FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: SLIDING ELECTRICAL CONTACT ARRANGEMENT FOR DRAW OUT TYPE SWITCHGEARS
2. Applicant(s):

(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 THE INVENTION
The present invention relates to the field of circuit breakers, more particularly the present invention relates to a sliding arrangement of cradle and breaker terminal in a draw out type circuit breakers.
BACKGROUND AND THE PRIOR ART
The circuit breaker is the device used in protection of electric systems. Whenever a fault occurs in the line it is the duty of nearest circuit breaker to isolate the healthy section of the line from faulty one and thus protect the healthy line from fault.
Circuit breaker has three main parts:
(a) Mechanism, (b) current path and (c) arcing chamber
Mechanism of circuit breaker causes the motion of moving contact towards fixed contact and thus the contact between fixed and moving part is established.
Current path element of circuit breaker carries current when circuit breaker is on i.e. in no fault condition. It breaks the electric supply by opening contact in case of faults. While the arcing chamber quenches the arc which is produce during separation of fixed and moving contacts.
Basically circuit breakers are of two types. Fixed type and draw-out type, in fixed type of circuit breaker bus bars are directly connected to the terminal of breaker (breaker terminals) while in draw out type the breaker goes in the cradle which is like a chamber or enclosure for breaker, in draw-out type the bus bars are connected to the terminals of cradle (cradle terminal).
Breaker and cradle are connected electrically with the help of sliding contacts between breaker terminals and cradle terminals. A rack and pinion arrangement is used to move the breaker in and out (called Rack in and rack out) the cradle.
In these conventional arrangements different jaw cluster which are combined to form contact between breaker and cradle. Because of high spring force the assembly of jaw cluster is difficult and requires a separate fixture arrangement to assemble it which causes extra cost.

Also jaw clusters arrangement requires an additional conductor element (breaker terminal adaptor) which fixes on breaker terminal to maintain contact with jaw clusters which causes to increase current path resistance significantly and thus power losses.
US 6229106 Bl is a circuit breaker movement structure is provided for use with a circuit breaker to move the circuit breaker be connected with or be disconnected from a circuit breaker connecting apparatus. The movement structure comprises a draw bracket assembly and constructed and arranged to be mounted to the circuit breaker connecting apparatus. A guide assembly is constructed and arranged to be mounted to the circuit breaker. The draw bracket assembly includes drive structure constructed and arranged to be actuated to engage the guide assembly and cause the circuit breaker to move with respect to the circuit breaker connecting apparatus. The draw bracket assembly includes a movable structure coupled thereto so as to be moved in a linear manner between first, second, and third positions while maintaining the movable structure in one of the positions. The movable structure is constructed and arranged such that: In the first position, the movable structure permits the circuit breaker to be initially connected with or be disconnected from the circuit breaker connecting apparatus, and prevents actuation of the drive structure. In the second position, the movable structure prevents the circuit breaker to be connected with or be disconnected from the circuit breaker connecting apparatus, and prevents actuation of the drive structure. In the third position, the moveable structure permits the circuit breaker to be connected with or be disconnected from the circuit breaker connecting apparatus but prevents the circuit breaker from being completely disengaged with respect to the draw bracket assembly and, and the movable structure permits actuation of the drive structure.
US20090000925 is a cradle and a method for adapting a circuit breaker for mounting in a switchgear cabinet having a bus bar system. The cradle includes a frame to which a racking apparatus and a locking apparatus are mounted. The racking apparatus is operable to move the cradle into and out of electrical connection with the bus bar system. The locking apparatus has a first operating state, wherein the locking apparatus prevents the circuit breaker from being disposed in the frame and allows the racking apparatus to operate, and a second operating state, wherein the locking apparatus allows the circuit breaker to be disposed in the frame and prevents the racking apparatus from operating.
US 5338228 is a fuse holder retains and removably connects a fuse to fuse clip within an electrical device. The fuse holder includes a fuse drawer having an open top to hold the fuse.

