FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. - CONTACT LOCKING MECHANISM FOR
CIRCUIT BREAKER WITH CONTACT POSITION ACTUATION
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 INVENTION
The present invention relates to a contact locking mechanism for circuit breakers. In particular, the invention relates to a contact locking mechanism for circuit breakers capable of providing actuation. More particularly, the invention relates to a contact locking mechanism for circuit breakers capable of providing actuation depending on contact position to external mechanisms such as tripping mechanism of breakev and for external indication. Furthermore, the invention relates to a contact locking mechanism for circuit breakers capable of providing actuation without any direct contact with the moving contact of circuit breaker. The invention also relates to a contact locking mechanism for circuit breakers provided with movement of multiple points across which spring is connected resulting in higher repel open speed.
BACKGROUND OF THE INVENTION
The circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers are used to protect electrical circuitry and equipment from damage due to abnormal condition, such as an overload condition or a relatively high level short circuit or fault condition.
These switching devices typically have two positions corresponding to the status of the separable contacts. For example, these positions would include an ON position, in which the separable contacts are closed, an OFF position in which the contacts are open. In a few switching device there could be a third state which would include TRIP position in which the contacts are tripped open.
These switching devices are usually installed in an enclosure so as to have all the control and distribution network laid in form of metallic sheets and or cable wires inside and all operating means from outside so as to prevent access to high voltage and thus a potential hazard.
One such switching device is a molded case circuit breaker (MCCB) which is generally used to provide over current protection for various types of electrical equipment. MCCBs have three stable positions - ON, OFF and TRIP in which conditions of contacts as described above.
When circuit breaker is in ON condition and a short circuit fault condition arises, high amount of current flows through the circuit and in which case, circuit breaker has to move the contacts to open position by sensing the fault condition through short circuit sensing mechanism such as magnetic arrangement. The time taken from a fault condition appearing

and the current being limited by circuit breaker determines the let through energy of the circuit interrupter. A circuit interrupter is more efficient when the let through energy is lesser,
Let through energy of circuit interruption device depends on lot of parameters one among them being the time for opening of the contacts from closed condition. The short circuit sensing mechanism of circuit breaker involves mechanical elements in between and thus takes a finite time before giving a trip open signal to the contacts thus increasing the let through energy.
Short circuit conditions involves high amount of current levels which induces repulsion forces between suitably arranged contacts. Thus if the contacts can be locked in the repelled open position, the let through energy can be drastically reduced. This improves life of the equipments and systems connected downstream and greatly reduce the hazardous conditions which can damage the downstream equipments.
Thus many of the circuit breakers use such locking systems for contact locking under short circuit conditions. Further, efficiency of a contact locking system is measured by the velocity it can induce to the contacts once they have repelled open. It is also important to have the desired contact force in the ON condition.
A general locking mechanism is a toggle mechanism, which consists of one or more links and springs. The mechanism consists of two stable positions. Those positions are reached whenever the direction of spring force changes on the mechanism by virtue of motion of mechanism element such as link. This principle is used in most contact locking mechanisms to toggle the movable contacts from a normal closed condition to a lock open position. When the repulsion forces due to current in the contact is more than the spring force for toggling, the contacts repel open and get locked.
In conventional two link type of locking mechanisms, one end of the spring is connected to either moving contact or locking link and the other end is fixed to the driveshaft. The prior arrangements will be clearly interpreted after understanding the below mentioned inventions.
US4644121 teaches a circuit breaker characterized by a movable contact carrying arm movable about a pivot and a helical torsion spring movable on the arm to and from the pivot for applying a varying force as the arm moves from closed to open positions. It also teaches about spring actuated movable contact arm of circuit breaker by which it reduce the amount of let through current.
US5633483 discloses a circuit breaker is provided having a stationary contact, a movable contact and a blade which has a first end and a second end. The movable contact is secured

