FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)

1. Title of the invention: AN IMPROVED TRIP PLATE FOR USE IN
CIRCUIT BREAKERS AND A CIRCUIT BREAKER COMPRISING THE SAME.
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 moulded case circuit breakers. Particularly, the invention is concerned about a unique profile of trip plate which would constrain rotation of the plunger so that its orientation does not changes even after few operations. The invention further relates to a moulded case circuit breaker (MCCB) comprising the said trip plate.
BACKGROUND OF THE INVENTION
A circuit breaker is a device used for the protection of circuits from faults ranging from marginal increase in rated current upto very high current. The MCCB provides high current protection through repel opening of the contacts or through tripping of the mechanism after receiving signal from the magnetic protection device or both repel opening as well as mechanism tripping completes the fault clearing process. The repel opening is due to repel forces developed because of the opposite direction of current in the contacts, forcing the movable contacts to move upward away from lower contact. The repulsion force is further augmented by the presence of slot motor in the contact opening region.
US4594491 discloses a molded case circuit breaker including an elongated intermediate latch lever disposed between and in engagement with an intermediate latch plate and a trip bar. The intermediate latch lever is pivotable about a pivot axis and includes a first elongated portion between the latch plate and the pivot axis of a length substantially less than the length of a second elongated portion between the pivot axis and the trip bar. The intermediate latch lever so configured reduces the force required and the amount of travel of the trip bar required to effect a trip operation.
Thus, there is a need to overcome the problems of the prior art. Therefore, the present inventors have developed an improved trip plate for use in circuit breakers and a circuit breaker comprising the same. The present invention would find its

application in the magnetic protection part for transferring the signal from magnetic trip device to the mechanism and is called Trip-plate. The shapes and sizes of the trip-plate is dependent on the type of signal given by the magnetic protection devices. Magnetic protection devices are devised on the basis of rated current flowing through the Molded case circuit breaker, so for the low rated current Molded case circuit breaker, solenoid type of magnetic protection is used and the Trip-plate captures the signal produced.
OBJECTS OF THE INVENTION
One object of the present invention is to overcome the disadvantages/drawbacks of the prior art.
A basic object of the present invention is to provide a trip plate which would constrain rotation of the plunger so that its orientation does not changes even after few operations.
Another object of the present invention is to provide a moulded case circuit breaker comprising the said trip plate.
Another object of the present invention is to provide receiving of signal from the magnetic-protection device of the MCCB and convert translational movement of the Plunger of Solenoid assembly into rotational movement of the Trip-plate.
These and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided an improved
trip plate for use in circuit breakers, said trip plate comprising:
a surface
wherein said surface being substantially elliptical in shape having its rotational
axis running through any one of its foci;
wherein said surface comprising
a rib means;
a leg means protruding out of said surface to engage itself with a conventional
mechanism assembly;
said rib means being operatively engaged with a tripper means so as to avoiding
rotation of said tripper means and maintaining its proper orientation.
According to another aspect of the present invention there is provided a circuit
breaker comprising :
magnetic assembly;
mechanism assembly adapted to receive signal from said magnetic assembly;
plunger means;
tripper means;
a trip plate means comprising:
a surface
wherein said surface being substantially elliptical in shape having its rotational
axis running through any one of its foci;
wherein said surface comprising
a rib means:
a leg means protruding out of said surface to engage itself with a conventional
mechanism assembly;
said rib means being operatively engaged with said tripper means so as to
avoiding rotation of said tripper means and maintaining its proper orientation.

DETAILED DESCRIPTION OF THE INVENTION
The present invention is about Trip-plate with elliptical surface used in the Moulded case circuit breaker. Signal for the tripping of MCCB is received by the mechanism on rotation of the Trip-plate. The rotational axis of the Elliptical trip-plate is through one of the foci of Elliptical profile.
Mechanism assembly receives signal from magnetic assembly and respond accordingly. Magnetic assembly senses the high current fault which initiates the movement of the plunger of the solenoid type magnetic assembly in the downward direction. Tripper of the plunger consequently moves in the downward direction. Initial position of the Elliptical trip-plate is due to the extension spring pulling the Elliptical trip-plate in the backward direction and the leg of the trip-plate resting on the mechanism assembly. The cylindrical face of the tripper, which rests on the Elliptical trip-plate surface applies force normal to the Elliptical trip-plate's surface.
The forces applied on the trip-plate acts as torque for the trip-plate about its rotational axis. Rotational axis of the trip-plate is not through the centre of the Elliptical trip-plate, it is through one of the foci of the Elliptical trip-plate. Elliptical shape of the trip-plate avoids the applied force on it by tripper to pass through the rotational axis of the Elliptical Trip-plate and due to its elliptical shape, the torque on the Trip-plate increases with the downward movement of the plunger thereby ensuring complete rotation once it has started. Thereby allowing the Mechanism to sense signal for tripping for the Molded case circuit breaker. Rib on the surface of Elliptical trip-plate is engaged with the channel of the tripper thus avoiding rotation of tripper and maintaining its proper orientation.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Other features as well as the advantages of the invention will be clear from the following description.
In the appended drawings:
Fig. 1 illustrates Molded case circuit breaker cut section depicting different components in the assembled state.
Fig. 2 illustrates Different sub-assemblies of Molded case circuit breaker in opened state.
Fig. 3 illustrates Magnetic assembly and Trip-plate in detailed view with their proper alignment in the Molded case circuit.
Fig. 4 illustrates Trip-plate with its elliptical profile.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following detailed description, reference is made to the accompanying drawings that form a part thereof, and illustrate the best mode presently contemplated for carrying out the invention. Further functioning of the profile has been discussed below to describe the way the profile operates. However, such description should not be considered as any limitation of scope of the present unit. 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.

