FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ARC QUENCHING ASSEMBLY FOR CIRCUIT BREAKERS;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION
The invention relates to circuit breakers, and more particularly to arc quenching in circuit breakers. BACKGROUND OF THE INVENTION
Circuit breakers protect electrical circuits from damage by isolating the circuit, when there is an unusual surge. However when a circuit breaker isolates an electrical circuit from this unusual surge, an uncontrolled arc may travel to the circuit breaker and damage it.
An arc basically is a discharge of electric current which results from the unusual surge crossing between contacts of a circuit breaker, when these contacts are opened to isolate the electric circuit. Arcs may vary in size and intensity depending on the amount of surge, and minimizing the arc is important as the arc can damage the contacts and can also severely damage the circuit breaker and surrounding equipments.
The severity of arc current depends on how long the current flows, what's the level of fault current flowing. To protect the appliance from damage there is a requirement for circuit breaker to sense the fault in earlier stage and quench the arc at lower current in lesser time.
In view of the above there is a need for quenching arc in circuit breakers at lower current, and in lesser time.

SUMMARY OF THE INVENTION
Accordingly the present invention in one aspect provides an assembly for arc quenching for a circuit breaker, the circuit breaker having a pair of a moving and a fixed contact, the assembly comprising an arc chute; and a magnet, the magnet being in the form of an enclosure, the enclosure having an enclosure portion, the enclosure portion accommodating the fixed contact, the enclosure providing a repulsion force on the contacts; and a slanting extended portion, the slanting extended portion provided along an arc running path of the fixed contact, the magnet driving the arc towards the arc chute.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 shows a circuit breaker comprising an assembly for arc quenching in accordance with an embodiment of the invention.
Figure 2 shows a magnet of the arc quenching assembly in detail in accordance with an embodiment of the invention.
Figure 3 shows an insulating element adapted to the magnet of the arc quenching assembly in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
Various embodiments of the present invention provide an assembly for arc quenching for a circuit breaker, the circuit breaker having a pair of a moving and a fixed contact, the assembly comprising an arc chute; and a magnet, the magnet being in the form of an enclosure, the enclosure having an enclosure portion, the enclosure portion accommodating the fixed contact, the enclosure providing a repulsion force on the contacts; and a slanting extended portion, the slanting extended portion provided along an arc running path of the fixed contact, the magnet driving the arc towards the arc chute.
Figure 1 shows a circuit breaker 100 comprising an assembly 102 for arc quenching. Assembly 102 for arc quenching includes an arc chute 104 and a magnet 106.
In an embodiment of the invention magnet 106 is in form of an enclosure. The enclosure is an open enclosure has an enclosure portion 108 and a slanting extended portion 110 as shown in figure 2. Enclosure portion 108 of magnet 106 accommodates fixed contact 112 and increases repulsion force on contacts when an arc is generated aiding contacts to open faster, which increases electro dynamic force acting on the arc and pushes it away from the contacts. Slanting extended portion 110 of magnet 106 is provided along fixed contact 112 which is along an arc running path. Slanting extended portion 110 thus increases magnetic intensity along the arc running path, and drives the arc faster towards arc chute.
In an embodiment of the invention, fixed contact 112 is fixed to magnet 106 via means for fixing. The means for fixing as shown in figure 2 is a screw 114.
In an embodiment of the invention, enclosure portion 108 of magnet 106 functions as a slot motor and slanting extend portion 110 of magnet 106 functions as an open core magnet.

In an embodiment of the invention, arc quenching assembly 102 further comprises an insulating element 116 as shown in figure 3. Insulating element 116 is adapted between magnet 106 and a terminal of fixed contact 112 to insulate magnet 106 from direct contact with the arc. Insulating element helps in maintaining clearance between supply side and load side. In an embodiment the insulating element is an ablative material.
In an embodiment of the invention, the assembly for arc quenching assembly can be used for both AC & DC application.
Advantageously, the present invention provides an arc quenching assembly that senses a fault in earlier stage and quenches the arc at lower current in lesser time.
While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

We Claim :
1. An assembly for arc quenching for a circuit breaker, the circuit breaker having a pair of a
moving and a fixed contact, the assembly comprising:
an arc chute; and
a magnet, the magnet being in the form of an enclosure, the enclosure having:
an enclosure portion, the enclosure portion accommodating the fixed contact, the enclosure providing a repulsion force on the contacts; and a slanting extended portion, the slanting extended portion provided along an arc running path of the fixed contact, the magnet driving the arc towards the arc chute.
2. The arc quenching assembly as claimed in claim 1 further comprises an insulating element, the insulating element adapted between the magnet and a terminal of the fixed contact to insulate the magnet from the arc.
3. The arc quenching assembly as claimed in claim 1, wherein the enclosure is an open enclosure.
4. The arc quenching assembly as claimed in claim 1, wherein the enclosure portion accommodating the fixed contact increases the repulsion force on the contacts.
5. The arc quenching assembly as claimed in claim 1, wherein the slanting extended portion increases the magnetic intensity on arc running path.
6. The arc quenching assembly as claimed in claim 1, wherein the enclosure portion accommodating the fixed contact functions as a slot motor.

7. The arc quenching assembly as claimed in claim 1, wherein the slanting extended portion functions as an open core magnet.