FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. A MECHANISM HANDLE INTERLOCK WITH SHORT CIRCUIT PROTECTION DEVICE FOR WITHDRAWABLE MODULES
15

2. Applicant(s)
(a) NAME :
(b) NATIONALITY
(c) ADDRESS :

LARSEN & TOUBRO LIMITED
An Indian Company.
L & T House, Ballard Estate, P.O. .Box: 278 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:

TECHNICAL FIELD
[001] The present subject matter described herein, in general, relates to an
electrical switches and/or switchboards and more particularly to a locking device for an electrical switch and/or modules on switchboards or a withdrawable rack with such locking device.
BACKGROUND
[002] There are two types of switchboards that are used to distribute the power;
Power Control Centre (PCC) and Motor Control Centre (MCC). Power Control Centre distributes the power to different Motor Control Centre (MCC) and Motor Control Centre (MCC) distributes that power intelligently to different motor loads, lamp loads using feeders/modules. Modules are nothing but a semi enclosed housing consisting of various electrical and mechanical equipments. Modules can be withdrawable or fixed.
[003] Withdrawable module in the switchboards has three distinct positions:
service, test and isolation, when both power contacts and auxiliary contacts are engaged, it is called as service position. When power contacts are engaged and auxiliary contacts are disengaged, it called as test condition. When both contacts are disengaged, it is called as isolation condition.
[004] These three positions are achieved using interlock mechanism which is
operated using a mechanism handle. The purpose of the interlock is to prevent the operation of a short circuit protection device (SCPD) when the mechanism handle is inserted in the module. Only when the mechanism handle is taken out of the module, the SCPD be operated. It should not be possible to insert the mechanism handle in the module, when SCPD is ON. An innovative arrangement of lever assembly prevents the

insertion of mechanism handle when SCPD is in ON condition. This lever assembly also plays the role of preventing SCPD operation when mechanism handle is inserted.
[005] In the existing interlock, when the SCPD is in ON condition, insertion of
mechanism handle is prevented thus blocking the operation of module when SCPD is ON. But after inserting the mechanism handle, SCPD operation is possible. This leads to loss in functionality of the mechanism.
[006] The different positions service, test and isolation in a withdrawable
module are achieved by operating a mechanism handle by inserting it in the module. In the existing interlock, operation of the SCPD is still possible when the mechanism handle is in the module. The purpose of interlock is to prevent the engagement of the power contacts with the busbar when the SCPD is ON. Because the power contacts are designed only for carrying current and not designed to be used for making or breaking current. In absence of this interlock, power contact can be engaged or disengaged by operating the mechanism handle when SCPD is in ON position, this may lead to fatal accident to operating personnel.
SUMMARY OF THE INVENTION
[007] 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/critical 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.
[008] An object of the present invention is to provide a mechanism handle
interlock with short circuit protection device for withdrawable modules in switchboards.

[009] Another object of the present invention is to provide an improved
interlock mechanism that eliminates the above mentioned problems by preventing the operation of the SCPD when the mechanism handle is inserted.
[0010] Yet another object of the present invention to provide a new interlock
mechanism, wherein flap cover opening is prevented when SCPD is in ON condition.
[0011] Yet another object of the present invention is to a new interlock
mechanism, which prevents insertion of mechanism handle when SCPD is in ON condition.
[0012] Yet another object of the present invention is to prevent flap opening for
mechanism insertion, leading to prevention of change in module state.
[0013] Yet another object of the present invention to provide positive locking of
SCPD operation when mechanism handle is inserted.
[0014] Accordingly, in one implementation, a locking device, displaceable
guidable by at least one flap cover of at least one withdrawable module/rack on switchboards, for interlocking an operation of short circuit protection device (SCPD) to insert a handle in said withdrawable module/rack is disclosed. The locking device comprises at least one stopping means operatively coupled with at least one shaft means; and at least one cable operatively coupled with said shaft means at one end and to said flap cover at other end. When said flap cover is displaced and/or opened, converts a movement, exerted by way of said cable into a rotation of said shaft means, wherein said shaft means and said stopping means are at right angles with respect to one another and movable, with said withdrawable module/rack, from a release position, in which said withdrawable module/rack is displaceable in said switchboard, into a locking position. The said locking device in said locking position enables a displacement of said withdrawable module/rack so as to insert.said handle thereby prohibiting said operation of short circuit protection device (SCPD).

