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 ACTUATING DEVICE FOR USE
IN 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:

FIELD OF THE INVENTION
The present invention relates to a trip actuating device of circuit breakers. More particularly, the present invention is concern about an improved magnetic trip actuating device for use in circuit breakers.
BACKGROUND OF THE INVENTION
US 6,791,442 discloses a device utilizing a permanent magnet latching assembly incorporating high-energy, permanent magnets of rare earth or other relatively fragile permanent magnet materials, and to provide a mechanical structure that protects such materials from damaging impact when subjected to motion of a solenoid plunger. The proposed invention mentions the isolation of permanent magnet from any mechanical impact and use of rare earth materials.
US 5,614,878 discloses two pole remote controlled circuit breaker, in which the solenoid is provided with two coil windings. The first coil winding is a low resistance high current (approximately 3 amp) winding which produces a strong magnetic force to pull plunger from its rest (extended) position to its activated (retracted) position where the plunger is withdrawn into the body of the solenoid. The second coil winding is a high resistance winding which, when connected in series with the low resistance winding, results in reduced power consumption for maintaining contacts in an open position. The switching from the low resistance high current winding to the high resistance winding connected in series with the low resistance winding is accomplished by a solenoid switch which is activated/deactivated by a switch lever.
US 7,633,728 discloses that a processor is structured to provide for detecting arc fault
conditions.
US 7,570,140 discloses a circuit breaker includes separable contacts, an operating mechanism structured to open and close the separable contacts, and a magnetic trip mechanism cooperating with the operating mechanism to trip open the separable contacts. The magnetic trip mechanism includes a support structure including a slotted support

portion therein, and a plunger assembly. The plunger assembly includes a movable core resting in the support portion of the support structure, and a plunger member including a first portion cooperating with the operating mechanism, a second portion coupled to the movable core, and a third portion engaging the support structure.
US 4,691,182 discloses a circuit breaker structure having an adjustable magnetic trip unit characterized by an insulating housing containing a, circuit breaker mechanism having separable contacts and containing a trip unit comprising a magnetic device responsive to overload current conditions for separating the contacts, the magnetic device having an armature and a calibrating screw for calibrating an air gap between the armature and an associated magnet, the trip unit also including a cam for varying the tension of the spring and the cam having spaced indexing indentations and an associated ball in the frame for rolling engagement with the cam surface and for seating in any indentation to provide positive settings of the spring tension.
US 5,206,618 discloses a magnetic latch includes a coil, a frame receiving magnetic flux from the coil when energized, a latching member mounted in the frame and rotatably movable between first and second positions with the latching member providing a magnetic flux bridge between flux carrying means of the frame by contacting the flux carrying means with the latching member is in a first position, a magnet providing magnetic flux carried by the flux carrying means and a portion of the latching member for magnetically retaining the latching member is a first position with the coil is deenergized and a spring biasing the latching member towards a second position with force sufficient to overcome magnetic retention of the latching member at the first position when the coil is providing magnetic flux to the flux carrying members of the frame in the direction opposite of that of flux provided by the magnet.
In the prior art, due to mechanical impact on the magnet, the material loses its property and the device tends to malfunction and also due to insufficient shielding, the external field interference disturbs the performance of the device by demagnetizing the magnet. Thus, there is a need to overcome the problems cited above. Therefore, the present

invention is providing an improved magnetic actuating device which is eliminating mechanical impact on the magnet, reducing interference problems, and reduction of leakage flux.
OBJECTS OF THE INVWENTION
An object of the present invention is to overcome the problems/disadvantages of the prior art.
Another object of the present invention is to provide an improved magnetic trip actuating device for use in circuit breakers.
Another object of the present invention is to provide a device with less energy consumption for flux reduction.
Further object of the present invention is to provide a device for reduction of interference problems.
Further object of the present invention is to provide a device with increased trip force.
Further object of the present invention is to provide a device for conversion of electric signal to a mechanical signal/output to trip the circuit breaker.
Yet, another object of the present invention is to provide isolation of the magnet from mechanical impacts.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided an improved trip actuating device for use in circuit breakers, said device comprising : plurality of fixed core members; moving core being located substantially coaxial to said fixed core members; magnet means placed in between said fixed core members such that appropriate air gap is maintained in the space between the fixed cores and magnet means; said magnet means establishing plural flux paths comprising first flux path and second

flux path whereby said moving core being attracted towards said core members by flux content in the said first flux path; plurality of identical coils wounded around said core members and connected serially to each other; wherein pair of adjacent identical coils being positioned with one coil facing toward top direction and another coil adjacent to it being located in a tilted direction such that the current in both the coils flows in opposite directions so as to establish flux opposing the flux prevailing in the said flux paths produced by the magnet means thereby reducing the resultant flux flowing through the moving core adapted to delatch the said moving core from the fixed core members.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig 1 illustrates an isometric view of magnetic trip actuating device.
Fig 2 illustrates a front view of magnetic trip actuating device at latched position.
Fig 3 illustrates a front view of magnetic trip actuating device at delatched position.
Fig 4 illustrates a front view of magnetic trip actuating device indicating positioning of
coils.
Fig 5 illustrates a schematic representation of magnetic trip actuating device.
Fig 6a illustrates a graph representing the rare earth magnets' BH curve
Fig 6b illustrates a graph representing AlNiCo's BH curve.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
According to the invention there is provided an improved magnetic trip actuating device for use in circuit breakers. As shown in figure 1, the magnetic trip actuating device comprising a moving core (1) , coils (2), magnet means (3), L-shaped core members (4) air gap (5), spring (9) and Wall of Circuit Breaker's enclosure (10).
The device consists of two parallel magnetic circuits made of two identical L-shaped cores (4) (generally high permeable material) of which one of the circuits holds a moving core (1) against a spring force. The other magnetic circuit has an air gap (5) in order to

