FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
FLUX SHIFT DEVICE WITH ELECTRICAL RESET MECHANISM AND A METHOD THEREOF;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to electrical switching devices and more particularly to flux shift device with electric reset mechanism for circuit breakers and a method of electric reset.
BACKGROUND OF THE INVENTION
Electrical switching devices are units designed to connect, carry and disconnect electrical supply in systems. An electrical circuit breaker may be defined as unit designed to connect, carry, disconnect and protect the equipments connected to an electrical circuit from damages caused by overload, under-voltage, or short circuit, etc.
A circuit breaker is a commonly used electrical switching device that can have protection devices either built-in or optional which can be selectively added or replaced later. The protection devices provide protection against under voltage, over voltage, over current, earth fault, short circuit, etc. Besides protection devices, the circuit breakers are also equipped with accessories for remote operations and electrical interlocking with other circuit breakers. Examples of remote operations and electrical interlocking may be shunt release, closing release, etc. The under voltage release provides protection against under voltage by disconnecting the supply when under voltage below a specified limit or power failure occurs. The shunt and closing releases may be used for remotely opening and closing the circuit breaker contacts respectively.
The under-voltage releases are generally electromagnets connected to the in-coming supply of the circuit breaker. Under healthy supply condition, the electromagnet remains closed. In case the power supply falls below 70% of the rated voltage including power failure, the

electromagnet drops off. This drop-off movement of the electromagnet may be utilized for switching OFF tripping the breaker.
The closing & shunt releases are generally electromagnets short time rated or continuous rated which are used to close the breaker when supply voltage is in the range of 85 - 110% of rated voltage and to trip the breaker when supply voltage is in the range of 70 -110% of rated voltage.
Electromagnetic actuators are devices that release tripping latches and initiate closing of circuit breakers. A complex form of magnetic actuator is a flux shift device that utilizes a permanent magnet and a dual magnetic path. By energizing coils which oppose flux of the main magnetic path, the magnetic flux can be diverted rapidly to another path. Such devices are arranged to be reset during the operation of the circuit breaker. The flux shift devices have a feature that the permanent magnets used in the device only supply a 'Force'. The magnetic energy 'lost' during operation must be minimal.
The existing devices and methods achieve reset mechanism through mechanical systems. But as a safety precaution, the resetting of flux shift device immediately after the circuit breaker is opened is not advisable. Once the flux shift device is reset, the circuit breaker is ready to be made-power ON. So, as soon as the circuit breaker is opened the circuit breaker is in a heated condition and it is not advisable to put the circuit breaker in power ON position immediately.
Therefore, there is a need for a mechanism wherein resetting of the flux shift device can be achieved with less power loss and heat generation.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a flux shift device configured with electric reset mechanism comprising a plurality of copper tubes attached to a rigid frame; a permanent magnet covered by the copper tubes; a flux diverter connected to the permanent magnet; a

movable magnet with a spring mounted at a tail of the movable magnet; a brass tube enclosing the movable magnet; a dual coil housing a demagnetizing coil and a reset coil; wherein the demagnetizing coil demagnetizes the permanent magnet thereby enabling tripping operation and the reset coil electrically resets the movable magnet.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1A shows a diagrammatic representation of an electric reset for electrical switching devices for reset pick up position according to an embodiment of the invention.
Figure 1B shows another diagrammatic representation of the electric reset for electrical switching devices for drop off position according to the embodiment herein.
Figure 2 is a circuit diagram showing connections of a coil and an auxiliary contact or control circuit according to the embodiment herein.
DESCRIPTION OF THE INVENTION
Various embodiments of the invention provide a flux shift device with an electric reset mechanism for electrical switching devices comprising a plurality of copper tubes attached to a rigid frame; a permanent magnet covered by the copper tubes; a flux diverter connected to the permanent magnet; a movable magnet with a spring mounted at a tail of the movable magnet; a brass tube enclosing the movable magnet; and a pair of a demagnetizing coil and a reset coil in a dual coil housing-, wherein the demagnetizing coil demagnetizes the permanent magnet thereby enabling tripping operation and the reset coil electrically resets the movable magnet.

FIG. 1 A and FIG. 1B illustrate diagrammatic representations of a flux shift device 100 with electric reset mechanism according to one embodiment of the invention. Flux shift device 100 includes a plurality of copper tubes 102 attached to a rigid frame 100a, a pair of a demagnetizing coil 106 and a reset coil 108, a flux diverter 110, a movable magnet 112, a spring 114, a brass tube 116, and a permanent magnet 118. Spring 114 is a differential spring. Pair of de-magnetizing coil 106, and reset coil 108 are housed in a dual coil housing 104.
Differential spring has non linear characteristics, which helps us in bringing down the VA burden of Reset Coil drastically.
In accordance with an embodiment of the invention, rigid frame 100a is a C-bracket magnetic frame as shown in Fig. 1 A and 1B and houses components in flux shift device 100. Copper tube 102 covers permanent magnet 118. De-magnetizing coil 106 and reset coil 108 are wound concentrically around flux diverter 108 and movable magnet 112. Demagnetizing coil 106 and reset coil 108 are wound one over the Other.
Movable magnet 112 is held to frame 100a using holding means. In an embodiment, holding means is a C-bracket cover 122.
In an embodiment flux shift device 100 has a spring guide 120 for spring of movable magnet 112.
In an embodiment of the invention, solid state releases are used to trip a circuit breaker under unstable condition, the solid state releases issue command to demagnetizing coil 104 of electric reset for tripping.
In an embodiment of invention, demagnetizing coil 106 demagnetizes permanent magnet 118 that helps in tripping operation of circuit breaker while reset coil 108 is used to reset movable magnet 112 to its original position. In this condition, no power is required to hold movable magnet 112 as the required force is provided by permanent magnet 118.
Under healthy condition, the circuit breaker is in ON condition & electrical reset in pick up condition as shown in FIG. 1A. When the electrical system becomes unstable due to over

