FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
Sliding system of contacts for MCC full width modules
2. APPLICANT(S)
(a) NAME : Larsen and Toubro Ltd.
(b) NATIONALITY: Indian
(c)ADDRESS : L&T House, Ballard Estate, Mumbai-400 001, India.
3. PREAMBLE TO THE DESCRITION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed
4. DESCRIPTION (Description shall start from next page)
5. CLAIMS (not applicable for provisional specification. Claims should start with the preamble -"I/We claim" on separate page)
6. DATE AND SIGNATURE (to be given on the last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on the separate page)
Note:
*Repeat boxes in case of more than one entry
*To be signed by the applicant(s)or the authorized registered patent agent
*Name of the applicant should be given in full, family name in the beginning
*Complete address of the applicant should be given stating with postal index no. / code, state and
country
*Strike out the column which is/are not applicable

Sliding system of contacts for MCC full width modules
Field of the invention:
The present invention relates to a set of sliding contacts used in Motor Control Centre modules and switchboards which consist of a fixed contact and a moving contact capable of operating in three states viz. isolation, test and service. The fixed and the moving contacts are connected to each other during all the three states of operation.
Background of the invention:
The existing system of contacts has a fixed contact and a moving contact connected by strands of braids. The fixed contact is mounted on a fixed housing. The moving contact is placed on a housing which is mounted on an arm which moves when the mechanism is operated. The silver plated braids are brazed to the fixed and moving contacts as shown in Fig.l. It has three positions namely isolation, test and service. Fixed and moving contact remains connected in all positions by the group of braids. The number of strands of braids will change accordingly to the different rating of current.
US 4733033, describes a movable contact arm or carrier which electrically connects with the trip unit or load side of the circuit breaker, without the use of flexible electrical conducting braids. The contact carrier is pivotally arranged within a contact carrier support to which the trip unit or load terminal lug is attached. However this design is not being implemented for switchboard contacts or MCCs and the presently discussed invention provides a simpler way of implementing it for switchboards as well.
US 5319166, describes a molded case circuit breaker moveable contact arm is pivotally-arranged between a single support post and the crossbar within the operating mechanism assembly. A pair of braid conductors are attached between

the movable contact arm and the support plate in a U-shaped arrangement to promote flex without fraying. However, this design employs the use of braids to connect the fixed contact with the movable contacts, which entails problems in design complexity, problems in brazing those braids to the contacts, backlash of the moving contacts due to the braids and higher costs due to silver plating of those braids. The present invention dispenses with the use of such braids between the fixed and the moving contacts and thus minimizes the above-mentioned problems.
Object of the invention:
The object of the invention is to provide efficient and effortless connections between a set of fixed and moving contacts used in switchboard assemblies. It focuses on providing a cheap and convenient system of contacts which does not use braids for establishing the connection between the fixed and the moving contacts.
It further aims at providing a mechanism of braid-less sliding contacts which move about between three states of operation viz. isolation, test and service.
Problems solved by the invention:
As the invention employs a sliding mechanism of operation for the contacts, it does away with the use of braids for connecting the moving and the fixed contacts, thus avoids the complex process of brazing those braids with the contacts.
Moreover, by not using braids for connecting the contacts, there is no need of silver plating those braids as in the case of other braided contracts, thus making the process quite cost effective.
Further it also solves the problem of backlash of the moving contacts during the operation when they are connected by braids. By using a sliding system of contacts and by removing braids from the system this problem is also solved.

Summary of the invention:
The braid-less sliding contact assembly consists of a fixed contact having a slot in it and the fixed contact is mounted in housing. A moving contact, connected to the fixed contact by a compression spring and nut arrangement The contact arm is moved by a mechanism thereby moving the housing as well as the moving contact along with it The moving contact, the housing and the whole embodiment can move along the slot on the fixed contact In the service position the moving contact touches the external current carrying links and the connection between the fixed and the moving contacts are also established. The compression spring is used to regulate the contact pressure in the three states of operation viz. isolation, test and service.
Description of the Drawings:
Fig. 1: Front view of the fixed and the moving contact assembly.
Fig. 2: Side view of the embodiments of the fixed contact and the moving contact
Fig. 3: Top view of the fixed and moving contact assembly with the bottom housing.
Fig. 4: Top view of the fixed and moving contact assembly with the top housing:
Fig. 5: The fixed and moving contact assembly in isolation position.
Fig. 6: The fixed and moving contact assembly in service position.
Detailed Description:
The braid-less sliding contact assembly consists of following components.
'U' spring(l], Fixed contact(2), Moving contact(3], Pin(4), Compression spring(5), Nut(6), Bottom Housing(7), Top housing(8), Contact Arm(9), Drivers(l0), Plastic mould(11).

The 'U' spring (1] is assembled on the moving contact (3). Then the fixed contact (2) is assembled with the moving contact (3] via pin (4], compression spring (5) and a nut (6] as shown in Fig 2. It is then kept on the bottom housing (7) and is closed at the top by top housing (8) as shown in Fig 4. It is then assembled on the contact arm (9) with the help of drivers (10).The fixed contact (2) is tightened to a fixed plastic mould (ll)(Ref Fig 5]. The contact arm is moved by a mechanism, there by moving the housing and the moving contact (3). The total displacement of contact arm along with the housing and fixed contact is for a fixed span. As the contact arm (9) moves, for the initial part of the span, the moving contact slides on the fixed contact moving towards the external link. The pin [4], nut (6] and the compression spring [5] also moves along with the moving contact (3} guided by a slot on the fixed contact [2). There is no enough contact pressure between the fixed and moving contacts, since there is negligible force from the compression spring which connects the fixed and moving contacts. Thus the friction between the fixed contact [2] and moving contact [3] is reduced. For the next part of the span of movement, the moving contact (3) makes contact with the external contacts. During the final phase of displacement by the moving contact (3) the embodiment on the fixed contact [2] comes into action thereby deflecting the compression spring (5) which provides enough force for contact pressure. This is the service position (Ref Fig 6]. Thus the fixed and moving contact makes contact while the moving contact makes contact with external links. To take it back to original position the mechanism is operated again. Thus the moving contacts moves and thus the embodiment moves away and the contact pressure reduces. The compression spring (5) which is being used to produce the contact pressure will vary according to the different ratings of current.

We claim,
1. A braid-less sliding contact assembly for electrical devices comprising of;
a fixed contact, the fixed contact having a slot along its length and enclosed in
a side housing;
a moving contact, the moving contact mounted on a bottom housing;
a connecting element for connecting the said fixed contact with the said
moving contact through the said slot; and
external current carrying links connected to the said moving contact in
service position.
2. A braid-less sliding contact assembly of claim 1; wherein in the test position, the moving contact slides along the slot and makes contact with the external links.
3. A braid-less sliding contact assembly of claim 1; wherein, in the service position, the moving contact makes a connection with the external links, and the fixed contact makes a connection with the moving contact.
4. A braid-less sliding contact assembly of claim 1; wherein the electrical devices are switchboards or MCC full width modules.
5. A braid-less sliding contact assembly of claim 1; wherein the connecting element is a spring laden nut.
6. A braid-less sliding contact assembly of claim 1; as described in any of the accompanying drawings.