FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
PROVISIONAL SPECIFICATION
(See Section 10 and rule 13) TITLE OF THE INVENTION:
A MECHANISM FOR DIFFERENTIAL CONTACT MOVEMENT IN FULL WIDTH FEEDER OF MOTOR CONTROL CENTER (MCC) SWITCHBOARDS
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra . INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The embodiments herein generally relate to the switching devices and more particularly it relates to contact movement in Motor Control Center (MCC) Switchboard.
B) BACKGROUND OF THE INVENTION
[0002] Switching devices such as miniature circuit breakers, residual circuit breakers and isolators etc are used in domestic and industrial applications for protection against over currents. It is generally required to control electrical power networks by switching circuit "ON", by carrying load and by switching circuit "OFF" under manual or automatic suspension. When there is an over current resulting in an electrical circuits, the contacts in the switching devices open or trips to block the current which is greater then the rating of the current device.
[0003] In some cases where circuit breakers used are relatively smaller in size and light in weight, the circuit breakers are provided with plug-in type primary disconnect contacts that do not require direct contact to effect their connection and disconnection with mating disconnect contacts of the switchboard. In these cases circuit breaker can be plugged in and unplugged from a live switchboard easily and safely.
[0004] For higher current applications, the circuit breakers used are large and quite heavy and so the movement of the circuit breaker to electrically connect and disconnect it from the switchboard is quite difficult. Due to increase of the current ratings, the contact pressures of the primary disconnect contacts becomes extremely difficult to handle. Drawout apparatus are used to support such electrical device for racking movement


between an extended position well out of an enclosure compartment and an engaged position within the compartment where the load current carrying primary disconnect contacts of the device and enclosure are fully engaged. A test position is provided for the device between its engaged and extended positions where the primary contacts are separated but the secondary contacts are still engaged. In this test position, the accessorial functions can be thoroughly tested in safety while the device is "dead".
[0005] It is a general object of the present invention to provide a mechanism for differential contact movement in full width feeder modules of Motor Control Center (MCC) Switchboards.
[0006] An additional object of the present invention is to provide a mechanism and assembly for the movement of electrical contacts where separate movement of main and auxiliary contacts are required i.e. when only one set of the contacts has to operate.
[0007] Other objects of the invention will in part be obvious and in part appear hereinafter.
C) BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:


[0009] FIG. I illustrates the front view of the assembly according to one embodiment of the present invention.
[0010] FIG. 2 illustrates the back view of the assembly according to one embodiment of the present invention.
[0011] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
D) DETAILED DESCRIPTION OF INVENTION
[0012] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0013] The various embodiments of the present invention provide a mechanism for differential contact movement in full width feeder modules of Motor Control Center (MCC) Switchboards.
[0014] As shown in FIG. 2, cylindrical piston (I) and cam (2) system operate for moving the contacts of feeder modules to vertical bus system (for engaging main contacts) and
- 1 APR 2009

rack -n- pinion (racks 3, 4 & pinion 6) system operate for moving the SICs (for engaging auxiliary contacts) separately, in case of Motor Control Center switchboards. For contact engagement, the mechanism is actuated by rotating the shaft (5) clockwise, which is positively coupled with the cylindrical follower. During the initial quarter turn of the cylinder (i.e. 0°-90°), the rack-n-pinion combination gets activated and the auxiliary contacts are engaged in the lateral direction. During the next quarter turn of cylinder (i.e. 90° - 180°), the cylinder-cam combination gets activated and the main contacts are engaged in longitudinal direction. The mechanism enables the power and auxiliary contacts to move independently. Hence, it helps to achieve distinct positions of service and isolation conditions.
[0015] Hence the invention provides a mechanism and assembly for the movement of electrical contacts where separate movement of main and auxiliary contacts are required i.e. when only one set of the contacts has to operate.
The detailed description of the invention with different embodiments shall be provided in the Complete Specification.
Dated this the 30th day of March 2009
RAKESH PRABHU
Patent Agent,
ALMT Legal,
#2, Lavelle Road, Bangalore-560 001
To,
The Controller of Patents, The Patent office, Mumbai