voltage, earth fault or short circuit or any other reason, the solid state releases are used to trip the circuit breakers by giving command to demagnetizing coil 106 of electrical reset. Demagnetizing coil 106 generates force opposite to magnetic field of permanent magnet 118. Hence, the net force decreases. Differential spring 114 overpowers permanent magnet 118. This results in electric reset to drop off as shown in FIG 1 B.
The solid state release senses the current through Current Transformer CT connected to circuit breaker incomer. Under any abnormalities when the current becomes unbalanced, the releases give command to the flux shift device which helps to make the system off trip the breaker.
It may be apparent to a person skilled in the art that the movable magnet moving from open magnet position to close magnet position is called reset position whereas movable magnet moving from close magnet position to open magnet position is called drop off position.
In an embodiment, electric reset is provided by supplying voltage to reset coil 108 and generating a magnetic field. The power supplied is controlled to overcome opposing force provided by differential spring 114. Movable magnet 112 and flux diverter 110 are contacted. Flux diverter 110 gets magnetized due to permanent magnet 118 and thereby holds movable magnet 112 due to the force. The force provided my magnet 118 is greater than the opposing force provided by differential spring 114 to attain reset position.
When the electrical system voltage gets restored and balances, the circuit breaker is switched ON by electric reset. For resetting, supply voltage is given to reset coil 106 and the magnetic field is generated. The power supplied is controlled such that it overcomes the opposing force provided by differential spring 114. Now, movable magnet 112 comes in contact with flux diverter 110. Due to permanent magnet 118, flux diverter 110 gets magnetized & holds movable magnet 112 even if the supply is disconnected. The force provided by permanent magnet 118 should be greater than the opposing force provided by differential spring 114 to

attain this position known as reset position. Differential spring 114 helps during reset due to its non-linear characteristics.
Fig. 2 is a circuit diagram describing the connections of reset coil 106 and control circuit 220 operation for electrically resetting the flux shift device.
The permanent magnet is rare earth type which achieves the required force in shortest possible volume. It has various advantages over ferrite one. It is able to deliver higher force which helps in maximizing the coil winding area. This further helps in reducing the VA burden of reset coil. The invention provides electrical reset that utilizes optimum power for operating the electrical switching device and eliminates the' excess power loss and heat generation. Therefore, the invention enhances the performance, increases reliability of the electrical switching device and life of the electrical switching device and makes the system sturdy. The invention may also be extended for use as under voltage release & other volt metric releases.
The flux shift device with the inbuilt electrical reset feature requires no make-shift arrangements to be made at site. The size of the whole assembly is compact enough even with the additional feature. The flux shift device with the inbuilt electrical reset feature provides the possibility of a remote resetting of the flux shift device for ease of operation. Also, the resetting of the flux shift device can be decisively made.
The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since, modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the appended claims.

We Claim
1. A flux shift device configured with electric reset mechanism comprising:
a plurality of copper tubes attached to a rigid frame; a permanent magnet covered by the copper tubes; a flux diverter connected to the permanent magnet; a movable magnet with a spring mounted at a tail of the movable magnet; a brass tube enclosing the movable magnet; and a pair of a demagnetizing coil and a reset coil in a dual coil housing; wherein the demagnetizing coil demagnetizes the permanent magnet thereby enabling tripping operation and the reset coil electrically resets the movable magnet.
2. The flux shift device as claimed in claim 1, wherein the demagnetizing coil and the reset coil are wound one over the other.
3. The flux shift device as claimed in claim 1, wherein the movable magnet is held to the frame using holding means.
4. The flux shift device as claimed in claim 1 has a spring guide for the spring of the movable magnet.
5. The flux shift device as claimed in claim 1, wherein the differential spring is used due to its non linear characteristics which helps in reducing VA burden of Reset Coil
6. The flux shift device as claimed in claim 1, wherein solid state releases are used to trip a circuit breaker under unstable condition, the solid state releases issue command to the demagnetizing coil of electric reset for tripping.
7. The flux shift device as claimed in claim 5, wherein the demagnetizing coil generates force opposite to magnetic field of the permanent magnet thereby decreasing net force on the permanent magnet and resulting in tripping.

8. The flux shift device as claimed in claim 1, wherein the magnetizing coil is used to reset it.