Supply maximum flux to the first said path during normal condition and conditions. L-shaped core members (4) will provide two parallel paths both during latched and delatched condition of the device.
The magnet (3) which is held between the two L-shaped core (4) with air gaps on both sides of it in order to avoid any mechanical impact. The permanent magnet is completely isolated from any mechanical impacts. As shown in figure 2, the magnet's total flux has been split into two parts, one travelling in the first flux path (7) and the remaining in the second flux path (8). The flux content flowing in *the said first path will attract the moving core (1) towards the surface 1 (6) of the L-shaped core (4) (as shown in Fig 1) against a spring force. The trip force produced as the output of the device is also increased (from 700gms to 2kg) and the interference effect is taken care with the use of rare earth materials as shown in figure 6a over the conventional AINiCo magnets as shown in figure 6b.
The moving core (1) is the moving part of the device, which is held by magnetic attraction force against a spring force. The moving core is maintained near to saturation and all the other components will operate only at the region below this saturation level (The saturation level for mild steel is 1.9 Weber per square meter). So, always there will be enough surface area for the magnets' flux to flow through. The dimensions of the moving core (1) 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 two identical coils (2) are wound over two L-shaped cores (4) and are connected serially in order to facilitate tripping of the device. Two identical coils serially connected one in top faced direction and another is in tilted direction as shown in figure 4. The coil of the existing design has approximately 200 AT with AINiCo magnet (inferior than rare earth) at 12 V to trip the circuit breaker (Single Coil). The current invention uses only 250 AT with rare earth magnet at 5 V to trip the circuit breaker (Two Coils). The magnetic circuit is designed in such a way that, flux diversion takes place with lesser

energy given to the coil. Multiple coils provide multistage flux reduction for the actuator and thus will provide effective flux reduction in required part of the device.
Air gap (5) provided in the device is used to control the supply of flux in available parallel paths. By adjusting the air gap (5) in the second flux path (8), the actuator can be configured for various ratings of the circuit breaker. During fault condition, when coils get energized, the flux flowing through the first flux path (7) reduces and the flux through second flux path (8) increases. At this condition, since the air gap (5) in the path is very less, the leakage flux will be less only and even this can be neglected, since, this condition will prevail only for a maximum operating time of 2 ms.
The magnetic trip actuating device is usually placed along with the microprocessor based release in the circuit breaker as shown in figure 5. When the breaker senses the fault situation in the system, it will give low energy electrical signal to the breaker which will be converted to trip force required to trip the breaker by allowing the signal to pass through the two identical coils (2) wound over two L-shaped cores (4). The two coils (2), when energized will produce flux in such a way that, it opposes the magnets' (3) prevailing flux in the circuit, thereby reducing the resultant flux flowing through the moving core (1). Once it is done, the spring force which is pulling the moving core off the L-shaped core (4) will take the control of it and trip the circuit breakers' mechanism. The two identical coils(2) which are connected serially helps in delatching the moving core (1) from the L-Shaped core (4) during fault conditions of the circuit breaker as shown n figure 3.
ADVANTAGES OF THE INVENTION
1. The device can be easily scaled for various ratings of the circuit breaker.
2. Simple construction with ease of manufacturing and assembling. This also helps in reducing the amount of leakage flux.
3. The permanent magnet is isolated from any mechanical impact.
4. Use of rare earth magnet helps in reducing interference problems.

The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its spirit. The invention is not limited to the details cited above. The magnet, moving core, coils, and L-core as stated do not limit the scope of the present invention. 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.

We Claim
1. An improved trip actuating device for use in circuit breakers, said device
comprising :
plurality of fixed core members;
moving core being located substantially coaxial to said fixed core members; magnet means placed in between said fixed core members such that appropriate air gap is maintained in the space between the fixed cores and magnet means; said
magnet means establishing plural flux paths comprising first flux path and second
flux path whereby said moving core being attracted towards said core members by
flux content in the said first flux path; plurality of identical coils wounded around said core members and connected serially to each other; wherein pair of adjacent identical coils being positioned with one coil facing toward top direction and another coil adjacent to it being located in a tilted direction such that the current in both the coils flows in opposite directions so as to establish flux opposing the flux prevailing in the said flux paths produced by the magnet means thereby reducing the resultant flux flowing through the moving core adapted to delatch the said moving core from the fixed core members.
2. Device as claimed in claim 1 wherein said core members being substantially L-shaped.
3. Device as claimed in claims 1 and 2 wherein said core members being adapted to establish plurality of parallel flux paths during latched and delatched conditions.
4. Device as claimed in claim 1, wherein said air gap is adjustable.
5. Device as claimed in claim 1 wherein said moving core comprises flux density close to saturation point of said fixed core members.

6. Device as claimed in claim 1. wherein said magnet means is rare earth magnet.
7. An improved trip actuating device for use in circuit breakers as herein substantially described and illustrated with the accompanying drawings.