According to one aspect of the present invention, there is provided an improved trip plate for use in circuit breakers and a circuit breaker comprising the same. A circuit breaker as shown in FIG. 1 consists of housing in which magnetic assembly (6), mechanism assembly (5) and contact assembly (4) are mounted as shown in fig. 2.
Contact assembly (4) quenches the arc by opening of the moving contact (7) in the upward direction either through the repel opening of the moving contact by the force developed between moving contact (7) and static contact (8) or by the opening of contacts on receiving the signal from the mechanism assembly (5) as shown in figure 2.
Mechanism assembly (5) receives signal from magnetic assembly (6) and respond accordingly. Magnetic assembly (6) senses the high current fault which initiates the movement of the plunger (12) of the solenoid type magnetic assembly (6) in the downward direction. As shown in figure 3, Tripper (11) of the plunger (12) consequently moves in the downward direction. Initial position of the Elliptical trip-plate (9) is due to the extension spring (16) pulling the Elliptical trip-plate (9) in the backward direction and the leg of the trip-plate (17) resting on the mechanism assembly(5). The cylindrical face of the tripper(13), which rests on the Elliptical trip-plate surface (14) applies force normal to the Elliptical trip-plate's surface as shown in figure 4.
The forces applied on the trip-plate (9) acts as torque for the trip-plate about its rotational axis. Rotational axis of the trip-plate (9) is not through the centre of the Elliptical trip-plate, it is through one of the foci of the Elliptical trip-plate. Elliptical shape of the trip-plate (9) avoids the applied force on it by tripper (11) to pass through the rotational axis of the Elliptical Trip-plate and due to its elliptical shape, the torque on the Trip-plate increases with the downward movement of the plunger (12) thereby ensuring complete rotation once it has started. Thereby allowing the Mechanism to sense signal for tripping for the Molded case circuit

breaker (1). Rib on the surface of Elliptical trip-plate (15) as shown in figure 4, is engaged with the channel of the tripper (11) thus avoiding rotation of tripper (11) and maintaining its proper orientation.
COMPONENTS USED IN THE PRESENT INVENTION
1 - MCCB (Molded case circuit breaker)
2 -Housing
3 - Cover
4 - Contact assembly
5 - Mechanism assembly
6 - Magnetic assembly
7 - Moving contact(Upper contact)
8 - Fixed contact(Lower contact)
9 - Trip-plate
10 - Mechanism plate
11- Tripper
12- Plunger
13- Cylindrical surface of tripper 14-Elliptical surface of Trip-plate

15- Rib on Elliptical Trip-plate surface.
16- Extension spring
17- Leg of Elliptical trip-plate

WE CLAIM
1. An improved trip plate for use in circuit breakers, said trip plate
comprising:
a surface
wherein said surface being substantially elliptical in shape having its
rotational axis running through any one of its foci;
wherein said surface comprising
a rib means;
a leg means protruding out of said surface to engage itself with a
conventional mechanism assembly;
said rib means being operatively engaged with a tripper means so as to
avoiding rotation of said tripper means and maintaining its proper
orientation.
2. A circuit breaker comprising :
magnetic assembly;
mechanism assembly adapted to receive signal from said magnetic
assembly;
plunger means;
tripper means:
a trip plate means comprising:
a surface
wherein said surface being substantially elliptical in shape having its
rotational axis running through any one of its foci;
wherein said surface comprising
a rib means;
a leg means protruding out of said surface to engage itself with a
conventional mechanism assembly;

said rib means being operatively engaged with said tripper means so as to avoiding rotation of said tripper means and maintaining its proper orientation.
3. The breaker as claimed in claim 2 further comprising an extension spring means.
4. The breaker as claimed in claim 2, wherein said tripper means comprising substantially a cylindrical face.
5. The breaker as claimed in claim 2, wherein said tripper means being located on the elliptical trip plate surface.
6. An improved trip plate means for use in circuit breakers as herein substantially described and illustrated with the accompanying drawings.
7. A circuit breaker as herein substantially described and illustrated with the accompanying drawings.