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: CIRCUIT BREAKER ASSEMBLY WITH UNIDIRECTIONAL TRIPPING MECHANISM

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:

A) TECHNICAL FIELD

The present invention generally relates to switching devices and particularly relates to miniature circuit breakers (MCB), residual current circuit breakers (RCCB), isolators and residual current circuit breakers with overload protection (RCBO). The present invention more particularly relates to an accessory device in a circuit breaker assembly to prevent independent tripping due to a reverse tripping command.

B) BACKGROUND OF THE INVENTION

A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. The circuit breaker detects a fault condition in current flow and interrupts the continuity thereby immediately discontinuing the electrical flow. Unlike a fuse, which operates once and then has to be replaced, the circuit breaker can be reset (either manually or automatically) to resume normal operation.
When supplying a branch circuit with more than one live conductor, each live conductor must be protected by a breaker pole. To ensure that all live conductors are interrupted when any pole trips, a "common trip" breaker must be used. These may either contain two or three tripping mechanisms within one case, or for small breakers, may externally tie the poles together via their operating handles.

Generally, in certain applications/systems employing multiple circuit breakers which are assembled together in a side-by-side relationship to provide for multi-pole systems, the automatic tripping of any one of the circuit breakers results in tripping of the other circuit breakers. However, tying all the circuit breakers together for a common automatic tripping makes it impossible to independently trip a circuit breaker in the group. Also, when the number of circuit breakers is interconnected, the interaction between the common trip components of the adjacent circuit breakers may accumulate, thereby making the tripping slow and unreliable.

In view of the foregoing discussion, there exists a need to provide a tripping mechanism which provides for independent tripping of the circuit breakers for multiple circuit breakers placed within one circuit breaker assembly. Further there exists a need for a circuit breaker mechanism that joins two different circuit breakers by a common link in which one circuit breaker is mechanically interdependent on the other circuit breaker. Furthermore, there is a need to provide a tripping mechanism which is compatible with the tight space constraints of the circuit breaker assembly.

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

The primary object of the present invention is to provide a tripping mechanism in circuit breaker assembly for actuating independent tripping of one or more circuit breakers connected in conjunction with each other.

Another object of the present invention is to provide a trip mechanism in a circuit breaker assembly which trips the circuit breakers only when the circuit breaker assembly experiences a fault condition.

Another object of the present invention is to provide a tripping mechanism with a unique slot design for the pivot in aid in tripping the circuit breaker.

Yet another object of the present invention is to provide a trip mechanism for arranging the pivot of one circuit breaker in conjunction with the pivot of the other circuit breaker.

Yet another object of the present invention is to provide a trip mechanism in the circuit breaker such that the operation of the circuit breaker is unidirectional.

Yet another object of the present invention is to provide a trip mechanism in the circuit breaker to prevent an independent trip of the mechanism due to a reverse trip command.
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

The various embodiments of the present invention provide a trip mechanism for a circuit breaker assembly comprising a first circuit breaker, a first pivot, a second circuit breaker, a second pivot and a pivot pin to interconnect the first circuit and the second circuit breaker. The first pivot is designed to trip the second circuit breaker simultaneously with tripping of the first circuit breaker during a fault condition in the first circuit breaker. The first pivot is designed to allow a free movement of the second circuit breaker pivot without moving the first pivot thereby tripping the second circuit breaker during a fault condition of the second circuit breaker.

According to an embodiment of the present invention, the design of the first pivot comprises a pivot slot adapted to fit in a pivot pin.

According to an embodiment of the present invention, the pivot pin provides for mounting the first circuit breaker on to the second circuit breaker.

According to an embodiment of the present invention, the first pivot resets the first circuit breaker to turn ON the second circuit breaker during a fault condition of the first circuit breaker.

According to an embodiment of the present invention, the first circuit breaker is an accessory circuit breaker and the second circuit breaker is a Miniature Circuit Breaker (MCB).

