FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13)
TITLE OF THE INVENTION: ARC PULLER ASSEMBLY FOR CIRCUIT BREAKERS
APPLICANT: LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra
INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to the circuit breakers and particularly relates to a contact system in the molded case circuit breakers. More particularly the present invention relates to a contact system with an arc puller assembly for the molded case circuit breakers.
B) BACK GROUND OF THE INVENTION
[0002] Circuit breakers are the mechanical switching devices capable of making. carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and breaking currents under specified abnormal conditions. A circuit breaker basically consists of a pair of separable contacts and an interrupting medium. The function of the contacts is to conduct the electrical current when the breaker is closed and to withstand the arcs while interrupting. Generally the electrical contacts have a stationary part and a moving part. By bringing the moving contact to touch the stationary contact, an electric current flows and the breaker is closed. By driving the moving contact away from the stationary contact, an electric arc is developed and by quenching the electrical arc, the flow of electrical current is stopped and the breaker is opened.
[0003] In the existing techniques, the circuit breakers are extensively used in the power distribution systems to provide a protection for an electrical equipment from the electrical fault conditions such as current overloads, short circuits and abnormal level voltage conditions. The short circuit capacity of any circuit breaker is governed by the performance of an arc quenching chamber in the circuit breakers. Further, in the existing techniques, the circuit breakers consist of the arc chamber assembly which when subjected to a short circuit current of few kilo amperes quench the arc with the long arcing times. The long arcing times leads to the creation of a stress on the downstream equipments due to a large amount of let through energy.

[0004] In the existing techniques, the circuit breaker does not include an efficient arc puller mechanism for enhancing the magnetic pull on the arc towards the arc chute assembly. Further in the existing technique, the circuit breakers include conventional arc chamber assemblies that do not generate an effective magnetic pull on the arc generally during short circuit conditions.
[0005] Hence there is a need for an arc puller mechanism in the molded circuit breakers for enhancing the magnetic pull on the arc towards the arc chute assembly.
[0006] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
C) OBJECT OF THE PRESENT INVENTION
[0007] The primary object of the present invention is to provide an arc puller assembly in the molded case circuit breakers to enhance a magnetic pull on the arc towards the arc chute assembly.
[0008] Another object of the present invention is to provide an arc puller assembly in the molded case circuit breakers to reduce an arc running time in the arc chute assembly.
[0009] Yet another object of the present invention is to provide an arc puller assembly in the molded case circuit breakers to generate a Higher arc voltage.
[0010] Yet another object of the present invention is to provide an arc puller assembly in the molded case circuit breakers to reduce the total arcing time and a let through energy.
D) SUMMARY OF THE INVENTION

[0011] The various embodiments of the present invention provide a contact assembly for a molded case circuit breaker. The contact assembly includes an arc chute assembly, a plurality of de-ion plates arranged in the arc-chute assernbly, a moving contact, a fixed contact and an arc puller assembly. The arc puller assernbly is adapted to enhance an inward magnetic pull on an arc which allows the arc to penetrate into the plurality of de-ion plates thereby fastening the arc movement towards the arc chamber assembly.
[0012] According to one embodiment of the present invention, the arc puller assembly comprises an arc puller and an arc puller enclosure.
[0013] According to one embodiment of the present invention, the arc puller assembly is made up of a highly permeable magnetic material.
[0014] According to one embodiment of the present invention, the arc puller along with an arc puller enclosure is inserted into a cavity of the are chute assembly.
[0015] According to one embodiment of the present invention, the arc puller enclosure is made up of an insulating material with high are resistance.
[0016] According to one embodiment of the preset invention, the arc puller assembly is placed immediately after the arc chute assembly to maximize the inward magnetic pull on the arc towards the arc chute assembly.
[0017] According to one embodiment of the present invention, the arc puller assembly is placed on either sides of the arc chute assembly or at the center of the arc chute assembly.
[0018] According to one embodiment of the present invention, the cross-section of the arc puller is square shaped.

[0019] According to one embodiment of the present invention, the contact assembly includes a release assembly and a knob.
[0020] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings in which:
[0022] FIG. 1 illustrates a cross sectional view of the molded case circuit breaker according to one embodiment of the present invention.
[0023] FIG.2 illustrates a top side perspective view of the arc puller assembly in molded case circuit breakers, according to one embodiment of the present invention,
[0024] FIG.3 illustrates a front view of a molded case circuit breaker without a cover, according to one embodiment of the present invention.
[0025] FIG.4 illustrates a front view of a molded case circuit breaker with a cover. according to one embodiment of the present invention.
[0026] Although the specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

