DESC:TECHNICAL FIELD

The present subject matter described herein, in general relates to a circuit breaker, and more particularly, an operating mechanism of circuit breaker which enables it to make, carry and break current under normal circuit condition and also break during abnormal conditions.

BACKGROUND

Circuit Breaker is a mechanical switching device capable of making, carrying and breaking currents. Under normal circuit conditions it will make the circuit closed, carry current for a specified time and breaks the circuit under specified abnormal circuit conditions.

Circuit Breakers are employed for current interruption. More particularly Circuit Breakers are utilized to protect instruments from damage during adverse conditions prevailing during the operation of the circuit in which circuit breaker is employed. During adverse conditions like short circuit, over current or the current rises to an alarmingly high level. This high current may cause damage to the parts in the electrical system. Hence during these conditions the circuit has to be opened to protect the parts after the breaker.

A circuit breaker can be manually opened and closed, as well as automatically opened to protect conductors or equipments from damage caused by excessive heating due to over current in abnormal conditions such as overload or short-circuit.

The mechanism of the circuit breaker plays a vital role in determining the credibility of the breaker. A good mechanism should ensure quick and manually independent opening and closing of contact system.

Five operations are to be performed by the Circuit Breakers mechanism. They are
1. ON
2. OFF
3. TRIP
4. TRIP FREE
5. RESET
The first two operations are initiated by operator whereas the trip signal is given by the release which senses the abnormal conditions and gives TRIP command to the mechanism, so that the latter opens the circuit.

The operator has access to the mechanism through the knob which will be projected outwards from the housing of the breaker. The knob is placed over the fork of the operating mechanism. Conventional type Circuit Breakers will feature three positions in the top cover near the knob to show ON, OFF and TRIP.

When the knob indicates ON it means the breaker is in ON condition i.e., the current path is closed. Similarly the position of the knob indicates the state of the circuit breaker.

According to standards, the top position of the knob (if the breaker is placed vertically) or the longest distant position of the knob away from the operator (if the breaker is mounted horizontally) should be marked as ON POSITION. The other extreme end in both cases is marked as the OFF POSITION. The knob will be near the center (based on the design of the mechanism) to indicate the TRIP POSITION.

As said above, TRIP command is given automatically to the contacts by the release if it senses an abnormal condition like overload and short circuit. If the trip signal is given, the breaker opens the circuit and the knob goes to the trip position to show the operator that a fault has occurred in the system.

If the operator wants to switch ON the breaker after the breaker is tripped, he/she cannot do it without resetting the breaker. This is to make sure that the operator shouldn't switch ON the breaker before clearing the fault.

Resetting of the breaker is done by moving the knob (Driver link) towards the OFF position from the TRIP position. This movement loads the mechanism spring and now it is possible for the operator to ON the breaker. All these mechanisms are called semi-automatic mechanisms since for ON and OFF operation, the knob of the breaker has to be taken from their respective ON or OFF positions to a position called dead center beyond which he mechanism becomes independent of the operator and completes the respective action by its own automatically.

The prior-art document US 4528531 discloses a molded case circuit breaker includes a highly integrated operating mechanism having an over-center toggle mechanism for opening and closing a pair of electrical contacts and a trip mechanism for responding to overload and short circuit or fault current conditions to separate the pair of electrical contacts. A generally flat, intermediate latch plate includes an upper latch surface for latching with a movable cradle of the over-center toggle mechanism and a lower latch surface for latching with a trip bar of the trip mechanism and a pair of outwardly projecting pivot arms disposed between the upper and lower latch surfaces. The over-center toggle mechanism includes a pair of upper toggle links and a pair of lower toggle links interconnected by a toggle spring pin. To increase the speed of separation of the first and second electrical contacts during a trip operation, the cradle is physically configured to engage and upwardly propel the toggle spring pin and, also, the upper toggle links have projections for physically contacting a rigid stop.