According to an embodiment of the present invention, the accessory circuit breaker comprising a connecting link, a lock lever, a U-shaped pin connected to the connecting link and the lock lever, a knob connected to the U-shaped pin, a first pivot and a pivot pin. The pivot pin connects the lock lever to the pivot slot of the accessory circuit breaker.

According to one embodiment of the present invention, the Miniature Circuit Breaker comprising, a connecting link, a lock lever, a U-shaped pin connected to the connecting link and the lock lever, a knob connected to the U-shaped pin, a second pivot and a pin. The pin connects the lock lever to the second pivot of the second circuit breaker.

According to an embodiment of the present invention, the profiles of the pivot in the accessory circuit breaker and the miniature circuit breaker are distinct in shape.

According to an embodiment of the present invention, the pivot pin connects the connecting link and a moving contact assembly in the miniature circuit breaker.

According to another embodiment of the present invention, the moving contact assembly is connected to a fixed contact assembly in the miniature circuit breaker.

According to one embodiment of the present invention, the pivot slot is designed to interconnect the first circuit breaker and the second circuit breaker such that the first circuit breaker is independent of the second circuit breaker and the second circuit breaker is dependent on the first circuit breaker.

E) BRIEF DESCRIPTION OF THE DRAWINGS
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:

FIG.1 illustrates a front perspective view of the accessory circuit breaker and the miniature circuit breaker being mounted in conjunction and connected by a common pivot pin according to an embodiment of the present invention.

FIG.2 illustrates an exploded perspective view of a pivot assembly in a trip mechanism for the circuit breaker according to an embodiment of the present invention.

FIG.3 illustrates a side perspective view of the pivot assembly according to an embodiment of the present invention.

FIG.4 illustrates a side sectional view of a miniature circuit breaker assembly mounted with an accessory circuit breaker according to an embodiment of the present invention.

FIG.5 illustrates a side sectional view of the accessory circuit breaker in conjunction with the miniature circuit breaker according to another embodiment of the present invention.

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

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.

The various embodiments of the present invention provide an accessory mechanism for a circuit breaker which connects one or more circuit breakers in series through a pivot pin, wherein the operation of one circuit breaker is independent of the operation of the other circuit breaker. The mechanism comprising at least two circuit breaker connected by a pivot pin wherein the first circuit breaker is known as a the accessory circuit breaker and the circuit breakers connected with the accessory circuit breaker is known as the miniature circuit breakers.

The accessory circuit breaker and the miniature circuit breaker comprise a pivot which includes a slot for receiving the pivot pin thereby connecting the accessory circuit breaker and the miniature circuit breaker.
FIG.1 illustrates a front perspective view of the accessory circuit breaker and the miniature circuit breaker being mounted in conjunction and connected by a common pivot pin 103 according to an embodiment of the present invention. With respect to the FIG.1, the accessory circuit breaker 101 and the miniature circuit breaker 102 comprises a pivot (Fig. 2) internal to the circuit breaker casing wherein the pivot includes a slot design to fit in the pivot pin 103. The pivot pin 103 connects the pivots of accessory circuit breaker 101 and the miniature circuit breaker 102 there by any tripping operation of the accessory circuit breaker 101 is reflected on the tripping operation of the miniature circuit breaker 102. When the accessory circuit breaker 101 changes the trip state from one state to another, the pivot of the accessory circuit breaker 101 provides commands to the pivot of the miniature circuit breaker to actuate simultaneous tripping of the miniature circuit breaker 102 which is connected through a pivot pin 103. The accessory circuit breaker 101 trips generally when there is a fault condition, which in turn trips the miniature circuit breaker also.

FIG.2 illustrates an exploded perspective view of the pivot assembly according to an embodiment of the present invention. With respect to the FIG.2, the pivot assembly includes a pivot 201 and the pivot pin 103. The pivot pin 103 is adapted to interconnect two or more circuit breakers. The pivot includes a pivot slot 202 which allows the pivot pin 103 to fit inside the pivot slot 202. The pivot slot 202 has a unique design profile such that the pivot slots 202 grips the pivot pin 103 closely constrained such that the pin will not dislocate and fall out when the accessory circuit breaker 101 is mounted on the miniature circuit breaker 102.

