FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: ARC CHUTE ARRANGEMENT FOR USE IN A
CIRCUIT BREAKER
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 invention relates to arc chutes for an electrical circuit breaking devices, more particularly relates to arch chute arrangement with different materials, to increase the life of deion plates by reducing material corrosion.
BACKGROUND OF THE INVENTION
Circuit breaker is an absolutely essential safety device in modern electrical systems. Circuit breaker is as automatically operated electrical switch designed to protect an electrical circuit from damage caused by over load current or short circuit, by detecting the fault current and interrupt the flow of current in the circuit.
Arc voltage is the voltage that created across the contacts of circuit breaker, upon the opening of circuit breaker contacts, due to flow of over current in the circuit, during which the current flow is maintained in the form of an arc. Such an arc must be extinguished immediately to prevent the damages to electrical circuits and wirings. Circuit breaking devices are designed to raise the voltage gradient across the contact gap, such that the arc is too long for voltage to keep it going. Circuit breakers are designed to cause the arc to move away from the contacts and move the arc into arc chutes. Arc chute is a set of spaced apart arc plates with air gap between them to confine the arc and prevent it from causing damage.
Basically arc chute stretches the arcing that takes place when a circuit breaker opens, such that the arc is too long for voltage to keep it going. When an arc occurs it is expelled into the arc chute such that it wraps between the arc plates, which effectively stretches the length of the arc and raises the voltage of the arc to a level which permanently exceeds the recovery voltage and quenches the arc.

DESCRIPTION OF THE PRIOR ART
US 3483343 discloses an electric circuit breaker having a pair of contacts between which an arc may be drawn along a predetermined path and a pair of elongated conductors each connected to one of the contacts, the conductors being positioned with respect to the contacts and the arc path so that the magnetic fields associated with the current flowing in the conductors act on the arc to move it out along a pair of diverging arc runners away from the aforesaid electrical conductors. It uses magnetic field to pull the arc in to arc chutes for fast arc quenching.
US 4082931 discloses An arc chute for a circuit breaker characterized by a pair of spaced side walls for an interior arc extinguishing chamber, the surfaces of the walls forming the chamber being covered with a coating of an arc resistant ceramic material, such as aluminium oxide, zirconium oxide, chromic oxide, magnesium oxide, and calcium oxide. It uses coating of arc chutes with arc resistance ceramic material to get thermal resistivity for the arc chutes.
The durability of a circuit breaker depends on the durability of the arc plates, which enables the arc to be broken down and facilitate the arc to be extinguished.
On frequent fault current flow in the circuit, the arc plates will be recurrently exposed to extremely hot gases and spark caused by the arc, and can damage the arc plates by corrosion and other means.
These actions can diminish the life of the arc plates and the performance of the circuit breaker will be reduced. Without a proper as arrangement of arc plates and lack of suitable material for arc plates, achieving the desired electrical result can be complicated and expensive.
There is therefore a need to provide a new and improved arc chute, wherein the plates are constructed or coated with efficient materials and arranged as to improve the ability to extinguish the arc, while increasing the life of the arc plates, and reducing the cost of manufacturing and operation.

OBJECTS OF THE INVENTION
The basic object of the invention is to overcome the drawbacks or disadvantages of the known art.
It is an object of the invention to provide a high performing arc chute arrangement in a low voltage switch gear design.
Another object of the invention is to provide an aforesaid arc acute arrangement in a circuit breaker to increase the life of deion plates by reducing material erosion.
Another object of the invention to provide an arc chute with enhanced corrosion resistance and thermal conductivity, to extinguish the arc formed across the contact upon a fault current.
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.
In accordance with the present embodiment of the invention, there is provided, an arc chute arrangement in a circuit breaker, with readily separable circuit breaker contacts, and an arc chute configuration for rapidly cooling and extinguishing an arc that occurs upon separation of contacts during fault current.
In accordance with one of the embodiment, the invention provides an arc chute configuration with plurality of deion plates spaced apart with air gaps between them.

