FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13)
TITLE OF THE INVENTION: ROTARY HANDLE MECHANISM FOR CIRCUIT BREAKERS
APPLICANT: LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
MumbaL 400 001, Maharashtra
INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to the circuit breakers and particularly relates to a rotary handle mechanism in the molded case circuit breakers. More particularly the present invention relates to an arrangement of the rotary handle operating mechanism for providing torque on the handle to operate a molded case circuit breakers instead of applying a pull and push type of feree.
B) BACK GROUND OF THE INVENTION
[0002] Circuit breakers are mechanical switching devices capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and breaking currents under specified abnormal conditions. A circuit breaker basically consists of a pair of separable contacts and an interrupting medium. The function of the contacts is to conduct the electrical current when the breaker is closed and to withstand the arcs while interrupting. Generally the electrical contacts have a stationary part and a moving part. By bringing the moving contact to touch the stationary contact, an electric current flows and the breaker is closed. By driving the moving contact away from the stationary contact, an electric arc is developed and by quenching the electrical arc. the flow of electrical current is stopped and the breaker is opened.
[0003] In the existing technique, a small gear and a big gear meshed with each other are used in the rotary handle operating mechanism and two bevel gears enable the rotary operation of the circuit breakers. Further in the existing technique, the rotation of the small gear is more than that of the rotation of the big gear due to which more torque needs to be applied on the small gear. The existing techniques require a pul! and push type of force to be applied on a knob of the molded case circuit breakers for operation. Further in the existing technique, the pull and push type of

force may not be applied in the circuit breakers mounted on the panel. Also the existing technique necessitates the use of one or more extra accessories to have a rotary operated handle arrangement in the molded case circuit breakers.
[0004] Hence there is a need for a rotary handle mechanism arrangement for molded case circuit breakers that provides a better control to the operator for operating the circuit breakers. There also exists a need for a rotary handle mechanism arrangement with a minimal number of components adapted to be arranged in predefined space.
[0005] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
C) OBJECT OF THE PRESENT INVENTION
[0006] The primary object of the present invention is to provide a rotary handle mechanism arrangement in the molded case circuit breakers to enable an operator to operate the circuit breakers by rotating a handle.
[0007] Another object of the present invention is to provide a rotary handle mechanism arrangement in the molded case circuit breakers utilizing less space and with less number of components.
[0008] Yet another object of the present invention is to provide a rotary handle mechanism arrangement to obtain a desired control on the ON-OFF, OFF-ON and TRIP-RESET operations of the circuit breakers by an operator.

[0009] Yet another object of the present invention is to provide an integrated rotary handle operating mechanism for operating the circuit breakers by rotating a handle.
[0010] Yet another object of the present invention is to provide a rotary handle mechanism arrangement in which the rotation of the handle leads to storing potential energy in one or more springs during a charging operation.
D) SUMMARY OF THE INVENTION
[0011] The various embodiments of the present invention provide a rotary handle operating mechanism for circuit breakers. The mechanism includes a fixed contact, a moving contact, a knob bevel gear guided in a plurality of mechanism side plates, a fork bevel gear, a rotary handle inserted in the knob level gear, a circuit breaker cassette, a mechanism module mounted on the circuit breaker cassette and a plurality of springs. A torque is applied on the rotary handle by an operator to operate the breaker which causes a rotation of the fork bevel gear in a clockwise direction. A plurality of mechanism springs connected to fork gear get charged up to dead center and rotor moves from OFF to ON position and vice versa.
[0012] According to one embodiment of the present invention, the rotary handle
is locked in the OFF position when no torque is applied.
[0013] According to one embodiment of the present invention, the plurality of
springs stores a potential energy due to a rotation of the rotary handle.
[0014] According to one embodiment of the present invention, the fork bevel gear is pivoted on one side plate of the mechanism module.

[0015] According to one embodiment of the present invention, the knob bevel gear and the fork bevei gear enable an operator to operate the circuit breaker from at least one of the three switching operations namely an ON-OFF position, an OFF-ON position and a TRIP-RESET position.
[0016] According to one embodiment of the present invention, the rotary handle is rotated in the clockwise direction to operate the breaker from OFF to ON condition.
[0017] According to one embodiment of the present invention, the rotary handle is rotated in the anti clockwise direction to operate the breaker from ON to OFF condition.
[0018] According to one embodiment of the present invention, the axis of rotation of the knob bevel gear and the fork bevel gear are perpendicular to each other.
[0019] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings in which:

[0021] FIG. 1 illustrates an isometric view of a circuit breaker cassette with the circuit breaker in an OFF condition, according to one embodiment of the present invention.
[0022J FIG. 2 illustrates an isometric view of a circuit breaker cassette with the circuit breaker in an ON condition, according to one embodiment of the present invention.
[0023] FIG.3 illustrates an isometric view of the rotary handle operating mechanism in an ON condition with a circuit breaker cassette hidden, according to one embodiment of the present invention.
[0024] FIG.4 illustrates an isometric view of the rotary handle operating mechanism in an intermediate position from an ON condition to an OFF condition, according to one embodiment of the present invention.
[0025] FIG.5 illustrates an isometric view of the rotary handle operating mechanism in an OFF condition in the circuit breaker, according to one embodiment of the present invention.
[0026] FIG.6 illustrates an isometric view of the rotary handle operating mechanism in a TRIP condition in the circuit breaker, according to one embodiment of the present invention.
[0027] Although the specific features of the present invention are shown in some
drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

F) DETAILED DESCRIPTION OF THE INVENTION
[0028] In the following detailed description, a reference is made to the
accompanying drawings that form a part hereof and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0029] The various embodiments of the present invention provide a rotary handle operating mechanism for circuit breakers. The mechanism includes a fixed contact, a moving contact, a knob bevel gear guided in a plurality of mechanism side plates, a fork bevel gear, a rotary handle inserted in the knob bevel gear, a circuit breaker cassette, a mechanism module mounted on the circuit breaker cassette and a plurality of springs. A torque is applied on the rotary handle by an operator to operate the breaker which causes a rotation of the fork bevel gear in a clockwise direction and a plurality of springs connected to the fork bevel gear are charged which in turn rotates the rotor from OFF to ON position and vice versa to a dead center.
[0030] FIG. I illustrates an isometric view of a circuit breaker cassette with the circuit breaker in an OFF condition, according to one embodiment of the present invention, while FIG.2 illustrates an isometric view of the circuit breaker cassette with the circuit breaker in an ON condition, according to one embodiment of the present invention. With respect to the FIG.l and FIG.2, the molded case circuit breaker includes a circuit breaker cassette 102, a rotor 104, a mechanism module 106 and a rotary handle 108. The mechanism module 106 is mounted on the circuit breaker cassette 102 and consists of various linkages. The mechanism module 106 in the circuit breaker is a four bar mechanism.

[0031] The circuit breaker is capable of making, carrying and breaking current
Under normal circuit conditions. Further the circuit breaker is also capable of breaking current during abnormal circuit conditions such as short-circuit. The short circuit current is sensed automatically and a signal is given to the mechanism module 106 as a TRIP command. The signal provided leads to opening of the contacts. However during normal ON-OFF and OFF-ON operation, an input is provided to the mechanism module 106 by rotating the rotary handle 108 manually. The rotation of the rotary handle 108 leads to storing potential energy in the plurality of springs which in turn restricts the contact movement during the charging operation.
[0032] The rotary operating mechanism arrangement includes a knob bevel gear and a fork bevel gear. The knob bevel gear is guided in a plurality of side plates and includes a provision for a handle shaft insertion. The fork bevel gear is on the mechanism pin. Further the knob bevel gear is meshed with the fork bevel gear and a rotary handle 108 is inserted in the knob bevel gear.
[0033] A torque is applied on the rotary handle 108 by an operator to operate the
circuit breaker. The torque applied on the rotary handle 108 causes a rotation of the fork bevel gear in a clockwise direction. At least one end of the plurality of springs is connected to the fork bevel gear. The plurality of springs connected to the fork bevel gear are charged which in turn rotates the rotor 104 from an OFF to ON position and vice versa to a dead center.
[0034] When the rotary handle 108 is rotated in the clockwise direction, the
plurality of springs gets charged up to the dead centre and the potential energy stored in the plurality of springs is utilized to rotate the rotor 104 from the OFF to ON position. Further as the rotor 104 houses a moving contact assembly, the moving contact also gets rotated from the OFF to ON position as shown in FIG.l.

[0035] When the rotary handle 108 is rotated in an anti clockwise direction, the plurality of springs gets charged up to dead centre and the potential energy stored in the plurality of springs is utilized to rotate the rotor 104 from the OFF to ON position as shown in FIG.2. The rotation axis of the Knob bevel gear and the fork bevel gear are perpendicular to each other. The plurality of mechanism side plates supports the knob bevel gear as shown in the Fig. 1 and Fig. 2.
[0036] FIG.3 illustrates a rotary handle operating mechanism in an ON condition with a circuit breaker cassette hidden, according to one embodiment of the present invention, while F1G.4 illustrates a rotary handle operating mechanism in an intermediate position from an ON condition to an OFF condition, according to one embodiment of the present invention. With respect to FIG.3 and FIG.4, the molded case circuit breaker includes a plurality of mechanism side plates 302, an upper link 304. a lower link 306. a fork bevel gear 308. a knob bevel gear 310 and a plurality of springs 312.
[0037] The plurality of mechanism side plates 302 is a part of the mechanism module 106. The upper link 304 decides a position of the dead centre during the ON-OFF operation and the OFF-ON operation. Further one end of the upper link 304 is fixed during the ON-OFF and OFF-ON operation. The lower link 306 is connected between the upper link 304 and the rotor 104.
[0038] The knob bevel gear 310 is guided in the plurality of mechanism side
plates 302. Further the rotary handle 108 is inserted in the knob beve! gear 310 to operate the circuit breaker. The fork bevel gear 30i5 is connected to one end of the plurality of springs 312. The fork bevel gear 308 and the knob level gear 310 are meshed with each other for operating the circuit breakers.