The prior-art document US 4864263 discloses an industrial rated molded case circuit breaker having an electronic trip circuit contained within the circuit breaker enclosure includes a reset spring in cooperation with the circuit breaker latch spring to insure manual reset of circuit breaker after an automatic trip function. The reset spring allows the circuit breaker latch assembly to be manually reset upon minimum travel of the circuit breaker operating handle due to internal circuit breaker component space restrictions. The circuit breaker latch assembly is robotically loaded to the operating mechanism which is then attached to the circuit breaker case by an automated fastening process.

The prior-art document US 6479774 discloses a circuit breaker operating mechanism comprises a movable handle yoke, a mechanism spring extending in tension from the handle yoke to a pin, and a lower link extending from the pin to a crank connected to a contact arm bearing a movable contact. The crank can be positioned in open and closed conditions, being in an open position when the movable contact is separated from an associated fixed contact and being in a closed position when the movable contact is mated to said associated fixed contact. The circuit breaker further comprises an interface formed on said crank and a blocking prop having a first surface that engages said interface, the first surface preventing the crank from rotating towards the closed position.

The prior-art document US 6590172 discloses a circuit breaker is provided wherein the circuit breaker comprises a contact arm movable between a closed position, an open position and a blown open position wherein the contact arm is disposed in the circuit breaker. A bumper disposed to contact the contact arm when the contact arm is in the blown open position. In addition, a stop member disposed to be in contact with a linkage assembly so as to create a gap between the bumper and the contact arm when the contact arm is disposed in the open position.

The prior-art document US 5369384 discloses a breaker mechanism for power circuit breakers is the energy storage link between the handle and the contact systems. Known breaker mechanisms are generally too expensive to manufacture. When contact welding occurs, there is also the risk that, in spite of the tripping of the breaker mechanism, the contact system will not open. The new breaker mechanism reliably opens the contact system and consists of fewer and technologically simpler individual parts. It is inserted between two symmetrical breaker plates held in die cast housing, and in which a connecting piece is mounted. Two toggle levers are connected at a distance from one another by means of a connecting shaft engaged in crossbar cam slots. A toggle lever spring is engaged between the connecting piece and the connecting shaft. A bracing lever which can be driven by the connecting piece is friction locked in the breaker plates, and the toggle levers in the bracing lever. A latch lever and a latch holding the latter in the locked position are friction locked by means of a latch spring in recesses of the breaker plates.

The prior-art document DE 102006038191 which came up on the International Search Report discloses an invention regarding the fixing of a switching mechanism device onto a carrier whereas present invention is regarding the operating mechanism for a switching device itself.

The prior-art document US 20020100674 which came up on the International Search Report discloses an invention regarding a motor operator which is a driving means for the operating mechanism of a switching device whereas present invention is regarding the operating mechanism for a switching device itself.

The prior-art document EP 0798755 which came up on the International Search Report discloses an invention regarding only the latching system and release mechanism for electrical switching devices whereas present invention is regarding the operating mechanism of a switching device.

The prior-art document DE 102006059307 discloses an invention where the object is of converting a double breaker switching device to a single breaker switching device, with higher commonalities. The specified single breaker switching device requires a higher rotation with respect to the double breaker switching device within the same boundary conditions. The invention increases the trip rotation by increasing the distance between the supporting lever axis and the upper lever, lower lever pivot by pivoting the lower lever on a different additional axis.

Apart from the above mentioned prior-art and their limitations, there are various prior-arts available for the circuit breaker and its assembly, but they also have many drawbacks, few of the drawbacks are mentioned below:

1. The traditional breakers work by increasing the distance between the latch link axis and lower link axis as a means to increasing the shaft rotation during ON to TRIP but it is still limited when very high rotation of contact system (drive shaft) is required for the same boundary conditions.
2. The traditional breakers use same axis for connecting lower link, upper link (4b) and spring connection axis. And thereby limits the scope for optimizing various deliverables viz., Contact Pressure, Contact Rotation etc.
3. During TRIP to RESET the mentioned prior art use a rolling pin attached to the fork link and cam action between the pin and a profile on the latch link.