to the first end of the blade. The blade is rotatable about a pin between a BLOWN OPEN position and a CLOSED position, wherein the movable contact is separated from the stationary contact when the blade is in the BLOWN OPEN position and the movable contact engages the stationary contact when the blade is in the CLOSED position. The blade further has a protrusion portion extending from its second end. The circuit breaker further includes a catcher rotatably coupled to a pivot pin and having a nose portion for engagement with the blade protrusion portion. A spring is mounted about the pivot pin and engages the catcher for biasing the catcher towards the blade whereby the nose portion rests against the protrusion portion of the blade when the blade is in the CLOSED position and the nose portion overlaps the protrusion portion when the blade is in the BLOWN OPEN position thereby holding the blade in the BLOWN OPEN position.
US5874699 teaches a molded case circuit breaker has a moving conductor assembly which includes a modular carrier assembly incorporating a plurality of spring biased contact cam members each of which engages contact pressure lobes on a pair of contact arm laminations to provide contact pressure. In response to the magnetic repulsion forces generated by a short circuit, the springs compress allowing the cam members to pivot and side step the contact pressure lobes so that the contact arm blows-open with little resistance. The cam members and springs are preassembled in a transverse channel in the carrier body and laterally retained in place by side plates for easier pivotal attachment of the contact arm laminations to the lobes on the side plates. The side plate lobes raise the contact arm relative to the mass of the carrier to reduce eddy current heating and provide a positive off indication for welded contacts by restricting movement of lower toggle links of the operating mechanism which are coplanar with the side plates. A modular crossbar includes molded bearings engaged by or made integral with hexagonal metal shaft sections which extend into hex openings in the carrier bodies of adjacent poles.
US5844455 teaches a current-limiting apparatus for a circuit breaker which makes it possible to effectively protect an electric load element by quickly blocking an electric flow path when an excessive current flows due to a ground, shortage, etc. at an electric flow path and preventing a re-formation of an electric flow path after the electric flow path is blocked. The apparatus includes a guide pin passing through the second pin hole and being extended from both side surfaces of the movable contact member, a holder, a portion of which support both ends of the movable contact member rotation center pin, for rotatably supporting the movable contact member, a current-limiting latch having a curved guide surface formed on one outer circumferential surface of the same on which the guide pin slidably moves, a support groove formed on another outer circumferential surface of the same, and a pin hole for supporting the holder, a rotation center pin inserted into the pin hole of the current-limiting

latch, both ends of which rotation center pin are inserted into portions of the holder, and a contact spring, both ends of which are supported by the support groove of the current-limiting latch and the support surface of the holder, for generating a variable force which prevents the movable contact member from being rotated.
US4539538 teaches a molded case circuit breaker includes a movable upper electrical contact having a base portion with a slot formed therein for releasabiy receiving a portion of an elongated spring biased locking pin disposed in a rotatable cross bar of an operating mechanism of the circuit breaker. The locking pin is biased in the slot by a pair of tension springs secured to the cross bar, enabling the upper electrical contact to move in unison with the cross bar. Upon the occurrence of a high level short circuit or fault current of sufficient magnitude, the pin is displaced from the slot enabling the independent rotational movement of the upper contact arm. During such movement, an elongated leaf spring is downwardly deflected and then released by the base portion. Subsequently, the upper electrical contact is prevented from contacting the lower electrical contact by the engagement of the leaf spring with the base portion. A subsequent trip operation of the operating mechanism removes the latching feature of the leaf spring.
US4626811 teaches a gap distance separating the contacts of a low-voltage circuit breaker in the tripped position is increased by utilizing resilient stop means which is located at the bottom wall of the breaker housing rather than at the top wall (or on the handle of the breaker) in accordance with prior art practice. The movable contact arm is pivotally mounted and structured to strike the stop means as the contacts are separated and being blown open during short circuit conditions and, after the circuit breaker is tripped, the collapsed toggle assembly of the operating mechanism shifts the movable contact arm away from the stop means and allows the arm to move an additional distance away from the fixed contact and thus increase the gap distance between the opened contacts.
US4245203 teaches a circuit interrupter includes two parallel pivoting contact arms, the lower of which is connected to a stationary conductor member using a clinch-type contact. The contact arm has an axle member rigidly attached thereto which is supported by a bearing member attached to the conductor. In one embodiment, the bearing member comprises a pair of bifurcated arms which are clamped about each end of the axle member. In an alternative embodiment, the conductor member lies generally parallel to the lower contact arm and is slotted to form a pair of elongated conductor arms, each of which supports a journal bearing member. One end of the axle is extended through each journal bearing.

