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: SYSTEM FOR OPEN DOOR OPERATION OF MOTOR CONTROL CENTRE MODULES USING A CAM LEVER

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

The present invention relates generally to a system for control of motor control centre and more particularly to a system for open door operation of motor control centre modules using a cam lever that provide for the operation of the module from isolated to test to service and vice versa through linear motion in one rotation.

BACKGROUND AND THE PRIOR ART

Present invention relates to cam operated mechanism for motor control centre. Motor control centre receives power from power control centre and feed it to a number of load points, majority of them are motors operating on an electrical installations. It is a multi compartment with a common bus system to distribute power. On a common bus system motor control units are mounted individually to feed respective motors. These individual feeders normally called as ‘modules’. Individual feeders are typically constructed as withdrawables, semi-withdrawable, and plug-in and it contains motor controlling, protection and monitoring equipments. When modules are operated, it connects/disconnects the incoming bus to motor through control and protection equipments. Withdrawable module has a special type of mechanism to envisage the operation.

Existing modules has closed door operation as well as open door operation. In closed door operation module positions are achieved when door is closed whereas in open door operation door need be open to achieve these positions. In existing module open door operation can be achieved with rack and screw mechanism. In this mechanism Nut is a stationary part which is part of the tray whereas screw is mounted on module. Total movement of module is depending on no of threads. Handle of mechanism need to be rotated no of times to achieve Isolation to test position and test to service position. This requires rotating more no of turns and more time.

Therefore there is a need to operate the module in only one rotation to avoid the pain of operator. The present mechanism involves the cam shaped lever which has to be rotated with the help of handle through 120º which will move the module in linear direction in one rotation only. The invention is basically a cam operated mechanism for motor control centre modules for open door operation. It is a new mechanism philosophy for the operation of the module from isolated to test to service and vice-a-versa. The module should have linear movement while travelling. This linear movement has to be achieved through a mechanism. The present mechanism involves the cam shaped lever which has to be rotated with the help of handle through 120º which will move the module in linear direction.

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 a system for open door operation of motor control centre modules using a cam lever that provide for the operation of the module from isolated to test to service and vice versa through linear motion in one rotation.

Yet another object of the present invention is to provide for a simple indication mechanism for different positions.

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 a system for open door operation of motor control centre modules using a cam lever that provide for the operation of the module from isolated to test to service and vice versa through linear motion in one rotation.

Other embodiment of the present invention is to provide for a simple indication mechanism for different positions.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig. 1 illustrates the design of dedicated hydraulic circuit diagram.

Fig. 2 illustrates the cam lever.

Fig. 3 illustrates the bush.

Fig. 4 illustrates isolated position of the module.

Fig. 5 illustrates test position of the module.

Fig. 6 illustrates service position of the module.

Fig. 7 illustrates follower pin.

DETAILED 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.

Reference is first invited to Fig 1 where the top view of the module base assembly is shown. It shows mounting arrangement of the cam lever (2). Also the positioning of depth-wise channel (2) and the pivoting point (3) of the cam lever is shown.

Fig. 2 shows the cam lever. The lever fixed to the depth-wise channel with the help of bush (9).

Fig. 3 shows BUSH. Entry chamfer for the follower pin that helps to adjust the cam lever and absorb the tolerance present in the position of follower pin and the pivot of the cam is shown.

Fig. 4 shows isolated position of the module wherein one arrow is visible which points towards I embossed on the front channel of the module. Also, the pin having square profile at point 3 is shown.

Fig. 5 shows test position of the module providing for all the three arrows. In this case, two arrows will point towards the third arrow which will then point towards ‘T’ embossed on the front channel of the module.

Fig. 6 shows service position of the module providing only one arrow visible that will point towards ‘S’ embossed on the front channel of the module.

Fig. 7 shows the follower pin used for the mechanism.

The invented system is thus an a system for open door operation of motor control centre modules using a cam lever that provide for the operation of the module from isolated to test to service and vice versa through linear motion in one rotation.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly in the present invention provides a Cam mechanism for open door operation of motor control centre.
Cam follower method:
It is a mechanism that uses a cam and a follower to create a specific motion. The cam has had an unusual shape or profile machined onto it. This cam is attached to a shaft which enables it to be turned by applying a turning action to the shaft. As the cam rotates it is the profile or shape of the cam that causes the follower to move in a particular way. The movement of the follower is then transmitted to another mechanism or another part of the mechanism.

The primary object of the present invention is to provide open door operation for motor control centre. To achieve this object, present invention provides cam lever located on the module base assembly and employs the cam follower method to achieve the operation of the module from isolated to service and vice-a-versa.

The operation can be explained as follows:
Module in the switchboards has 3 distinct positions. Service, Test and Isolation, When Power Contacts and Auxiliary contacts both 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.

The mechanism uses cam follower method in which cam lever is mounted on the module base and a follower which is fixed on the tray. When operator operates the module with handle, cam lever has to be rotated in horizontal plane. As the follower is fixed, the cam slot in the lever converts the rotating movement of the cam lever in the linear movement of the cam. As the cam lever is mounted on the module base, it will cause the module to move linearly.
In present scenario, module can have three distinct positions without physically moving it and with door closed condition. So, the mechanism in this case is such that it moves SICs and power contacts without actually moving the module. But when open door operation of the module is intended, the new mechanism has to be developed.

Open door operation signifies the operation of the module mechanism while keeping the door open. The mechanism is based on cam follower concept. Normally, in cam follower concept cam is fixed and follower is the moving component. But, in the new mechanism, modification is done in such a way that the cam lever is travelling with the module while the follower is fixed on the tray. The assembly of the mechanism involves the cam lever pivoted at the bottom side of the module base assembly with the help of one bush. So, the lever rotates as well as travels along with the module. The tray is fixed part of the module on which the follower is located.