Openings in the fuse drawer are adapted to receive the fuse clips. A guide within the electrical device facilitates sliding the fuse drawer between an open position outside of the electrical device and a closed position within the device. In the closed position, the fuse clips extend through the openings in the fuse drawer and engage the fuse within the fuse drawer to close the electrical circuit within the electrical device. An individual is unable to contact the fuse when the fuse drawer is closed within the electrical device. Similarly, the fuse is disengaged from the fuse clips and the electrical circuit is broken when the fuse drawer is opened so that it is not possible for an individual to contact the fuse while the fuse is connected to the electrical circuit
The disadvantage of existing arrangements is that it is very bulky as it contains many different parts and so requires more copper. Also the number of joints is more in this case which cause extra cost and energy losses.
Contact area between the breaker terminal adaptor, jaw clusters and cradle terminal very less so temperature rise at this contact is very high causing overall increase in the breaker temperature.
OBJECTS OF THE INVENTION
An object of the present invention is to overcome the problems/disadvantages of the prior art.
Another object of the invention is to provide a sliding arrangement of cradle and breaker terminal in a draw out type circuit breaker.
Another object of the invention is to provide a sliding arrangement which can replace the breaker terminal adaptor and jaw clusters by a single structure.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
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/critica! 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.
In accordance with present embodiment of the invention, there is provided a sliding arrangement of cradle and breaker terminals for a draw out type circuit breakers.
In accordance with other embodiment of the invention, there is provided a breaker with breaker top terminal and breaker bottom terminal.
In accordance with another embodiment of the invention, there is provided a holder with a pallet structure, a base surface, a slot, and an opening in the pallet structure.
In accordance with another embodiment of the invention, the holder is bolted to breaker top terminal and breaker bottom terminal.
In accordance with another embodiment of the invention there is provided a cradle terminal comprising two copper straps and introduced in the holder.
In accordance with another embodiment of the invention there is provided a wire spring attached to the opening of pallet structure for maintaining better contact with cradle terminal.
In accordance with a further embodiment of the invention there is also provided a moving contact and a fixed contact for closing and opening and closing the circuits.
In accordance with further embodiment of the invention there is also provided a bus bar attached with cradle terminals for maintaining electrical connection between cradle and breaker terminal.
In accordance with yet another object of the invention there is also provided a block forming a part of arcing chamber for extinguishing the arc formed during current interruption.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the

scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
FIGURE 1: shows the complete current path assembly of suggested arrangement.
FIGURE 2: shows the isometric view of the holder.
FIGURE 3: shows the holder before bending.
FIGURE 4: shows the wire formed (spring).
FIGURE 5: shows cradle terminal assembly.
FIGURE 6: shows isometric view of single part of cradle terminal.
FIGURE 7: shows assembly of cradle terminals and holders.
FIGURE 8: shows top view of cradle terminal and holder assembly.
FIGURE 9: shows the complete assembly of breaker with cradle and other parts.
DETAILED DESCRIPTION OF THE ACCOMPANYING INVENTION
Accordingly in the present invention FIG.l illustrates the total current path suggested by this improved arrangement. The moving contacts (7) and fixed contact (8) are in close position. As per the diagram holder (1) is bolted to the breaker terminal top (3) and breaker terminal bottom (4). The cradle terminal (2) inserts in the holder in both top and bottom side as breaker racks-in. Breaker top terminal (3) has strip of silver alloy (8) attached by brazing which forms the stationary contact (fixed contact) of circuit breaker. The flexible contact called braids (5) is crimped to the bottom terminal (4). Braids (5) are attached to the fingers (6) which has a brazed the moving contact (7) called contact buttons. Block (9) is a part of arcing chamber made up of non-conductive material for fixing of complete current path arrangement.
FIG.2 illustrates a holder (1) (fig 2) has a base surface (lb) which is directly bolted to the breaker terminals (3 and 4) at slots (lc), and openings (Id) in pallet like structure (la). It also has pallets like structure (la) which has spring action and hence form sliding contact to holds the cradle terminal (2). The holder (1) is made up of a copper strap