US 6590172 teaches 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.
US 5266760 teaches a molded case circuit breaker having collapsible toggle linkage with rectangular cross section knee pin non-rotatably held within open rectangular slots in upper link, bifurcated movable contact fingers loosely guided for pivotal movement about fixed pin to break contact welds, helical compression springs biasing bifurcations against faces of a stationary connector, trapezoidal cross section shaft biasing shaft against a fixed corner of clamping strap and frame, increasing clamping force and increasing tool clearance, operating handle which changes pivot point moving to RESET position, reducing lateral force component of operating springs for reliable return of handle to OFF position, dual stops for movable contact fingers to spread impact forces along fingers, greater contact separation in poles not containing operating mechanism, slot motor laminations providing metal reinforcement to separate arc chamber housing which is cooperatively interlocked with base to distribute structural strength, terminal cover with arc vent extension angled downwardly, extended lug cover with second arc vent extension interlocked to terminal cover and arc chamber housing for no-fastener securement, trip unit armature pivoted in crested surface of molded pocket and connected to trip bar by wire bail for space-efficient location of parts, and accessory devices supported on and secured to trip unit housing have throw-away pin locking operator lever in correct position during installation.
US7217895 teaches a contact assembly for a circuit breaker includes a fixed contact, a movable contact, and a movable contact arm. The movable contact arm includes a first end carrying the movable contact, a second end, and a pivot portion proximate the second end. A moving arm portion extends from the first end toward the pivot portion. The moving arm portion has a width, an upper edge, a lower edge, and a height defined by the distance between the upper edge and the lower edge. In response to a trip condition, the movable contact separates from the fixed contact and the movable contact arm pivots open at an angular opening velocity. The height of the moving arm portion of the movable contact arm is at least four times the width of the moving arm portion, thus minimizing the moment-of-inertia of the movable contact arm, and increasing the angular opening velocity.
US 4255732 teaches a molded case current limiting circuit interrupter includes a pair of pivoting contact arms each supporting a contact and being connected to wiring terminals

such that current flows through the contact arms in opposite directions. One of the contact arms has a movable pivot point. A magnetic drive slot motor device is provided to generate electrodynamic contact opening force upon the contact arms during short circuit conditions. A high-speed magnetic trip device releases the operating mechanism under short circuit conditions to move the arm pivot point before the contact arms reclose. A spring latch is provided to latch the upper contact arm in a contact-separated position during short circuit conditions until such time as the over current flow through the breaker operates a thermal and magnetic trip mechanism to move an operating mechanism to the tripped position. Alternatively, a cam is provided which is connected by a link to the upper contact arm and positioned such that upon short circuit conditions the contact opening motion of the upper contact arm caused by electrodynamic repulsion forces will cause the connecting link to rotate the cam and move the armature of the magnetic trip device to actuate the trip mechanism and release the operating mechanism to the tripped position, thereby preventing reclosing of the contact arms before the operating mechanism is able to trip. The operating mechanism includes a bracket to allow normal contact reset yet provide a positive closed contact indication if the contacts are welded together. An anti-rebound contact arm shock absorber is provided which is made of material having a high mechanical hysteresis loop to provide maximum energy dissipation.
US 4910485 teaches a breaking device for a low voltage circuit breaker comprises in each pole a switching bar, a pair of stationary contacts connected to the connection terminals, a double-break rotary contact extending in a housing of the bar, and two arc chutes disposed on each side of the bar. Two contact pressure springs ensure elastic positioning of the rotary contact along the longitudinal direction of the pole. Pivoting of the rotary contact takes place around a fictitious axis mounted floating with respect to the fixed rotation axis of the bar.
US 6084489 teaches a circuit breaker characterized by separable contacts operable between a closed and an open position a contact arm having a latching surface and a latch arranged to engage the latching surface when the contacts are blown-open under short-circuit conditions. The arrangement of the latch allows for a positive lock under high magnitude short circuit levels while minimizing the force required by a mechanism to unlock the arm.
US 4916421 teaches current limiting circuit interrupter consisting of a modular unit housed in an insulating case and provided with two fixed contact arms and two movable contact arms. The movable contact arms can be actuated automatically by means of a rod coupled to an operating mechanism as well as by means of an electromagnetic actuator. The operating mechanism includes a lever and a rotating bracket arranged to hold the movable contacts in

