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: COMPOSITE ARC CHAMBER 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 circuit breakers and particularly relates to molded case circuit breakers. The present invention more particularly relates to an arc chamber assembly in 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 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, electric current flows and the breaker is closed. By driving the moving contact away from the stationary contact the electric arc develops and by quenching it the current stops flowing and the breaker is open.
[0003] In the existing technique, the circuit breakers are extensively used in the power distribution systems to provide protection for electrical equipment from electrical fault conditions such as current overloads, short circuits and abnormal level voltage conditions. Further the short circuit capacity of any circuit breaker is governed by the performance of an arc quenching chamber in the circuit breakers.
[0004] Further in the existing technique, the circuit breakers consist of an arc chamber assembly which when subjected to a short circuit current of few kilo amperes quench the arc with long arcing times. The long arcing times leads to

creating a stress on the downstream equipments due to large amount of let through energy. Further the arcing time increases due to the inability to cool the arc effectively during high fault conditions in the circuit breakers.
[0005] In the existing technique, the insulation surrounding the arc is subjected to deposition of carbon material due to burning of the insulation during the arcing process. Further the deposition of carbonaceous material forms tracking of the insulation which leads to flashover between one pole and another pole.
[0006] Hence there is a need for a system to build dielectric quickly and to reduce the total arcing time and let through energy.
[0007] 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
[0008] The primary object of the present invention is to provide an arc chamber assembly with an inbuilt heat sink in circuit breakers.
[0009] Another object of the present invention is to provide an arc chamber assembly with one or more heat sinks that reduces let through energy by faster cooling of the arc.
[0010] Yet another object of the present invention is to provide an arc chamber assembly with one or more heat sinks to dissipate the arc energy generated during short circuit conditions quickly.

[0011] Yet another object of the present invention is to provide an arc chamber assembly which reduces the arcing time by. cooling the arc rapidly and quickly.
[0012] Yet another object of the present invention is to provide an arc chamber assembly which facilitates effective channelizing of gases.
[0013] Yet another object of the present invention is to provide an arc chamber assembly which is easy to assemble.
[0014] 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.
D) SUMMARY OF THE INVENTION
[0015] The various embodiments of the present invention provide a circuit breaker with an arc chamber assembly having a heat sink assembly arranged between a front vent and a back vent. The heat sink assembly has a plurality of rectangular slots. Pluralities of heat sinks are inserted into the rectangular slots of the heat sink assembly for effective arc cooling. Each heat sink includes a high thermally conductive material placed in such a way that the maximum surface area of the high thermally conductive material is exposed to hot ionized gases. At the same time, the high thermally conductive material channelizes the path for gases to exit.
[0016] The heat sinks have higher gaps at the extremes to allow gases to enter the heat sinks. The heat sink assembly is made rigid by crimping the heat sinks from both ends so that the heat sinks sustain high pressures during short circuit conditions.

[0017] The heat sink assembly is placed vertically between the front vent and the back vent in such a way that the direction of the pluralities of the heat sinks converges the hot gases towards an exit. The hot gases generated during short circuit conditions pass through converging channels of heat sinks and are effectively being cooled before they exit.
[0018] The hot gases are channelized between the front vent and the back vent through the heat sink assembly. The design of front vent is modified to effectively channelize the gases. An area inside the arc chamber assembly is completely de-ionized and dielectric strength is increased due to the channelizing of the one or more hot gases.
[0019] The pluralities of heat sinks reduce let through energy by faster cooling of the arc. The pluralities of heat sinks reduce stress on the downstream equipments by virtue of the low let through energy.
[0020] According to one embodiment of the present invention, the pluralities of heat sinks in the heat sink assembly are vertical in shape. The heat sinks dissipate the arc energy generated during short circuit conditions. The heat sinks reduce an arcing time by faster cooling of the arc. The heat sink assembly is made rigid by crimping the heat sinks.
[0021] According to one embodiment of the present invention, each heat sink has a fin made up of a high thermal conductive material such as any ferrous or non ferrous material with good thermal conductivity like brass, stainless steel, mild steel, copper etc. The plane of heat sink is perpendicular or parallel or inclined to the arc chamber de-ion plates provided in the arc chamber assembly.

