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 CIRCUIT BREAKER ASSEMBLY PROVIDING HIGHER MAGNETIC FLUX
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 circuit breakers. More particularly, the invention relates to an improved circuit breaker assembly providing higher magnetic flux for producing high blow out force.
BACKGROUND AND THE PRIOR ART
When contact is opened during short circuit, arc is formed. Then this arc is broaden in arc chamber & pulled towards arc chute because of magnetic blowing field. Then it is splitted in arc chute & extinguished. More the speed at which arc moves away from the main contacts towards arc chute, less is contact wearing which ultimately increases breaking capacity. Different arrangements are provided to increase the blowout force.
Some of the prior arts of the present field of invention are as follows:
US 7081596 B2 provides an Arc quenching device for circuit breaker having double break contact. This patent is about method of intensifying the magnetic blow action on an arc formed by providing blowing loop between arc runners. It uses U-shaped flux enhancing device. When the contacts are separated & arc is formed, arc jumps on first arc runner. Then through magnetic blowing loop, it is connected to second arc runner & then to terminal. Current direction in the loop is such that it enhances magnetic blowing action.
Limitation with this concept is it is suitable only for double break contact system. Also U-shaped device stated in description do not provide optimum blowout force. Flux enhancing device stated in our invention is suitable for single break & double

break contact as well. Also U-shape with variable thickness gives more blowing force as compare to simple U-shape.
US 6831536 Bl provides a Circuit breaker slot motor having stepped out portion. It uses slot motor assembly which includes housing & plurality of plates. Plates generally correspond to shape of housing. The plates are such that a narrow portion is located near the movable contact & the wide portion is located near the movable contact when it is open. Slot motor is made of magnetically permeable material. The electrical current interacts electromagnetically with slot motor to induce magnetic field in magnetic material of the slot motor which in turn interacts with separating contact arm to accelerate opening process.
If there is uniform gap between legs of U-shape slot motor, it can subject to failure due to carbon built up which creates voltage path when contacts are in open position. Over a time, carbon built up allows voltage to travel from movable contact through carbon to fix contact. This is unacceptable as current may flow even if breaker is tripped or manually open. As per this invention, in operation, when breaker is closed, slot motor corresponds to narrow portion. The proximity of contacts to slot motor inner surface enhances the strength of magnetic field created by arc during initial separation. As movable contact moves out gap widens which is sufficient to prevent voltage path from forming along inner surface of slot motor even if inner surface is coated with carbon.
If we compare our invention with this prior art, this art is about providing variable gap on inner surface of slot motor to have sufficient clearance & to avoid current flow in open position due to carbon deposition. In our invention, inner gap remains same. Outside gap is made variable in such that magnetic field we get has a specific gradient which helps in pulling arc in required direction. Thus these two patents are different.

US 7259646 B2 provides an Electrical service device having an arc pre-chamber area pre-chamber plates & a current limiting arc quenching device. This invention is used in circuit breaker. It has fix & moving contact forming switching points, an arc produced in arc prechamber area between switching points which enters in arc quenching device via guide rails. Prechamber plates are placed in prechamber area & return flow channel is formed between prechamber plates & housing. Housing walls has cutouts from outside in region of prechamber plates. In these cutouts, iron plates are inserted for AC switching device whereas permanent magnet plates are inserted for DC switching device which allows it for heavy duty switching.
If we compare our invention with this prior art, this art is about placing flux enhancing plates from outside of housing so that it is not necessary to decide at preliminary stage weather device is standards or heavy duty. Housing is also same. Only additional plates are required to be inserted from outside. This allows economic & cost saving manufacture. It does not talk about variation in thickness to increase blow out magnetic force. Thus this invention is different.
US 2008296264 Al provides an Electrical service switching device with an arc blowout device. This art is related to electrical switching device. It has switching points, arcing chamber & arc quenching unit. An AC blowout device comprising two iron plates adjacent to arcing chamber in lateral direction is provided. The housing wall has opening in area of iron plates through which permanent magnet can be inserted in order to create an AC/DC blowout device which guides arc into arc quenching device in both AC & DC operation when housing is assembled. This prior art thus talks about inserting permanent magnet to make device suitable for DC switching. Thus our invention is not related to us.