an open condition when the electromagnet within the electromagnetic actuator is de-energized.
It happens that the contact repels open and gets locked due to fault condition but the breaker protection system takes a finite time to trip the mechanism when compared to the time taken by the contact to repel open. Some time it also happens that the protection system fails to trip the mechanism. In such case, the knob will be indicating ON position but since the contacts have repelled open, the breaker is not conducting current to the downstream equipment. This condition is a non compliance to the standard and thus has to be eliminated. Thus it is desired to have positive and faster tripping from the protection system.
The actuation can be taken from the contacts once they are locked and can be used to trip the breaker by giving signal to the protection system. The actuation can also be used to give an indication on the breaker (Like ON-OFF) to give the true contact position. So that if the protection system fails to trip then the indication will be actuated and will show if the contacts have repelled open.
Moving components reduce the efficiency of the mechanism as there is some amount of energy lost in overcoming friction. Friction also adds to the amount of heat generated at the surfaces in contact. It also increases wear and tear of the parts, thereby reducing the overall life of the system. Also, there will be variation in the contact force over a period of time due to such wear and tear.
It is also desirable to make the contacts move faster once it crosses the toggling position resulting in faster cut-off of fault current increasing the current limiting capability of the circuit breaker. It is also very important to achieve optimum contact force in the ON condition to keep the potential drop at the contact buttons to the minimum.
These and other limitations and needs of the conventional mechanisms necessitate an improved contact locking mechanism. Such a locking mechanism has been disclosed here which overcomes the limitations over and above the improvements and flexibility provided additionally.
The present invention achieves a better method of receiving actuation from the locking system than that considered in the prior methods. The invention can be used to give a signal to the protection system so that it trips as soon as the contacts lock. It also provides better repel open speed after toggling and at the same time provide higher contact force with high degree of flexibility to fix the position of toggling which are normally not possible in the

existing mechanisms. An inherent advantage of the system is the absence of direct contact between moving contacts and lock link which eliminates the friction between them. This will greatly increase the efficiency, and reduce the wear and tear thereby increasing the life of the system.
OBJECTS OF THE INVENTION
An object of the present invention is to overcome the problems/disadvantages of the prior art.
Basic object of the present invention is to provide a contact locking mechanism for circuit breakers which can give actuation to external mechanisms based on moving contact position.
Another object of the present invention is to provide a contact locking mechanism for circuit breaker which gives positive indication of the state of circuit breaker such as ON, OFF TRIP.
Another object of the present invention is to provide a contact locking mechanism for circuit breakers which can induce high velocity to moving contacts on occurrence of fault conditions and rapidly lock the moving contacts to open condition.
Yet, another object of the present invention is to provide a contact locking mechanism for circuit breaker which increases the deflection of the spring using lock link driven by the force exerted by the contact locking spring.
Yet, another object of the present invention is to provide a contact locking mechanism for circuit breaker in which toggling position is closer to the circuit breaker ON condition without affecting other parameters such as contact force.
Yet, another object of the present invention is to improve efficiency of the system due to reduction in friction in the system.
Yet, another object of the present invention is to increase life of the system due to absence of wear and tear between the components comprising the locking mechanism.
Yet, another object of the present invention is to provide a contact locking mechanism for circuit breaker to improve the life of the breaker by reducing the erosion of contacts due to arcing.
Yet, another object of the present invention is to provide a contact locking mechanism for circuit breakers which facilitates positive tripping of the circuit breaker.

