FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION :A push to trip assembly for manual tripping of circuit breakers..
2. APPLICANT(S)
(a) NAME : Larsen and Toubro Ltd.
(b) NATIONALITY: Indian
(c)ADDRESS : L&T House, Ballard Estate, Mumbai-400 001, India.
3. PREAMBLE TO THE DESCRITION
PROVISIONAL COMPLETE
The following specification describes The following specification particularly describes the
invention invention and the manner in which it is to be performed
4. DESCRIPTION (Description shall start from next page)
5. CLAIMS (not applicable for provisional specification. Claims should start with the preamble -"I/We claim" on separate page)
6. DATE AND SIGNATURE (to be given on the last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on the separate page)
Note:
*Repeat boxes in case of more than one entry
*To be signed by the applicant(s)orthe authorized registered patent agent
*Name of the applicant should be given in full, family name in the beginning
*Complete address of the applicant should be given stating with postal index no. / code, state and
country
*Strike out the column which is/are not applicable

A push to trip assembly for manual trip in circuit breakers
Field of the invention
The present invention relates to the field of protection devices like circuit breakers. More particularly the invention relates to an arrangement to trip the breaker for purposes of maintenance and checks.
Background of the invention
Most switchgear manufacturers provide for manual tripping function. This is usually done by pushing a button exposed to the user. The linear motion created while pushing is transmitted to a tripping member inside the mechanism via various linkages. The industry is rife with a variety of linkages to convert the motion.
Traditionally the push to trip interface member is located in a region which is directly above the pivotably placed tripping member in a plane projected on the front cover visibly placed in the assembly for the user. This leads to constraints in the placement of other features of the product in the nearby area of the front cover. In US Patent No. 4713639 by Grunert et al a push to trip assembly in a circuit breaker is described. A push-to-trip button for a circuit breaker characterized by a circuit breaker within an insulating housing and having trip means for releasably holding a circuit breaker operating mechanism in an untripped position and including a trip bar biased in an untripped position, a trip delay member biased away from the trip bar and including an adjustment bar for applying a pressure on the member, a trip button extending through the housing and having a first surface contacting the trip bar. and the adjustment bar having a second surface for applying limited pressure on the trip button for holding the first surface in contact on the trip bar, without moving the trip bar to a tripped position.
In Us Patent No. 5004994 by Jacek M. Korczynski, Thomas J. Stack . a low voltage high-amp circuit breaker having a substantially reactangular bimetallic bistable element. The bistable element is attached to have one end move from a first normal electrically conductive position to a second non-electrically conductive position. The manual reset circuit breaker includes a manual reset lever and a non-conductive heat resistant extension blade connected to the reset lever via a rotatable shaft. The extension blade being positioned adjacent the moveable end of the

bistable element and when the element is moved to its second position, the blade is moved to prevent the element from returning to its first conductive position until the circuit breaker is manually reset. A push-to-trip button pushes plate downward causing fingers to move upward lifting bracket to deform bistable element placing the breaker in an open circuit condition.
What is required is to avail freedom in the placement of the interface device, regardless of the area available in the part of the assembly accessible to the user.
Object of the invention:
One object of the present invention is to provide a mechanism to actuate the tripping action of the circuit breaker by pushing a button and provides for reversal of the direction of transmission of motion.
Another object of the present invention is to provide a user-friendly manual tripping mechanism with minimum components.
Yet another object of the present invention is to provide a compact design with pivot axis in the cover of the electrical device. Summary of the invention:
The interface lever is housed in a prismatic cavity in the front cover of the electrical device. The interface lever is longitudinally connected to the cam lever and inserts itself rigidly into the blind hole in the cam lever. The motion of the interface lever is restricted by the compression of a retrieval spring placed axially over the cam lever and the shaft of the interface lever. This spring rests on a step in the prismatic cavity of the front cover. The spring is restricted on the other side by the interface lever. The cam lever is connected to a rotating member through a connection between a pip in the cam lever and the cam slot present on one end of the rotating member. Other end of the rotating member is pivotably connected to the front cover via a caster in the font cover. The rotating member contacts the trip plate which is placed pivotably in the mechanism assembly. The contact leads to a rotation of the trip plate in an intended direction, thus causing the breaker assembly to trip. The motion of the interface lever, the cam lever and the rotating member is governed by the actuation by the user. Also the return motion is governed by the

