FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention. - IMPROVED CIRCUIT BREAKER MECHANISM PROVIDING ELECTROMECHANICAL COMPENSATION
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 mariner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to circuit breaker and more particularly, the invention relates to an improved circuit breaker mechanism providing electromechanical compensation.
BACKGROUND AND THE PRIOR ART
Most of the current limiting circuit breakers are designed to quickly initiate contact separation in the event of a short-circuit fault. While this has the advantage of low let-through energies and faster arc quenching, however the method poses challenges when it comes to co-ordination and discrimination amongst upstream and downstream devices. The upstream devices in most of the cases (when they are MCCBs) open partially and reclose during a fault which is cleared by downstream. This causes disturbances in the other branches of the system and also some damage to the contact buttons of the upstream device too. When the upstream is a category B breaker, it has to remain closed for a pre-set duration before it opens in case the downstream fails to clear the fault.
US 4276526 discloses a miniature current limiting circuit breaker incorporates double break circuit interrupting contacts capable of being abruptly separated by a high fault current responsive solenoid acting to first trip the breaker mechanism and then forcibly effect contact separation. The arc chamber is constructed to achieve enhanced blowout of the arc into the arc chute and to develop gas pressures acting to accelerate contact separation. The circuit breaker is trip-free and includes both thermal tripping and internal common tripping capabilities. However, several means for actuating but not limited to actuation by means of a solenoid was not known in the prior art and also not to allow the contacts to separate due to repulsive forces on account of high fault currents was not known in the prior art.

US 34, 83,343 disclose two extended limbs attached to the fixed contacts in a direction which aids the arc movement during short-circuit conditions. However, having a relative simpler shape of the fixed contact which assists in withstanding higher fault currents when used with the corresponding moving contact assemblies was not known in the prior art.
Circuit breaker is a device employed to protect the equipments in an installation in case of over currents arising out of fault conditions. An electric circuit breaker contact system is provided including at least one stationary contact member and at least one movable contact member and biasing means between the movable contact member and a normally stationary support member to provide contact closing pressure during normal condition. It is also required to interrupt the fault current rapidly in one or more circuit's paths upon the occurrence of an over current in any one circuit path so as to minimize damage to the installation resulting from thermal and mechanical stresses.
Thus, there is a need to provide comprehensive coordination with downstream protection devices, the device in consideration is required to withstand the maximum through fault current. The upstream device in this case will withstand until a time which is marginally higher than fault clearing time of downstream, thereafter the contacts shall open by means of a mechanism, in case the downstream fails to clear the fault. Compensation of these forces can be done either through special current path configurations or from the combination of both such configurations and mechanical locking arrangements. The compensation by electromagnetic means is derived from the very geometry of the contacts. The mechanical aspect can be any circuit breaker mechanism or even a coil operated plunger which acts upon the moving contact(s) under consideration.

Therefore, the present inventors have developed an improved circuit breaker mechanism having a linear attraction type contact system. In which, the upstream breaker would withstand for a short duration which is marginally more than the fault clearing time of the downstream. Beyond which, the upstream opens by means of an external mechanism and clears the fault. The contacts have to be held together against the high electromagnetic forces produced by the high current flow. The present invention would achieve achieves this by means of electro-mechanical compensation.
OBJECTS OF THE INVENTION
A basic object of the present invention is to enable the contact system to withstand the forces during short circuit. This is achieved by the very geometry of the contact system. Another object of the present invention is to an improved circuit breaker mechanism which shall enable the opening of the said contact in the event the downstream breaker fails to clear the fault
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
There is provided a circuit breaker mechanism.
According to one embodiment of the present invention, there is provided improved circuit breaker mechanism providing electromechanical compensation, said mechanism comprising:

atleast one fixed contact arm for carrying current having a fixed contact button attached thereto;
atleast one moving contact arm having a moving contact button attached thereto, said moving contact arm shielded using a moving contact shield;
atleast one fixed runner connected to said fixed contact for efficient movement of electric arc during fault;
atleast one link connected to said moving contact using a link pin;
atleast one moving contact link, said link substantially C shaped and shielded using a shield;
atleast one pivot pin about which said moving contact arm rotating thereby making contact with said contact buttons;
atleast one slider pin about which said moving contact arm slide during mechanism operation,
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the appended drawings:
Fig. 1 illustrates an isometric view of the B type moving contact arrangement along with the fixed contacts in ON condition.
Fig. 2 illustrates an isometric view of the B type moving contact arrangement along with the fixed contacts in OFF condition. It shows different components used.

Fig. 3 illustrates an isometric view of the B type moving contact arrangement along with the fixed contacts in ON condition with current directions.
Fig. 4 illustrates an isometric view of the B type moving contact arrangement with current directions.
Fig. 5 illustrates an isometric view of the B type moving contact arrangement.
Fig. 6 illustrates a sectional view of the B type moving contact arrangement.
Fig. 7 illustrates an isometric view of the I type moving contact arrangement along with the fixed contacts in ON condition.
Fig. 8 illustrates an isometric view of the I type moving contact arrangement along with the fixed contacts in OFF condition.
Fig. 9 illustrates an isometric view of the I type moving contact arrangement with link.
Fig. 10 illustrates an isometric view of the I type moving contact arrangement.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.

