FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. - AN IMPROVED TOP TERMINAL ARRANGEMENT FOR
HIGHER BREAKING CAPACITY IN LOW VOLTAGE SWITCHGEAR
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:

FIELD OF THE INVENTION
The present invention relates to clearing faults in low voltage switchgears using arc quenching technologies. More particularly, the invention is concerned about an improved top terminal arrangement for better quenching of the arc and to increase the electrical life of breaker by initiating better running of arc. This technology is used in the switchgear industry and allied areas.
BACKGROUND OF THE INVENTION
When live contacts of a circuit breaker open, an electric arc strikes between them. This arc travels from the contacts to the de-ion plates wherein it is cooled by means of splitting. An arc runner resting on the top terminals facilitates movement of the arc from the contacts towards the de-ion plates.
US5969314A discloses an integral stationary arcing contact and arc runner for electrical switching apparatus is formed by an electrically conductive member secured to the line conductor adjacent the stationary main contact thereby providing a joint free path for the arc to pass from the arcing contact to the arc runner. Preferably, the electrically conductive member is a sheet metal member having a base section secured to the line conductor, an arcing contact section adjacent the stationary main contact and extending generally perpendicular to the line conductor and a runner section extending at an obtuse angle to the arcing contact section toward the arc chute. K support -member between the arcing contact section and the housing transmits reaction forces imposed by the moving conductor assembly on the sheet metal member into the housing.
US6689979B1 discloses a switching contact arrangement for a low-voltage power circuit breaker includes a switching contact arrangement with a stationary contact group and a movable contact group which interacts with it. The contact groups include interacting main contacts, as well as interacting intermediate contacts and

consumable contacts. Furthermore, both contact groups are equipped with an arcing horn for passing a switching arc to an arc quenching chamber. The consumable contacts are integrated in the arcing horns. Only the main contacts are in the form of contact facings, while the other contact points are formed by the busbars or arcing horns. The switching contact arrangement is of a single design and achieves a longer mechanical and electrical life. Furthermore, particularly short switching times are achieved.
The existing designs do not facilitate smoother transition of the arc from arcing contacts to the arc runner. There is no facility to make sure that the arc is struck in the center of the chamber. Also in the existing design the arcing contacts are not effectively utilized.
For better movement of the arc it is necessary to smoothen the transition of the arc from the top terminal to the arc runner. With faster movement of the arc, effective time required for quenching is reduced. The invention helps to achieve this purpose.
The present inventors have developed a top terminal provided with a unique protrusion and a feature that helps in the arc being struck at the center of the terminal and easier movement of the arc from the terminal towards the arc runner respectively is possible. The current design also helps in effective utilization of arcing contacts which protects the main contacts.
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 improved top terminal arrangement for better quenching of the arc.

Another object of the present invention is to increase the electrical life of breaker by initiating better running of arc.
These and 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
According to one aspect of the invention, there is provided an improved top
terminal arrangement having higher breaking capacity in low voltage switchgear,
said arrangement comprises:
main contact means having substantially a rectangular profile;
arcing contact means having substantially a protruded profile ;
said protruded profile comprises an extra protrusion feature means being
operatively located almost at the center of said plurality of arcing contacts thereby
allowing the arc to strike almost at the center of said contacts so that heat
distribution being almost uniform over said contact surface.
According to another aspect of the invention, there is provided an improved
switchgear comprising:
moving contact means;
arc runner means;
plurality of de-ion plate means;
fixed contact means;
wherein said fixed contact means arrangement comprises :
main contact means having substantially a rectangular profile;
arcing contact means having substantially a protruded profile ;
said protruded profile comprises an extra protrusion feature means being