US 7532097 provide a Slot motor housing & circuit interrupter including the same. It includes a circuit breaker housing, separable contacts, an operating mechanism structured to open & close the separable contacts, a power conductor including a first conductor & a second reverse loop conductor carrying one of the separable contacts a slot motor. The slot motor includes a first slot motor portion & a second slot motor portion including plurality of u-shaped slot motor laminations, a first insulating housing portion & a second insulative housing portion interlock with one another to form u-shape insulative slot motor housing. The first & second insulative housing portion cooperatively receives the generally u-shaped slot motor laminations.
We see that, this art talks about assembly point of view of two piece slot motor housing. Our idea is different from this invention.
Therefore there is a need to overcome the disadvantages of the prior art. The present invention is related to use of suitable magnetic flux enhancer of specific shape so as to increase magnetic blowing force. This causes arc to move more rapidly & ultimately increases breaking capacity of breaker.
OBJECTS OF THE INVENTION
A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
Another object of the present invention is to provide an improved circuit breaker assembly providing higher magnetic flux for producing high blow out force.
Another object of the present invention is to provide a flux enhancer arrangement for circuit breakers.

Yet another object of the present invention is to provide for increased magnetic blowout force in forward direction.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
There is provided an improved circuit breaker assembly providing higher magnetic flux for producing high blow out force.
According to one embodiment of the present invention, there is provided an improved circuit breaker assembly providing higher magnetic flux for producing high blow out force, said assembly comprising atleast one fixed contact fixed to a housing means; atleast one moving contact coupled to an operating mechanism; atleast one magnetic release means to move moving contact from said fix contact; atleast one coil means, whereby terminal of said coil connected to a fix contact through said magnetic release means; atleast one arc runner means; at least one flux enhancer arrangement comprising a plurality of magnetic flux enhancer plates of substantially U shape, a pair of long plates and a pair of short plates; atleast one arc chamber; atleast one arc chute comprising a plurality of plates placed substantially horizontally; atleast one insulation means provided between said flux enhancer plate and said arc chamber; and atleast one vent means for moving out gases.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
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.
Fig 1 illustrates a Perspective view of contact system & flux enhancing device.
Fig 2 illustrates another perspective view of contact system & flux enhancing device.
Fig 3 illustrates Sectional front view of contact & arcing system. Also shows details of arc movement.
Fig 4 illustrates Perspective view of magnetic flux enhancer assembly.
Fig 5 illustrates Exploded view of magnetic flux enhancer assembly.
Fig 6 illustrates Perspective view of another embodiment of magnetic flux enhancer assembly.
Fig 7 illustrates Perspective view of another embodiment of magnetic flux enhancer assembly with contact system & arc chute.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Accordingly the present invention is related to low voltage circuit breaker. The device is used for protection of electrical lines from consequences of an overload & short circuit current. They have generally thermal release, electromagnetic release & contact arrangement. A normal circuit breaker forms contact system by a fix contact & moving contact. Contact is opened in arc chamber & arc is guided using arc runner to arc chute (arc splitter).

When contact is opened during short circuit, arc is formed. Then this arc is broaden in arc chamber & pulled towards arc chute because of magnetic blowing field. Then it is splitted in arc chute & extinguished. More the speed at which arc moves away from the main contacts towards arc chute, less is contact wearing which ultimately increases breaking capacity.
The present invention is related to use of suitable magnetic flux enhancer of specific shape so as to increase magnetic blowing force. This causes arc to move more rapidly & ultimately increases breaking capacity of breaker.
Description of parts:
1. Coil terminal
2. Magnetic release
3. Fix contact
4. Moving contact
5. Braid
6. Arc runner terminal
7. Arc chute
8. Arc runner
9. Insulation
10. Magnetic flux enhancer assembly

