FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
UNDERVOLTAGE RELEASE DEVICE FOR CIRCUIT BREAKERS;
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 THE INVENTION
The invention relates to circuit breakers, and more particularly to an under-voltage release device for circuit breakers.
BACKGROUND OF THE INVENTION
An under-voltage release device protects circuit breakers and equipment connected to it from damage that may be caused due to drop in voltage. The under-voltage release device trips and turn OFF a circuit breaker when voltage of the circuit breaker drops below a critical level.
Generally, under-voltage release device have electro-magnetic sensing devices which sense a drop in voltage below a critical level and trip the circuit breaker.
The critical level at which the under-voltage release device trips the circuit breaker is generally a fixed voltage. This limitation calls for use of different under-voltage release devices for different application depending upon low voltage rating. Also, when the under-voltage release device trips the circuit breaker it is necessary to indicate that the tripping is due to a drop in voltage as there are other causes because of which circuit breaker may trip. Also it is a challenge to provide compact under-voltage release device for miniature circuit breakers with multiple features.
In view of the above, there is a need for an under-voltage release device to overcome the above said limitations.

SUMMARY OF THE INVENTION
Accordingly, the present invention in one aspect provides an under-voltage release device for a circuit breaker, the device comprising a pivot, the pivot mounted on a housing of the under-voltage release device, the pivot being capable of rotating a circuit breaker pivot; and a solenoid, the solenoid comprising a core having a shield, a fixed part, the fixed part being fixed to the shield and a moving part, the moving part adapted to the fixed part via a compression spring, the compression spring enabling the moving part to move relative to the fixed part depending upon voltage condition of the circuit breaker, and the moving part moves the pivot; and a coil of wire wound around the core.
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 1 shows an under-voftage release device for circuit breakers in accordance with an embodiment of the invention.
Figure 2 shows a solenoid of the under-voltage release device in accordance with an embodiment of the invention, where
Figure 2A shows the solenoid in energized state; and

Figure 3 shows an under-voltage release device with means for testing in accordance with an embodiment of the invention.
Figure 4 shows the under-voltage release device coupled to a miniature circuit breaker in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Various embodiments of the present invention provide an under-voltage release device for a circuit breaker, the device comprising a pivot, the pivot mounted on a housing of the under-voltage release device, the pivot being capable of rotating a circuit breaker pivot; and a solenoid, the solenoid comprising a core having a shield, a fixed part, the fixed part being fixed to the shield and a moving part, the moving part adapted to the fixed part via a compression spring, the compression spring enabling the moving part to move relative to the fixed part depending upon voltage condition of the circuit breaker, and the moving part moves the pivot; and a coil of wire wound around the core.
Figure 1 shows an under-voltage release device 100 for a circuit breaker in accordance with an embodiment of the invention, wherein under-voltage release device 100 trips the circuit breaker when voltage drops below a pre-determined level i.e. 35 to 70% of rated voltage. Under-voltage release device 100 includes a pivot 102 and a solenoid 104. Trip voltage is the voltage at which under-voltage device will trip the circuit breaker.
Pivot 102 is mounted on a housing 130 of under-voltage release device 100 as shown in figure 1. In an embodiment pivot 102 is mounted on a torsion spring (not shown) on the housing 130 of under-voltage release device 100. Pivot 102 has a bottom arm. The arm moves relative to movement of pivot 102. The arm engages with internal operating means of under-voltage release device 100. In an embodiment pivot 102 is capable of engaging under-voltage release device 100 to the circuit breaker. Pivot 102