In accordance with another embodiment of the invention, some of the deion plates are mild-steel deion plates, which are coated with corrosion resistant materials, preferably Nickel or zinc.
In accordance with another embodiment of the invention, some of the deion plates are bare graphite plates with high thermal conductivity.
In accordance with further embodiment of the invention, the arc chute arrangement comprises corrosion resistant material coated mild-steel deion plate and bare graphite deion plates arranged alternatively at right angles to the arc.
In accordance with further embodiment of the invention, the deion plates arranged alternatively facilitate moving the arc away from the contact and stretches the length of the arc such that the arc is too long for the voltage to keep it going.
In accordance with further embodiment of the invention, movement of arc away from the contact is presided over by gas dynamics and magnetic pull of said mild-steel deion plate.
In accordance with further embodiment of the invention, graphite deion plate exhibit high thermal conductivity and assist the reduction of plasma temperature and increases the life of the deion plate.
In accordance with further embodiment of the invention, the movement of the arc away from the contact maintains the integrity of the contact for longer life.
In accordance with yet another embodiment, the present invention is to improve the arc voltage build up by developing higher resistivity de-ion plates.
BRIEF DESCRIPTION OF THE 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 schematic diagram of arc chutes.
FIG.2 illustrates schematic diagram of de-ion plate.
FIG.3 illustrates schematic diagram of rough de-ion plate.
FIG.4 illustrates schematic diagram of rough de-ion plate.
FIG.5 illustrates schematic diagram of arc splitting.
FIG.6 illustrates analysis results of variation of cathode voltage drop with different work function values.
DETAILED DESCRIPTION OF THE DRAWINGS
Accordingly in the present invention FIG.l illustrates an arc chute arrangement incorporated in low voltage circuit interrupting devices such as circuit breakers.
Arc chute as claimed in FIG.l, includes an arc chute segment (3) and circuit breaker contacts (2). The arc chute segment (3) includes deion plates (1) made up of different types of material plates.
Arc chute segment (3) includes mild steel deion plate (1.1) coated with corrosion resistant materials like zinc or nickel, and a deion plate with high work functional materials like graphite (1.2).
When there is a flow of fault current, the circuit breaker contacts (2) opens up the circuit, forming an arc is between the contacts, and transferred into the chute by electromagnetic and thermal blow our forces. The arc formed is moved away from the contacts (2) by mild-steel deion plate (1.1) and graphite deion plate (1.2) of the arc chute segment (3).

Mild-steel deion plate (1.1) and graphite deion plate (1.2) of the arc chute segment (3), stretches the length of the arc, such that, the length of the arc is too long for the voltage to keep it going and finally quenches the arc.
Graphite deion plate (1.2) of the arc segment (3) have a high thermal conductivity to reduce the plasma temperature of the circuit.
Graphite deion plate (1.2) of the arc segment (3) have a high thermal conductivity increases the durability of the deion plates (1).
FIG.2 illustrates mild steel deion plate (1.1) coated with corrosion resistant materials like zinc or nickel, and a deion plate with high work functional materials like graphite (1.2) arranged alternatively in arc chute segment (3) in a preferred combination.
FIG.3. illustrates mild steel deion plate (1.1) coated with corrosion resistant materials like zinc or nickel, and a deion plate with high work functional materials like graphite (1.2) arranged alternatively in arc chute segment (3) in another preferred combination.
FIG.4 illustrates mild steel deion plate (1.1) coated with corrosion resistant materials like zinc or nickel, and a deion plate with high work functional materials like graphite (1.2) arranged alternatively in arc chute segment (3) in another preferred combination.
FIG.5 illustrates arc chute arrangement having a arc chute segment (3) with mild-steel deion plate (1.1) and graphite deion plate (1.2) arranged alternatively at right angles to length of the arc, with spacers between the plates, which allow the arc to split up into smaller series arc (4) between the arc chute segments (3).
The moverment of the arc away from the contact (2) by the mild-steel deion plate (1.1) and graphite deion plate (1.2) and makes them to split up to into smaller series arc (4) between the arc chute segment (3) preserves the integrity of the contacts and increases the life time.