retrieval spring compression. Linear motion of the interface lever is converted to a revolute motion of the rotating member.
Description of the Drawings:
Fig1. Shows breaker assembly
Fig 2 shows front cover assembly
Fig3 shows front cover assembly cross-section
Fig 4 shows front cover
Fig 5 shows front cover prismatic cavity
Fig 6 shows cross-section of the front cover prismatic cavity
Fig 8 shows Interface lever
Fig 9 shows cam lever
Fig 10 shows rotating member
Fig 11 shows retrieval spring
Fig 12 shows trip plate
Fig 13 shows pre-trip condition of the breaker assembly
Fig 14 shows post-trip condition of the breaker assembly
Detailed Description:
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The assembly comprises of a front cover assembly 1 consisting of a front cover 1, an interface lever 12, a cam lever 13, a rotating member 14, a Retrieval spring 15. This arrangement affects the trip plate 22 in the mechanism assembly 2. The interface lever 12 is substantially'T" shaped. The horizontal surface of the "T" shaped movable lever is accessible to the user and a slider is provided at the centre of the "T" shaped lever. The interface lever 12 is exposed to the user, as it is housed in a prismatic cavity 111 present in the front cover 11. The interface lever 12 is longitudinally connected to the cam lever 13 and inserts itself rigidly into the blind hole in the cam lever 131. The cam lever is connected to a rotating member 14 through a connection between a pip in the cam lever 132 and the cam slot 142 present in the rotating member. The rotating member is connected pivotably to the front cover 11 via a caster 113 in the font cover. The motion of the interface lever 12 is restricted by the compression of a retrieval spring 15 placed axially over the cam lever 13 and the shaft of the interface lever 121. This spring 15 rests on a step 112 in the prismatic cavity 111 of the front cover 11. The spring is restricted on the otherside by the interface lever 12. The shaft of the interface lever is smaller than the exposed face of the interface lever 12.
The motion of the interface lever 12 and thus that of the cam lever 13, the rotating member 14 is governed by the actuation by the user. Also the return motion is governed by the retrieval spring compression. Thus, the linear motion of the interface lever 12 is converted to a revolute motion of the rotating member 14.
The rotating member contacts the trip plate 22 which is placed pivotably in the mechanism assembly 2. The contact leads to a rotation of the trip plate 22 in an intended direction, thus causing the breaker assembly to trip.
Some of the advantages of the present invention are:
Minimal usage of parts
Compactness of design
Reversal of the direction of transmission of motion
Provision of a pivot axis in the cover

We claim,
1) A push to trip assembly for operating electrical devices, the assembly comprising;
cover of the electrical device, the top surface of the cover having a prismatic cavity extending in the electrical device and the cavity walls have atleast one locking step and a side surface of the cover having a caster cavity;
a substantially "T" shaped movable interface lever mounted in the said prismatic cavity, the horizontal surface of the lever being accessible to the user and slider portion extending from the centre of the horizontal surface slides in the said prismatic cavity through the space between said locking steps and downward movement of the horizontal surface of the "T" shaped lever in the cavity is restricted by the said locking steps;
a retrieval spring, the spring mounted around the said "T" shaped movable interface lever, one end of the spring rests on the said locking step and other end touches horizontal surface of the said "T" shaped movable interface lever, wherein the spring allows retrieval of the "T" shaped moveable interface lever when the horizontal surface of the lever is pressed by the user;
a cam lever, first end of the cam lever being connected to the said slider portion of the "T" shaped movable interface lever by male-female arrangement and second end of the cam lever has a pip projection on it;
a rotating member, first end of the rotating member connected to the said pip
projection of the cam lever and second end of the rotating member is pivotably
mounted in the said caster cavity, the rotating member having a projection at its
centre;
a trip plate; first end of the trip plate resting against the said projection at the centre of
rotation member and other end connected to the trip mechanism of the electrical
device;

Wherein, pressing the horizontal surface of the "T" shaped movable lever by the user pushes cam lever away from the plane of the front cover and rotates the rotating member around the pivot thereby releasing the first end of the trip plate resting against the rotating member and the other end of the trip plate is displaced to trip the breaker.
2) A push to trip assembly for operating electrical devices of the claim 1 wherein, the electrical device is circuit breaker.
3) A push to trip assembly for operating electrical devices of the claim 1 wherein, other end of the said trip plate trips the breaker.
4) A push to trip assembly for operating electrical devices of the claim 1 wherein, the first end of the cam lever has a hole to engage it to the slider portion of the "T" shaped movable lever.