FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: IMPROVED ELECTRICAL SWITCH DISCONNECTOR
ASSEMBLY FOR USE IN DISTRIBUTION AND MOTOR CIRCUITS
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 Switch Disconnectors. More particularly, the present invention relates to an improved electrical, switch disconnector assembly for use in distribution and motor circuits.
BACKGROUND OF THE INVENTION AND PRIOR ART
A mechanical switching device carries current and operates by ON/OFF switching operation which compiles to the requirements of standard, specified for the switching function.
In the current scenario, switch disconnectors are available with 12 In (125A x 12 = 1500A) short
time withstand current capacity. Present withstand capacity is sufficient to install the product for
installation.
However few products fail due to high spike of current. Internal parts / external parts are getting
burnt/melt.
Hence the need of good product arises and pushes to invent new product. Which requires an Electrical switch disconnector with enhanced short time withstands performance.
Drawbacks/disadvantages/limitations:
• Less in Short time withstands performance.
• Cannot sustain high spikes of current.
• Installation like wiring or breaker may burn.
• Contacts may get weld.
The present invention therefore provides an enhanced short time withstand performance that saves from breakdown, failure due to high spike of current and subsequent melting of internal parts / external parts.
OBJECTS OF THE INVENTION
One object of the present invention is to overcome the disadvantages / drawbacks of the prior art.

A basic object of the present invention is to provide an Electrical switch disconnector device with enhanced short time withstands performance.
Another object of the present invention is to provide a Electrical switch disconnector assembly where chances of failure are reduced of installation /products which fail for burnt/melt due to high spike of current.
These and other advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.
According to one of the aspect of the present invention the system is provided an improved electrical switch disconnector assembly for use in distribution and motor circuits, said assembly comprising a housing means; a cover means; a fixed contact; a moving contact having a silver tip at contact point to complete current path; a knob means operably connected to linkages; a contact carrier means and a pin means engaged with said knob means; a terminal means having a terminal screw attached thereto; a multipole link means; a contact carrier spring means and said contact carrier means connected to a moving contact; a back up spring means integrated to said contact carrier means for making separate contact while switching off said knob means; and a bus bar termination area having an incoming supply means and an outgoing termination means connected thereto.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
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.
Figure 1 illustrates open view of the present system.
Figure 2 illustrates new contact system with linkage.
Figure 3 illustrates overall size of the present system.
Figure 4 illustrates overall view of the present system.
Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
DETAILED DESCRIPTION OF THE INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but

these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms "a," "an," and 'the" include plural referents unless the context clearly dictates otherwise.
By the term "substantially" it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
It is a mechanical switching device capable of making, and carrying currents under normal condition which may include specified operating condition. Switch disconnectors units to be used in distribution circuits and motor circuits. Enhanced short time withstand performance has following features
• Enhance in Short time withstands performance.
• Sustains high spikes of current.
• Saves from burn/melt of Installation like wiring or breaker.
• Saves from contacts weld.

• Compact design saves space.
• Compact design saves cost.
• Enhanced STW performance saves breakdown and breakdown cost.
Switch disconnectors are mounted in a panel or in electrical installation. Incoming supply is connected to one side at cable or bus bar termination area in off condition. Then out going termination is also connected to the opposite side of incoming supply side.
Design of this switch disconnector is such way that internally contact carrier and U pin is engaged with on off knob, then contact carrier and contact carrier spring is connected with moving contact & moving contact gets connected to fixed contact which has a silver tip at two contact points to complete the current path. When we operate the on off knob to switch on the product, internally linkages gets operated and only moving contact touches to fixed contact. This moving contact has a silver tip at two contact point (Touching of Fixed contact tip to Moving contact tip at two places simultaneously as shown in figure 1) to complete the current path. Back up spring is provided with contact carrier to make separate contacts quickly while switching off the switch disconnector. Thus we claim safe and sustainable for high spikes of current make/break device. Assembly view shows the internal constructional details of the same.
The present invention having enhanced 3 kA short time withstand capacity. Consisting of 15 parts which takes care of to sustain for 3 kA. There are two important parameters in the design, one is repulsion force and another is cross sectional area of contacts to sustain for 3kA.
Components:
Housing - 125A Isolator Cover -125A Isolator On / Off Knob - 125 A Isolator Terminal - 125A Isolator

