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 TRIPPING ASSEMBLY FOR CIRCUIT BREAKERS
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:

TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to circuit breakers. More particularly the invention relates to an improved tripping assembly for circuit breakers.
BACKGROUND AND THE PRIOR ART
Tripping assembly forms one of the most important parts of a breaking system. It is susceptible to interference and other disturbances. Some of the prior arts related to present field of invention are as follows:
EP 2204833 (A2) provides a trip device comprising: a power source side heater connected to a power source side of a molded case circuit breaker (MCCB) to receive current; a load side heater connected to a load side of the MCCB to receive the current; and a bimetal including a direct heat unit contacting the power source side heater and an indirect heating unit facing the power source side heater, wherein the bimetal is partially fixed between the power source side heater and the load side heater and is curved when over-current or short-circuited current flows in the MCCB.
KR 20100032612 (A) provides a safety device to prevent negligent accidents by controlling the operation of a MCCB (Molded Case Circuit Breaker) according to the opening and closing of the front cover, A front cover is installed in the front side of a MCCB main body. A steering wheel, a reset lever and a safety trip lever are installed in the inside of the MCCB main body. A safety trip lever controls the operation of a reset lever according to the opening and closing of the front cover. The safety trip lever prevents operation of the steering wheel when the front cover is opened. The safety trip lever has an L-shape. A shaft hole is formed in the central part

of the safety trip lever. An annular part is formed in one end of the safety trip lever. An operating unit is formed in the other end of the safety trip lever.
US 2008.180196 (Al.) provides an electronic trip unit for a circuit breaker, comprising a processing circuit responsive to input signals representative of a current in the circuit breaker; and a real time clock circuit in signal communication with the processing circuit, the real time clock circuit being operational in the absence of current in the circuit breaker; wherein in response to an off event at the circuit breaker following a current flow condition thereat, the real time clock circuit is configured to generate time information relating to the circuit breaker being off as a result of the off event for use by the processing circuit.
WO 2009024177 (Al) provides a Magnetic/hydraulic trip unit for molded case circuit breakers (MCCBs) comprising: a non-ferromagnetic hollow case filled with a viscous fluid; a frame structure extending in a z-direction and having a ferromagnetic upper end arranged above and a ferromagnetic lower end arranged below said hollow case; a ferromagnetic armature being arranged such that the armature is restrained from connecting said frame structure by a restoring force; a longitudinally extending ferromagnetic core being pivot-mounted inside said case such that the core rotates in a y-z plane - from a first, rated current position, in which the axis of the core is not aligned with the z-axis, such that gaps (A, A1) are formed between the upper end and the lower end of the frame structure, to a second, over current position, in which the axis of the core is aligned with the z-axis such that the gaps (A, A' ) between the upper end and the lower end of the frame structure are bridged, at least one spring being attached to said core such that the core is restrained from moving from its first position to its second position; and a current conductor being arranged such that it is connected to a main electric current path of the circuit breaker, and such that the magnetic field generated by its inside current flow acts in a z- direction to rotate the core from its first position to its second position.

In the prior arts due to mechanical impact on the magnet, the material loses its property and the device tends to malfunction. Also due to insufficient shielding, the external field interference disturbs the performance of the device by demagnetizing the magnet. In the present invention, the magnet does not have any physical contact with the moving body, thereby eliminating mechanical impact related problems. Also when the external field tends to disturb the circuit, the use of metal body outside the main circuit diverts the external magnetic field during adverse conditions.
OBJECTS OF THE INVENTION
A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
Another object of the present invention is to provide an improved tripping assembly for circuit breakers.
Yet another object of the present invention is to provide a second flux path as magnetic shield, reducing the interference problems and also complexity of the device.
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
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an

extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.
There is provided an improved tripping assembly for circuit breakers.
According to one embodiment of the present invention, there is provided an improved tripping assembly for circuit breakers comprising at least a trip latch; atleast a moving core held by magnetic attraction against a spring; atleast a magnet held in a plastic holder on a base plate thereby avoiding direct mechanical impact; atleast a coil wound over said moving core kept stationary thereby facilitating tripping of device; atleast a spring kept inside said moving core continuously pulling off said base plate surface; atleast an outer frame; an air gap to control flux in available parallel paths; wherein said outer frame providing a second parallel path during de-latched condition and acting as an electromagnetic shield during latched condition.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
So that those having ordinary skill in the art will more readily understand how to construct an improved tripping assembly for circuit breakers in accordance with the present disclosure, exemplary embodiments are described in details herein below with reference the accompanying drawings wherein:
Fig 1 illustrates the cut section view of the invention is shown. It shows different elements used in the invention.

