FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
AN IMPROVED KNOB MECHANISM FOR CIRCUIT BREAKERS;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to operating knobs of circuit breakers. BACKGROUND OF INVENTION
A circuit breaker is a mechanical switching device, capable of making, carrying and breaking currents under normal circuit conditions and a/so making, carrying for a specified time and breaking currents under specified abnormal circuit conditions such as those of short circuit.
Circuit breakers have three positions corresponding to the status of the separable contacts. These positions typically include an 'ON' position, in which the separable contacts are closed, an 'OFF' position in which the contacts are open and a Trip' position in which the contacts are tripped open.
The forces applied for operating a circuit breaker, influence the life span of that circuit breaker. Higher the operating forces, higher would be stress generated in the operating mechanism of the circuit breaker. If the operating forces are higher than it is difficult to operate the circuit breaker for an average health personnel and if the circuit breaker is installed at non-easily reachable location (top corner of the panel board) then it is really cumbersome to operate the circuit breaker with ease.
Also, when the circuit breakers are operated with an electrically operated mechanism (EOM), the life of the EOM depends on the operating forces of circuit breaker. EOM consists of a mechanism driven by an electric motor which generates enough torque to rotate the mechanism of EOM & hence operate the circuit breaker. The current drawn by the electric motor depends upon the torque (load) requirement. Higher the torque higher would be current drawn. Typically, it may be observed that if the electric motor draws current more than the rated current for more number of times than the safe limit, the electric motor burns.
The operating knob of a circuit breaker must therefore have features that utilize maximum applied forces without losses. The energy required to operate the mechanism should be minimum. Maximum is the efficiency of the mechanism and maximum is the life span of operating means (manual or automatic by EOM) of the circuit-breaker.

A novel operating knob for a typical circuit breaker is therefore required and the same is disclosed as follows.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide improved designs in the operating knob of a circuit breaker; the knob having features that utilize maximum applied forces without losses.
Another object of the present invention is to facilitate a user to apply minimum energy to operate a circuit breaker.
In accordance with this, there is provided an improved knob mechanism for a circuit breaker. The knob comprises a first surface positioned towards contact system of the circuit breaker, a second surface positioned towards protection release system and a fork for mounting the knob. The imaginary line passing through the first surface and the second surface also passes through the centre of the fork. Further, the surface on which the force is applied is parallel to the line passing through the centre of rotating profile thereby utilizing applied forces to maximum extent without losses and reducing the efforts required to operate the circuit breaker.
In one embodiment of the present invention when the knob is rotated, the fork gets rotated at pivot point till latching surface on main latch goes below latch bracket of the circuit breaker.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Fig. 1 is the front view of the knob showing two profiles according to an embodiment of the present invention.
Fig. 2 A shows assembly of fork and knob according to an embodiment of the present invention.
Fig. 2 B shows assembly of fork and knob in wireframe according to an embodiment of the present invention.
Fig. 2 C shows assembly of fork and knob with explaining the surfaces passing through the pivot of fork according to an embodiment of the present invention.
Fig. 3 shows the front view of the start of the resetting process rn wireframe according to an embodiment of the present invention.
Fig. 4 shows the front view of the end of the resetting / switching OFF process in wireframe according to an embodiment of the present invention.
Fig. 5 shows the front view of the start of the switching ON process in wireframe according to an embodiment of the present invention.
Fig. 6 shows the front view of the end of the switching ON process in wireframe according to an embodiment of the present invention.
Fig. 7 shows total assembly mechanism with knob in wireframe according to an embodiment of the present invention.
DESCRIPTION OF THE INVENTION
The present invention provides improved designs in the operating knob of a circuit breaker having features that utilize maximum applied forces without losses. The operating knob facilitates a user to apply minimum energy to operate a circuit breaker.
Fig. 1 is the front view of the knob according to an embodiment of the present invention The knob comprises a first surface 101 positioned towards contact system of the circuit breaker, a second surface 102 positioned towards protection release system and a fork for mounting the knob. The imaginary line passing through the first surface 101 and the second surface 102 also passes through the centre of the fork. Further, the surface (101 or 102) on which the force is applied is parallel to the line passing through the centre of rotating profile thereby utilizing applied forces to maximum extent without losses and reducing the efforts