[0022] According to one embodiment of the present invention, the one or more heat sinks is a divergent type heat sinks so that the heat sink assembly is rotated by 180 degrees and inserted between the front vent and the back vent to diverge the hot ionized gas towards the exit.
[0023] According to one embodiment of the present invention, the circuit breaker includes a release and a knob.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
[0025] FIG. 1 illustrates a cross sectional view of the molded case circuit breaker according to one embodiment of the present invention.
[0026] FIG. 2 illustrates a sectional view of a molded case circuit breaker with one or more heat sinks according to one embodiment of the present invention.
[0027] FIG.3 illustrates a front, top, side and isometric views of a heat sink assembly in molded case circuit breakers according to one embodiment of the present invention.
[0028] FIG.4 illustrates a front side view of the molded case circuit breaker without cover according to one embodiment of the present invention.

[0029] 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
[0030] 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.
[0031] The various embodiments of the present invention provide a circuit breaker assembly with an arc chamber assembly, a heat sink assembly, a front vent, a back vent, one or more heat sinks and one or more heat sink supports. The one or more heat sinks are inserted into a one or more rectangular slot of the heat sink assembly for effective arc cooling. The heat sink assembly is placed vertically between the front vent and the back vent in such a way that the direction of the one or more heat sinks converges the one or more hot gases towards an exit. The one or more hot gases are channelized behind the arc chamber assembly between the front vent and the back vent through the heat sink assembly.. The area inside the arc chamber assembly is completely de-ionized and dielectric strength is increased due to the channelizing of the one or more hot gases.

[0032] The one or more heat sinks reduces let through energy by faster cooling of the arc and reduces stress on the one or more downstream equipments by virtue of the low let through energy,
[0033] According to one embodiment of the present invention, the one or more heat sinks of the heat sink assembly are vertical in shape. The one or more heat sinks dissipate the arc energy generated during short circuit conditions. The one or more heat sinks absorbs the heat from the hot air passing across it and reduces the arcing time by faster cooling of the arc. The heat sink assembly is made rigid by crimping the one or more heat sink.
[0034] FIG. 1 illustrates a cross sectional view of the molded case circuit breaker according to one embodiment of the present invention, while FIG. 2 illustrates a sectional view of the molded case circuit breaker with one or more heat sinks according to one embodiment of the present invention. With respect to the FIG.1 and FIG.2, the molded case circuit breaker includes an arc chamber assembly 102, a heat sink assembly 104, a front vent 106, a back vent 108, an upper contact assembly 110, a lower contact assembly 112 and a housing 202.
[0035] The hot gases generated in the circuit breakers are channelized behind the arc chamber assembly 102 between the front vent 106 and the back vent 108 through the heat sink assembly 104. The heat sink assembly 104 includes one or more heat sinks which are placed in the assembly either horizontally or vertically. The one or more heat sinks are made up of highly thermally conductive material such as brass. Further a ferrous or non ferrous materia! with good thermal conductivity such as brass, stainless steel, mild steel and copper is also used for making one or more heat sinks.

[0036] FIG.3 illustrates an isometric view of the heat sink assembly in molded case circuit breakers according to one embodiment of the present invention while FIG.4 illustrates a front side perspective view of the molded case circuit breaker without cover according to one embodiment of the present invention. With respect toFIG.3 and FIG.4, the molded case circuit breaker includes a release 402, a knob 404, the one or more heat sinks 302 and a heat sink support 304.
[0037] The hot gases are first channelized between the front vent 106 and the back vent 108 during a short circuit condition. The hot gases are then passed through the one or more heat sinks 302 for effectively cooling. The process of passing the hot gases through the vents and then through the one or more heat sinks 302 helps in faster dielectric built up and also reduces the total arcing time and let through energy.
[0038] The faster cooling of the arc reduces the let through energy of the circuit breakers. The reduction of the let through energy in turn reduces the stresses on the one or more equipments in the electric system. The one or more heat sinks 302 are inserted into the one or more rectangular slots of the heat sink assembly 104 for effective arc cooling and the heat sink assembly 104 is placed vertically between the front vent 106 and the back vent 108 in such a way that the direction of the one or more heat sinks 302 converges the hot gases towards an exit.
[0039] The one or more heat sinks 302 consist of a highly thermally conductive material and are placed in such a way that the maximum surface area is exposed of the one or more heat sinks 302 to the hot ionized gases. The one or more heat sinks 302 also channelize the path for the hot gases towards an exit. The one or more heat sinks 302 are inserted in the rectangular slots of one of the heat sink support 304. The