[0015] In one implementation, a locking device for interlocking an operation of
short circuit protection device (SCPD) to insert a handle in at least one withdrawable module/rack of switchboards is disclosed. The locking device comprises at least one stopping means operatively coupled with at least one shaft means having at least one groove, and at least one cable operatively coupled with said shaft means at one end and to at least one flap cover of said withdrawable module/rack at other end. When said flap cover is displaced and/or opened, said cable experiences a movement causing an activation of said stopping means so as to get engaged with said groove of said shaft and enable insertion of said handle, thereby prohibiting said operation of short circuit protection device (SCPD).
[0016] Other aspects, advantages, and salient features of the invention will
become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:
[0017] Figure 1 illustrates various components, in accordance with an
embodiment of the present subject matter.
[0018] Figure 2 illustrates a stopping mechanism, in accordance with an
embodiment of the present subject matter.
[0019] Persons skilled in the art will appreciate that elements in the figures are
illustrated for simplicity and clarity and may have not been drawn to scale. For example,

the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0020] The following description with reference to the accompanying drawings
is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.
[0021] 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 of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
[0022] The terms and words used in the following description and claims are net
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.
[0023] It is to be understood that the singular forms "a," "an," and "the" include
plural referents unless the context clearly dictates otherwise.
[0024] 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.
[0025] Features that are described and/or illustrated with respect to one
embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
[0026] It should be emphasized that the term "comprises/comprising" when
used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.
[0027] The various components present invention which will be used through
the specification are as given below:
1. Stopping Pin/ Lever
2. Shaft CAM / camshaft
3. Nylon cable assembly
4. Flap cover
[0028] In one implementation, the operation of SCPD is prevented using a
stopping lever The stopping lever gets engaged with the CAM in the groove provided. Once stopping pin gets engaged, operation of SCPD in clockwise direction is not possible. This will directly lead to prevention in operation of SCPD.
[0029] In one implementation, the actuation of stopping pin is achieved through
nylon cable assembly which in turn gets movement from flap cover.
[0030] In one implementation, an insertion of mechanism handle is possible
only when flap cover is opened. The person operating the module has to open the flap cover in order to insert the mechanism handle. Mechanism handle is used to bring the

module in different states. As soon as flap cover is opened, mechanism gets actuated locking the CAM shaft. Once CAM shaft movement is locked, operation of SCPD is not possible. Once the flap is closed, operation of SCPD is possible.
[0031] In one implementation, the present invention provides a push pull
mechanism (PPM). When SCPD is in ON condition, CAM will turn by 90 degrees in clockwise direction. According to mechanism requirement insertion of mechanism handle should not be possible. In this state if the operator tries to open the flap cover to insert mechanism handle, movement of nylon cable is restricted by CAM. This prevents opening of flap cover and eventually insertion of mechanism handle. The CAM profile is designed in such a way that it allows movement of stopping pin only when SCPD is in OFF condition.
[0032] In one implementation, the limitation in previous existing mechanism is
solved using a push pull mechanism (PPM). The PPM increases the reliability of the mechanism as movement transfer through nylon is much more effective if it is being pulled rather than pushed. Various iterations were carried out to prove the above mentioned hypothesis.
[0033] Accordingly, in one implementation, a locking device, displaceable
guidable by at least one flap cover of at least one withdrawable module/rack on switchboards, for interlocking an operation of short circuit protection device (SCPD) to insert a handle in said withdrawable module/rack is disclosed. The locking device comprises at least one stopping means operatively coupled with at least one shaft means; and at least one cable operatively coupled with said shaft means at one end and to said flap cover at other end. When said flap cover is displaced and/or opened, converts a movement, exerted by way of said cable into a rotation of said shaft means, wherein said shaft means and said stopping means are at right angles with respect to one another and movable, with said withdrawable module/rack, from a release position, in which said withdrawable module/rack is displaceable in said switchboard, into a locking position. The said locking device in said locking position enables a displacement of said