Yet, another object of the present invention is to provide a contact locking mechanism which reduces overall tripping time of the breaker thereby giving a higher degree of protection to the downstream equipments.
Further object of the present invention is to provide faster cut-off of fault current which increases the current limiting capability of the circuit breaker due to higher velocity of moving contact after toggling.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a contact locking mechanism for giving actuation to external mechanisms based on the contact position, at the same time have high repel open speed of moving contacts, , said contact locking mechanism comprising:
drive shaft means;
movable contact means;
lock link means;
plurality of spring means;
plurality of pin means;
plurality of slot means;
wherein said movable contact means having a predetermined degree of freedom being pivoted by one of said pin means to said rotatabie drive shaft means; one of said plurality of pin means travelling through said movable contact means such that said movable contact means being engaged with the said pin means in a manner to facilitate operative connection with said spring means at the ends of the pin means;
said lock link means being mounted on another pin means wherein said pin means being operatively disposed in said slot means such that predetermined lengths of said pin means project out of said slot means so as to engage with said spring means
such that movement of said movable contact means co-operatively extends said spring means which correspondingly moves said lock link means whereby said movement of lock link means being guided by pin means disposed in the said slot means and being further guided by another set of slot means which allows and accommodate the movement of said

lock link means such that during a fault condition movement of the movable contact means is restricted beyond a predetermined position by the said pin means disposed in the slot means and the spring means extending to a predetermined deflected position whereby the movable contact is brought back to its normal ON position by the said spring means when repulsion force on said movable contact means being not enough to move it beyond toggling position.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates an isometric view of the locking mechanism of the present invention used in a single pole of a circuit breaker.
Figure 2 illustrates another isometric view showing the rear end of the locking mechanism of the present invention used in a single pole of a circuit breaker.
Figure 3 illustrates a top view of the locking mechanism of the present invention.
Figure 4 illustrates an exploded view of the components of the locking mechanism (excluding springs) of the present invention.
Figure 5A illustrates a front view of the locking mechanism at its Norma! or assembled condition.
Figure 58 illustrates a sectional view of the locking mechanism at its Normal or assembled condition.
Figure 6A illustrates a front view of the locking mechanism at its ON condition.
Figure 6B illustrates a sectional view of the locking mechanism at its ON condition.
Figure 7A illustrates a front view of the locking mechanism at its toggle condition.
Figure 7B illustrates a sectional view of the locking mechanism at its toggle condition.
Figure 8A illustrates a front view of the locking mechanism at its locked condition
Figure 8B illustrates a sectional view of the locking mechanism at its locked condition.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
According to the invention, there is provided a contact locking mechanism for providing contact position actuation as shown in figure 1. According to preferred embodiment of the invention, the contact locking mechanism comprises a rotating member of the circuit breaker

mechanism, driveshaft (1) to which the upper contact (2) is pivoted at pin (6). Rotation of this driveshaft will cause upper moving contacts to come in contact with the lower contacts and thereby complete the electrical circuit. Spring (5) is connected at one end to Pin (7) and the other end to pin 4 which slides in the slot provided in the driveshaft (1). Pin (4) is in turn is fixed to a lock link (3) which can slide in the slots (9) provided in driveshaft on top and bottom sides (11, 12). The motion of moving contact and lock link are inter-related due to connection between the two using spring. Movement of either of them will result in the change in direction of the force on the other component and thus result in moving the other component.
Figure 1 shows the 3D view of the arrangement for a single pole of the circuit breaker. For multiple poles multiple such assemblies will be used side by side using a common connecting driveshaft across all the poles. The driveshaft (1) is connected in turn to the circuit breaker mechanism. Movement of the mechanism to different positions makes the driveshaft rotate and thereby making moving contacts (2) open or close the circuit. Figure 2 shows the 3D view from the rear end of the driveshaft (1). Figure 3 is the top view of the arrangement and figure 4 shows an exploded view of the internal arrangement i.e. excluding the springs.
The working of the invention is shown in Figures 5, 6, 7 & 8 with different positions.
The working of the invention is shown in Fig 5, 6, 7 & 8 with different positions. The same is explained below. In the figs mentioned, sub-figure A refers to the front view of the invention and B refers to the sectional view of the invention in which the changes in internal components can be observed.
Fig 5 shows the arrangement in the normal or assembled condition. This is the position in which the moving contact cannot go further down since it stops on the driveshaft.
When the contact locking mechanism is assembled in the circuit breaker along with the mechanism and operated, in ON condition, the moving contact will be slightly upward when compared to the normal position (fig 5). This is due to the intended over travel provided in the circuit breaker mechanism to achieve a certain minimum contact force. This position is shown in figure 6.
When the fault occurs, there is an upward force on the moving contact (2) thereby which it will rotate about the pivot 6. This movement of the contact will cause the direction offeree on the lock link to change and thereby move upward. The points across which the spring (5) is connected will therefore be moving.