FIG.3 illustrates a perspective view of the pivot assembly showing the pivot pin 103 connecting the accessory circuit breaker 101 and the miniature circuit breaker 102 according to an embodiment of the present invention. With respect to the FIG.3, the pivot pin 103 has a unique design profile which connects the accessory circuit breaker pivot 301 and the miniature circuit breaker pivot 302 through a common pivot slot 202. The accessory circuit breaker pivot 301 and the miniature circuit breaker pivot 302 are kept closely constrained such that the operation of the accessory circuit breaker pivot 301 triggers the equivalent operation on the miniature circuit breaker pivot 302.
FIG.4 illustrates a side sectional view of the miniature circuit breaker assembly in conjunction with the accessory assembly according to an embodiment of the present invention. With respect to FIG.4, a knob 402 is connected to a U-pin 403 which is further connected to a connecting link 404 and a lock lever 405. The connecting link 404 is connected to a moving contact assembly 407 which has a provision to mount a pin 408. The pin 408 connects the moving contact assembly 407 and the connecting link 404 together. Further the lock lever 405 is connected to a pivot 401 and the moving contact assembly 408 is connected to a fixed contact assembly 409 forming the miniature circuit breaker tripping assembly.

During the reset state i.e. OFF to ON operation, the accessory circuit breaker 101 is switched ON which in turn switches ON the miniature circuit breaker 102 as both the devices have dependent knobs. The resetting operation inside the miniature circuit breaker 102 or the accessory circuit breaker 101 will be of the same in case the same mechanism is used in the accessory circuit breaker 101 and the miniature circuit breaker 102. In case a different mechanism is used for the accessory circuit breaker 102, the pivot slot 201 profile and the position of the pivot 401 must be maintained in synchronization with the miniature circuit breaker 102. The tripping force is transmitted through the knob 402 which is connected to the U-pin 403 wherein the U-pin 403 is connected to the lock lever 405 and the connecting link 404. The output of the connecting link 404 is fed to the moving contact assembly 407. The moving contact assembly 407 is connected to the fixed contact assembly 409 which in turn changes the state of the miniature circuit breaker 102.

During the fault condition (Short Circuit or Over current) condition i.e. ON to OFF operation, the miniature circuit breaker 102 clears the fault which does not change the status of accessory circuit breaker 101. The mechanisms of the miniature circuit breaker 102 and the accessory circuit breaker 101 are connected internally by the pivot 401. The purpose of connecting the pivot internally is that the miniature circuit breaker 102 is designed such that the pivot 401 will move only in case of fault and for normal operation and it will not have any movement during other conditions. Thus, the output of the miniature circuit breaker pivot 401 is connected to accessory circuit breaker pivot 501 (FIG.5) by a pivot pin 103. When a fault occurs, the miniature circuit breaker pivot 401 will move giving a movement to the accessory circuit breaker Pivot 501(FIG.5) which is connected together by a pin 406. The accessory circuit breaker pivot 501(FIG.5) has a unique design profile slot. The slot is shaped to allow a free movement of the miniature circuit breaker pivot 401 without itself moving so that the accessory circuit breaker pivots 501 (FIG.5) does not move and hence will not trip along with the miniature circuit breaker 102.

FIG.5 illustrates a side sectional view of the accessory circuit breaker assembly in conjunction with the miniature circuit breaker assembly according to another embodiment of the present invention. With respect to FIG.5, the accessory circuit breaker 101 comprises of identical components similar to the miniature circuit breaker 102 but with a different pivot slot 501 profile. The unique pivot slot 501 accommodates the uniquely designed pivot pin 103 tightly there by connecting the accessory circuit breaker pivot 301 and the miniature circuit breaker pivot 302 closely constrained.