FIG.6 shows the analysis result of variation of cathode voltage drop with different work function values.
The arc chute as illustrated in FIG.1 helps in achieving less material corrosion and high arc voltage, as it has the advantage of mild-steel deion plate (1.1) and graphite deion plate (1.2). Graphite deion plate (1.2) is non magnetic, so it cannot pull the arc towards deion plates (1), mild-steel deion plate (1.1) will overcome the problem as being soft magnetic material, it can pull the arc into deion plates (1). The graphite plates used in the arrangement have thickness ranging from 1.5 to 3.5 mm.
After the arc has completely entered into de-ion plates (1), the higher electrical resistivity ensures that the resistance of the electrical circuit is much higher thus allowing for a larger voltage drop in the Arc Chute segment (3).
Another embodiment of the present invention describes more than one mild steel deion plates placed between two successive graphite deion plates in a symmetric alternate manner. Such combination not shown in the present figures illustrated in the present disclosure.
In another embodiment of the present invention describes more than one mild steel deion plates placed between two successive graphite deion plates in an asymmetric alternate manner. Such combination not shown in the present figures illustrated in the present disclosure.
Table -1 physical and electrical properties of graphite and iron

Parameters Iron Graphite
Ionization potential(eV) 7.9025 11.2603
Electrical resistivity (ohm.m) 9.61E-8 5E-6
Melting point(K) 1808 4098

Boiling point(K) 3134 5100
Thermal conductivity(W/cmK) 0.802 1.65
Density (293 K)(g/cm3) 7.86 2.62
work function(eV) 4.67-4.81 5
Table 1 shows the comparison of different physical, electrical and thermal properties of graphite with Iron as de-ion plate's materials. It shows the melting point and boiling point temperature of graphite is quite high compared to iron. Also the thermal conductivity of graphite is high compared to iron. As a result of using graphite as de-ion plate, high temperature withstand capability i.e. low de-ion plate erosion and high heat conduction i.e. fast cooling, of arc is achieved.
ADVANTAGES
• Decreases the time taken to quench the arc thus reducing the energy dissipated in circuit breaker.
• High boiling point of de-ion plate causes low erosion and allows for consistent and repeatable performance and enhances life of switching device.
• High work function causes an increase in the arc root voltage which leads to better arc voltage build up.
• High resistivity causes high arc voltage drop across de-ion plate thus reducing the arc quenching time.
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 arc chute arrangement for use in a circuit breaker comprising,
a housing means;
a pair of detachable contacts, forming an arc voltage, upon a flow of over current in the circuit;
plurality of deion plates spaced apart with predetermined air gaps between them for quenching the arc formed during flow of over current; whereby said plural deion plates comprising mild-steel deion plates and bare graphite plates; and
wherein said mild-steel deion plates and graphite deion plates being arranged in an alternate sequence so as to move the arc away from the contact thereby splitting the arc into smaller arc series to effectively quench the arc voltage.
2. Arc chute arrangement as claimed in claim 1, wherein said mild-steel deion plate is coated with one or more corrosion resistant material.
3. Arc chute arrangement as claimed in claim 2, wherein said corrosion resistant coating material is selectively Nickel, Zinc and the like.
4. Arc chute arrangement as claimed in claim 1, wherein said graphite deion plate exhibit high thermal conductivity.
5. Arc chute arrangement as claimed in claim 1, wherein said graphite deion plate having high thermal conductivity facilitating reduction of plasma temperature.

6. Arc chute arrangement as claimed in claim 1, wherein said deion plates being arranged substantially at right angles to length of the arc.
7. Arc chute arrangement as claimed in claim 1 wherein said graphite plates having thickness ranging approximately from 1.5 mm-3.5 mm.
8. Arc Chute arrangement as claimed in claim 1 wherein said mild steel and graphite deion plates combination optionally comprising one or more said mild steel deion plates dispersed in between two graphite de-ion plates in an alternate or symmetrically alternate or asymmetrically alternate manner.
9. An arc chute arrangement for use in a circuit breaker as herein described and illustrated with reference to accompanying drawings.