CLIAMS:1. In a draw out type of circuit breaker, the circuit breaker is supported on a rail assembly (15) or a draw out assembly, which is an integral part of a cradle assembly (11), the cradle assembly (11) comprising:
at least one base plate (12);
a racking assembly (13) mounted on the at least one base plate (12) adapted to perform at least one racking operation;
at least one side plate (14) for guiding the breaker and the rail assembly (15);
at least one rail lock latch (16) to latch the rail assembly (15) in at least one position;
at least one lever (17);
at least one rail latch interlock (18);
at least one transfer link (19);
at least one de-latch link (20);
at least one de-latch pivot (21); and
at least spring (22, 23) located between the rail lock latch (16) and the de-latch link (20);
wherein the at least one racking operation is performed by uplifting the at least one lever (17) thereby dropping the at least one rail lock latch (16), to interlock the at least one rail latch interlock (18), due to the at least spring (22, 23) to latch the rail assembly (15) in the at least one position.

2. The cradle assembly (11) according to claim 1, further comprising a detachable crank which is rotatable, wherein the rotation of the detachable crank causes the circuit breaker to move in or out of the cradle assembly (11).

3. The cradle assembly (11) according to claim 2, wherein the rotation of the detachable crank is in a clockwise direction or in a counter-clockwise direction.

4. The cradle assembly (11) according to claim 1, wherein the at least one position is selected from a group comprising of a disconnected position, a test position, and a connected position.

5. The cradle assembly (11) according to claim 1, wherein the de-latch link (20) is affixed on the de-latch pivot (21), which rotates downward to pushes the transfer link (19).

6. The cradle assembly (11) according to claim 5, wherein the transfer link (19) makes contact with the rail latch interlock (18) causing it to rotate against the at least spring (22, 23), thereby releasing the rail lock latch (16).
,TagSPECI:TECHNICAL FIELD
The present invention described herein, in general relates to a circuit breakers, and more particularly, to an improved racking system for draw out type circuit breaker arrangement.

BACKGROUND
An electrical circuit breaker may be defined as a unit designed to carry, make and break current and protect the equipments connected in the electrical circuit from abnormal conditions like overload, under-voltage or short circuit etc. A circuit breaker is commonly used as an electrical switching device.

There are two popular versions of circuit breakers namely, fixed and draw-Out type. In the draw out type, the breaker can be removed without dismantling the terminals, in order to facilitate maintenance and secure stability. Unlike fixed breakers, draw out breakers are housed inside the cradle or cassette. They can be racked-in and out from cradle.

In a draw out type of circuit breaker, positions of breaker with respect to cradle are normally defined as 'Disconnected/ Isolated', 'Test' & 'Connected/ Service'. In a draw out type of breaker, the breaker can be racked in by use of detachable crank; from 'Disconnected' position to ‘Test position’ and then to 'Connected' position and racked out in the reverse order.

While performing rack-in operation, the position of the breaker in the cradle is indicated by a position indicator. There is a possibility that, the position indication gets neglected by the user. This may be due to unawareness of the positions and their related safety instructions. Also, in case the breaker is not racked in sufficiently and it is switched ON (closing the power circuit), due to insufficient overlap between the breaker terminals and the cradle jaws, the contact area might be less, resulting in overheating and flashover.

Due to above mentioned drawbacks; there exists a need to have a locking arrangement at distinct positions with no lag, which can prevent further rack-in or rack-out operations, unless acknowledged by the user. Such an arrangement needs to be very economical; also it should adhere to the space limitations of the breaker.

SUMMARY
This summary is provided to introduce concepts related to a mechanism to an improved assembly for interlocking mechanism of racking position of a circuit breaker. This summary is not intended to identify essential features of the subject matter nor is it intended for use in determining or limiting the scope of the subject matter.

In one implementation, the invention is intended to provide an improved draw out type circuit breaker arrangement.

In one implementation, the disclosed mechanism is an improved design for interlocking of racking position of breaker.

In one implementation, a mechanized position locking of rail and user cognizance in draw out type circuit breakers is disclosed.

In one implementation, the disclosed mechanism avoids the over stressing of racking screw because locking is provided on cradle rail.

In one implementation, the disclosed assembly resolves the problem of disparity between the genuine breaker position and the intended position of the breaker by introducing locking of the rail.

In one implementation, the disclosed assembly gives positive locking at the distinct positions irrespective of the sequence of racking in racking-out operation and eliminates backlash error.