[0039] The pluralities of springs 312 are used for storing the potential energy. The mechanism module 104 is connected to various mechanism linkages such as the upper link 304, the lower link 306. the knob level gear 310 and the fork bevel gear 308. When the rotary handle 108 operating mechanism is in the ON condition, the rotor 104 is in the ON condition and the rotary handle 108 inserted in the know bevel gear 310 is in the ON position as shown in FIG.3.
[0040] When the rotary handle 108 is rotated in the anti clock wise direction, the fork bevel gear 308 is rotated and the plurality of springs 312 connected between the fork bevel gear 308, the upper link 304 and the lower link 306 pin gets charged as shown in the FIG.4. The rotor 104 remains in the ON position when the plurality of springs 312 gets charged as shown in FIG.4.
[0041] FIG.5 illustrates a rotary handle operating mechanism in an OFF
condition in the circuit breaker, according to One embodiment of the present invention, while FIG.6 illustrates a rotary handle operating mechanism in a TRIP condition in the circuit breaker, according to one embodiment of the present invention. With respect to FIG.3 and FJG.4, the circuit breaker is in the ON condition and when a short circuit occurs, a TRIP command is given as an input to the circuit breaker which causes the rotor 104 to come in the OFF position as shown in FIG.5. The fork bevel gear 308 does not come to the original position in the OFF condition and as a result the knob bevel gear 310 also stqps in the intermediate position between the ON and OFF condition. The intermediate position is known as the TRIP position as shown in FIG.6.
G) ADVANTAGES OF THE INVENTION
[0042] The various advantages are that the present invention includes a rotary handle mechanism integrated to the operating mechanism. Further no additional space

and components are required for the rotary operating mechanism arrangement in the present invention as compared to the conventional circuit breakers. A torque is applied with fewer efforts in the rotary operating mechanism arrangement in the present invention as compared to the conventional pull and push type knob operated circuit breakers.
[0043] The rotary handle operating mechanism in the present invention provides better control and enables to operate the circuit breakers easily in at least one of the three switching operations like ON-OFF, OFF-ON and TRIP-RESET operations. The various advantages of the present invention enables an operator to operate the circuit breaker by rotating the handle easily and effortlessly due to the two bevel type gears.
[0044] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.
[0045] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.

CLAIMS
What is claimed is:
1. A rotary handle operating mechanism for circuit breakers, the mechanism
comprising :
a fixed contact;
a moving contact;
a circuit breaker cassette ;
a mechanism module mounted on the circuit breaker cassette; and
a plurality of side plates provided in the mechanism module;
a knob bevel gear guided in the plurality of mechanism side p/ates;
a fork bevel gear;
a rotary handle inserted in the knob level gear; and
a plurality of springs;
Wherein a torque applied on the rotary handle by an operator causes a rotation of the fork bevel gear in a clockwise direction with respect to the plurality of the side plates and the plurality of springs connected to the fork bevel gear are charged which in turn rotates the rotor from an OFF position to an ON position and vice versa to a dead center.
2. The rotary handle operating mechanism according to claim 1, wherein the
rotary handle is locked in the OFF position when no torque is applied.
3. The rotary handle operating mechanism according to claim 1. wherein the plurality of springs stores a potential energy due to a rotation of the rotary handle.
4. The rotary handle operating mechanism according to claim 1, wherein the fork bevel gear is pivoted on one side plate of the mechanism module.
5. The rotary handle operating mechanism according to claim I, wherein the knob
level gear and the fork level gear enables the operator to operate the circuit
breaker from at least one of an ON-OFF position, an O.FF-ON position and a
TRIP-RESET position.

6. The rotary handle operating mechanism according to claim 1. wherein the rotary handle is rotated in the clockwise direction with respect to the plurality of side plates and the rotor is operated from the OFF to ON position during the circuit breaker ON condition.
7. The rotary handle operating mechanism according to claim 1, wherein the rotary handle is rotated in the anti clockwise direction with respect to the plurality of side plates and the rotor is operated from the OFF to ON position during the circuit breaker OFF condition.
8. The rotary handle operating mechanism according to claim 1, wherein the axis of rotation of the knob bevel gear and the fork bevel gear are perpendicular to each other.