Fig 2 illustrates the front view of the invention at its latched position with the flux lines marked over it.
Fig 3 illustrates the front view of the invention at its de latched position with the flux lines marked over it.
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 cut section view of the invention is shown. It shows different elements used in the invention. It shows bobbin (1), moving core (2), air gap (3), coil (4), spring (5), plastic holder (6), magnet (7), outer frame (8) and base plate (9).
Fig 2 shows the front view of the invention at its latched position with the flux lines marked over it.
Fig 3 shows the front view of the invention at its de latched position with the flux lines marked over it.
The invented system is thus an improved tripping assembly for circuit breakers.

DETAILED DESCRIPTION OF THE INVENTION
Accordingly in the present invention a magnetic actuating device is provided which will actuate the trip latch of the circuit breaker during fault conditions with the help of permanent magnet & electromagnetic coils. The device consists of two parallel magnetic circuits (generally high permeable material) of which one of the circuits holds a moving core against a spring force. The other magnetic circuit has an air gap in order to supply maximum flux to the first said path during normal condition and also to provide least reluctance path during fault conditions.
The first said path have an electromagnetic coils which when excited, will trip the circuit breaker during fault conditions by releasing the moving core. This invention is intended for the conversion of low energy electric signal to a mechanical signal/output required to trip the circuit breaker mechanism. It is an improved trip actuator in circuit breakers wherein the permanent magnet is completely isolated from any mechanical impacts. The interference effect is taken care with the use of secondary flux path as external magnetic shield which is an integral part of this product thereby reduces additional component for electromagnetic shielding.
Fig 1 provides different components:
Moving Core (2): It is the moving part of the invention which is held by magnetic
attraction force against a spring force.
Magnet (7): It is held in a plastic holder on the base plate to avoid any direct mechanical impact.
Coil (4): The coil is wound over moving core but kept stationary in order to facilitate tripping of the device.

Spring (4): The spring is kept inside the moving core continuously pulling off the base plate surface.
Outer Frame (8): This will provide second parallel path during de latched condition of the device and acts as an electromagnetic shield during latched condition of the device.
Air gap (3): The purpose of this is to control the supply of flux in available parallel paths.
In Fig 2, the magnet's total flux is travelling in the first flux path and the second flux path remains empty and acts as a magnetic shield. The flux content flowing in the said first path will attract the moving core towards the surface 1 of the base plate (shown in Fig 1) against a spring force.
The dimensions of the moving core are selected in such a way that, the flux density is near to saturation point of the high permeable material used. So that maximum attracting force can be experienced in the moving core thereby helping in increasing the devices' output force.
The coil (shown in Fig 1) connected helps in de latching the moving core from the base plate during fault conditions of the circuit breaker. The coil, when energized will produce flux in such a way that, it opposes the magnets' prevailing flux in the circuit, thereby reducing the resultant flux flowing through the moving core. Once it is done, the spring force which is pulling the moving core off the L-shaped core will take the control of it and trip the circuit breakers' mechanism.
This invention is usually placed along with the microprocessor based release in the circuit breaker. When the breaker senses the fault situation in the system, it will give

low energy electrical signal to the tripping device which will be converted to trip force required to trip the breaker by allowing the signal to pass through the coil wound over moving core and thereby tripping the breaker as explained earlier.
Features:
- The permanent magnet is completely isolated from any mechanical impacts.
- Ease of manufacturing
- Simple construction/assembly reduces the amount of leakage flux.
Benefits:
- Use of second flux path as magnetic shield, reduces the interference problems and also complexity of the device.
- The device can be easily scaled for various ratings of the circuit breaker
Advantages:
1. Use of second flux path as magnetic shield, reduces the interference problems and also complexity of the device.
2. The permanent magnet is isolated from any direct mechanical impact.
3. The device can be easily scaled for various ratings of the circuit breaker.
4. Simple construction with ease of manufacturing and assembling. This also helps in reducing the amount of leakage flux.
5. The device is fully enclosed and hence dust-proof.

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 tripping assembly for circuit breakers comprising:
atleast a trip latch;
atleast a moving core means held by magnetic attraction against a spring;
atleast a magnet means held in a plastic holder on a base plate thereby avoiding direct mechanical impact;
atleast a coil means wound over said moving in a manner to facilitate tripping of device;
atleast a spring means kept inside said moving core continuously pulling off said base plate surface;
atleast an outer frame;
an air gap to control flux in available parallel paths;
wherein said outer frame providing a second parallel path during de-latched condition and acting as an electromagnetic shield during latched condition.
2. Assembly as claimed in claim 1 wherein said air gap providing a least reluctance path during fault condition.
3. Assembly as claimed in claim 1 wherein said moving core having flux density substantially near to saturation point.

4. Assembly as claimed in claim 1 wherein said coil adapted to de-latch said moving core from said base plate during fault condition.
5. Assembly as claimed in claim 1 wherein said coil on getting energized adapted to reduce flux moving through said moving core.
6. Assembly as claimed in claim 1 wherein said coil is kept almost stationarily wounded around said moving core means.
7. An improved tripping assembly for circuit breakers as herein described and illustrated with respect to the accompanying drawings.