In the view of above mentioned drawbacks and limitations, and to avoid the above mentioned drawbacks, a new assembly, and an operating mechanism of circuit breaker is required which enables it to make, carry and break current under normal circuit condition and also break during abnormal conditions.

SUMMARY

This summary is provided to introduce concepts related a mechanical device for operating and controlling circuit breakers.This summary is not intended to identify essential features of the subject matter nor is it intended for use in determining or limiting the scope of the subject matter.
In one implementation, the present invention relates to a circuit breaker. More particularly, the invention is concerned about an operating mechanism of circuit breaker which enables it to make, carry and break current under normal circuit condition and also break during abnormal conditions.
In one implementation, the present invention discloses a different means of solving the problem by providing a navigation means on the side plates.
In one implementation, the present invention has split the function of the spring hinge and upper lever, lower lever pivot for transmitting greater force at ON within the boundary conditions as detailed in the summary.
In one implementation, the rolling pin is attached to the latch link engaging a cam profile on the fork link.
In one implementation, the present invention uses a concentric extension springs are used to cater to high force requirements within the boundary conditions as detailed in the summary.
In one implementation, a metal component is inserted into plastic trip plate for high wear resistance and to avoid nuisance tripping.
In one implementation, a spring drawn from a single wire acts as an extension and torsion spring (TorEx Spring).

Accordingly, in one implementation, an improved operating mechanism of circuit breaker is disclosed. The improved operating mechanism comprises of an operating knob (4i) means fixed onto a fork link (4f) means which drives a dead-centre based mechanism consisting of a plurality of upper link (4b) means, a plurality of lower link (4c) means, and at least one spring mounted between a spring pin (4f1) means and a floating pin (4b2) means; whereinan upper spring hinge from said plurality of upper link (4b) means is located on said fork link (4f) means and said lower spring hinged on said floating pin (4b2) means located on the upper link (4b) means; said upper link (4b) means and said lower link (4c) means being pivotally connected to each other and said lower link (4c) means being operatively connected between said upper link (4b) means and said rotor (2) means; one end of said upper link (4b) means is pivoted on a latch link (4a) means which is operatively mounted on a plurality of side plate means and said end is attached to said latch link (4a) means is a reset pin which engages a cam profile on the fork link (4f) means during TRIP-RESET operation; andsaid side plate means comprising at least one side plate profile means.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 illustratesan isometric view of the 3 pole Circuit Breaker cassette with breaker is in ON condition is shown, in accordance with an embodiment of the present subject matter.
Figure 2 illustrates an isometric view of the single pole Circuit Breaker cassette with breaker is in ON condition is shown, in accordance with an embodiment of the present subject matter.
Figure 3 illustrates an isometric view of mechanism in ON condition is shown, in accordance with an embodiment of the present subject matter.
Figure 4 illustrates an exploded view of the mechanism is shown, in accordance with an embodiment of the present subject matter.
Figure 5 illustrates the cross sectional view mechanism assembly in the ON condition is shown, in accordance with an embodiment of the present subject matter.
Figure 5 (a) illustrates the mechanism assembly in the ON condition is shown, in accordance with an embodiment of the present subject matter.
Figure 6 illustrates the cross sectional view mechanism assembly in the OFF condition is shown, in accordance with an embodiment of the present subject matter.
Figure 6 (a) illustrates the mechanism assembly in the OFF conditionis shown, in accordance with an embodiment of the present subject matter.
Figure 7 illustrates the cross sectional view mechanism assembly in the TRIP condition is shown, in accordance with an embodiment of the present subject matter.
Figure 7 (a) illustrates the mechanism assembly in the TRIP condition is shown, in accordance with an embodiment of the present subject matter.
Figure 8 illustrates intermediate position of mechanism between ON to trip is shown, in accordance with an embodiment of the present subject matter.
Figure 9 (a) illustrates positions of mechanism in TRIP position is shown, in accordance with an embodiment of the present subject matter.
Figure 9 (b) illustrates intermediate position of mechanism between TRIP and RESET position is shown, in accordance with an embodiment of the present subject matter.
Figure 9 (c) illustrates intermediateposition of mechanism in RESET condition is shown, in accordance with an embodiment of the present subject matter.
Figure 10 illustrates difference between trip plate with and without insert is shown, in accordance with an embodiment of the present subject matter.
Figure 11 illustrates the figure of spring assembly in mechanism is shown, in accordance with an embodiment of the present subject matter.
Figure 12 illustrates the figure of extension cum torsion spring with TM reset link in mechanism is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