engages with a circuit breaker pivot (not shown) using a dumble pin and is capable of rotating the circuit breaker pivot.
Solenoid 104 is shown in detail in figure 2A and 2B. Solenoid 104 includes a core 106 and a coil of wire wound around core. Core 106 includes a shield 108, a fixed part 110, and a moving part 112 as shown in figure 2B. Fixed part 110 is fixed to shield 108 and moving part 112 is adapted to fixed part 110 through a compression spring 114. Compression spring 114 enables moving part 112 to move relative to fixed part 110 depending upon voltage condition of the circuit breaker. In an embodiment, movement of moving part 112 rotates pivot 102 which rotates the circuit breaker pivot.
During normal operating condition solenoid 104 is in an energized state as shown in figure 2A, and when the voltage drops below the pre-determined level, solenoid 104 is de-energized and moving part 112 moves away from fixed part 110 as shown in figure 2B. Movement of moving part 112 drives pivot 102 to rotate. Rotation of pivot 102 on under-voltage release device 100 rotates the circuit breaker pivot of the circuit breaker which trips the circuit breaker.
In an embodiment under-voltage release device 100 includes means for varying the trip voltage. The trip voltage is the voltage at which under-voltage device will trip the circuit breaker. Means for varying the trip voltage includes a screw 116 and a screw guide 118. Screw 116 when rotated is guided through screw guide 118, wherein screw 116 when rotated moves moving part 112 linearly about fixed part 110 varying distance between moving part 112 and fixed part 110. Variation in distance between moving part 112 and fixed part 110 varies the trip voltage of under-voltage release device 100. In an embodiment the trip voltage of under-voltage release device 100 can be varied from 85% to 65% in multiples of 10% voltage variation.
Figure 3 shows an under-voltage release device with means for testing in accordance with an embodiment of the invention. The means for testing allow manual

tripping of the circuit breaker. In an embodiment, the means for testing is a test button 320. Test button 320 is mounted on a housing 330 of under-voltage release device 300. Test button 320 engages with a pivot 302 of under-voltage release device 300. Test button 320 is engaged with a pivot 302 using a test button spring 322. Test button 320 when pressed, rotates pivot 302, wherein rotation of pivot 302 rotates the circuit breaker pivot on the circuit breaker to trip the circuit breaker.
In an embodiment under-voltage release device 100 includes an indicator 124 as shown in figure 1. Indicator 124 indicates a trip condition of the circuit breaker. In an embodiment under-voltage release device 100 further comprises a window (not shown) on housing 130 of under-voltage release device 100. Indicator 124 is visible through the window. In this regard, indicator 124 is visible through the window during an under-voltage condition and is not visible through window during a normal operating condition.
In an embodiment of the invention, the under-voltage release device 100 is coupled to circuit breakers such as a miniature circuit breaker 400 as shown in figure 4, wherein under-voltage release device 100 trips miniature circuit breaker 400 during an under-voltage condition.
Advantageously, the under-voltage release device trips the circuit breaker when the voltage drops below a pre-determined level, indicates the trip condition and the device also allows the trip voltage of the device to be varied as per requirement.
While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

We Claim :
1. An under-voltage release device for a circuit breaker, the device comprising:
a pivot, the pivot mounted on a housing of the under-voltage release device, the
pivot being capable of engaging a circuit breaker pivot; and
a solenoid, the solenoid comprising: a core having a shield;
a fixed part, the fixed part being fixed to the shield; and a moving part, the moving part adapted to the fixed part via a compression spring, the compression spring enabling the moving part to move relative to the fixed part depending upon voltage condition of the circuit breaker, and the moving part moves the pivot; and a coil of wire wound around the core.
2. The device as claimed in claim 1, wherein the pivot rotates the circuit breaker pivot through a dumble pin.
3. The device as claimed in claim 1 further comprises means for varying the trip voltage of under-voltage release device includes varying the trip voltage includes means for varying distance between the moving part and the fixed part.
4. The device as claimed in claim 3, wherein means for varying trip voltage comprises a screw and a screw guide, the screw when rotated is guided through the screw guide and moves the moving part linearly about the fixed part.
5. The device as claimed in claim 1 further comprises means for testing the under-voltage release device, the means including rotation of the pivot to trip the circuit breaker.

6. The device as claimed in claim 1 further comprises an indicator for indicating a trip condition of the circuit breaker, the indicator being mounted on the pivot to indicate condition of the circuit breaker depending upon voltage condition of the circuit breaker.
7. The device as claimed in claim 1, wherein the pivot has a bottom arm, the bottom arm engages with internal operating means of the device.