FORM 2
THE PATENT ACT 1970
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(section 10 and rule 13)
1. TITLE OF THE INVENTION:
"An Arc Chute Assembly of a Moulded Case Circuit Breaker"
2. 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
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification
particularly describes the invention and the manner in which it is to be performed

An Arc Chute Assembly of a Moulded Case Circuit Breaker
Fifed of the invention
The present invention relates to a moulded case circuit breakers and more particularly to an arc chute assembly of assembly of a moulded case circuit breaker.
Background of the invention
Electrical switching apparatuses, such as circuit breakers, are employed in diversified power distribution systems to provide protection for electrical equipment from electrical fault conditions such as for example current overload, short circuit, and abnormal level voltage conditions. The short circuit capacity of any circuit breaker is substantially dependent on the performance of its arc quenching chamber.
However, the conventional arc quenching chamber assemblies of the prior art circuit breakers have a tendency to quench the arc with a long arcing time, when subjected to a short circuit current of few kilo amperes. The long arcing time leads to severe stresses on the downstream equipments due to large amount of let through energy. The prior art circuit breakers fail to have efficient arc lengthening mechanisms to reduce the arcing time.
The prior art circuit breakers do not have any efficient arc lengthening mechanisms. The conventional arc chamber assemblies fail to efficiently elongate arc under short circuit conditions as the arc voltage built up is low in these devices as illustrated in Figure 1. Also, the prior art arc chamber assemblies have drawbacks of higher rates of cut off current and let through energy. As shown in Figure 1, the prior art arc chamber assemblies produce an

are of limited length thereby making the arc columns of these devices to have substantially reduced voltage across the arc columns. Also, the quenching of the arc add lowering of the voltage rise in the arc column of these prior art arc chamber assemblies.
There is need of an arc chute assembly of a moulded case circuit breaker that maximizes arc voltage build up thereby reducing cut off current & let through energy of the circuit breaker.
Objects of the invention
An object of the present invention is to provide an arc chute assembly of a moulded case circuit breaker that provides enhanced are lengthening and builds up higher arc voltages.
Another object of the present invention is to provide an arc chute assembly of a moulded case circuit breaker that enhances fault clearing capacity or a breaking capacity.
Yet another object of the present invention is to provide an arc chute assembly of a moulded case circuit breaker that lowers arcing times & cut off current to reduce let through energy.
Summary of the invention
The present invention discloses an improved arc chute assembly of a moulded case circuit breaker that comprises an opposed pair of arc chute lining , a plurality of first deion plates and a plurality of second deion plates. The first deion plates and the second deion plates rigidly support on a plurality of rectangular slots defined on the arc chute lining using a mechanical clamping means. The first deion plates and the second deion plates are eccentrically

positioned within the arc chute lining that forms an additional space to producing a magnetic pull essential for lengthening an electric are.
Brief description of drawings
Figure I shows an arc movement profile of an arc chute assembly of the prior art;
Figure 2 is a right hand side view of an arc chute assembly of assembly of a moulded case circuit breaker construed in accordance with the present invention;
Figure 2A is a front view of the arc chute assembly of Figure 1 with a top cover;
Figure 3 is a front view of the arc chute assembly of Figure I without a top cover;
Figure 4 is a cross-sectional front view of the arc chute assembly taken along a Y pole line of Figure 3;
Figure 5A is a front view of an arc energy extractor assembly of the arc chute assembly of Figure 1 showing a deion plate profile;
Figure 5B is a rear view of an arc energy extractor assembly of the arc chute assembly of Figure I showing a deion plate profile;
Figure 5C is a top view of the arc energy extractor assembly of the arc chute assembly of Figure 5 A;
Figure 5D is a sectional view of the arc energy extractor assembly of the arc chute assembly of Figure 5A;

