FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13)
TITLE OF THE INVENTION:
A FLUX SHIFT DEVICE FOR AIR CIRCUIT BREAKERS
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra . INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to circuit breakers and particularly to a flux shift device with an inbuilt electrical reset feature for air circuit breakers.
B) BACKGROUND OF THE INVENTION
[0002] An electrical switching device may be defined as a unit designed to connect, carry, and disconnect electrical supply. An electrical circuit breaker may be defined as a unit designed to connect, carry, disconnect, and protect equipments connected in the electrical circuit, from damage caused by overload, undervoltage, or short circuit etc. A circuit breaker is a commonly used electrical switching device. The circuit breaker may have protection devices either built-in or optional which may be selectively added or replaced later. The protection devices may provide protection against under voltage, over voltage, over current, earth fault, short circuit etc. Apart from a protection device the circuit breaker may also be equipped with accessories meant for remote operation and electrical interlocking with other circuit breakers. The example of remote operation and electrical interlocking may be shunt release, closing release etc. The shunt and closing releases may be used for remotely opening and closing the contacts of the circuit breaker respectively. The under voltage release provides protection against the under voltage by disconnecting the supply when the under voltage (below specified limit) or power failure occurs. A flux shift device is used to automatically actuate (i.e. to open the circuit breaker) when a fault is detected.


[0003] The flux shift device comprises of a DC power operated electromagnet and permanent magnet system. Generally, the flux shift device has a flux diverter, a spring loaded movable magnet, a coil around the flux diverter and movable magnets. When DC power passes through the coil, an electromagnet field is produced around the coil. In presence of the electro magnetic field, the spring loaded movable magnet moves towards the flux diverter and remains touching the flux diverter. This position is called a closed magnet position in which the magnets are touching together.
[0004] The movable magnet moving from an open magnet position (in which the magnets are apart) to the close magnet position is called pick-up of the magnet and holding the movable magnet in close magnet position is called a hold-on position. Also, movable magnet moving from the close magnet position to the open magnet position is called drop-off the magnet.
[0005] The coil draws large amount of power to bring the magnets closer from the open magnet position. Once the magnets reach the closed magnet position the power required to hold the magnets together is much lower. However, the large amount of power drawn by the coil remains unchanged, unless the power is controlled by some other device associated with the electromagnet. This excess power drawn by the coil is a loss of power. Further, this excess power generates lot of heat and problems related to an elevated temperature.


[0006] The existing methods show how the reset mechanism is achieved 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 the circuit breaker is not advisable to be made power ON immediately. Therefore, there is a requirement of a flux shift device wherein resetting of the flux shift device can be decisively made. In addition to this, remote resetting of the flux shift devices is also advisable for ease of operation.
[0007] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
C) OBJECT OF THE INVENTION
[0008] The primary object of the present invention is to provide a flux shift device with an inbuilt electrical reset feature with no addition of any accessories for air circuit breakers,
[0009] Another object of the present invention is to provide a flux shift device with a remote resetting facility for ease of operation.
[0010] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.


D) SUMMARY OF THE INVENTION
[0011] The various embodiments of the present invention provide a flux shift device with an inbuilt electrical reset feature for air circuit breakers. According to one embodiment of the present invention, a flux shift device has a housing in which a permanent magnet is arranged inside. A flux diverter is arranged to contact the permanent magnet. A spring loaded plunger is arranged below the flux diverter. A pick up coil and a de energizing coil are wound in the same coil bobbin arranged to surround the plunger. The pick up coil and the de energizing coil are wound concentrically around the flux diverter and the plunger. An incoming power supply is connected to the pick up coil while a microcontroller is connected to the de energizing coil. The pick up coil is connected to the incoming power supply till the plunger is moved to contact the flux diverter and the incoming power supply to the coil is cut off, when the plunger is latched to the permanent magnet through the flux diverter during the resetting operation. The de energizing coil is excited to demagnetize the permanent magnet to delatch the plunger, in case of abnormality in the power supply circuit.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:


[0013] FIG. 1 illustrates a sectional view of a flux shift device with an inbuilt electrical reset feature according to one embodiment of the present invention.
[0014] FIG. 2 illustrates a block circuit diagram the incoming power supply and logic circuitry in the flux shift device according to one embodiment of the present invention.
[0015] FIG. 3 illustrates a block circuit diagram a de-energizing circuit in the flux shift device according to one embodiment of the present invention.
[0016] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF THE INVENTION
[0017] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.


[0018] The various embodiments of the present invention provide a flux shift device with an inbuilt electrical reset feature for air circuit breakers. According to one embodiment of the present invention, a flux shift device has a housing in which a permanent magnet is arranged inside. A flux diverter is arranged to contact the permanent magnet. A spring loaded plunger is arranged below the flux diverter. A pick up coil and a de energizing coil are wound in the same coil bobbin arranged to surround the plunger. The pick up coil and the de energizing coil are wound concentrically around the flux diverter and the plunger. An incoming power supply is connected to the pick up coil while a microcontroller is connected to the de energizing coil. The pick up coil is connected to the incoming power supply till the plunger is moved to contact the flux diverter and the incoming power supply to the coil is cut off, when the plunger is latched to the permanent magnet through the flux diverter during the resetting operation. The de energizing coil is excited to demagnetize the permanent magnet to delatch the plunger, in case of abnormality in the power supply circuit.
[0019] According to one embodiment of the present invention, the flux shift device with an inbuilt electrical reset feature comprises of a permanent magnet, a flux diverter, a plunger, two coils around the core that are a pick-up coil and a de-energizing coil, a spring, and a magnetic frame housing them all. The pick-up coil is connected to an incoming power supply of the air circuit breaker to magnetize the core and the plunger. Once the incoming power supply is supplied to the pick-up coil, due to magnetization the plunger moves towards the flux diverter. When the incoming power supply to the pick-up