Fixed Contact L & R - 125A Isolator Moving Contact - 125A Isolator Multipole Link -125A Isolator Terminal Screw - 125A Isolator U Pin-125A Isolator Contact Carrier Spring - 125A Isolator Backup Spring - 125A Isolator Fixed Contact Tip -125A Isolator
There are two following important factors to withstand the total contact system in good condition. And in this design the utmost care is taken to withstand the contact system.
1) Repulsion force on contacts - By a design calculation repulsion force is maximum 0.60 kg at contact point which nullifies by external force applied by the contact system spring which is minimum 1.3 kg. So in any case maximum side of repulsion force nullified by minimum side of contact system spring force.
2) Cross sectional area - By a design calculation minimum cross sectional area required is 12.78 sq. mm at contact point to withstand 3 kA and in the design it is maintained minimum from 14.00 sq mm. So in any case required cross sectional area to withstand 3kA is maintained in the design and further safety cross sectional area designed up tol9.00 sq.mm.
Following are the parameters to achieve the desire results.

Repulsion force:
Current in kA at one contact = 3kA
Contact Area = 16.4 mm2
External Force applied at that contact = 1.3 kg
n (peak to rms current ratio) = 1.42
Repulsion force at one contact = 0.60 kg
The repulsion force is 0.60 kg and in the design contact spring force (external force) is 1.3 kg which will take care of repulsion at contact area for 3 kA. Thus we claim safe and sustainable for 3 kA make/break device.
Cross sectional area:
Current in = 3kA
Initial temperature = 70°C
Time in second = 1 sec.
Minimum cross sectional area required = 12.78 mm2
The cross sectional area required is 12.8 mm2 and in the design cross sectional area available is 14 mm2 which will take care of repulsion at contact area for 3 kA. Thus we claim safe and sustainable for 3 kA make/break device.
Advantages:
Enhanced short time withstand performance has following benefits:
• Enhance in Short time withstands performance.
• Sustains high spikes of current.
• Saves from burn/melt of Installation like wiring or breaker.
• Saves from contacts weld.
• Compact design saves space.

• Compact design saves cost.
• Enhanced STW performance saves breakdown and breakdown cost.
• 125A Switch disconnector with 3 kA (enhanced) short time withstands performance. Available in the market are 1.5 kA short time withstands performance.
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 invention.
It is also to be understood that the description is 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 electrical switch disconnector assembly for use in distribution and motor
circuits, said assembly comprising:
a housing means;
a cover means;
a fixed contact having a fixed contact tip;
a moving contact having a silver tip at contact point to complete current path;
a knob means operably connected to linkages;
a contact carrier means and a pin means engaged with said knob means;
a terminal means having a terminal screw attached thereto;
a multipole link means;
a contact carrier spring means and said contact carrier means connected to a moving
contact;
a back up spring means integrated to said contact carrier means for making separate
contact while switching off said knob means; and
a bus bar termination area having an incoming supply means and an outgoing termination
means connected thereto.
2. Assembly as claimed in claim 1 configured to sustain substantially high spike of current and adapted to substantially improved short time withstand capacity thereby preventing breakdown.
3. Assembly as claimed in claim 1 wherein said knob means adapted for providing switching ON/OFF knob means.
4. Assembly as claimed in claim 1 having approximately 3 kA short time withstanding capacity.

5, An improved electrical switch disconnector assembly for use in distribution and motor circuits as herein described and illustrated with reference to accompanying drawings.