F) DETAILED DESCRIPTION OF THE INVENTION
[0027] In the following detailed description, a reference is made to the accompanying drawings that form a part hereof and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0028] The various embodiments of the present invention provide a contact assembly in a molded case circuit breaker. The contact assembly includes an arc chute assembly, a plurality of de-ion plates arranged in the arc-chute assembly, a moving contact, a fixed contact and an arc puller assembly. The arc puller assembly is adapted to enhance an inward magnetic pull on an arc which allows the arc to penetrate into the plurality of de-ion plates thereby increasing the length of the arc.
[0029] FIG. 1 illustrates a cross sectional view of the molded case circuit breakers according to one embodiment of the present invention while FIG.2 illustrates a perspective view of the arc puller assembly in molded cass; circuit breakers, according to one embodiment of the present invention. With respect to the FIG.l and FIG.2, the molded case circuit breaker includes a housing 102, a release assembly 104, a knob 106. a moving contact 108, a fixed contact 110, an arc chute assembly 112, a front vent 1! 4, a back vent 116. an arc puller 202, an arc puller enclosure 204 and a plurality of de-ion plates arranged in the arc chute assembly 132.
[0030] An arc puller assembly is designed in such a way that the arc puller exerts a maximum magnetic pull on the arc. The arc puller assembly is inserted into the molded case circuit breakers at the final assembly phase. The arc puller assembly includes the arc puller 202 and the arc puller enclosure 204.

[0031] The are puller 202 in the arc puller assembly is made up of a magnetic material with high permeability. The arc chute assembly 112 is inserted into the molded case circuit breaker as shown in F1G.1. The arc puller assembly along with the arc pull enclosure is inserted into a cavity of the arc chute assembly ] 12 as shown in FIG.2.
[0032] The arc puller assembly remains enclosed in the cavity of the arc chute assembly 112. The arc puller enclosure is made up of an insulating material with high arc resistance that can sustain a high temperature during the short circuit conditions.
[0033] The arc puller assembly enhances the breaking capacity of the circuit breakers by increasing an inward magnetic pull on the arc. Further due to the enhancement of the inward magnetic pull, the arc penetrates into the plurality of de-ion pistes which in turn increases the length of the arc. The are movement in the arc chute assembly 112 reduces the total arcing time and the let through energy. According to one embodiment herein, the cross section of the arc puller 202 is in a square shape. Also, the arc puller 202 can be provided with any shape suitable for the ease of manufacturability.
[0034] FIG.3 illustrates a front view of the molded Case circuit breaker without a cover, according to one embodiment of the present invention, while FIG.4 illustrates a front view of the molded case circuit breaker with a cover, according to one embodiment of the present invention. With respect to FIG.3 and F1G.4, the molded case circuit breaker includes a cover 402. The arc puller assembly is located immediately after the arc chute assembly 112 and maximizes the inward magnetic pull on the arc towards the arc chute assembly 112 as shown in FIG.3.
[0035] The arc puller assembly is located on either sides of the arc chute assembly 112 or at the centre or both. The arc puller assembly is adapted to enhance an inward magnetic pull on an arc which allows the arc to penetrate into the plurality of de-ion plates thereby increasing the length of the arc and also the arc voltage built up. The built up higher arc voltage reduces the cut off current which in turn reduces the total arcing time and let through energy.

G) ADVANTAGES OF THE INVENTION
[0036] The various advantages of the present invention are that the arc puller assembly in the molded case circuit breaker reduces an arc running time and a total arcing time. The lower arcing time in turn reduces the total let through energy passed on to the downstream side equipments. Further the arc puller assembly is adapted to enhance an inward magnetic pull on an arc. The inward magnetic pull exerted on the arc allows the arc to penetrate into the plurality of de-ion plates thereby increasing the length of the arc. The increase in length of the arcincreases the arc voltage which in turn reduces the cut off current. Further the contact opening time is reduced and the arc velocity is increased.
[0037] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.
[0038] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.

CLAIMS
What is claimed is:
1. A contact assembly of a molded case circuit breaker comprising:
an arc chute assembly;
a plurality of de-ion plates arranged in the arc-chute assembly;
a moving contact;
a fixed contact; and
an arc puller assembly;
wherein the arc puller assembly is adapted to enhance an inward magnetic pull on
an arc which allows the arc to penetrate into the plurality of de-ion plates thereby
fastening the arc movement towards the arc chamber assembly.
2. The contact assembly according to claim I, wherein the arc puller assembly comprises an arc puller and an arc puller enclosure.
3. The contact assembly according to claim 1, wherein the arc puller assembly is made up of a highly permeable magnetic material.
4. The contact assembly according to claim 2, wherein the arc puller along with the arc puller enclosure is inserted in a cavity of the arc chute assembly.
5. The contact assembly according to claim 1, wherein the arc puller enclosure is made up of an insulating material with high arc resistance.
6. The contact assembly according to claim 1. wherein the arc puller assembly is placed immediately after the arc chute assembly to maximize the inward magnetic pull on the arc towards the arc chute assembly.
7. The contact assembly according to claim 1. wherein the arc puller assembly is placed on either sides of the arc chute assembly or at the center of the arc chute assembly.
8. The contact assembly according to claim 1, wherein a cross-section of the arc puller is of any regular shape or irregular shape.

9. The contact assembly according to claim 1, wherein a cross-section of the arc puller is square shaped.
10. The contact assembly of claim 1 further comprises a release assembly and a knob.