Each holder (1) has three flexible pallets (la) which are used for establishing contact with the cradle terminal (2). Also the current coming from breaker top terminal (3) and breaker bottom terminal (4) gets divide into three parallel paths hence reduction in watt loss and temperature. As the design of pallets (lb) is rectangular one it has better contact with cradle terminal unlike the prior art where the area in contact with jaws and cradle terminal is very less (tangential contact). Less contact area leads to formation of hot spots and thus rises the breaker temperature.
FIG.3 illustrates the holder (1) before bending. The design of holder is such that there is minimum waste of material while cutting it. As the design eliminates the need for separate breaker adaptor and has minimum wastage of material while making, it is very cost effective solution over the existing design.
FIG.4 illustrates the surfaces (4a) of a wire spring attached to holder (1) at opening (Id) for better contact with cradle terminal (2). The cradle terminal (2) has to work against the spring while entering the holder so better contact is maintained by the pressure applied by the spring.
FIG.5 illustrates two straps (2a) and (2b) are riveted to form a single cradle adaptor assembly which goes inside the holder. Cradle terminal (2) is formed by riveting two copper straps. This innovative design of cradle terminal eliminates the need for extrusion process which is very expensive over cutting and bending.
FIG.6 illustrates a single part of a cradle terminal. Initially the cradle terminal assembly is attached in the terminal support which is on the cradle of a breaker.
FIG.7 illustrates a cradle terminal introduced in the holder. The holder (1) is bolted to the breaker bottom terminal (3) breaker top terminal (4). As the breaker is racked in the cradle, holder (1) forms contact with cradle terminal (2) to which the bus bars are attached further. Thus electric connection is maintained between the breaker and cradle.
FIG.8 illustrates a cradle terminal (2) introduced into the holder (1).
FIG.9 illustrates the complete arrangement of breaker and cradle joined together with the help of holders. Cradle terminals (2) with two straps (2a) and (2b), introduced into holders (1) comprising a pallet structure (la) for better contact with cradle terminal. Holder (1) is bolted with breaker top terminal (3) and breaker bottom terminal (4), and braids (5) connected with

breaker bottom terminal (4). The current coming from breaker top terminal (3) and breaker bottom terminal (4) gets divide into three parallel paths hence reduction in watt loss and temperature.
While the invention has been shown and described with respect to particular embodiments thereof, those embodiments are for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein described will be apparent to those skilled in the art, all within the intended spirit and scope of the invention. Accordingly, the invention is not to be limited in scope and effect to the specific embodiments herein described, or in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention

WE CLAIM:
1. A sliding electrical contact arrangement for a draw out type switchgear system, said arrangement comprising:
a) a plurality of moving contacts attached with finger means and fixed contacts;
b) a plurality of breaker comprising a breaker bottom terminal and breaker top
terminal;
c) a plurality of holder means having pallets and base for bolting; said holder means being connected to top and bottom terminals by bolting at its base (lc)
d) a plurality of cradle terminals introduced in said holder means such that said Cradle terminal and holder means form a sliding joint at the pallets of the holder means
e) one or more braids attached with the said fingers; and
f) a block, forming part of a arcing chamber.
wherein, said top and bottom terminals connect the said fixed and moving contacts to said holder and cradle terminal.
2. A sliding electrical contact arrangement as claimed in claim 1, wherein said holder means comprising a plurality of pallet structures, a plurality of slots, a plurality of opening in said pallet, and a base surface.
3. A slide electrical contact arrangement as claimed in claim 2, wherein said holder means is boiled with said breaker bottom terminal and breaker top terminal by means of said base surface.
4. A sliding electrical contact arrangement as claimed in claim 2, wherein said pallet structure is of different shapes, selectively rectangular, for better contact with cradle terminal.
5. A sliding electrical contact arrangement as claimed in claim 4, wherein a wire spring is attached to opening in said pallet structure, aiding better contact with cradle terminal.
6. A sliding electrical contact arrangement as claimed in claim 1, wherein said cradle terminal comprising one or more straps riveted forming a single cradle adaptor assembly.

7. A sliding electrical contact arrangement of claim 6, wherein said straps were made of different types of materials, selectively copper.
8. A sliding electrical contact arrangement as claimed in claim 6, wherein said cradle terminal further comprising bus bars maintaining electrical connection between said breaker terminals and cradle terminal.
9. A sliding electrical contact arrangement for a draw out type switchgear as herein described and illustrated with reference to accompanying drawings.