coil is cut-off using electronic switches, the permanent magnet takes over to hold the plunger. Once the flux shift device is reset, the circuit breaker is ready to be made power ON.
[0020] The de-energizing coil is connected to a micro-controller based device. Once the fault current is reported by the micro-controller based device, the de-energizing coil de-energizes the magnetic field of the permanent magnet. Hence, the permanent magnet releases the plunger and the plunger comes to the normal position due to the action of the spring force. Thus, a flux shift device is actuated to trip/open the contacts of the circuit breaker when an abnormality such as overload, short-circuit, earth fault and so on.
[0021] FIG. 1 illustrates a diagrammatic representation of a flux shift device with an inbuilt electrical reset feature according to one embodiment of the present invention. With respect to FIG.l, the flux shift device with an inbuilt electrical reset feature for the electrical switching device includes a magnetic frame 100, a copper tube 110, a de-energizing coil 120-a, a pick up coil 120-b, a flux diverter 130, a plunger 140, a spring 150, a permanent magnet 160, and a bobbin 170. The magnetic frame 100 is used to house all the components in the flux shift device and the copper tube 110 covers the permanent magnet 160. The de-energizing coil 120-a and the pick up coil 120-b are wound in the same bobbin 170 placed concentrically around the flux diverter 130 and the plunger 140. The de-energizing coil 120-a is connected to a micro-controller based device and the pick up coil 120-b is connected to the incoming power supply of the circuit breaker.


[0022] FIG. 2 illustrates a circuit diagram describing connections of a pick-up coil with the incoming power supply and logic circuitry according to one embodiment of the present invention. With respect to FIG. 2, the pick up coil 120-b is connected to an incoming power supply 210 through an electronic circuit 220. When one wishes to reset the flux shift device, the incoming power supply 210 is made power ON. When current flowing through the pick-up coil 120-b, a magnetic field is produced around the pick-up coil 120-b. Due to this magnetic field, the plunger 140 is attracted towards the flux diverter 130 (i.e. close magnet state). Once the permanent magnet 160 (in FIG. 1) holds the plunger 140, the power supply from the incoming power supply 210 to the pick-up coil 120-b can be cut-off.
[0023] FIG. 3 illustrates a circuit diagram describing connections of a de-energizing coil with a micro-controller based device and logic circuitry according to one embodiment of the present invention. With respect to FIG. 3, the de-energizing coil 120-a is connected to a micro-controller based device 310 through a de-energizing circuit 220. In case of abnormality in power supply/fault, the de-energizing circuit 220 excites the de-energizing coil 120-a thereby demagnetizing the permanent magnet 160 and actuating/de-latching the plunger 140 from the permanent magnet 160 in FIG. 1. This return movement of the spring loaded plunger is utilized for tripping/opening of the circuit breaker.


G) ADVANTAGES OF THE INVENTION
[0024] Thus the various embodiments of the present invention provide a flux shift device with an inbuilt electrical reset feature for air circuit breakers. The flux shift device uses a special permanent magnet with an inbuilt electrical reset feature with no addition of any accessories for the air circuit breakers. 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.
[0025] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.

[0026] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.
Date: March 30, 2008. RAKESH PRABHU
Place; Bangalore. Patent Agent

CLAIMS
What is claimed is:
1. a flux shift device with for switching device comprising:
a housing;
a permanent magnet arranged inside the housing;
a flux diverter arranged to contact the permanent magnet;
a plunger arranged below the flux diverter;
a coil bobbin arranged to surround the plunger;
a pick up coil wound in the coil bobbin;
a de energizing coil wound in the coil bobbin:
an incoming power supply connected to the pick up coil; and
a microcontroller connected to the de energizing coil;
wherein the pick up coil is connected to the incoming power supply till the
plunger is moved to contact the flux diverter and the incoming power supply to
the coil is cut off, when the plunger is latched to the permanent magnet through
the flux diverter during the resetting operation.
2. The device according to claim 1, wherein the de energizing coil is excited to
demagnetize the permanent magnet to delatch the plunger, in case of abnormality
in the power supply circuit.


3. The device according to claim 1, wherein the pick up coil and the de energizing coil are wound in the same coil bobbin.
4. The device according to claim 1, wherein the pick up coil and the de energizing coil are wound concentrically around the flux diverter and the plunger.
5. The device according to claim 1, wherein the plunger is a spring loaded plunger.
6. The device according to claim 1, wherein the flux diverter is arranged below the permanent magnet.
Dated this the 30th day of March 2009

RAKESH PRABHU Patent Agent,
ALMT Legal,
#2, Lavelle Road, Bangalore-560 001
To,
The Controller of Patents. The Patent Office, Mumbai