The terms and words used in the following description are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

In one implementation, a mechanical device for operating and controlling circuit breakers.

In one implementation, an improved operating mechanism of circuit breaker is disclosed. The improved operating mechanism comprises of an operating knob (4i) means fixed onto a fork link (4f) means which drives a dead-centre based mechanism consisting of a plurality of upper link (4b) means, a plurality of lower link (4c) means, and at least one spring mounted between a spring pin (4f1) means and a floating pin (4b2) means; whereinan upper spring hinge from said plurality of upper link (4b) means is located on said fork link (4f) means and said lower spring hinged on said floating pin (4b2) means located on the upper link (4b) means; said upper link (4b) means and said lower link (4c) means being pivotally connected to each other and said lower link (4c) means being operatively connected between said upper link (4b) means and said rotor (2) means; one end of said upper link (4b) means is pivoted on a latch link (4a) means which is operatively mounted on a plurality of side plate means and said end is attached to said latch link (4a) means is a reset pin which engages a cam profile on the fork link (4f) means during TRIP-RESET operation; andsaid side plate means comprising at least one side plate profile means.

In one implementation, the higher rotation of moving electrical contacts of circuit breaker (Drive shaft) by means of separating upper link (4b) lower link joining point from spring connection point and providing navigation to linkages by means of cam provided on latch link is enabled.

In one implementation, said side plate profile means comprising a plurality of predetermined sized slot means operatively located on said side plate means and a surface of said plate profile comprises of a surface having a cam profile;

In one implementation, said cam profile guides at least one pin or bend portion or protrusion of the upper link (4b) means during ON to TRIP operation to enable higher contact rotation for comparatively lower latch link (4a) rotation.

In one implementation, said improved operating mechanism comprises of a latch bracket (4d) means adapted to lock and unlock said latch link (4a) means.

In one implementation, said improved operating mechanism comprises of a trip plate means adapted to lock and unlock said latch bracket (4d) means.

In one implementation,said bend portion of latch link (4a) means being operatively located on one side of said latch link (4a) means.

In one implementation, said cam profile of fork link (4f) means operatively located on end portions of side limbs of said fork link (4f) means, engages a rolling reset pin means operatively connected to the latch link (4a) means during TRIP-RESET operation.

In one implementation, said cam profile on the side plate means engages a navigation pin means operatively connected to said upper link (4b) means.

In one implementation, a single wire drawn spring is provided which acts as extension and torsion spring.

In one implementation, improved operating mechanism of circuit breaker is characterized in delivering high spring force through assembly of springs into one another achieved by a peculiar spring hooks design.

In one implementation, the force required to reset the breaker from trip position s reduced. By positioning rolling resetting pin away from the latch link axis of rotation and forming rolling joint with respect to cam provided on fork. Profile of said cam is optimized to achieve lower operating force during resetting operation.

In one implementation, the invention proposes an operating mechanism for circuit breakers.

