F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. Title of the invention: AN IMPROVED ARRANGEMENT HAVING REDUCED SKIN EFFECT LOSSES FOR USE IN CIRCUIT BREAKERS

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 NVENTION

The present invention relates to circuit breakers. More particularly, the invention is concerned about an improved arrangement having reduced skin effect losses for use in circuit breakers.

BACKGROUND OF THE INVENTION

Circuit breakers are used for protection of electric network/circuit and equipments. A circuit breaker consist of a outer enclosure in which switching (make/break) takes place, a current path which is connected to the main supply line and make/break electric supply, a mechanism which may be a combination of a number of mechanical links or may be any arrangement which stores energy and releases in mechanical form when required. The current path/conductor of circuit breaker is made of highly electric conductive materials to reduce the I2R losses. In current path mainly two types of losses takes place which are I2R losses (DC losses) and eddy current or AC losses (skin and proximity effect losses).

Conventionally there are use of flexible braids of a conductive material is common current path assembly. In some applications flexible strips of a conductive material which stacked in a bunch are also used. A flexible conductor is required to allow the free movement of the moving contact. In case of DC supply the main losses are due to the resistance of the conductor path. So the existing technologies are effective enough. But when the circuit breakers used for AC supply some extra losses due to changing magnetic field of AC occurs. These losses are mainly skin effect losses and proximity effect losses. However the proximity effect can be reduced by the use of some kind of ferromagnetic or conductive shielding. One available solution for skin effect is to use an arrangement of hollow conductor parts. Since the hollow conductors can reduce some amount of skin effect but the use of it in the circuit breakers is difficult. Since the hollow conductor has less material mass there will be a great reduction of the heat dissipation capacity of the conductor. Since the whole conductor path arrangement of a circuit breaker is enclosed by a housing the temperature of the conductor will increase drastically due to poor heat dissipation. This incorporates extra losses in the circuit breakers because the resistance of the conductor path goes on increasing with the increment in the temperature.

US 4,546,210 discloses a plurality of strands each comprising a conductor covered with an insulating layer and then with an adhesive layer are twisted together and fixed to each other by fusing of the adjacent adhesive layers to form a litz wire which will not be deformed even by an external force.

US 4,549,042 discloses a litz wire comprises three or more insulated strands consisting essentially of an inner conductor and an outer insulating layer on said conductor. The strands are twisted symmetrically with respect to the center line of the wire, so that a current density distribution in the litz wire becomes uniform. Three or more such litz wires are twisted to form a composite litz wire. The composite litz wires are suitable for use in a high-frequency coil.

US 2006162952 (A1) discloses an improved the electrical and mechanical properties of a litz wire conductor (1) for coils of electric machines. For this purpose, the interstices between the filaments (3) of a conductor (1) are filled with an elastic potting compound (4). In order to allow for more regular marginal field intensities in the circumferential area, the potting compound (4) can be electrically conducting. For filling the interstices, the individual filaments (3) can also be provided with a coating which accelerates curing of the steeping agent.

Thus, there is a need to overcome the problems of the prior art. There is a need to reduce the eddy current (AC losses) losses in the conductor path by the use of a special arrangement such a manner that the overall skin effect losses of the assembly reduced significantly. So, the present inventors have developed an improved arrangement having reduced skin effect losses for use in circuit breakers for reducing the overall skin effect losses of the system.

OBJECTS OF THE INVENTION
An object of the present invention is to overcome the problems/disadvantages of the prior art.

Another object of the present invention is to provide an improved arrangement having reduced skin effect losses for use in circuit breakers.

These and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided an improved arrangement having reduced skin effect losses for use in circuit breakers, said arrangement comprising:
a housing;
plurality of conductor path assemblies;
wherein each said conductor path assembly comprising:
plurality of terminal means comprising a main terminal means, terminal means;
plurality of flexible conductor means ;
plurality of conductor finger means;
wherein said main terminal means being operatively assembled in said housing; said flexible conductor means being operatively arranged between said main terminal means and said conductor finger means such that skin effect losses being reduced when current flows between said plurality of terminal means.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Other features as well as the advantages of the invention will be clear from the following description.
In the appended drawings:

FIGURE 1: shows the complete arrangement of various components assembled together.

FIGURE 2: shows the housing in which conductor path assembly will be fixed.

FIGURE 3: shows the two different views of conductor path assembly of circuit breaker.

FIGURE 4: shows the basic construction of litz wire with both ends soldered.

FIGURE 5: shows the back view of the housing and conductor assembly shown in fig 1.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and illustrate the best mode presently contemplated for carrying out the invention. Further functioning of the arrangement has been discussed below to describe the way the arrangement operates. However, such description should not be considered as any limitation of scope of the present unit. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.