withdrawable module/rack so as to insert said handle thereby prohibiting said operation of short circuit protection device (SCPD).
[0034] In one implementation, a locking device for interlocking an operation of
short circuit protection device (SCPD) to insert a handle in at least one withdrawable module/rack of switchboards is disclosed. The locking device comprises at least one stopping means operatively coupled with at least one shaft means having at least one groove, and at least one cable operatively coupled with said shaft means at one end and to at least one flap cover of said withdrawable module/rack at other end. When said flap cover is displaced and/or opened, said cable experiences a movement causing an activation of said stopping means so as to get engaged with said groove of said shaft and enable insertion of said handle, thereby prohibiting said operation of short circuit protection device (SCPD).
[0035] In one implementation, said shaft means comprises at least one groove
configured to receive said stopping means and get engaged to prohibit movement of said shaft means.
[0036] In one implementation, said stopping means is configured to get engaged
with said shaft means in said groove thereby prohibiting an operation of short circuit protection device (SCPD).
[0037] In one implementation, said stopping means is at least one pin or at least
one lever.
[0038] In one implementation, said shaft means is a camshaft.
[0039] In one implementation,said cable is a nylon cable
[0040] In one implementation,when stopping means is engaged, said operation
of said SCPD is restricted in clockwise direction.

[0041] In one implementation,when said flap cover is closed, said SCPD is in
ON condition, and said shaft means will turn by right angle in clockwise direction.
[0042] In one implementation, if a user tries to open said flap cover to insert
mechanism handle, the movement of said cable means is restricted by said shaft means, so as to prevent opening of said flap cover and eventually insertion of said handle.
[0043] It may be understood by the person skilled in that art that, the coupling,
joining, fitting of the two components mentioned the present invention may be achieved by any of the existing coupling techniques that may include but not limited to nut and bolt arrangement, gluing, pasting, welding, and the like.
[0044] Although a mechanism handle interlock with short circuit protection
device for withdrawable modules have been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples cf implementations of the mechanism handle interlock with short circuit protection device for withdrawable modules.

WE CLAIM:
1. A locking device, displaceably guidable by at least one flap cover of at least one
withdrawable module/rack on switchboards, for interlocking an operation of
short circuit protection device (SCPD) to insert a handle in said withdrawable
module/rack, said locking device CHARACTERIZED IN THAT comprising:
at least one stopping means operatively coupled with at least one shaft means;
at least one cable operatively coupled with said shaft means at one end and to said flap cover at other end; and
when said flap cover is displaced and/or opened, converts a movement, exerted by way of said cable into a rotation of said shaft means, wherein said shaft means and said stopping means are at right angles with respect to one another and movable, with said withdrawable module/rack, from a release position, in which said withdrawable module/rack is displaceable in said switchboard, into a locking position; and
said locking device in said locking position enables a displacement of said withdrawable module/rack so as to insert said handle thereby prohibiting said operation of short circuit protection device (SCPD).
2. The locking device as claimed in claim 1, wherein said shaft means comprises at least one groove configured to receive said stopping means and get engaged to prohibit movement of said shaft means.
3. A locking device for interlocking an operation of short circuit protection device (SCPD) to insert a handle in at least one withdrawable module/rack of switchboards, said locking device CHARACTERIZED IN THAT comprising:
at least one stopping means operatively coupled with at least one shaft means having at least one groove;

at least one cable operatively coupled with said shaft means at one end and to at least one flap cover of said withdrawable module/rack at other end;
wherein, when said flap cover is displaced and/or opened, said cable experiences a movement causing an activation of said stopping means so as to get engaged with said groove of said shaft and enable insertion of said handle, thereby prohibiting said operation of short circuit protection device (SCPD).
4. The locking device as claimed in claims 2 and 3, wherein said stopping means is configured to get engaged with said shaft means in said groove thereby prohibiting an operation of short circuit protection device (SCPD).
5. The locking device as claimed in claims 1 and 3, wherein said stopping means is at least one pin or at least one lever.
6. The locking device as claimed in claims 1 and 3, wherein said shaft means is a camshaft.
7. The locking device as claimed in claims 1 and 3, wherein said cable is a nylon cable.
8. The locking device as claimed in claims 1 and 3, wherein when stopping means is engaged, said operation of said SCPD is restricted in clockwise direction.
9. The locking device as claimed in claims 1 and 3, wherein, when said flap cover is closed, said SCPD is in ON condition, and said shaft means will turn by right angle in clockwise direction.
10. The locking device as claimed in claim 9, wherein, if a user tries to. open said flap cover to insert mechanism handle, the movement of said cable means is

restricted by said shaft means, so as to prevent opening of said flap cover and eventually insertion of said handle.