rectangular slots of the other heat sink support are aligned with the heat sink assembly 104 and are made rigid by crimping.
[0040] The heat sink assembly 104 includes 9 heat sinks 302 that are placed vertically and held by the heat sink support 304 from both end sections as shown in FIG.3. The distance between the one or more heat sinks 302 varies from 2 to 2.5 mm. Further the gap between the one or more heat sinks 302 are kept at the extremes to allow the hot gases to enter the heat sink assembly 104. The thickness of each of the heat sink fin 302 is kept at 1 mm. The heat sink assembly 104 is made rigid by crimping the one or more heat sinks 302 from both ends so that the one or more heat sinks 302 can sustain high pressures during the short circuit conditions.
[0041] The hot gases generated during short circuit conditions pass through converging channels of the one or more heat sinks 302 and are effectively being cooled before the hot gases exit. The convergent type of the heat sink fin 302 is used in the heat sink assembly 104. Further a divergent type of the heat sink fin 302 can also be used by rotating the heat sink assembly 104 in 180° clockwise direction and then inserted between the two vents. The direction of the heat sink 302 is such that the gases are diverged towards exit. The plane of the one or more heat sinks 302 is perpendicular to the arc chamber de-ion plates and are placed vertically. The plane of the one or more heat sinks 302 is parallel or inclined to the arc chamber assembly 102.
G) ADVANTAGES OF THE INVENTION
[0042] The various advantages of the present invention are that the arc energy generated during short circuit conditions is efficiently dissipated by heat sinks. The hot gases are channelized in an efficient way through the heat sink between the front

vent and the back vent and thus the area inside the arc chamber is completely de-ionized and dielectric strength is built up rapidly. This substantially reduces burden on the downstream equipments by virtue of low let through energy.
[0043] 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.
[0044] 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. An arc chamber assembly for a circuit breaker assembly comprising:
a pluralities of de-ion plates;
a heat sink assembly;
a front vent;
a back vent;
one or more heat sinks integrated within the heat sink assembly; and
one or more heat sink supports;
wherein the heat sink assembly is placed vertically between the front vent and the
back vent in such a way that a direction of the one or more heat sinks converges a
hot ionized gas towards an exit.
2. The assembly according to claim 1, wherein the one or more heat sinks are inserted into one or more of the heat sink support of the heat sink assembly and exposed to the hot ionized gas for effective arc cooling.
3. The assembly according to claim 1, wherein the heat sink assembly has a plurality of slots, to receive the one or more heat sinks.
4. The assembly according to claim 1, wherein the plurality of slots has any shape.
5. The assembly according to claim 1, wherein the one or more heat sinks includes a fin made of thermally conductive material.
6. The assembly according to claim 1, wherein the fins are received in the plurality of slots of the one or more heat sinks.

7. The assembly according to claim I, wherein the front vent and the back vent are arranged to channelize the hot ionized gas to completely de-ionize an area and to increase a dielectric strength inside the area.
8. The assembly according to claim 1, wherein the fins are arranged between the one or more heat sink supports in such a way to converge the hot ionized gas towards an exit.
9. The assembly according to claim 1, wherein the fins of one or more heat sinks are arranged so as to expose a maximum surface area to the hot ionized gases.
10. The assembly according to claim 1, wherein the one or more heat sinks of the heat sink assembly is vertical in shape.
11. The assembly according to claim !, wherein the one or more heat sinks of the heat sink assembly is inclined in shape.
12. The assembly according to claim 1, wherein the one or more heat sink is arranged perpendicular to the pluralities of de-ion plates of the arc chamber assembly.
13. The assembly according to claim I, wherein the one or more heat sink is arranged in parallel to the pluralities of de-ion plates of the arc chamber assembly.
14. The assembly according to claim I, wherein the one or more heat sink is arranged inclined to the pluralities of de-ion plates of the arc chamber assembly.
15. The assembly according to claim 1, wherein the one or more heat sinks of the heat sink assembly is arranged horizontally between the front vent and the back vent.
16. The assembly according to claim 1, wherein the one or more heat sinks of the heat sink assembly is arranged vertically between the front vent and the back vent.

17. The assembly according to claim 1, wherein the one or more heat sinks of the heat sink assembly is arranged inclined between the front vent and the back vent.
18. The assembly accordingly to claim 1, wherein the heat sink assembly is made rigid by any means.
19. The assembly accordingly to claim 1, wherein the heat sink assembly is made
rigid by crimping the one or more heat sinks.
20. The assembly according to claim 1, wherein the one or more heat sinks is a divergent type heat sinks so that the heat sink assembly is rotated by 180 degrees and inserted between the front vent and the back vent to diverge the hot ionized gas towards the exit.