FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Arc-Chute Assembly for Circuit Breaker"
APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: Larsen & Toubro Limited
Electrical & Automation
North Wing, Gate 7, Level 0,
Powai Campus, Saki Vihar Road,
Mumbai 400 072, INDIA
2. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Arc-Chute Assembly for Circuit Breaker
Field of invention
The present invention relates to an arc-chute assembly for an electrical switching device, such as circuit breaker, a disconnector and a contactor to be used preferably in low voltage electrical systems.
Background of the invention
Electrical switching apparatus, such as circuit breakers, are used in diverse capacities in power distribution systems, for example, to provide protection for electrical equipment from electrical fault conditions. Therefore, the short circuit capacity of any circuit breaker is totally governed by the performance of its contact system and arc quenching chamber i.e. arc-chute.
The function of arc chamber is to isolate the system in faulty condition by effectively quenching the arc generated due to contact separation. In conventional circuit breakers the arc chamber consists of linings made up of insulating material to hold the stack of Deion plates made up of magnetic material. Generally, the Deion plates are assembled with insulating linings either by riveting or crimping process.
In the event of fault the circuit breaker contact opens to isolate the system. When the contact separates, an electric arc is affected in between them. The arc is then moved by the arc runners to the arc-chute whereby it splits into several series of small arcs and cools down, increasing the arc voltage and thereby causing faster quenching of the arc. During arcing phase Deion plates exerts magnetic pull on the arc.

During arcing phase, a very high pressure is generates inside the arc-chute. The insulating lining of the arc-chute must withstand this pressure and hold Deion plate stack assembly in intact condition. In conventional arc-chutes, the crimping joint or the riveting joint provides the mechanical strength to the insulating linings to hold Deion plate stack assembly in intact condition. The arc-chute should not transmit this high pressure on circuit breaker housing and coyer.
In conventional arc quenching mechanism, when the two contacts separate, an electric arc is struck in between them. The arc is then moved by the arc runners towards the Deion plate stack assembly. The magnetic field produced in the Deion plates exerts pulling force on the arc. The arc moves towards the lower ends of Deion plates, as it provides least reluctance path for the magnetic flux lines. This results in slower insertion of arc inside Deion plate assembly. The arc will not penetrate deeper inside Deion plate stack assembly and will jump at the lower ends of the Deion plates. This phenomenon may result in arc retrogression, slower build up of arc voltage and hence higher arcing time.
Objects of the invention
An object of the present invention is to provide an arc-chute, which eliminates riveting or crimping process required for Deion plate assembly thereby enhancing the productivity.
Another object of the present invention is to provide an arc-chute, which avoids arc retrogression thereby reducing arcing time.
Yet another object of the present invention is to provide an arc-chute, which has comparatively quicker quenching time.

Summary of the invention
According to the present invention there is provided an arc-chute assembly for an electrical switching devices such as, breaker, a disconnector and a contactor, the arc-chute comprising:
a left arc-chute lining and a right arc-chute lining configure sides to integrate an arc barrier;
a plurality of plates disposed between the left arc-chute lining and the right arc-chute lining, the arc barrier guide the arc towards the plates and prevent connotation with the plates;
a plurality of supports disposed between the plates and the left arc-chute lining and the right arc-chute lining, the plurality of supports support the plates to secured over the left arc-chute lining and the right arc-chute lining; and
a clamp disposed over the plates and between the left arc-chute lining and the right arc-chute lining for securing thereof, the clamp enables to enhance mechanical strength to the arc-chute assembly to withstand the high pressure generated during short circuit fault.
Brief description of the drawing
Figure 1 illustrates a perspective view of an arc-chute assembly in accordance with the present invention;
Figure 2 illustrates another perspective view of figure 1;
Figure 3 illustrates sectional view of arc-chute assembly; and
Figure 4 illustrates positions of different components of an arc-chute assembly.

Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
Accordingly, the present invention provides an arc-chute for an electrical switching device for example, breaker, a disconnector or a contactor to be used preferably in low voltage electrical systems.
Referring now to Figure 1 to 4, which shows various views of an arc-chute assembly consisting of a left arc-chute lining (1), a right arc-chute lining (2), a plurality of plates (3), a plurality of plate supports (4) and a clamp (5). In an embodiment, the plate (3) is a Deion plate.
The arc-chute as shown in Figure 1 to 4, the plates (3) are assembled in the arc-chute linings (1 and 2) by sliding them into the corresponding slots provided on the arc-chute linings (1 and 2) and with a gap between each of the plate. The arc-chute lining left (1) and the arc-chute lining right (2) together holds the Deion plates (3).
The arc-chute linings (1 and 2) are designed in such a way that it integrates arc barrier construction which helps in avoiding electrical connection between arc and the lower ends of the plates (3). The arc barrier guides the arc towards the plates (3) for faster penetration of arc inside the arc-chute which helps in faster build up of arc voltage, lesser erosion of contacts and lesser arcing time. The total space available between the two arc-chute linings (1 and 2), where the moving contacts move during ON-OFF operation of the circuit breaker, is same as that of the prior art arc-chute without arc barrier. This compact design of arc-chute lining with integrated arc barrier helps to design compact circuit breaker having higher

breaking capacity. The arc-chute linings (1 and 2) holds the plates (3) throughout its length thereby minimizing the chances of flashover or re-strike caused by deposition of the molten material at the side edges of the plates (3) which forms electrical connection between adjacent Deion plates (3).
When arc enters inside the plates (3), it separates into a series of small arcs, and forms anode and cathode arc roots on the plates (3), thereby increasing the arc voltage which helps in faster quenching of the arc. After assembling the plate support (4) as shown in Figure 3, at the corresponding position provided on insulating lining restricts the sliding movement of the plate (3). The lower end of the plate gets locked with the arc-chute linings (1 and 2) and holds them together.
As shown in figure 4, the clamp (5) is assembled by sliding the clamp (5) in the corresponding slot provided on arc-chute linings (1 and 2). The plates (3) locked with the arc-chute linings (1 and 2) and the clamp (5) assembled with the arc-chute linings (1 and 2) provides very high mechanical strength to the arc-chute assembly to withstand the high pressure generated during short circuit fault. The assembly of the plates (3) and the clamp (5) with arc-chute linings (1 and 2) requires simple sliding operation. This ease of assembly enhances productivity. The plate support (4) holds the plates (3) in their corresponding position and restricts them to move in any direction. The clamp (5) strongly holds the arc-chute linings (1 and 2) and provide a high strength to the arc-chute to withstand high pressure during short circuit fault so as to minimize the stresses induced on the molded case circuit breaker (MCCB) housing and cover.
Advantages of the present invention
1. An arc-chute which eliminates riveting or crimping process required for plate (3) assembly thereby enhancing the productivity and reduces the cost.

2. The integrated arc barrier construction of arc-chute lining (1 and 2) helps the arc to move faster towards the plates (3) and reduces the chances of arc retrogression.
3. The present invention provides quicker quenching time.
4. The possibility of a connection between two adjacent the plates (3) due to the electrical connection established by molten material is minimized by supporting the plates (3) throughout its total length.
5. The clamp (5) provided to hold both the insulating linings provides high mechanical strength to arc-chute assembly (Figure 1 to 4) for withstanding high pressure generated during short circuit fault.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.
The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We Claim:
1. An arc-chute assembly for an electrical switching devices such as, breaker,
a disconnector and a contactor, the arc-chute assembly comprising:
a left arc-chute lining and a right arc-chute lining configure sides to integrate an arc barrier;
a plurality of plates disposed between the left arc-chute lining and the right arc-chute lining with a gap between each of the plate, the arc barrier guide the arc towards the plates and prevent connotation with the plates;
a plurality of plate supports disposed between the plates and the left arc-chute lining and the right arc-chute lining, the plurality of supports support the plates to secure over the left arc-chute lining and the right arc-chute lining; and
a clamp disposed over the plates and between the left arc-chute lining and the right arc-chute lining for securing thereof, the clamp enables to enhance mechanical strength to the arc-chute assembly to withstand the high pressure generated during short circuit fault.
2. The arc-chute assembly as claimed in claim 1, wherein the plates are Deion plates.
3. The arc-chute assembly as claimed in claim 1, wherein the left arc-chute lining and a right arc-chute having plurality of slots for securing the plate.