The present invention will serve the purpose of moving the MCC module from isolated to test to service position and vice a versa with 120º rotation of the handle. In addition to that, it will provide the indication for three distinct positions without adding any extra component.

Construction:

The main embodiment of this patent consists of cam mechanism which will allow the module to achieve three distinct positions viz. Isolated, Test and Service. Figure 1 shows the top view of the module base assembly in general. Here module refers to individual feeders in motor control centre and it typically consists of control, protection and monitoring equipments for motors. It shows the mounting arrangement of the cam lever indicated by 2 in Figure1. The cam lever is pivoted to the depth wise channel of the module base assembly with the help of one bush below the base assembly. The positioning of the depth wise channel is as indicated by no. 2 and the pivoting point of the cam lever is represented by no. 3 in Figure 1. It is bolted with the depth wise channel with the help of one bush. Bush is as shown in figure 3.

Figure 2 shows the cam lever. The lever is fixed to the depth wise channel with the help of bush. Bush is provided at point ‘9’ shown in figure 2. Bush is as shown in figure 3. 1 shows the entry chamfer for the follower pin. It will help to adjust the cam lever and absorb the tolerance present in the position of follower pin and the pivot of the cam. When the module is inserted in, the pin will enter through entry chamfer and the movement of the module will stop when the position ‘2’ of the cam is reached. Position ‘2’ is nothing but the isolated position of the module. Now for the further movement of the module, the cam lever has to be rotated in clockwise direction through 60º. During this rotation, the cam will follow the path ‘3’ shown in figure 2. When the cam reaches to position ‘4’ the module reaches to ‘test’ position. Because of the rotation of the lever in clockwise direction, the module will move in linear direction inside the panel. The shape of the cam at point 4 ensures that once the cam lever reaches position 4, the further movement of the module is possible only if the lever is rotated. The module cannot be simply pushed in unless and until the cam lever is rotated. For the further movement of the module, the cam lever has to be rotated through 60º in clockwise direction. After the rotation of the lever, the cam will reach to position 6 as shown in figure 2. Correspondingly, the module will move linearly inside the panel. This is the ‘service’ position of the module. While moving the module in opposite direction, the lever has to be rotated in anticlockwise direction. The outer profile of the cam lever is as shown by curve ‘7’ in Figure 2. This profile prevents the insertion of the module inside the panel if accidentally the cam lever is left in any position other than isolated position. This profile will ensure that in any case the SIC and power contacts will not get engaged if the module is inserted while the handle is in any position other than ‘isolated’.

For the operation of the mechanism, the handle has to be inserted in the cam lever. For the insertion of the handle, entry chamfer is provided at ‘11’. The handle can be inserted till it reaches point ‘10’ as shown in figure 2.

There is one hole provided on the cam lever for spring pin. The position of the spring pin is such that it will not allow the anticlockwise rotation of the cam lever beyond isolated position. It will also ensure that the lever cannot be rotated in clockwise direction after service condition. The height of the spring pin is such that the pin will hit the depth wise channel if the lever is rotated beyond the specified positions. As it can be seen in Figure 2, three arrows are provided on the cam lever for position indication. The position indication can be explained in following manner.

When the module is in isolated position, only one arrow is visible which will point towards the ‘I’ embossed on the front channel of the module as this can be seen in figure 4. This will indicate isolated position. Figure 5 demonstrates that when the module is in Test position, all the three arrows are visible. In this case, 2 arrows will point towards the third arrow which will then point towards ‘T’ embossed on the front channel of the module. When the module is in service position, only one arrow is visible which will point towards ‘S’ embossed on the front channel of the module as shown in Figure 6.

Figure 7 shows the follower pin used for the mechanism. The pin has diameter of 6mm which is able to withstand the forces of power contact engagement during the module operation. The pin has square profile at point 3 as shown in Figure 4. So, the pin has to be placed in the square slot provided on the tray which will ensure the anti-rotation of the pin. Tapping is provided on the pin represented by no. 4 to fix the pin with the tray with the help of the M6 nut. The resting surface of the pin on the tray is made strong and has diameter of 10mm. Chamfer is provided on the pin at ‘2’ to ensure that even if the cam lever is tilted in the downward direction, the lever will ride above the chamfer.
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. A system for open door operation of motor control centre modules having a cam lever providing for operation of the module from isolated to test to service and vice versa through linear motion in one rotation, said system comprising:
a plurality of slots provided in said cam lever for converting the rotating movement of the cam lever in the linear movement of the cam;
said cam lever pivoted at the bottom side of the module base assembly with the help of bush;
a shaft connected to said cam lever providing for turning action;
a tray which is a fixed part of said module providing square slot;
a follower pin having square profile and chamfer fixed on the tray in the said square slot;
said follower pin providing for tapping to fix the pin with the tray;
a spring pin inserted in the hole provided on the said cam lever preventing anti-clockwise rotation;
a handle to provide for movement of the module in linear direction.
2. System as claimed in claim 1 wherein said cam lever further comprising an entry chamfer for inserting the handle.
3. System as claimed in claims 1 and 2 wherein said cam lever being adapted to be rotated leading to movements of the said follower pins.
4. System as claimed in claims 1 to 3 wherein said cam lever rotation through 120° produces complete racking in of the module from isolated to service position.
5. System as claimed in claim 1 providing indication for three distinct positions namely, isolated, test and service.
6. A system for open door operation of motor control centre modules using a cam lever that provide for the operation of the module from isolated to test to service and vice versa through linear motion in one rotation as herein substantially described and illustrated with reference to the accompanying drawings.