Figure 7 shows the toggling or the locking position. If due to fault the moving contact rotates beyond the position shown in the figure, it will get locked to the position shown in figure 8 due to a net force provided by the spring (5) in that direction. Thus, the spring (5) which is stretched to its maximum deflection reaches an equilibrium state by reducing its length and releasing energy in the process to move the moving contact. If the repulsion force on the moving contact is not enough to move the positions beyond the toggling position, the arrangement will fall back to the positions shown in figure 6 i.e. in their ON condition.
According to preferred embodiment of the invention, once the moving contact (2) gets locked, it is brought back to the normal condition when the circuit breaker protection system subsequently trips the mechanism due to fault. When the signal is given, the driveshaft rotates in the upward direction. The moving contact then comes in contact with the cover / top portion of the circuit breaker and experiences a reaction force in the downward direction in a way as to make the moving contact cross the toggling position. Once the moving contact crosses the toggling position, it goes to the normal position by virtue of the force exerted by the spring. Therefore, process of unlocking of moving contact is just the opposite of the locking process.
Lock link or the moving contact can be used to give a trip signal or actuation to the protection system using an intermediate mechanism or arrangement of links. This is possible since the present invention has definite positions in ON and in locked condition. This will ensure that breaker always trips speedily when the contacts repel open. This can also be used to give indication on the circuit breaker which will indicate if the contacts are in ON or locked condition. An example for this can be in the form of a pop up arrangement. If the pop up arrangement is directly mounted above the rear end of the lock link, there will be two positions for the pop up indicator. Firstly in the ON condition when the rear end of the lock link is towards the bottom, the popup will be depressed from the outer surface of the breaker. When the contacts get locked, the rear end of the lock link moves up and thus takes the pop up along with it upward. In this case, the popup would be projecting out from the surface of the breaker giving an indication that the contacts have got locked. Similarly, the invention can be used for tripping the breaker or for completing an electrical circuit once the contacts are in a particular position.
In the prior art methods, the only way of giving such actuation or indication was using the moving contacts which had a distinct position in the ON and in the locked / opened position. However, since the moving contact is among the components of the circuit breaker where there is high temperature, the use of such additional mechanism or arrangement would cause damage to the contacts or to the parts that are in contact with it. Thus, the disclosed

invention overcomes the disadvantage by providing an additional component from which such an actuation can be taken.
The lock link is moved in the mechanism without direct physical contact with the moving contacts. In the prior methods there will be a mechanical joint between the moving contact and the lock link which reduces the efficiency of the mechanism as there is some amount of energy lost in overcoming friction. Friction also adds to the amount of heat generated at the surfaces in contact. It also increases wear and tear of the parts, thereby reducing the overall life of the system. In the present invention, the inherent disadvantages are eliminated as the lock link and the moving contact are connected only through a spring as against a direct mechanical joint. Avoiding such a mechanical joint there will be consistency in the contact force over a period of time as there is reduction in wear and tear between the lock link and the moving contact which is an important advantage that the prior methods cannot achieve.
Since moving contact and lock link both move after toggling, there is faster energy release by the spring after toggling, resulting in higher velocity of moving contact. This results in faster cut-off of fault current increasing the current limiting capability of the circuit breaker.
Toggling position is that instant at which the points or pins (7, 6 & 4) come in the same line. The orientation of the line is fixed on various parameters by design. The effectiveness of the toggling position is decided by the closeness of the toggling position to the ON position. Since, in such case the amount of rotation required by the moving contact to reach the toggling position and get locked will be lesser. If the pin 4 were stationary, for the given toggling position, the amount of rotation would be higher when compared to that required in the present invention. This can be explained since both the moving contact and lock link are moving at the same time towards the toggling position, they reach the toggling position earlier and since one of the points / pins in earlier invention is fixed, the amount of travel by the moving contact to achieve the toggling position will be higher. Thus on occurrence of fault, the present invention can get locked faster than in the prior methods. This will reduce the let through energy of the mechanism to the downstream equipments.
Above disadvantage can be removed in the prior methods by keeping toggling position closer to the ON positron. This will reduce the amount of rotation of moving contact for getting locked. This however will reduce the contact force between the moving and fixed contacts in the breaker due to lesser angle between spring and moving contact. In order to achieve the same contact force with toggling position closer to the ON position, higher load spring can be used. This however will increase the stress levels in the spring and thus reduce the overall factor of safety in the spring and thus the whole mechanism. Also, since

