FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
Door Interlock Assembly of Motor Control Centre Module
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. 0. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Door Interlock Assembly of Motor Control Centre Module
Field of the invention
The present invention relates to a low voltage switchboard and more particularly, to a door interlock assembly of a motor control centre module operable in closed door
condition.
Background of the invention
Door interlock is basically a lock used to prevent opening of the door when the motor control centre (MCC) module is either in test or connected position. To open the door in connected position of the MCC module, the interlock has to be defeated using a tool for example a screw driver. Existing door interlock does not have self-locking feature and also assembly is not fool-proof.
Accordingly, there is a need to provide a door interlock for a motor control centre motor control centre module that overcomes the problems in the prior art.
Objects of the present invention
An object of the present invention is to achieve operator independence during closing of a door of a motor control centre (MCC) module by providing a self-locking feature.
Another object of the present invention is to provide a simplified and fool-proof
door interlock.

Yet another object of the present invention is to provide a door interlock that does not require a tool to be used to close the door when the MCC module is in test or connected position.
Summary of the invention
Accordingly, the present invention provides a door interlock assembly of a motor control centre (MCC) module. The door interlock assembly comprises a base member, a first lever, a spring, a bracket and a connecting means. The base member includes a side plate and a bottom plate. The side plate is secured to a door of the MCC module. The side plate includes a first slot. The first lever rests onto the bottom plate through a first side thereof. The first lever includes a second slot on the first side thereof.
The first lever is capable of deflecting for removably engaging with a module lever of the MCC module. The spring provides torque control and deflection force to the first lever. The spring rests between the first lever and the side plate. The bracket is fitted to the first lever on the bottom plate. The bracket includes a third slot. The bracket is adapted to guide the first lever to deflect in one direction. The connecting means extends from the first slot into the third slot by passing through the second slot thereby connecting the side plate, the first lever and the bracket. The connecting means for example a screw is tightened using a nut.
The first lever includes a sliding bend on a second side thereof. The first lever is capable of deflecting through the sliding bend to snap fit/lock onto the second lever while closing the door in a connected position of the MCC module. The first lever disengages from the second lever for opening the door in the connected position of

the MCC module by turning/rotating the connecting means in an anti-clockwise direction using a tool for example a screw driver.
Brief description of the invention
The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,
Figure 1 shows a door interlock assembly of a motor control centre (MCC) module, in accordance with the present invention;
Figure 2 shows the door interlock assembly of figure 1 assembled on a door of the MCC module;
Figure 3 shows the MCC module in an isolated position having a second lever in an unlocked position and the door in a partially open condition, in accordance with the present invention;
Figure 4 shows the MCC module in the isolated position having the second lever in the unlocked position and the door in a closed condition with the door interlock assembly of figure 1;
Figures 5-6 show the MCC module in a connected position with the second lever in a locked position and the door in the partially open condition;
Figures 7-8 show close-up view of how the first lever deflects and locks on to second lever when the door is closed in the connected position;

Figure 9 is a sectional view of the MCC module showing the second lever in the '
locked position with the first lever after closure of the door in the connected position; and
Figures 10-11 illustrate defeating of the door interlock assembly for opening the door in the connected position of the MCC module.
Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems
and shortcomings associated with the prior art, techniques and approaches are
overcome by the present invention as described below in the preferred embodiment.
The present invention provides a door interlock assembly of a motor control centre (MCC) module. The assembly of the present invention is a simplified and foolproof door interlock that incorporates a self-locking feature to achieve operator independence and tool free closing of a door of the MCC module. The assembly of the present invention ensures that the door gets locked when the MCC module is put to test or connected position. This prevents the operator from opening the door when the MCC module is live. However, the interlock is defeatable with a tool that is used under live condition consciously when the door needs to be opened.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various
figures.
Referring now to figures 1-11, there is shown a door interlock assembly (herein after 'the assembly (100)') of a motor control centre module (150) (herein after 'the

