F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. Title of the invention:
IMPROVED RACKING MECHANISM TO RACK IN AND RACK OUT MOTOR CONTROL CENTRE MODULES

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:

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to a racking mechanism for Motor control centre (MCC) modules. More particularly the present invention relates to an improved mechanism to rack in and rack out Motor control centre modules inside panel of a switchboard.

BACKGROUND AND THE PRIOR ART

Switchboards are structures which houses equipments and used to regulate, monitor current flow and to protect the load in abnormal condition. Switchboards are generally classified into two parts MCC and PCC. Motor control centre (MCC) generally will have draw-out modules. These draw-out modules will have components as explained above. Draw-out modules will have rack-in rack-out mechanism.

The existing technology makes use of a rack & pinion mechanism to accomplish the racking in-out process using an external handle. The handle is inserted into the racking slot provided in the module fascia and turned clockwise, which thereby guides the module through three positions viz. Isolated, Test and Service. This setup is essentially a closed door operation.

Conventional mechanism has the following disadvantages:

1. Complex processes are involved in fabrication of components.

2. A complex assemblage to achieve the racking in-out process which consequently demands more time to construct the assembly.

3. The problem of mechanism backlash exists due to impact of the braid.

Therefore there is a need to overcome the disadvantages of the conventional mechanism. The present invention therefore provides a link-based mechanism to rack in and rack out MCC modules inside the panel of a switchboard. Present invention provides a simple mechanism links which are easier to manufacture and assemble. This mechanism has a guidance system for the three states S-T-I. The arrangement also prevents mechanism backlash coming from braids. This assembly also ensures the force applied by the operator is much less than the force required for contact engagement (nearly 2/3rd).

OBJECTS OF THE INVENTION

A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.

Another object of the present invention is to provide an improved mechanism to rack in and rack out Motor control centre (MCC) modules

Another object of the present invention is to prevent mechanism backlash coming from braids.
Yet other object of the present invention is to reduce assembly time and skill level of worker required to assemble the mechanism.

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

There is provided an improved mechanism to rack in and rack out Motor control centre (MCC) modules.

According to one embodiment of the present invention, there is provided an improved mechanism to rack in and rack out Motor control centre (MCC) modules inside panel of a switchboard, said mechanism comprising a pair of link means whereby a first link means (2) connected to a secondary isolating contact and a second link means (3) connected to a power contact arm (5); a handle means (1) inserted in said first link, said handle rotated to achieve different positions of said module; a guide means (6) to restrict the motion of said handle means; wherein said first link adapted to transfer said module from isolated to test position on rotation of said handle thereby resulting in alignment of said first link to said second link and on further rotation of said handle resulting in complete engagement of said power contacts and said secondary isolating contacts.

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.

Fig 1 illustrates the different elements of the present invention. It shows handle means (1), first link means (2), second link means (3), power contact arm (5), guide means (6), handle means comprising a profile (7), means (8) fixed on said link adapted to ensure position of said link on removal of said handle.

Fig 2 illustrates the guide means (6).

Fig 3 illustrates the handle means comprising a profile (7).

Fig 4 illustrates the means (8) fixed on said link adapted to ensure position of said link on removal of said handle.

Fig 5 illustrates other view the means (8) fixed on said link adapted to ensure position of said link on removal of said handle.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly in the present invention an improved mechanism to rack in and rack out Motor control centre modules inside panel of a switchboard is provided.

The module has a guide pattern on which the links move. The traverse from Isolated to service position is achieved through a two-step process. A customized handle is used to turn the first link by an angle of 20° clockwise which moves the SIC from Isolated to test position. At the end of this first step, the first and second links are aligned with each other. Now, upon turning the link by another 20°clockwise, the second link that is in contact with the power contact arm, engages the power contact and SIC as well completely. Thus, the traverse from test to service is achieved here.

The purpose of this new mechanism is to reduce assembly time and skill level of worker required to assemble the mechanism. It will help in reducing lead time for production and user dependency while assembling. The mechanism also ensures the force applied by the operator is much lesser than the force required engaging the contacts. As the guidance takes place along the groove, the problem of backlash is eliminated in this arrangement. The simplicity of this link-based guiding mechanism provides a direct indication of the state of the module without any additional components.

ADVANTAGES:

1. Simpler assembly
2. Simpler links
3. Reduced operating force
4. Provides a direct indication for the three states in MCC modules

The Service-Test- Isolation positions in an MCC module are achieved by simple link-based mechanism.

This is a simple mechanism based on two links. It is a two-stage mechanism that carries the module through all three states(S-T-I) successively during racking in and out. The first link (2) is connected to the SIC arm and makes the control contact i.e. takes the module from Isolated to Test position. The second link (3) is connected to the power contact arm (5).

Handle (1) is inserted into the 1st link (2) and rotated clockwise to get test position, as it sets only SICs into motion. SICs travel to the right. The guide (6) restricts the rotation to 20°. The end of the first step results in the alignment of first link (2) with second link (3). Now, the handle accommodates both the links to be turned around. The next 20°rotation will allow both power contacts as well as SIC to move and engage fully. The profile (7) in the handle which engages with the guide (6) ensures proper contact. The arrangement (8) fixed on the link ensures that the links maintain their position once the handle is removed. This also helps in preventing mechanism backlash. A direct indication without any additional component makes the overall mechanism simpler and hassle free.

Present Invention comprise a means (8) fixed on link to ensure position of link is maintained on removal of handle. It also prevents mechanism backlash coming from braids.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:

1. An improved mechanism to rack in and rack out Motor control centre (MCC) modules inside panel of a switchboard, said mechanism comprising:
a pair of link means whereby a first link means (2) connected to a secondary isolating contact and a second link means (3) connected to a power contact arm (5);
a handle means (1) inserted in said first link, said handle rotated to achieve different positions of said module;
a guide means (6) to restrict the motion of said handle means;
wherein said first link adapted to transfer said module from isolated to test position on rotation of said handle thereby resulting in alignment of said first link to said second link and on further rotation of said handle resulting in complete engagement of said power contacts and said secondary isolating contacts.

2. Mechanism as claimed in claim 1 for carrying said module through three states namely service, test and isolation during said rack in and rack out operation.

3. Mechanism as claimed in claim 1 wherein said handle means comprising a profile (7) adapted to engage with said guide means (6) ensuring proper contacts.

4. Mechanism as claimed in claim 1 further comprising a means (8) fixed on said link adapted to ensure position of said link on removal of said handle.

5. Mechanism as claimed in claim 1 and 8 wherein said means (8) adapted to prevent mechanism backlash coming from braids.

6. An improved mechanism to rack in and rack out Motor control centre (MCC) modules inside panel of a switchboard as herein described and illustrated with reference to accompanying drawings.