101. U-shaped plate
102. Long plate
103. Short plate

11. Arc chamber
12. Magnetic flux enhancer assembly second embodiment

121. Variable thickness left plate
122. Variable thickness right plate

13. Magnetic flux enhancer assembly with variation in assembly 12
131. Assembly of stack up plate left
132. Assembly of stack up plate left
Fig. 1 & Fig. 2 shows perspective view of entire current path including contact system & arc extinguishing system. Two switching points are formed by fix contact 3 fixed to the housing & moving contact 4coupled to operating mechanism (not shown). First connection is given to coil terminal 1. It is connected to fix contact 3 via magnetic release. In closed position, moving contact 4 is connected to fix contact 3. Then moving contact 4 is connected to arc runner terminal 6 through braid 5 to complete current path. Conventionally some form of flux enhancing device made up of high permeable material (simple parallel plates or U-shaped plates) is provided to confined & increase the flux.
In the event of short circuit or over current, the moving contact 4 is moved away from fix contact 3 by means of release. As contact starts moving, arc is formed between fix contact 3 & moving contact 4. The magnetic field in arc chamber 11 side of an arc compared to that in contact side of an arc helps in generating blow out force. As the arc strikes between the contacts, the presence of high permeable flux enhancer plates creates required flux gradient. Current flows from coil terminal 1 to magnetic release 2 then fix contact then to arc runner 8 though arc & then to arc runner terminal 6. This arc moves towards arc chute 7 through arc chamber 11 because of magnetic blowing field. Fig. 3 shows movement of arc in arc chamber 11 by arrows. Insulation 9 is provided between magnetic flux enhancer 10 & arc chamber 11. When this arc enters arc chute 7, it is splitted because of horizontal plates in arc chute 7. This increases length of arc & arc is finally extinguished. Gases are moved out of breaker through proper vent.

It is required to have high magnetic blowout forces to move arc more rapidly. More the speed of arc less is the erosion of contact. This finally increases breaking capacity & electrical life of product. One limitation of current designs (parallel plates or uniform thickness U-plate) is that, as arc moves in arc running stage, the uniform thickness plates reduces the flux gradient, thus the blow out forces on an arc are not optimum.
Current invention is related to use of magnetic flux enhancer of specific shape which gives highest pulling action or magnetic blowout force to move arc towards arc chute 7.
Figure 4 shows perspective view & Fig 5 shows exploded view of magnetic flux enhancer assembly 10. It consists of U-shaped plate 101, two long plates 102 & two short plates 103. These components are made from high permeable material such that iron or steel. These are spot welded in a manner as shown in figure to forms gradient towards arc chute 7. U-shape confines and increases the flux flow around arc runner 8 in effective way. More mass towards arc chute 7 reduces the flux density in front of an arc while it is in running stage. This phenomenon creates the flux gradient in such a way that it increases the magnetic blow out force in forward direction. As per this invention, it is required to have more thickness towards arc chute 7 & to have gradient of thickness. Numbers of plates are stacked up & spot welded by considering manufacturing feasibility as shown in Fig 4.One can even use variable thickness plate bent in U-shape.
If one cannot provide U-shaped plate due to assembly or space constraints, one can even provide plates without U-shape.
Figure 6 shows perspective view of other embodiments of magnetic flux enhancer assembly 12 & assembly 13. Assembly 12 shows variable thickness plates 121 &

plate 122. Assembly 13 shows two sub assemblies 131 & 132 made using stack of plates.
Figure 7 shows perspective view of this embodiment of magnetic flux enhancer assembly 12 with contact system & arc chute 7. The novel feature is to have variable thickness (higher thickness towards arc chute). This thickness can be provided by making stack of individual plates or providing plates with variable thickness. Also it can be used with U-shaped plate or as individual plates.
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 claims.
It is also to be understood that the following claims are 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 circuit breaker assembly providing higher magnetic flux for
producing higher blow out force, said assembly comprising:
atleast one fixed contact fixed to a housing means;
atleast one moving contact coupled to an operating mechanism;
atleast one magnetic release means to move moving contact from said fix
contact;
atleast one coil means, whereby terminal of said coil connected to a fix
contact through said magnetic release means;
atleast one arc runner means;
atleast one arc chamber;
flux enhancer arrangement comprising at least one magnetic flux enhancer
plate or plates with variable thickness, placed in arc chamber
atleast one insulation means provided between said flux enhancer plate and
said arc chamber; and
atleast one vent means for moving out gases.
2. Assembly as claimed in claim 1 wherein said moving contact connected to said arc runner through a braid thereby completing current path.
3. Assembly as claimed in claim 1 wherein said flux enhancer plates are substantially high permeability plates creating required flux gradient made of iron, steel and the like.

4. Assembly as claimed in claim l wherein said flux enhancing arrangement is spot welded forming gradient towards said arc chute thereby increasing magnetic blowout force in forward direction.
5. An improved circuit breaker assembly providing for higher magnetic flux as herein described and illustrated with reference to accompanying drawings.