with an embodiment of the invention.
Fig. 1B shows a side view of the fuse assembly, in accordance with an embodiment of the invention.
Fig. 1C shows an isometric view of the fuse assembly, in accordance with an embodiment of the invention.
Figure 2 shows an actuation button of the fuse assembly, in accordance with an embodiment of the invention.
Figure 3 show the actuation button mounted on an actuation spring, in accordance with an embodiment of the invention.

Figure 4 shows front and isometric views of fuse holders, in accordance with an embodiment of the invention.
Figure 5 shows the fuse assembly at a different stage of operation, in accordance with an embodiment of the invention.
DESCRIPTION OF THE INVENTION
Various embodiments of the invention provide a fuse assembly comprising, a pair of fuse holders; a fuse knife; a retention spring for providing a contact pressure force to the fuse holders for gripping the fuse knife; an actuation button mounted on an actuation spring between the fuse holders, wherein when the fuse knife is pushed towards the actuation button, it enables the fuse holders to grip and un-grip the fuse knife.
Fig. 1A, 1B and 1C show a fuse assembly 100, in accordance with an embodiment of the invention. Fuse assembly 100 comprises a pair of fuse holders 110 (110a, 110b), a fuse knife 120, a retention spring 130, and an actuation button 140.
In accordance with an embodiment of the invention, retention spring 130 provides a contact pressure force to fuse holders 110 so that fuse holders 110 are able to grip fuse knife 120. Actuation button 140 is adapted between fuse holders 110. Actuation button 140 is mounted on an actuation spring 150.
When fuse knife 120 is pushed towards actuation button 140, actuation button 140 enables fuse holder 110 to grip and un-grip fuse knife 120.
According to an embodiment, actuation button 140 has a broader top 140a and a bottom 140b, compared to a center 140c as shown in Fig. 2.
In an embodiment of the invention, fuse holders 110 have a pair of depressions 112a, 112b at the end portions. The depressions are like humps as shown in Fig. 4. The depressions are in an arrangement with fuse assembly 100 such that the depressions are facing each other as shown in Fig. 1. In an embodiment of the present invention, actuation button 140 is adapted between depressions 112a, 112b of fuse holders 110 (Fig. 1, 5).

The actuation mechanism of fuse assembly 100 is now explained. For actuating fuse assembly 100, fuse knife 120 is pushed to actuate actuation button 140, the actuation allowing fuse holders 110 to grip fuse knife 120 with the contact pressure on fuse knife 120, the contact pressure being applied by the retention spring 150.
The return mechanism of fuse assembly 100 is now explained. In return mechanism, fuse knife 120 is pushed to recede actuation button 140; actuation button 140 under the force of actuation spring 150 locks fuse holders 110 in expanded position. The force of actuation spring 150 enables fuse holders 110 to un-gripfuse knife 120.
Initially, fuse holders 110 are already kept separated from each other to a distance which is greater than the width of fuse knife 120 by means of actuation button 140. Thus, whenever the fuse is inserted into the fuse holder 110, no opposition is observed. Further, when fuse knife 120 reaches its critical position where it is supposed to rest in assembled position, it actuates actuation button 140 which then allows fuse holders 110 to come to their natural position under the effect of retention spring 130 and hence grip fuse knife 120, thus applying contact pressure on fuse knife 120.
Similarly, while withdrawal, fuse knife 120 is pushed just a bit which allows actuation button 140 to again lock fuse holders 110 in expanded position and then the fuse can be easily removed. Also, the return mechanism of the actuation button 140 is made in such a way (under the force of actuation spring 150) that it locks the fuse holders 110 in expanded position even before they regain their natural position, thus allowing the fuses to be inserted easily again over and over.
In an embodiment, fuse assembly 100 is in a first position as shown in Fig. 1a, the first position being an ON position of fuse assembly 100. The fuse is at ON position when center 140c of actuation button 140 rests at the end of the pair of depressions 112a, 112b of fuse holders 110 as shown in Fig. 1a.

In an embodiment, fuse assembly 100 is in a second position (OFF position). For OFF position, fuse knife 120 is pushed to recede actuation button 140. The fuse is at OFF position when top end 140a of actuation button 140 separates fuse holders 110 thereby maintaining a gap between fuse knife 120 and fuse holders 110.
According to an embodiment, the present invention provides fuse assembly 100 in second position as shown in Fig. 5; the second position being an OFF position of fuse assembly 100.
The advantage gained through this assembly is that the silver plating present on the fuse holders 110 can have a higher electrical life as the sliding friction between the fuse holders 110 and the fuse knife 120 gets eliminated.
Advantageously, the present invention enables ease of assembly, reduced insertion
force, reduced withdrawal force, resistant to customer abuse, and prevention of silver plating
deterioration.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

We Claim
1. A fuse assembly comprising:
a pair of fuse holders;
a fuse knife;
a retention spring for providing a contact pressure force to the fuse holders, the fuse holders gripping the fuse knife;
an actuation button adapted between the fuse holders, wherein when the fuse knife is pushed towards the actuation button, the actuation button enables the fuse holder to grip and un-grip the fuse knife, the actuation button being mounted on an actuation spring.
2. The fuse assembly as claimed in claim 1, wherein the fuse knife is pushed to actuate the actuation button, the actuation enabling fuse holders to grip the fuse knife with the contact pressure force.
3. The fuse assembly as claimed in claim 1, wherein the fuse knife is pushed to recede the actuation button, the actuation button under the force of actuation spring locking the fuse holders in an expanded position.
4. The fuse assembly as claimed in claim 3, wherein the force of actuation spring enables the fuse holders to un-grip the fuse knife.
5. The fuse assembly as claimed in claim 1, wherein the actuation button is broader at a top end and a bottom end of the actuation button compared to a centre of the actuation button.
6. The fuse assembly as claimed in claim 1, wherein the actuation button is adapted between a pair of depressions of the fuse holders.
7. The fuse assembly as claimed in claim 5 and 6, wherein the fuse is at a first position when the center of the actuation button rests at the end of the depressions of the fuse holders.

8. The fuse assembly as claimed in claim 1 and 5, wherein the fuse is at a second position when the top end of the actuation button separates the fuse holders thereby maintaining a gap between the fuse knife and the fuse holders.