In one implementation, an improved operating mechanism of circuit breaker, said mechanism module is disclosed. An operating knob means fixed onto a fork link means which drives a dead-centre based mechanism consisting of a plurality of upper link (4b) means, lower link means, and at least one spring mounted between a spring pin means and a floating pin means; the upper spring hinge located on the fork link means and the lower spring hinged on the floating point located on the upper link (4b) means; The said upper link (4b) means and said lower link means being pivotally connected to each other and said lower link means being operatively connected between said upper link (4b) means and said rotor means; The other end of said upper link (4b) means is pivoted on a latch link means which is operatively mounted on a plurality of side plate means. Also attached to said latch link means is a reset pin which engages a cam profile on the fork link means during TRIP-RESET operation. Said side plate means comprising at least one side plate profile means. The said side plate profile means comprising plurality of predetermined sized slot means operatively located on said side plate means and a surface of said plate profile comprises of a surface having a cam profile; Said cam profile guides at least one pin or bend or protrusion of the upper link (4b) means during ON to TRIP operation to enable higher contact rotation for comparatively lower latch link rotation.

In one implementation, the latch bracket means adapted to lock and/or unlock said latch link means without any extra biasing spring. The mechanism further comprises of a trip plate means adapted to lock and/or unlock said latch bracket means. A knob means is operatively connected to the fork link means. The bend portion of latch link means may be operatively located on one side of said latch link means. The cam profile of fork link means operatively located on end portions of side limbs of said fork link means, engages a rolling reset pin means operatively connected to the latch link means during TRIP-RESET operation. The cam profile on the side plate means engages a navigation pin means operatively connected to the upper link (4b) means. The trip plate may have a Center of Gravity (C.G.) near to pivot point of trip plate due to addition of mass in upward side of the trip plate by means of metal inserted to avoid nuisance tripping in shocks and vibrations.

In one implementation, the trip life has been increased because of direct metal to metal contact between trip plate and the latch bracket. The proposed invention reduces the number of components by a single wire drawn spring acting as extension and torsion spring. The proposed invention, delivers high spring force without compromising on life of spring. This is achieved through assembly of springs into one another. Assembly possible through peculiar spring hooks design.

In one implementation, the invention discloses an improved operating mechanism of circuit breaker. Figure 1 shows an isometric view of the 3 pole Circuit Breaker cassette with breaker is in ON condition. Circuit breaker cassette is a cassette on which circuit breaker mechanism module is mounted. Figure 2 shows an isometric view of the single pole Circuit Breaker cassette with breaker is in ON condition. Figure 3 shows an isometric view of mechanism in ON condition with breaker cassette hidden. Figure 4 shows an exploded view of mechanism consists of upper link (4b), lower link (4c), latch link (4a), fork link (4f). A spring pin (4f1) is connected to the fork link (4f) and floating pin (4b2) is connected to the upper link (4b). Extension spring (4h and 4h1) are connected between spring pin (4f1) and floating pin (4b2). Knob (4i) connected to the fork link (4f) through which user gives the input. Lower link (4c) is connected to the rotor (2) to which moving contact (4) is attached. During OFF-ON and ON-OFF operation latch link (4a) is locked by latch bracket (4d).

During normal ON-OFF and OFF-ON operation, input to mechanism is given through the rotation of knob (4i) by manual means. The rotation of knob (4i) leads to storing potential energy (spring charging) in the spring member (4h and 4h1) while restricting the contact movement during the charging operation. At a specified instance the potential energy of spring is released in form of Kinetic energy through Mechanical Linkages leading rotation of the contacts at high velocity. Circuit breaker mechanisms use dead centre based Extension spring arrangements.

Figure 5 shows the sectional view of the Mechanism which is in ON position and figure 5a shows the mechanism assembly in ON condition When knob (4i) is rotated by user applied force spring (4h and 4h1) connected between spring pin (4f1) and floating pin (4b2) get deflected up to dead centre condition and after the dead centre the stored energy in the spring is converted in to kinetic energy which is used to rotate the moving contact (5b) from ON to OFF position through upper link (4b) (4b) and lower link (4c).