Reference is first invited to Fig 1 where the isometric view of the B type moving contact arrangement along with the fixed contacts in ON condition is shown.
Fig. 2 shows an isometric view of the B type moving contact arrangement along with the fixed contacts in OFF condition.
Fig. 3 shows an isometric view of the B type moving contact arrangement along with the fixed contacts in ON condition with current directions.
Fig. 4 shows an isometric view of the B type moving contact arrangement with current directions.
Fig. 5 shows an isometric view of the B type moving contact arrangement.
Fig. 6 shows a sectional view of the B type moving contact arrangement.
Fig. 7 shows an isometric view of the I type moving contact arrangement along with the fixed contacts in ON condition.
Fig.8 shows an isometric view of the I type moving contact arrangement along with the fixed contacts in OFF condition.
Fig. 9 shows an isometric view of the I type moving contact arrangement with link.
Fig. 10 shows an isometric view of the I type moving contact arrangement.
The invented system is thus an improved circuit breaker mechanism providing electromechanical compensation.

DETAILED DESCRIPTION OF THE INVENTION
Accordingly in the present invention there is provided an improved circuit breaker mechanism having a linear attraction type contact system. Figures 2 and 3 show the details of B Contact arrangement. The position with the fixed contact (1) and the moving contact assembly comprising Moving contact C-link (7) and moving contact arm (6) shown corresponds to the contacts in ON state. As shown in figure 3, the current flows from fixed contact to fixed contact button, to moving contact button, to moving contact arm to moving contact C-link and flows out following a similar sequence through the other fixed contact.
In the vicinity of the contact buttons, the current in the corresponding limb of the fixed contacts(l) and the moving contact C-link (7) are in same direction which results in a net attractive force between the two. Each half of moving contact C-link (7) has a moving contact arm (6) attached to it, having a shape as shown in the figure. The relative directions of the currents in the above said arms and those in the corresponding fixed contact (1) arms are anti-parallel, which results in a repulsion between them. To minimize this repulsive force a moving contact shield (8) is placed in the slot as shown in the figure. In a similar manner another magnetic shield called as moving contact C-shield (9) is placed against the moving contact C-link to minimize the effect of the same.
Figure 7 shows the details of I Contact arrangement. The position with the fixed contact (1) and the moving contact assembly comprising Moving contact arm (6) shown corresponds to the contacts in ON state. The current flows from fixed contact to fixed contact button, to moving contact button, to moving contact arm and flow out through the other fixed contact. The moving contact assembly is pivoted around pivot

pin (11). During ON condition, the pivot pin is held tightly by an external mechanism. As the current flows from buttons (4) to (5), there is a repulsive force between each of the contact pairs. This generates a torque about the pivot. This torque results in an increased contact force between the contact button pair on the other side. This mechanism results in an increased contact pressure as the current increases. This enables the contact not to separate out due to repulsive or holmes forces under high fault currents. This provides a basis for high fault withstand in the present invention.
Constructional elements
1: Fixed contact: It is current carrying element of the circuit which remains fixed during the operation.
2: Fixed Runner: It is connected to the fixed contact for efficient movement of the electric arc formed during fault condition in the circuit breaker.
3. Link Pin: It is connected the link to the moving contact.
4. Fixed Contact Button: It is the button on the fixed contact.
5: Moving Contact Button: It is the button on the moving contact
6: Moving Contact Arm: It is one of the current carrying part of the moving contact
7: Moving Contact C Link: It is one of the current carrying part of the moving contact having C shaped in which the direction of current is same as that of the fixed contact.
8: Moving Contact Shield: It magnetically shields the moving contact arm . It can be any magnetic material.

9: Moving Contact C Shield: It magnetically shields the moving contact C link . It can be any magnetic material.
10. Link: It connects the mechanism with the moving contact.
11. Pivot Pin: It is the pivot pin of the moving contact. About this pin the moving contact can rotate so as to make proper contact at both the contact buttons.
12. Slider Pin: It is the slider pin of the moving contact. About this pin the moving contact will slide when the operating mechanism operates it.
13. Threshold value: It's the electro-mechanical compensation force essential to withstand the electro-dynamic forces exerted on the moving contact because of the high fault current. Electro-dynamic forces generated beyond the pre-set value will enable moving contact to rise over the threshold value thereby operating the same. Compensation mechanism can be tuned to achieve desired threshold value by changing the constructional parameters.
ADVANTAGES:
1. Without any external force arrangement, one can provide proper contact pressure even if the current increases to a high value. The same can be extended to multi-finger contact arrangement and/or any number of breaks.
2. Life of the breaker increases.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein

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 embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:
1. An improved circuit breaker mechanism providing electromechanical compensation, said mechanism comprising:
atleast one fixed contact arm for carrying current having a fixed contact button attached thereto;
atleast one moving contact arm having a moving contact button attached thereto;
atleast one fixed runner connected to said fixed contact for efficient movement of electric arc during fault;
atleast one link connected to said moving contact using a link pin;
atleast one moving contact link;
atleast one pivot pin about which said moving contact arm rotating thereby making contact with said contact buttons;
atleast one slider pin about which said moving contact arm slide during mechanism operation
whereby a net force of attraction is created between he fixed and moving contacts by the direction of flow of currents in the said contact system aiding in achieving discrimination between upstream and downstream breakers by enabling the upstream breaker to remain closed during the fault and in the event the downstream breaker fails to clear the fault the mechanism would pull open the contacts, thereby clearing the fault.
2. Mechanism as claimed in claim 1 wherein said moving contact link is adapted to provide current direction as that of said fixed contact.

3. Mechanism as claimed in claim 1 wherein said moving contact arm comprising a moving contact shield.
4. Mechanism as claimed in claim 1 wherein said moving contact shield is placed in a slot.
5. Mechanism as claimed in claim 1 wherein said moving contact link is substantially C shaped.
6. Mechanism as claimed in claim 1 wherein said moving contact link is shielded.
7. Mechanism as claimed in claim 1 wherein said shield providing substantially magnetic shielding to the repulsion force between the contacts.
8. An improved circuit breaker mechanism providing electromechanical compensation as herein described and illustrated with reference to accompanying drawings.