When a condition of fault occurs inside the accessory circuit breaker 101, the accessory circuit breaker 101 trips the miniature circuit breaker 102. This condition is required in accessory circuit breaker 101 as per the design because when the accessory circuit breaker 101 trips the miniature circuit breaker 102 also get tripped simultaneously. The serial tripping condition is achieved by the slot design of pivot 501 inside which the pivot pin 103 gets fitted. The accessory circuit breaker pivot slot 501 is designed such that it will trip the miniature circuit breaker 102 when it is experience a fault condition. The accessory circuit breaker 101 is then reset to turn on the miniature circuit breaker 102.

G) ADVANTAGES OF THE INVENTION

The various embodiments of the present invention provide a mechanism for connecting two or more circuit breakers in series through a pivot pin, wherein the operation of one circuit breaker is independent of the operation of the other circuit breaker.
The present invention provides a unique design for connecting two independent circuit breakers in which the operation of the first circuit breaker is independent of the operation of the second circuit breaker and the operation of the second circuit breaker is dependent on the first circuit breaker.

The present invention provides a unique pivot design in the circuit breakers which includes a unique slot design for receiving a pin. The pin connects the pivot of one circuit breaker to the pivot of another circuit breaker such that the movement of the pivot on the first circuit breaker is unidirectional.

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.

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.

WE CLAIM:

1. A circuit breaker assembly with unidirectional trip mechanism comprising:
a first circuit breaker;
a first pivot provided in the first circuit breaker;
a second circuit breaker;
a second pivot provided in the second circuit breaker; and
a pivot pin to interconnect the first circuit and the second circuit breaker;
wherein the first pivot comprises a pivot slot adapted to fit in the pivot pin and the first pivot is designed to provide a unidirectional trip action so that the first circuit breaker and the second circuit breaker are tripped simultaneously during a fault condition in the first circuit breaker while the first circuit breaker is not tripped due to a fault in the second circuit breaker.

2. The circuit breaker assembly according to claim 1, wherein the first pivot is designed to allow a free movement of the second pivot so that the second pivot is moved even without a movement of the first pivot to trip the second circuit breaker during a fault condition in the second circuit breaker.

3. The circuit breaker assembly according to claim 1, wherein the pivot pin is provided for mounting the first circuit breaker on to the second circuit breaker.

4. The circuit breaker assembly according to claim 1, wherein first pivot resets the first circuit breaker to turn ON the second circuit breaker during a fault condition of the first circuit breaker.

5. The circuit breaker assembly according to claim 1, wherein the first circuit breaker is an accessory circuit breaker and the second circuit breaker is a Miniature Circuit Breaker (MCB).

6. The circuit breaker assembly according to claim 1, wherein the first circuit breaker further comprising:
a first connecting link;
a first lock lever;
a first U-shaped pin connected to the first connecting link and the first lock lever;
a first knob connected to the first U-shaped pin.

7. The circuit assembly according to claim 1, wherein the second Circuit further comprising:
a second connecting link;
a second lock lever;
a second U-shaped pin connected to the second connecting link and the second lock lever;
a second knob connected to the second U-shaped pin;
a second pivot; and
a second pin;
wherein the second pin connects the lock lever to the second pivot of the second circuit breaker.

8. The circuit breaker assembly according to claim 1, wherein a profile of the first pivot in the first circuit breaker is different to a profile of the second pivot in the second circuit breaker.

9. The circuit breaker assembly according to claim 1, wherein the second pin connects the connecting link and a moving contact assembly in the second circuit breaker.

10. The circuit breaker assembly according to claim 1, wherein the moving contact assembly is connected to a fixed contact assembly in the second circuit breaker.

11. The circuit breaker assembly according to claim 1, wherein the pivot slot is designed to interconnect the first circuit breaker and the second circuit breaker such that a trip operation of the first circuit breaker is independent of a trip operation of the second circuit breaker and a trip operation of the second circuit breaker is dependent on the trip operation of the first circuit breaker.

12. The circuit breaker assembly according to claim 1, wherein the first circuit breaker trips the second circuit breaker when there is a fault in the first circuit breaker while the first circuit breaker is not tripped when there is a fault in the second circuit breaker thereby providing a unidirectional trip action and not a bidirectional trip action.