required to operate the circuit breaker. The resetting surface 103 also passes through the centre of fork pivot
In one embodiment herein, the first surface 101 is the first profile of the knob towards top of the circuit breaker. The second surface 102 is the second profile of the knob towards bottom of the circuit breaker. The first profile is used while resetting and switching OFF the circuit breaker. The second profile is used while switching ON the circuit breaker.
In one embodiment herein, when the knob is rotated, the fork gets rotated at pivot point till latching surface on main latch goes below latch bracket of the circuit breaker.
Fig. 2 shows the imaginary line passing through the first surface and the second surface. The imaginary line also passes through the centre of the fork on which the knob is mounted.
Fig. 2 A shows assembly of fork and knob according to an embodiment of the present invention.
Fig. 2 B shows assembly of fork and knob in wireframe according to an embodiment of the present invention. A Wire frame model allows visualization of the underlying design structure of a 3D model.
Fig. 2 C shows assembly of fork and knob with explaining the surfaces passing through the pivot of fork according to an embodiment of the present invention.
Fig. 3 shows the front view of the RESET-START 301, i.e. start of the resetting / process in wireframe according to an embodiment of the present invention.
Fig. 4 shows the front view of the RESET-END 401, i.e. end of the resetting / switching OFF process in wireframe according to an embodiment of the present invention.
Referring to Fig. 3 and Fig. 4, in tripped condition of circuit-breaker, when the knob is rotated, the fork gets rotated at pivot point till latching surface on main latch goes below latch bracket of the circuit breaker. To achieve maximum force utilization in rotating profile, the surface on which the force is applied should be parallel to the line passing through the centre of rotating profile. As explained in Fig.

2 C, the resetting surface 103 {first surface/profile 101 of Figure 1) is passing through the centre of fork pivot.
Fig. 5 shows the front view of the ON-START 501 i.e. start of the switching ON process in wireframe according to an embodiment of the present invention.
Fig. 6 shows the front view of the ON-END (ON) 601 i.e. start of the switching ON process in wireframe according to an embodiment of the present invention.
Referring now to Fig. 5 and Fig. 6, same principle of first surface / first profile applies to the second surface / second profile. The second profile is also passing through centre of fork pivot so that the least force is required to switch ON the circuit breaker.
Fig. 7 shows total assembly mechanism with knob in wireframe according to an embodiment of the present invention. The profiles of the improved knob as discussed above, utilizes applied forces to maximum without any losses. The energy required to operate the mechanism is the least and efficiency of the mechanism is maximum and the life span of the circuit-breaker thus becomes maximum with the use of the improved knob as discussed above.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

We Claim :
1. An improved knob mechanism for a circuit breaker, the knob mechanism comprising:
a first surface positioned towards contact system of the circuit breaker;
a second surface positioned towards protection release system;
a fork for mounting the knob; such that the imaginary line passing through the first surface and the second surface, also passes through the centre of the fork and the surface on which the force is applied is parallel to the line passing through the centre of rotating profile thereby utilizing applied forces to maximum extent without losses and reducing the efforts required to operate the circuit breaker.
2. An improved knob mechanism as in claim 1, wherein the first surface is the first profile of the knob.
3. An improved knob mechanism as in claim 1, wherein the second surface is the second profile of the knob.
4. An improved knob mechanism as in claim 2, wherein the first profile is used while resetting and switching OFF the circuit breaker.
5. An improved knob mechanism as in claim 3, wherein the second profile is used while switching ON the circuit breaker.
6. An improved knob mechanism as in claim 1, wherein when the knob is rotated, the fork gets rotated at pivot point till latching surface on main latch goes below latch bracket of the circuit breaker.