operatively located almost at the center of said plurality of arcing contacts thereby allowing the arc to strike almost at the center of said contacts so that heat distribution being almost uniform over said contact surface.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Other features as well as the advantages of the invention will be clear from the following description.
In the appended drawings:
FIG. 1 shows 3D view of the top terminal assembled with arc runner.
FIG. 2 shows 3D view of the top terminal.
FIG. 3 shows Front view of the top terminal.
FIG. 4 shows cross sectional view of the breaker assembled with the improved top
terminal.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following detailed description, reference is made to the accompanying drawings that form a part thereof, and illustrate the best mode presently contemplated for carrying out the invention. Further functioning of the arrangement has been discussed below to describe the way the arrangement operates. However, such description should not be considered as any limitation of scope of the present unit. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.
According to the invention there is provided an improved top terminal arrangement for better quenching of the arc. The current invention is on terminal arrangement (figures 2 and 3) (bus-connector/fixed contact) which is a component of switchgear. The main purpose of circuit breaker is to clear any fault in the

system as fast as possible with minimum damage to itself & the system. There are mainly two contacts in a circuit breaker, fixed (Fig.2, Fig.3. 1 in Fig 4) and moving (10 in Fig. 4). used for making & braking of the circuit. Whenever circuit breaker breaks a circuit by means of opening the contacts, an arc is formed in between the contacts (1 and 10 in Fig.4). The arc transits from the contacts to arc runner {9 in Fig.4) & then split at the de-ion plates (11 in Fig. 4). In this process, the electric arc erodes the contacts and henceforth reduces the life of the circuit breaker. Therefore the design of contacts needs to be as effective as possible to reduce the arcing time & contact material erosion. This invention provides an improved top terminal which reduces contact material erosion and also arcing time.
Top terminal consists of a rectangular section (8 in Fig.2) which is the main contact & a protruded section (2. 3 in Fig.2) as arcing contact. The extra protrusion feature (3 in Fig.2) at the center of the arcing contacts assures that the arc strikes at the centre of the contacts so that the heat distribution over the contact surface becomes uniform which in turn reduces material erosion & arc quenching time. The slot (4. 5, and 6 in Fig.2) on the top surface is designed for the placement of arc runner (9 in Fig.l) so that arc transition from arcing contacts to arc runner becomes smoother. The slot (7 in Fig.2) on the back side of top terminal is to hold nut plate. The front profile (1) of the top terminal shows clearly the said extra protrusion feature (3 in Fig.2) on the arcing contact.
ADVANTAGES OF THE INVENTION
1. Better quenching of the arc.
2. Increasing electrical life of breaker.

WE CLAIM
1. An improved top terminal arrangement having higher breaking capacity in
low voltage switchgear. said arrangement comprises:
main contact means having substantially a rectangular profile;
arcing contact means having substantially a protruded profile ;
said protruded profile comprises an extra protrusion feature means being
operatively located almost at the center of said plurality of arcing contacts
thereby allowing the arc to strike almost at the center of said contacts so
that heat distribution being almost uniform over said contact surface.
2. The arrangement as claimed in claim 1 further comprising plurality of slots adapted to place in a conventional arc runner means so that arc transition being smooth from said arcing contacts to said arc runner.
3. The arrangement as claimed in claim 1 further comprises a slot means adapted to hold a nut plate means.
4. The arrangement as claimed in claim 3, wherein said slot means being operatively located on almost back side of said top terminal means.
5. An improved switchgear comprising: moving contact means;
arc runner means;
plurality of de-ion plate means;
fixed contact means;
wherein said fixed contact means arrangement comprises :
main contact means having substantially a rectangular profile;
arcing contact means having substantially a protruded profile ;
said protruded profile comprises an extra protrusion feature means being

operatively- located almost at the center of said plurality of arcing contacts thereby allowing the arc to strike almost at the center of said contacts so that heat distribution being almost uniform over said contact surface.
6. An improved top terminal arrangement for higher breaking capacity in low voltage switchgear as herein substantially described and illustrated with the accompanying drawings.
7. An improved switchgear as herein substantially described and illustrated with the accompanying drawings.