Figure 5E is an isometric view of the arc energy extractor assembly of the arc
chute assembly of Figure 5A; and
Figure 6 shows an arc movement profile of the arc chute assembly of Figure 1.
Detail 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.
The present invention consists of an improved arc chute assembly of a moulded case circuit breaker. The prime feature of present invention is the way arc lengthening mechanism is designed to maximize arc voltage build up which ultimately results in reduced cut off current & let through energy.
Referring to Figures 2 and 2A, a moulded case circuit breaker (MCCB, hereinafter) 100 is shown. The MCCB 100 includes a housing 1 and a cover la. The cover 2 is adapted to be removably positioned atop the housing 1. The cover la facilitates an access to an arc chute assembly positioned within the housing 1 of the MCCB 100. The cover la is positioned with a knob 3.
As shown in Figures 3 and 4, the MCCB 100 includes a release assembly 2, an upper contact assembly 4 and a lower contact assembly 5. The MCCB 100 includes an arc chute assembly 6 that is positioned in the proximity to the upper contact assembly 4 and the lower contact assembly 5. The arc chute assembly 6 is adapted to be inserted inside an arc chamber of the MCCB 100. The MCCB 100 includes a front vent 7 and a back vent 8 located in the proximity to the arc chute assembly 6.

Referring to Figures 5 A- 5D. the arc chute assembly 6 includes an opposed pair of arc chute lining 9, a plurality of first deion plates 10 and a plurality of second deion plates 11. The first deion plates 10 and the second deion plates II are positioned within the opposed pair of arc chute lining 9 in this one particular embodiment. The first deion plate 10 and the second deion plate II are preferably aligned along a plurality of rectangular slots defined on the arc chute linings 9. The first deion plate 10 and the second deion plate 11 are eccentrically positioned within the arc chute lining 9 as seen in Figures 5A and 5D. The first deion plate 10 and the second deion plate 11 have their ends rigidly supported on the arc chute lining 9 using mechanical clamping means such as crimping in this one particular embodiment. However, it is understood that other types of clamping means that are well known in the art may be used in conjunction with the arc chute lining in other alternative embodiments of the present invention.
As shown in Figure 5E, the first deion plate 10 and the second deion plate 11 have a configuration such that a dimension X of the first deion plate 10 is relatively higher than a dimension Y of the second deion plate. The dimensions X and Y facilitate the first deion plate 10 and the second deion plate 11 to be eccentrically positioned within the arc chute lining 9 at varying lengths such that a magnetic pull generated by the deion plates 10. 11 is pulled inside the spacing between the deion plates 10, 11. This facilitates the deion plates 10, 11 to lengthen the arc within the arc chute assembly 6.
As shown in Figure 6, a lengthened arc profile 13 within the arc chute assembly 6 is by virtue of additional space available between the deion plates 10. 11. The additional space within deion plates 10, II increases voltage across an arc column (not shown) that helps the MCCB 100 to cross system voltage in relatively faster manner and elongate the arc column in relatively higher extent. The deion plates 10, 11 significantly improve an arc voltage built up of the circuit breaker 100 that ultimately results in faster fault clearance, low arcing time, low cut off current and low let through energy.

Advantages of the present invention:
I. The deion plates 10, 11 enhance arc lengthening builds up higher arc voltages within the MCCB 100.
II. The deion plates 10, 11 significantly improve an arc voltage built up of the circuit breaker 100 that ultimately results in faster fault clearance or breaking capacity of the MCCB 100.
III. The deion plates 10, 1! significantly reduce arcing times & cut off current which also help to reduce total let through energy passed on to the downstream equipments.
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 improved arc chute assembly of a moulded case circuit breaker, the
arc chute assembly comprising:
an opposed pair of arc chute lining having a stack of a plurality of first deion plates and a plurality of second deion plates, the first deion plates and the second deion plates rigidly supporting on a plurality of rectangular slots defined on the arc chute lining through a mechanical clamping means, the first deion plates and the second deion plates eccentrically positioned therein to form an additional space, the first deion plates and the second deion plates producing a magnetic pull for lengthening an electric arc therein.
2. The arc chute assembly as claimed in claim 1, wherein the mechanical
clamping means is crimping.
3. The arc chute assembly as claimed in claim 1. wherein the first deion
plates and the second deion plates mutually improve an arc voltage built up.
4. The arc chute assembly as claimed in claim 1, wherein the first deion
plates and the second deion plates mutually facilitate a fast fault clearance, a low
arcing time, a low cut off current and a low let through energy.