According to the invention there is provided an improved arrangement having reduced skin effect losses for use in circuit breakers. The arrangement comprises an outer enclosure or housing 1 as shown in figure 1. The housing (1) has another half part to form complete enclosure. The housing provides insulation of the current carrying conductor path from the outer environment. The housing (1) is made of some insulator material. The conductor path is assembled in two slots 11 and 12 provide in the housing (1) as shown in figure 2. The number of conductor paths depending on the supply can be assembled in the chambers provided on the housing. As shown housing (1) in figure 2 can have three conductor path assemblies in three chambers 13, 14 and 15.

Conductor path assembly as shown in figure 3 is the arrangement of the various conductor parts. It has a main terminal 3 which is assembled in the housing 1 in bottom side slot 12, a flexible litz wire 7, and conductor finger 10. Both the ends of the litz wire as shown in figure 4 are soldered. An advanced technique of soldering is used which removes the enamel of wire by high temperature heating and then solidifying it. The litz wire is joined at joint 9 with the terminal 3 by crimping or pressure welding. The other end of the wire is joined at 5 with the conductor finger 10 by crimping or pressure welding.

The conductor path can have a number of fingers as shown in figure 3, each individual fingers are connected to the terminal 3 by respective litz wire. A hole 16 is provided in all fingers to aline all fingers by a pin. This pin also provides a hinge point for free movement with litz wires. On the each finger profile 8 is provided to assemble springs. Springs are assembled to provide sufficient contact force when the breaker is closed. A high conductive material (Ag alloys) button 4 is brazed on the finger to make the low resistance contact with terminal 2 when breaker closes. The top profile 6 of the finger provides an angular path to the arc thus improves the arc elongation and arc running properties when breaker opens.

When the circuit breaker assembly is connected to the main supply, the supply is connected to the terminals 2 and 3 from the back side of the housing 1 as shown in figure 5 . As long as the breaker is open there is no contact between finger button 4 and top terminal 2 so no any current flows. When the breaker closes with the help of some mechanism all fingers travel forward and make contact with terminal 2. Current start flowing from terminal 3 to litz wire 7 to finger 10 to button 4 to terminal 2 or it may in opposite loop. Since the litz wire comes in main current path, the overall skin effect seen by current in complete arrangement is less as compare to existing techniques. So the watt loss which occurs from starting point of the terminal 3 to end point of terminal 2 is less. As a result by the use of conductor path arrangement shown in present invention the overall current carrying capacity and thus overall efficiency of the circuit breaker increases.

The present invention is provided with a conductor path arrangement which have several components assembled together in such a manner that the overall skin effect losses of the assembly reduced significantly. The arrangement has conductor material terminal, flexible conductors, conductive material fingers which move to make or break the circuit with the help of a mechanism. The flexible conductor is made of litz wire. Since the litz wire has the special arrangement of the insulated wire strands the skin effect losses in the litz wire is very less as compare to other flexible conductor. The arrangement of the insulated strands in litz wire is such that the each and every strand of wire comes on the outer surface of the complete wire. This evenly distribute the current in cross section of complete wire thus reduces the overall skin effect losses of the system in which it is assembled.

ADVANTAGES OF THE INVENTION
1. Reducing skin effect losses
2. Reduction in watt loss

WE CLAIM

1. An improved arrangement having reduced skin effect losses for use in circuit breakers, said arrangement comprising:
a housing;
plurality of conductor path assemblies;
wherein each said conductor path assembly comprising:
plurality of terminal means comprising a main terminal means, terminal means;
plurality of flexible conductor means ;
plurality of conductor finger means;
wherein said main terminal means being operatively assembled in said housing; said flexible conductor means being operatively arranged between said main terminal means and said conductor finger means such that skin effect losses being reduced when current flows between said plurality of terminal means.

2. Arrangement as claimed in claim 1, wherein said housing comprising plurality of slots.
3. Arrangement as claimed in claim 1, wherein said flexible conductor means both ends being soldered and the like.
4. Arrangement as claimed in claim 1, wherein said flexible conductor means is a litz wire and the like.
5. Arrangement as claimed in claim 1, wherein said main terminal means comprises a joint means.
6. Arrangement as claimed in claim 1, wherein said each conductor finger comprises a hole means.
7. Arrangement as claimed in claim 6, wherein said hole being adapted to have a pin means.
8. Arrangement as claimed in claim 1, wherein said each conductor finger adapted to assemble plurality of spring means.

9. An improved arrangement having reduced skin effect losses for use in circuit breakers as herein substantially described and illustrated with the accompanying drawings.