A) TECHNICAL FIELD

[1] The present invention generally relates to low voltage circuit breakers and particularly to Moulded Case Circuit Breakers (MCCB). The present invention more particularly relates to providing plug-in contact system for the MCCB to electrically connect the MCCB to panel boards.

B) BACKGROUND OF THE INVENTION

[2] Circuit interrupters are widely used in domestic, commercial and light industrial installations. Circuit breakers provide protection for electrical systems from electrical fault conditions such as current overloads, short circuits, and low level voltage conditions. Plug-in contact system helps the circuit breakers to electrically get connected to panel boards. In current scheme, in the plug-in contact system more than two parallel paths of current are employed in fixed contact. Thus, there exist two electrical joints per path. As the number of the electrical joints increases the I2R losses increases, which in turn increase the temperature of the contact system during usage condition. Further, the joint resistance is one of the major causes of the temperature rise in the plug-in contact systems. Usage of heavy springs will aid in increase in the diameter of the fixed contact which in turn increases the overall space requirement to accommodate the plug-in contact system.
[3] In another scheme, to plug out the circuit breaker from the plug-in base, a user has to hold the circuit breaker and apply outward force directly to the breaker. Further, greater spring force is required in order to bring down the contact resistance between the electrical joints. To achieve greater spring force, bigger springs are used, which will in turn increase the overall size of the plug-in contact system and the user has to exert more force to plug-in and plug-out the breaker from the plug-in base.
[4] Hence, there exists a need to provide an efficient plug-in contact system for circuit breaker to reduce temperature rise of the system with reduced electrical contact joints and reduced spring force.
[5] 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 INVENTION
[6] 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.
[7] The primary object of the present invention is to provide a plug-in contact system for circuit breaker to reduce temperature rise of the system with reduced electrical contact joints and reduced spring force.
[8] Another object of the present invention is to provide a plug-in contact system for circuit breaker with two parallel paths for current in fixed contact assembly of plug-in base.
[9] Another object of the present invention is to provide a plug-in contact system for circuit breaker to provide uniform radial pressure distribution for cylindrical type moving contacts while plugging in the circuit breaker into a plug- in base.
[10] Yet another object of the present invention is to provide a plug-in base contact system with reduced spring loaded electrical contacts.
Yet another object of the present invention is to provide a plug-in contact system for circuit breaker which occupies less operational space.
[12] Yet another object of the present invention is to provide a plug-in contact system for circuit breaker for easy disengagement of the circuit breaker from the plug-in base.
[13] Yet another object of the present invention is to provide a plug-in contact system for a circuit breaker to provide easy plug-in operation due to less spring force employed in contacts.
D) SUMMARY OF THE INVENTION
[14] The various embodiments of the present invention provide a plug-in contact system for a circuit breaker. The contact system includes a plug-in base, one or more fixed contact assemblies provided in the plug-in base and one or more moving contacts provided in the circuit breaker. The fixed contact assembly consists of two 'H' shaped half’s which are held in position with a plurality of garter springs provided at comers of the 'H' shaped half’s for applying required pressure radially on the moving contacts. The contact system reduces temperature rise of with reduced electrical contact joints and provides reduced spring force.
[15] According to one embodiment of the present invention, the contact system includes a shaft provided in the plug-in base, a connecting pin provided in the shaft, a folding handle provided on at least one side of the plug-in base and an ejector lever connected to the shaft. The moving contact of the contact system protrudes at rear side of the circuit breaker. The moving contacts are hollow and cylindrical in shape and are made of copper.
[16] The plug-in base is connected to a panel board. The terminals associated with the plug-in base are bolted to bus bars of the panel board. The two 'H' shaped half s of the fixed contact assembly are made of copper forming a rectangular block. Each of the 'H' shaped half of the fixed contact assembly is provided with a half cylindrical cut on one side facing each other. At least one holding pin is provided on two 'H' shaped half for holding the garter springs. The fixed contact system includes at least four garter springs to provide the required pressure.
[17] The fixed contact assembly further includes a 'L' shaped terminal, a bolt connecting the 'L' shaped terminal to the fixed contact assembly, a slit provided on top of each of the 'H' shaped half facing each other. A 'T' shaped connector is locked to one end of each of the 'H' shaped half with the help of the slit, a plastic rod connected to centre of the 'T' shaped connector by click fitting and a shield mounted on joining of the two 'H' shaped half. The 'L' shaped terminal is connected for both rear end electrical connection and front end electrical connection.
[18] The moving contact of the circuit breaker enters 'H' shaped copper block and the plastic rod moves into the hollow structure provided in the moving contact during plugging operation of the circuit breaker. The folding handle is manually rotated up to an angle of 90 degrees in the connecting pin to withdraw the circuit breaker from the plug-in base. The ejector lever pushes the circuit breaker away from the plug-in base while pulling the folding handle for withdrawing the circuit breaker from the plug-in base. The plug-in contact system reduces electrical contact joints, temperature rise and spring force. The contact system requires less operational space. The contact system provides easy plug-in operation due to less spring force employed in contacts. The contact system provides easy disengagement of the circuit breaker from the plug-in base with help of a folding handle.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[19] 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:
[20] FIG. 1 illustrates a side perspective view of a circuit breaker and plug-in base with the circuit breaker being plugged out from the plug-in base according to one embodiment of the present invention.
FIG. 2 illustrates a rear perspective view of the circuit breaker according to one embodiment of the present invention.
[22] FIG. 3 illustrates a front perspective view of the plug-in base according to one embodiment of the present invention.
[23] FIG. 4 illustrates a side perspective view of a fixed contact assembly of plug-in base according to one embodiment of the present invention.
[0024[ FIG. 5 illustrates an exploded view of the fixed contact assembly according to one embodiment of the present invention.
[25] FIG. 6 illustrates a side perspective view of the circuit breaker plugged into plug-in base and position of folding handle according to one embodiment of the present invention.
[26] FIG. 7 illustrates a side perspective view of a circuit breaker indicted with a direction of pull of folding handle and movement of ejector lever while plugging out the circuit breaker from plug-in base according to one embodiment of the present invention.
[27] FIG. 8 illustrates a rear perspective view of the plug-in base according to one embodiment of the present invention.
[28] FIG. 9 illustrates a perspective view of the moving contact of the circuit breaker and the fixed contact of the plug-in base according to one embodiment of the present invention.
[29] FIG. 10 illustrates a side perspective view of the moving contact of circuit breaker connected to the fixed contact of the plug-in base according to one embodiment of the present invention.
[30] Although 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
[31] In the following detailed description, 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.
[32] The various embodiments of the present invention provide a plug-in contact system for a circuit breaker. The contact system includes a plug-in base, one or more fixed contact assemblies provided in the plug-in base and one or more moving contacts provided in the circuit breaker. The fixed contact assembly consists of two 'H' shaped half s which are held in position with a plurality of garter springs provided at corners of the 'H' shaped half s for applying required pressure radially on the moving contacts. The contact system reduces temperature rise of with reduced electrical contact joints and provides reduced spring force.
[33] According to one embodiment of the present invention the contact system includes a shaft provided in the plug-in base, a connecting pin provided in the shaft, a folding handle provided on at least one side of the plug-in base and an ejector lever connected to the shaft. The moving contact of the contact system protrudes at rear side of the circuit breaker. The moving contacts are hollow and cylindrical in shape and are made of copper.
[34] The plug-in base is connected to a panel board and terminals associated with the plug-in base are bolted to bus bars of the panel board. The two 'H' shaped halfs of the fixed contact assembly are made of copper forming a rectangular block. Each of the 'H' shaped half of the fixed contact assembly is provided with a half cylindrical cut on one side facing each other. At least one holding pin is provided on two 'H' shaped half for holding the garter springs. The numbers of garter springs used in the fixed contact system are four.
[35] The fixed contact assembly further includes a 'L' shaped terminal, a bolt connecting the 'L' shaped terminal to the fixed contact assembly, a slit provided at top of each of the 'H' shaped half facing each other. A 'T' shaped connector is locked to one end of each of the 'H' shaped half with the help of the slit, a plastic rod connected to centre of the 'T' shaped connector by click fitting and a shield mounted on joining of the two 'H' shaped half. The 'L' shaped terminal is connected for both rear end electrical connection and front end electrical connection.
[0036| The moving contact of the circuit breaker enters 'H' shaped copper block and the plastic rod moves into the hollow structure provided in the moving contact during plugging action of the circuit breaker. The folding handle is manually rotated up to an angle of 90 degrees in the connecting pin to withdraw the circuit breaker from the plug-in base. The ejector lever pushes the circuit breaker away from the plug-in base while pulling the folding handle for withdrawing the circuit breaker from the plug-in base.
[37] FIG. 1 illustrates a side perspective view of a circuit breaker and plug-in base with the circuit breaker being plugged out from the plug-in base according to one embodiment of the present invention. With respect to FIG. 1, the circuit breaker 101 includes a moving contact 103 and the plug-in base 102 includes a fixed contact 104. The FIG.l shows three moving contacts 103 provided in the circuit breaker 101 and three fixed contacts provided in the plug-in base 102. The moving contacts 103 are hollow and cylindrical in shape and are made of copper. For electrically connecting the circuit breaker 101 to panel boards, the plug-in base 102 gets cormected to a panel board and terminals associated with the plug- in base 102 are bolted to bus bars of the panel board.
[38] FIG. 2 illustrates a rear perspective view of the circuit breaker according to one embodiment of the present invention. With respect to FIG. 2, the moving contact 103 of the circuit breaker 101 protrudes at rear side of the circuit breaker. The moving contacts 103 are hollow 105 and cylindrical in shape and are made of copper.
[39] FIG. 3 illustrates a front perspective view of plug-in base 102 according to one embodiment of the present invention. With respect to FIG.3, the plug-in base includes a fixed contact 104, a shaft 302, a connecting pin 303 provided in the shaft 302, a folding handle 304 is provided on right hand side of the plug-in base 102 and an ejector lever 305 is connected to the shaft 302. The folding handle 304 is manually rotated up to an angle of 90 degrees in the connecting pin 303 to withdraw the circuit breaker from the plug-in base 102. The rotation of the folding handle 304 causes a simultaneous rotation of until the ejector lever hits the connecting pin 303. Following the rotation of the ejector lever, the ejector lever 305 pushes the circuit breaker away from the plug-in base 102 while pulling the folding handle 304 for withdrawing the circuit breaker from the plug-in base 102.