the higher load value spring is greater in size, the cost will be higher and the size of the locking mechanism will increase which is undesirable.
Thus the above disadvantages of the prior methods can be avoided since the toggling position can be as closer to the ON position without having to sacrifice on the position of toggling and at the same time achieving the required contact force with lesser dimensions and weight of the entire system.
ADVANTAGES OF THE INVENTION
1. Actuation can be used for reducing the overall tripping time of the breaker by giving a higher degree of protection to the downstream equipments.
2. Actuation can be used for true contact position indication on the outside of breaker.
3. High velocity of moving contact after toggling resulting in faster cut-off of fault current increasing the current limiting capability of the circuit breaker.
4. Greater degree of flexibility in controlling the toggling angle which can be used in controlling the threshold current after which toggling should occur.
5. Improved efficiency of the system due to reduction in friction in the system.
6. Increased life due to absence of wear and tear between the components.
7. Consistency in the contact force throughout the life of the system.
The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its spirit. The invention is not limited to the details cited above. The moving contact, pins spring, lock link and driveshaft as stated do not limit the scope of the present invention. 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

We Claim
1. A contact locking mechanism for giving actuation to external mechanisms based on the contact position, at the same time have high repel open speed of moving contacts, said contact locking mechanism comprising.
drive shaft means (1);
movable contact means (2);
lock link means (3);
plurality of spring means (5);
plurality of pin means (4, 6, 7);
plurality of slot means (8,9);
wherein said movable contact means (2) having a predetermined degree of freedom being pivoted by one of said pin means (6) to said rotatable drive shaft means (1); one of said plurality of pin means (7) travelling through said movable contact means (2) such that said movable contact means being engaged with the said pin means (7) in a manner to facilitate operative connection with said spring means (5) at the ends of the pin means (7);
said lock link means (3) being mounted on another pin means (4) wherein said pin means (4) being operatively disposed in said slot means (8) such that predetermined lengths of said pin means (4) project out of said slot means (8) so as to engage with said spring means (5)
such that movement of said movable contact means (2) co-operatively extends said spring means (5) which correspondingly moves said lock link means (3) whereby said movement of lock link means being guided by pin means (4) disposed in the said slot means (8) and being further guided by another set of slot means (9) which allows and accommodate the movement of said lock link means such that during a fault condition movement of the movable contact means is restricted beyond a predetermined position by the said pin means (4) disposed in the slots (8) and the spring means extending to a predetermined deflected position whereby the movable contact means is brought back to its normal ON position by the said spring means when repulsion force on said movable contact means being not enough to move it beyond toggling position.

2. Mechanism as claimed in claim 1, wherein said lock link means (3) being adapted to provide actuation to external mechanisms such as circuit breaker protection system or to provide indication on the breaker.
3. Mechanism as claimed in claim 1, wherein said pin means (4, 7) being adapted to provide actuation to external mechanisms such as circuit breaker protection system or to provide indication on the breaker.
4. Mechanism as claimed in claim 1, wherein said movable contact means (2) being adapted to provide actuation to external mechanisms such as circuit breaker protection system or to provide indication on the breaker.
5. Mechanism as claimed in claim 1, wherein said set of slots are (8) provided on lateral sides (10) of said drive shaft means.
6. Mechanism as claimed in claim 1, wherein said another set of slots (9) are provided on top and bottom sides (11,12) of said drive shaft means (1).
7. Mechanism as claimed in claim 1, wherein said spring means (5) being selected from compression springs, torsion springs, leaf springs and the like.
8. A contact locking mechanism for giving actuation to external mechanisms based on the contact position, at the same time have high repel open speed of moving contacts, as herein substantially described and illustrated with the accompanying drawings,