In one implementation a draw out type of circuit breaker, the circuit breaker is supported on a rail assembly (15) or a draw out assembly, which is an integral part of a cradle assembly (11) is disclosed. The disclosed cradle assembly (11) comprises of at least one base plate (12), a racking assembly (13) mounted on the at least one base plate (12) adapted to perform at least one racking operations, at least one side plate (14) for guiding the breaker and the rail assembly (15), at least one rail lock latch (16) to latch the rail assembly (15) in at least one position, at least one lever (17), at least one rail latch interlock (18), at least one transfer link (19), at least one de-latch link (20), at least one de-latch pivot (21), and at least spring (22, 23) located between the rail lock latch (16) and the de-latch link (20). The cradle assembly (11) performs the at least one racking operations by uplifting the at least one lever (17) thereby dropping the at least one rai l lock latch (16), to interlock the at least one rail latch interlock (18), due to the at least spring (22, 23) to latch the rail assembly (15) in the at least one position.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 illustrates rail lock latched in Distinct Position of Breaker is shown, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates a disengaging lever defeating rail lock latch via rail latch interlock is shown, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates a release of rail latch interlock in intermediary condition of breaker is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION
Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. 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 and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

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.

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

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.

Accordingly, the present invention is an improved design for interlocking of racking position of breaker.

Construction of the racking system of the present invention is explained with reference to the accompanying figures.

List of components used in the figure are:

1. A cradle assembly (11)
2. Base plate (12)
3. A racking assembly (13)
4. A side plate (14)
5. A rail assembly (15)
6. Rail lock latch (16)
7. Lever (17)
8. Rail latch interlock (18)
9. Transfer link (19)
10. De-latch link (20)
11. De-latch pivot (21)
12. springs (22, 23)

In one implementation a draw out type of circuit breaker, the circuit breaker is supported on a rail assembly (15) or a draw out assembly, which is an integral part of a cradle assembly (11) is disclosed. The disclosed cradle assembly (11) comprises of at least one base plate (12), a racking assembly (13) mounted on the at least one base plate (12) adapted to perform at least one racking operation, at least one side plate (14) for guiding the breaker and the rail assembly (15), at least one rail lock latch (16) to latch the rail assembly (15) in at least one position, at least one lever (17), at least one rail latch interlock (18), at least one transfer link (19), at least one de-latch link (20), at least one de-latch pivot (21), and at least spring (22, 23) located between the rail lock latch (16) and the de-latch link (20). The cradle assembly (11) performs the at least one racking operation by uplifting the at least one lever (17) thereby dropping the at least one rail lock latch (16), to interlock the at least one rail latch interlock (18), due to the at least spring (22, 23) to latch the rail assembly (15) in the at least one position.

In one implementation, the cradle assembly (11) further comprises a detachable crank which is rotatable, wherein the rotation of the detachable crank causes the circuit breaker to move in or out of the cradle assembly (11). The rotation of the detachable crank is in a clockwise direction or in a counter-clockwise direction.

In one implementation, the at least one position is selected from a group comprising of a disconnected position, a test position, and a connected position.

In one implementation, the de-latch link (20) is affixed on the de-latch pivot (21), which rotates downward to pushes the transfer link (19). The transfer link (19) makes contact with the rail latch interlock (18) causing it to rotate against the at least spring (22, 23), thereby releasing the rail lock latch (16).

In one exemplary embodiment of the present invention, in a Draw out type of circuit breaker, the breaker may be supported on the rail assembly or any equivalent draw-out assembly, which may be an integral part of the Cradle assembly. The Cradle assembly (11) consists of the base plate (12), Racking assembly (13), side plates (14) for guiding breaker and rail assembly (15). Racking operation may be accomplished by the racking assembly mounted on the base plate (12). The rotation of detachable crank causes breaker to move in or out of the cradle depending upon the direction of rotation of crank i.e. whether it is a rack-in (clockwise) or rack-out (counter-clockwise) operation. When the racking handle is rotated in the clockwise direction, the breaker is racked in (Disconnected - Test - Connected) and on the other hand, when rotated in counter clock wise direction, the breaker is racked-out (Connected - Test - Disconnected).