Figure 6 shows the sectional view of the mechanism which is in OFF position. When knob (3g) is rotated by user applied force spring (4h and 4h1) connected between spring pin (4f1) and floating pin (4b2) get deflected up to dead centre condition and after the dead centre the stored energy in the spring is converted in to kinetic energy which is used to rotate the moving contact (5b) from OFF to ON position through upper link (4b) (4b) and lower link (4c). Moving contact (5b) touch to the fixed contact (5c) and breaker gets ON.

Figure 7 shows the sectional view of the Mechanism which is in TRIP position. When actuation signal is given to the trip plate (4g) it rotates and unlocks the latch bracket (4d) which results in enabling the rotation of latch link (4a). At ON position spring is having stored potential energy which enables the latch link (4a) rotation. Upper link (4b) and lower link (4c) are connected to the latch link (4a) so as rotation of latch link (4a) results in rotation of rotor (5a). Moving contact (5b) connected to the rotor (5a) also rotates and breaker gets disconnected and now in TRIP position.

Figure 8 shows the mechanism in ON condition. The navigation pin is touched to the side plate(3a).When TRIP signal is given latch link (4a) gets rotated and navigated by the cam connection between side plate (4e) and navigator pin (4b1). Figure 8 shows the intermediate condition from ON to TRIP. This navigation enables the full rotation of moving contact (5b) from ON to TRIP position and also helps in less rotation of latch link (4a).

Figure 9a shows the Mechanism in TRIP position. During TRIP to RESET operation user rotates the knob (4i). At TRIP position fork link (4f) is touched with the reset pin (4a1) which is inserted in the latch link (4a). So when force is applied on knob (4i), latch link (4a) is rotated which enables bringing the upper link (4b) (4b) and lower link (4c) from TRIP to RESET position. Reset pin (4a1) inserted in the latch link (4a) rolls and rolling coefficient of friction between fork link (4f) and reset pin (4a1) reduces the reset force. The slots provided on the side plate (4e) acts as a stopper for latch link (4a) rotation. While moving downwardsthe reset pin(4a1) pushes the latch bracket (4d ) downwards through the limb of the latch bracket (4d).The latch bracket(4d) rotates anticlockwise as shown in figure9b without any help.figure9c shows the reset position of mechanism in which the latch roller pin(4d1) overlaps the latch link(4a) while moving in anticlockwise direction. When the force on the knob(4i) is removed in reset condition then the latch link moves upwards due to spring force exerted by(4h and 4h1).and mechanism reaches to off position as per figure6.

The Center of Gravity (C.G) of a purely metallic or purely plastic trip plate is quite away from trip plate rotation pivot. This may cause nuisance tripping during shock and vibration tests. To counter this bulk mass in the form of metal insert has been added in the otherwise plastic trip plate. figure10 shows the difference between trip plate with metal insert and trip plate without metal insert in the C.G. of the trip plate has been shifted towards the trip plate pivot point(1) by addition of metal insert (4g1). The purpose of shifting the C.G. of the trip plate near the pivot point is to reduce the torque generated by force component acting at C.G. while it is accelerated during shock and vibration tests, thereby reducing the tendency to nuisance trip.

By addition of these metal insert two main purposes gets solved.
1. The Center of Gravity (C.G.) has been shifted to pivot side.
2. Direct metal to metal contact between trip plate (4g) and latch bracket (4d) is achieved thereby increasing wear resistance and hence the trip life of breaker.

As shown in figure 11 concentric extension springs have been used to deliver high force without exceeding the stress limits and thereby not compromising on life of spring in spring design and to accommodate them within a small area. The assembly of springs (insertion of inner spring into outer spring) is possible due to side hooks in the springs. To avoid tilting of springs due to side hooks one of the hook is on the side to facilitate assembly while the other hook of same spring is at the centre.

When Thermo-Magnetic Release (TMR) senses a fault it releases its latch which trips the breaker by hitting the trip plate. The resetting of the TMR latch happens along with resetting of breaker through TMR reset link driven by fork link. Post resetting the fork link returns to its OFF position from reset position by main spring force and the TMR reset link is brought back to its original position by biasing spring. When the breaker is tripped it is required that the fork link attain its trip position (between ON and OFF positions) for true indication of breaker state. To achieve this positively a biasing spring is used which pulls the fork link to trip position when the breaker is tripped.