[40] FIG. 4 illustrates a side perspective view of fixed contact assembly of the plug-in base according to one embodiment of the present invention. With respect to FIG.4, the fixed contact 104 consists of two 'H' shaped halves 401a, 401b which are held in position with a plurality of springs provided at comers of the 'H' shaped halves 401a, 401b for applying required pressure radially on the moving contacts (103, as shown in FIG.2) of the circuit breaker. The fixed contact assembly includes a plurality of elements for receiving moving contact of the circuit breaker and electrically connecting the circuit breaker to the panel boards. .
[41] FIG. 5 illustrates an exploded view of the fixed contact assembly according to one embodiment of the present invention. With respect to FIG. 5, The fixed contact assembly 104 includes a 'L' shaped terminal 501, a bolt 502 connecting the 'L' shaped terminal to the fixed contact assembly 103, and a slit 503 provided on top of each of the 'H' shaped half 401a,401b facing each other. A 'T' shaped connector 504 is locked to one end of each of the 'H' shaped half with the help of the slit 503. A plastic rod 505 is connected to centre of the 'T' shaped connector 504 by click fitting and a shield 506 is mounted on joining of the two 'H' shaped half 401a, 401b'. The 'L' shaped terminal is connected for both rear end electrical connection and front end electrical connection.
[42] Each of the 'H' shaped half is provided with two pins 508 for holding two garter springs 507 at the corner of each of the 'H' shaped half The moving contact (103, as shown in FIG.2) of the circuit breaker enters 'H' shaped copper block 401a, 401b and the plastic rod 505 moves into the hollow (105, as shown in FIG.2) structure provided in the moving contact during plugging action of the circuit breaker. Current from the bus-bar enters into the incoming 'L' shaped terminal 501, which is bolted to the 'T' shaped cormector 504. Further, the current divides into two and enters into the two 'H' shaped halves 401a, 401b. Once the current enters the 'H' shaped half, the contact pressure at this point is provided by the two springs at the terminal side. Further the current enters the moving contact and flows to the circuit breaker. The contact pressure at the moving contact side is provided by the pair of springs situated at the moving contact side.
FIG. 6 illustrates a side perspective view of circuit breaker plugged into the plug-in base and the position of the folding handle according to one embodiment of the present invention. The position of the folding handle 304 in the plug-in base 102 is as shown in the figure 6. The folding handle 304 is rotated in an anti-clockwise direction before plugging in the circuit breaker 101 into the plug-in base 102.
[44] FIG. 7 illustrates the direction of pull of folding handle and movement of ejector lever while plugging out the circuit breaker from plug-in base according to one embodiment of the present invention. With respect to FIG. 7, the folding handle 304 is manually rotated up to an angle of 90 degrees in the connecting pin to withdraw the circuit breaker 101 from the plug-in base 102. When the folding handle 304 is rotated, the shaft 302 (as shown in FIG. 3) also rotates simultaneously in a lockwise direction, the ejector lever 305 which connected in the shaft also rotates in the same degrees, until the ejector lever 305 hits in the connecting pin. The ejector lever 305 pushes the circuit breaker 101 away from the plug-in base 102 while pulling the folding handle 304 for withdrawing the circuit breaker 101 from the plug-in base 102.
[45] FIG. 8 illustrates a rear perspective view of plug-in base according to one embodiment of the present invention. With respect to FIG. 8, the 'L'shaped terminal 501 arranged in fixed contact of the plug-in base 102 connected for both rear end electrical connection and front end electrical connection.
[46] FIG. 9 illustrates an exploded view of the moving contact of circuit breaker getting connected to fixed contact of the plug-in base according to one embodiment of the present invention. With respect to FIG.9, while plugging the circuit breaker into plug-in base the moving contact 103 of the circuit breaker gets connected with the fixed contact 104 of the plug-in base. During plugging operation, the plastic rod 505 of the fixed contact assembly gets inserted into hollow 105 cylindrical shape moving contact of the circuit breaker.
[47] FIG. 10 illustrates side perspective view of moving contact of circuit breaker connected to fixed contact of plug-in base according to one embodiment of the present invention. With respect to FIG. 10, the moving contact 103 of the circuit breaker is connected to the fixed contact 104. Plastic rod (505, as shown in FIG 9) is inserted into hollow 105 cylindrical shape moving contact.
G) ADVANTAGES OF THE INVENTION
[48] The various embodiments of the invention provide a plug-in contact system for circuit breakers. The plug-in contact system reduces the temperature rise in the system by reducing the electrical contact joints and the spring force. The contact system requires less operational space as the springs are arranged inside the contact system, thereby reducing the horizontal space requirement in the plug-in base. The contact system provides easy plug-in operation due to less spring force employed in contacts. The folding handle of the contact system provides for easy disengagement of the .circuit breaker from the plug-in base.
[49] 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.
[0050] 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 plug-in contact system for a circuit breaker , the system comprising: a plug-in base;
one or more moving contacts provided in the circuit breaker;
one or more fixed contact assemblies provided in the plug-in base;
wherein the fixed contact assembly is provided with a predefined profile and a
plurality of springs are arranged inside the fixed contacts to apply a pressure on
the moving contacts to reduce temperature rise of the system with reduced the
electrical contact joints and reduced a spring force.