The invention locks the breaker in three distinct positions namely 'Disconnected' , 'Test' & 'Connected' positions. Initially, when the breaker is located in any of the distinct positions, the spring (22) load on both, the rail lock latch (16) and the de-latch link (20) causes them to align with & move into their corresponding slots on the rail assembly (15). User recognition of three distinct positions will be reflected by lowering of disengaging lever (17). The rail lock latch (16) will latch the rail assembly (15) in this condition and prevent any further racking operation from taking place, as shown in figure 1.

To proceed with racking operation, there is a provision for manually de-latching the rail, by uplifting of the disengaging lever (17). This will cause the rail lock latch to drop down, and due to spring (23) bias of the rail latch interlock (18), it will lock the rail lock latch (16) in this position, as shown in figure 2.

On further racking of the breaker, the de-latch link (20) is forced downward by cam action of the rail assembly (15) slots provided for the same. The de-latch link (20) is affixed on the de-latch pivot (21), which then swivels downward pushing the transfer link (19). This link makes contact with the rail latch interlock (18) causing it to swivel against its spring bias, releasing the rail lock latch (16) as shown in figure 3.

The breaker will now lie in an intermediate position between any of the three distinct positions and both, the rail lock latch (16) and the de-latch link (20) will rest against the lower surface of the rail assembly (15) due to their spring (22) bias. Once again if any distinct position is reached the aforementioned events will take place sequentially.

Referring now to figure 1 illustrates a rail lock latched in distinct position of breaker is shown, in accordance with an embodiment of the present subject matter. In an embodiment of the present invention, the detailed description of figure 1 is as given above.

Referring now to figure 2 illustrates a disengaging lever defeating rail lock latch via rail latch interlock is shown, in accordance with an embodiment of the present subject matter. In an embodiment of the present invention, the detailed description of figure 2 is as given above

Referring now to figure 3 illustrates a release of rail latch interlock in intermediary condition of breaker is shown, in accordance with an embodiment of the present subject matter. In an embodiment of the present invention, the detailed description of figure 3 is as given above.

Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features:

One feature of the invention is that, it gives positive locking at the distinct positions irrespective of the sequence of Racking in Racking -out operation and eliminates backlash error

Another feature of the invention is that, the proposed mechanism resolves the problem of disparity between the genuine breaker position and the intended position of the breaker by introducing locking of rail. Since it takes reference directly from the rail, it gives the correct indication when each of the three positions namely Connected, Test & Disconnected is reached.

Another feature of the invention is that, the proposed mechanism avoids the over stressing of racking screw because locking is provided on cradle rail.

Another feature of the invention is that, the proposed mechanism resolves the problem of over and under racking of air circuit breaker.

Another feature of the invention is that, the proposed mechanism maintains sufficient overlap between breaker terminals and jaws.

Another feature of the invention is that, the proposed mechanism provides a provision of accurate position indication at all three positions.

Another feature of the invention is that, the proposed mechanism will function irrespective of the mounting of breaker on cradle assembly.

Another feature of the invention is that, the proposed mechanism is a simple construction and the assembly is obtained effortlessly.

Another feature of the invention is that, using the proposed mechanism a manual override capability by locking disengaging lever in lifted condition is achieved.

Yet another feature of the invention is that, the proposed mechanism provides the locking and latching arrangement that are a combination of links, which take reference of the rail assembly of the switchgear, without actually affecting the functionality of racking mechanism

Yet another feature of the invention is that, in the proposed mechanism since there is no locking of racking screw avoid over stressing of racking arrangement, due to this, bending stresses on racking screw will be at a minimum.

Yet another feature of the invention is that, the proposed mechanism gives accurate and positive locking at the three distinct positions irrespective of the direction (rack-in / rack-out) of racking operation with negligible backlash error.

Yet another feature of the invention is that, in the proposed mechanism user cognizance of achievement of distinct position, for further racking operation, as displayed by resultant position of disengaging lever.

Yet another feature of the invention is that, in the proposed mechanism auto de-latch mechanism with minimal lag so as to attain infallible latching system is provided.

Still another feature of the invention is that, the proposed mechanism eliminates the need for constant observation of the existing visual continuous indication.

Although implementations for the a mechanism to an improved assembly for interlocking mechanism of racking position of a circuit breaker have been described in language specific to structural features and/or the methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features are disclosed as examples of, the mechanism to an improved assembly for interlocking mechanism of racking position of a circuit breaker.

It is intended that the disclosure and examples above be considered as exemplary only, with a true scope and spirit of disclosed embodiments being indicated by the following claims.