As shown in figure12 special type of spring (12a)is used to bias the Fork link towards the trip side for true indication of tripand the TMR reset link (12b)away from the TMR latch post resetting of TMR latch. The fork link requires an extension spring to bias whereas TMR reset link needs a torsion spring. Both these requirements have been addressed by the spring wound from a single wire thereby reducing the number of components.

Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features:

One features of the invention is that, the proposed invention enables higher rotation of moving electrical contacts of circuit breaker (Drive shaft) by means of separatingupper link (4b) lower link joining point from spring connection point and providing navigation to linkages by means of cam provided on latch link.
Another feature of the invention is that, the proposed invention reduces the force required to reset the breaker from trip position. By positioning rolling resetting pin away from the latch link axis of rotation and forming rolling joint with respect to cam provided on fork. Profile of said cam is optimized to achieve lower operating force during resetting operation

Another feature of the invention is that, the elimination of need of biasing spring on latch bracket

Still another feature of the invention is that, the proposed invention delivers high spring force in compact size without compromising on life of spring.

Yet another feature of the invention is that, the proposed invention provides no nuisance tripping in case of shock and vibration

Although a mechanical device for operating and controlling circuit breakers hasbeen described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of a mechanical device for operating and controlling circuit breakers.
,CLAIMS:1. An improved operating mechanism for circuit breakers, comprising:
an operating knob (4i) means fixed onto a fork link (4f) means which drives a dead-centre based mechanism consisting of a plurality of upper link (4b) means, a plurality of lower link (4c) means, and at least one spring mounted between a spring pin (4f1) means and a floating pin (4b2) means; wherein
an upper spring hinge from said plurality of upper link (4b) means is located on saidfork link (4f) means and said lower spring hinged on said floating pin (4b2) means located on the upper link (4b) means;
said upper link (4b) means and said lower link (4c) means being pivotally connected to each other and said lower link (4c) means being operatively connected between said upper link (4b) means and said rotor (2) means;
one end of said upper link (4b) means is pivoted on a latch link (4a) means which is operatively mounted on a plurality of side plate means and said end is attached to said latch link (4a) means is a reset pin which engages a cam profile on the fork link (4f) means during TRIP-RESET operation; and
said side plate means comprising at least one side plate profile means.

2. The improved operating mechanism as claimed in claim 1, wherein
said side plate profile means comprises a plurality of predetermined sized slot means operatively located on said side plate means and a surface of said plate profile comprises of a surface having a cam profile;
said cam profile guides at least one pin or bend portion or protrusion of the upper link (4b) means during ON to TRIP operation to enable higher contact rotation for comparatively lower latch link (4a) rotation.

3. The improved operating mechanism as claimed in claims 1 and 2 comprising a latch bracket (4d) means adapted to lock and unlock said latch link (4a) means.

4. The improved operating mechanism as claimed in claims 1-3comprising a trip plate means adapted to lock and unlock said latch bracket (4d) means.

5. The improved operating mechanism as claimed in claims 1-4, wherein said bend portion of latch link (4a) means is operatively located on one side of said latch link (4a) means.

6. The improved operating mechanism as claimed in claims 1-5, wherein said cam profile of fork link (4f) means operatively located on end portions of side limbs of said fork link (4f) means, engages a rolling reset pin means operatively connected to the latch link (4a) means during TRIP-RESET operation.

7. The improved operating mechanism as claimed in claims 1-6, wherein said cam profile on the side plate means engages a navigation pin means operatively connected to said upper link (4b) means.

8. The improved operating mechanism as claimed in claims 1-7, comprising a single wire drawn spring acting as extension and torsion spring.

9. The improved operating mechanism as claimed in claims 1-8 characterized by delivering high spring force through assembly of springs into one another achieved by a peculiar spring hooks design.