2. The plug-in contact system of claim 1, wherein the predefined profile of the fixed contact assembly includes at least two H shaped halves with a half cylindrical cut on at least one side facing each other.

3. The plug-in contact system of claim 1, wherein the plurality of springs are garter springs.

4. The plug in contact system of claim 1, wherein number of garter springs are four

5. The plug-in contact system of claim 1, wherein the plug-in base is connected to a panel board and terminals associated with the plug-in base are bolted to bus bars of the panel board.

6. The plug-in contact system of claim 1, wherein the two 'H' shaped half s of the fixed contact assembly are made of copper.

7. The plug-in contact system of claim 1, wherein each of the 'H' shaped half is provided with two pins for holding two springs at the comer of each of the 'H'
shaped half.

8. The plug-in contact system of claim 1, wherein the fixed contact assembly further comprising:
a 'L' shaped terminal;
a bolt connecting the 'L' shaped terminal to the fixed contact assembly; a slit provided at top each of the 'H' shaped half facing each other; a 'T' shaped connector locked to one end of each of the 'H' shaped half with t the slit;
a rod connected to centre of the 'T' shaped connector by click fitting; and a shield mounted on joining of the two 'H' shaped halves.

9. The plug-in contact system of claim 1, wherein the rod is made of plastic material.

10. The plug-in contact system of claim 1, wherein at least one holding pin is provided on two 'H' shaped half for holding the plurality of springs.

11. The plug-in contact system of claim 6, wherein the 'L' shaped terminal is connected for both rear end electrical connection and front end electrical connection.

12. The plug-in contact system of claim 1, wherein the moving contacts are hollow and cylindrical in shape.

13. The plug-in contact system of claim 1, wherein the moving contacts are made of copper.

14. The plug-in contact system of claim 6, wherein the H shaped halves are adapted to receive the moving contact of the circuit breaker and the rod moves into the hollow structure provided in the moving contact during a plugging action of the
circuit breaker.

15. The plug -in contact system of claim 1, further comprising:
a shaft provided in the plug-in base; a connecting pin provided in the shaft;
a folding handle provided on at least one side of the plug-in base; and an ejector lever connected to the shaft;

16. The plug-in contact system of claim 10, wherein the folding handle is manually rotated up to an angle of 90 degrees in the connecting pin to withdraw the circuit breaker from the plug-in base.

17. The plug-in contact system of claim 10, wherein the ejector lever pushes the circuit breaker away from the plug-in base while pulling the folding handle for withdrawing the circuit breaker from the plug-in base.