MCC module (150)'). in accordance with the present invention. The MCC module (150) is capable of moving to and fro an isolated position and a connected/ test/ live position. Specifically, the assembly (100) is mounted on a door (110) of the MCC module (150). The door (110) is closed with the assembly (100) when the MCC module (150) is in the comiected position.
The assembly (100) comprises a base member (10), a first lever (20), a spring (30), a bracket (40) and a connecting means (50). The base member (10) is secured on to the door (110). In an embodiment, the base member (10) is an L-shaped member that is welded to an inner side (not numbered) of the door (110). The base member (10) includes a side plate (not numbered) and a bottom plate (not numbered). Specifically, the side plate is secured to the door (110). The side plate includes a first slot (not shown).
The first lever (20), alternatively an interlock lever rests on the bottom plate through a first side (not numbered) thereof. The first lever (20) includes a second slot (not numbered) on the first side thereof. The improvement comprising that the first lever (20) includes a sliding bend (not numbered) on a second side (not numbered) thereof. The first lever (10) is designed with the sliding bend to provide a self-locking feature to the assembly (100). The first lever (20) is capable of deflecting automatically through a curvature of the sliding bend to snap fit/lock onto a second lever (120) of the MCC module (150) when the MCC module (150) is in the connected position and the door (110) is in a partially open (figure 5) or closed condition with the assembly (100) (figure 6).
In the isolated position of the MCC module (150) with the door (110) in the partially open condition (figure 3) or closed condition with the assembly (100)

(figure 4), the second lever (120) moves away to an unlocked position so that the first lever (20) does not lock to the second lever (120).
The spring (30) rests between the first lever (20) and the side plate for providing torque control and deflection force to the first lever (20) during closing of the door (110). The bracket (40) is fitted to the first lever (20) on the bottom plate. The bracket (40) includes a third slot (not shown). The bracket (40) guides the first lever (20) to deflect in one direction up to a certain angle.
The connecting means (50) extends from the first slot into the third slot by passing through the second slot thereby connecting together the side plate, the first lever (20) and the bracket (40). Specifically, the connecting means (50) is a screw being tightened using a nut (60). It is evident to those skilled in the art that any suitable means can be used for connecting the side plate, the first lever (20) and the bracket (40).
In an operation for closing the door (110) in the connected position of the MCC module, the first lever (10) automatically deflects by sliding along the curvature of the sliding bend and snaps/locks on to the second lever (120) as shown in figures 7-8. The assembly (100) in the locked position with the second lever (120) after closure of the door (110) in the connected position of the MCC module (150) is shown in figure 9. This will ensure that the assembly (100) is operator independent during closure and damage due to negligence is avoided.
In another operation to open the door (110) in the connected position of the MCC module (150), the assembly (100) is defeated by using a tool (not shown). The tool turns or rotates the connecting means (50) in an anti-clockwise direction as shown in figures 10 and 11. In an embodiment, the tool is a screw driver. The anti-

clockwise rotation of the connecting means (50) causes the first lever (20) to disengage from the second lever (120) thereby resulting in opening of the door (110) in the connected position of the MCC module (150).
Advantages of the present invention:
1. The assembly (100) is a simple door interlock having a self-locking feature to enable door (110) closing in the connected position of the MCC module (150).
2. The assembly (100) is made fool proof by providing key profile in the connecting means (50) and a corresponding slot (the second slot) in the first lever (20).
3. The assembly (100) does not require tool to close the door (110) when the MCC module (120) is in the connected position.
4. The assembly (100) is operator independent during closure and hence damage of the assembly (100) due to negligence is avoided.
5. The assembly (100) uses a single spring (30) that acts as torsion spring as well as compression spring.
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed

herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.

We Claim:
1. A door interlock assembly (100) of a motor control centre (MCC) module (150). the door interlock assembly (100) comprising:
a base member (10) having a side plate and a bottom plate, the side plate being secured to a door (110) of the MCC module (150), the side plate having a first slot;
a first lever (20) resting onto the bottom plate through a first side thereof, the first lever (20) having second slot on the first side thereof, the first lever (20) being capable of deflecting for removably engaging with a second lever (120) of the MCC module (150);
a spring (30) resting between the first lever (20) and the side plate for providing torque control and deflection force to the first lever (20);
a bracket (40) fitted to the first lever (20) on the bottom plate, the bracket (40) having a third slot, the bracket (40) being adapted to guide the first lever (20) to deflect in one direction; and
a connecting means (50) extending from the first slot into the third slot by passing through the second slot thereby connecting the side plate, the first lever (20) and the bracket (40),
characterized in that, the first lever (20) having a sliding bend on a second side thereof, the first lever (20) being capable of deflecting through the sliding bend to snap fit/lock onto the second lever (120) while closing the door (110) in a connected position of the MCC module (150), and the first lever (20) disengages from the second lever (120) for opening the door (110) in the connected position of the MCC module (150) by turning/rotating the connecting means (50) in an anti-clockwise direction using a tool.
2. The door interlock assembly (100) as claimed in claim 1, wherein the

connecting means (50) is a screw being tightened using a nut (60).
3. The door interlock assembly (100) as claimed in claim 1, wherein the tool is a screw driver.