CLIAMS:We claim –
1. A circuit breaker with under voltage release and shunt release and having a common circuit for the shunt release and the under voltage release, the common circuit comprising:
a potential divider configured to provide sample of input voltage;
a microcontroller configured to receive the sample of input voltage and control operation of the common circuit; and
an electromagnetic coil operatively coupled with the microcontroller and configured to provide both hold-on force and pick-up force that meet requirement of self resetting of under voltage release.
2. The circuit breaker of claim 1, wherein the common circuit further comprises a MOSFET configured to receive a PWM signal from the microcontroller and actuate the electromagnetic coil for pick up and hold on.
3. The circuit breaker of claim 1, wherein the common circuit further comprises an opto coupler configured between the microcontroller and the MOSFET to isolate the low voltage section from high voltage section.
4. The circuit breaker of claim 1, wherein the common circuit further comprises a rectifier at input that enables the common circuit to be used both for AC and DC applications.
5. The circuit breaker of claim 4, wherein the common circuit further comprises a MOV in front of the rectifier for surge protection.
6. The circuit breaker of claim 1, wherein the microcontroller is configured to provide means to avoid tripping of the circuit breaker due to momentary fluctuation of voltage.
,TagSPECI:TECHNICAL FIELD
[0001] The present disclosure relates generally to the field of switchgears used in low voltage power distribution systems. In particular it pertains to under voltage and shunt release in a circuit breaker.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art
[0003] An under voltage release is a device that triggers the breaker to open when the applied voltage falls below a predefined threshold value and is used in circuit breaker to offer protection to downstream equipment from under voltage or zero voltage conditions. Often, an under voltage release is operated from the system and is intended to cause the breaker to open in the event something happens to cause the system voltage to collapse Hence it goes along with the circuit breaker module as an internal accessory.
[0004] A shunt release is a solenoid device that mechanically triggers the breaker to open. It in turn can be triggered by any number of protective or control functions but mainly used for remote tripping by application of a control supply voltage. Both UV and shunt release use electromagnetic coil to provide the trip signal.
[0005] In high rated MCCBs and ACBs, the force required for tripping the circuit breaker is considerably large at the same time such applications demands self-resetting type UV/shunt release with high force output.. A continuous duty, self-resetting type electromagnetic coil for higher pick up force shall be of large size, therefore, providing means to reset the under-voltage/shunt release in a breaker mechanism is difficult. Therefore typically two separate coils are used for pick up and hold on.
[0006] In another aspect the under voltage and shunt release typically use separate circuits resulting in additional cost and space requirements.
[0007] There is therefore need in the art to provide a under voltage and shunt release that uses a common control circuit, a single electromagnetic coil for continuous duty to provide hold on force and to generate high pick up force (to satisfy self-resetting) with intermittent duty so that the resultant compact device can overcome the space constrains and provides corresponding cost benefits.
[0008] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0009] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0010] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0011] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0012] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

OBJECTS OF THE INVENTION
[0013] An object of the present disclosure is to overcome problems associated with conventional under voltage and shunt release.
[0014] Another object of the present disclosure is to provide a single electronic circuit for both under voltage and shunt release.
[0015] Another object of the present disclosure is to provide a single coil for both pick up and hold on.
[0016] Another object of the present disclosure is to provide a single electronic circuit for both under voltage and shunt release that uses PWM technique for achieving higher force output from a single coil even with low Volt-Ampere.
[0017] Another object of the present disclosure is to provide a self-resetting type, continuous duty under voltage and shunt release.
[0018] Another object of the present disclosure is to provide a under voltage and shunt release that incorporates means to avoid release due to momentary fluctuations of voltage.

SUMMARY
[0019] Aspects of present disclosure relate to a shunt and under voltage release in a circuit breaker. In an embodiment the disclosed shunt and under voltage release in corporate a common circuit.
[0020] In an embodiment, the disclosed shunt and under voltage release is self-resetting. In an aspect it uses a single electromagnetic coil for both hold-on force and pick-up force that meets the requirement of self resetting.
[0021] In an embodiment, the disclosed shunt and under voltage release employs Pulse Width Modulation (PWM) technique to control the duty cycle of the electromagnetic coil.
[0022] In an embodiment, the common circuit for the disclosed shunt and under voltage release comprises a power supply section to energize the circuit, a potential divider to provide sample of input voltage, a microcontroller that receives the sample of input voltage and controls the circuit operation, an opto-coupler to isolate the low voltage section from high voltage section, and Load/MOSFET section to drive the electromagnet.
[0023] In an embodiment, the microcontroller is configured to compare the sample of input voltage with a predefined threshold value and following an inbuilt logic issues PWM signals enabling electromagnet to pick up and sustain in hold-on condition. In an aspect, use of PWM technique to control the electromagnet results in achieving higher force output even with low volt ampere.
[0024] In an embodiment, the microcontroller enables passage of direct input voltage to electromagnet during pick-up condition and controlled continuous rated low voltage to electromagnet during hold-on condition. Though same circuit is used for shunt and under voltage release, difference in functionality is achieved using the electromagnet.
[0025] In an embodiment, the common circuit incorporates a rectifier at input that enables circuit to be used both for AC and DC applications.
[0026] In an embodiment, the microcontroller is configured to provide means to avoid tripping of the circuit breaker due to momentary fluctuation of voltage. When under voltage condition appears, microcontroller waits for a period of electromagnet response time for allowing sample voltage to recover to its normal voltage condition. If under voltage condition sustain even after wait period, then the PWM signal is stopped and electromagnet goes to drop-off condition. This delay avoids misinterpreting momentary dips in supply voltage as under voltage condition.
[0027] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components

BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0029] FIG. 1 illustrates an exemplary circuit diagram of shunt release and under voltage release in accordance with embodiments of the present disclosure.
[0030] FIG. 2 illustrates an exemplary flow diagram for logic followed by the microcontroller in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION
[0031] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0032] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0033] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0034] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0035] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0036] Embodiments of present disclosure relate to a shunt and under voltage release in a circuit breaker. In an embodiment the disclosed shunt and under voltage release incorporates a common circuit.
[0037] In an embodiment, the disclosed shunt and under voltage release is self-resetting. In an aspect it uses a single electromagnetic coil for both hold-on force and pick-up force that meets the requirement of self resetting.
[0038] In an embodiment, the disclosed shunt and under voltage release employs Pulse Width Modulation (PWM) technique to control the duty cycle of the electromagnetic coil.
[0039] In an embodiment, the common circuit for the disclosed shunt and under voltage release comprises a power supply section to energize the circuit, a potential divider to provide sample of input voltage, a microcontroller that receives the sample of input voltage and controls the circuit operation, an opto-coupler to isolate the low voltage section from high voltage section, and Load/MOSFET section to drive the electromagnet.
[0040] In an embodiment, the microcontroller is configured to compare the sample of input voltage with a predefined threshold value and following an inbuilt logic issues PWM signals enabling electromagnet to pick up and sustain in hold-on condition. In an aspect, use of PWM technique to control the electromagnet results in achieving higher force output even with low volt ampere.
[0041] In an embodiment, the microcontroller enables passage of direct input voltage to electromagnet during pick-up condition and controlled continuous rated low voltage to electromagnet during hold-on condition. Though same circuit is used for shunt and under voltage release, difference in functionality is achieved using the electromagnet.
[0042] In an embodiment, the common circuit incorporates a rectifier at input that enables circuit to be used both for AC and DC applications.
[0043] In an embodiment, the microcontroller is configured to provide means to avoid tripping of the circuit breaker due to momentary fluctuation of voltage. When under voltage condition appears, microcontroller waits for a period of electromagnet response time for allowing sample voltage to recover to its normal voltage condition. If under voltage condition sustain even after wait period, then the PWM signal is stopped and electromagnet goes to drop-off condition. This delay avoids misinterpreting momentary dips in supply voltage as under voltage condition.
[0044] Referring now to FIG. 1 wherein an exemplary circuit diagram 100 for shunt and under voltage release is disclosed. The disclosed circuit 100 can incorporate a rectifier 102connected to input supply. A MOV 104 can also be used in front of rectifier for surge protection. In an embodiment the rectifier 102 configured at input allows the circuit to be used for both AC and DC applications.
[0045] In an embodiment, output of the rectifier 102 can be connected in parallel to power supply section 106, potential divider section 108 and load section 110. In the power supply section 106 input is fed to high voltage regulator 112 where input voltage can be regulated to a lower voltage. This low voltage can further be connected to a low voltage regulator 114. Output of low voltage regulator 114 can be used as power supply for control circuit components. The potential divider 108 can feed low voltage input signal (referred to as sampled voltage hereinafter) to a microcontroller 116.
[0046] The load section 110 can comprise an electromagnetic coil 118 (also referred to as electromagnet or coil and the terms used interchangeably hereinafter) and a MOSFET 120 connected in series. An output signal from microcontroller 116 can be connected to gate of the MOSFET 120 through an opto coupler 122. The opto coupler 122 can isolate the low voltage section from high voltage section.
[0047] In an embodiment, microcontroller 116 can compare the sampled voltage from the potential divider 108 to a predefined threshold voltage level using an inbuilt ADC. Under normal voltage condition, microcontroller 116 can issue PWM signals enabling an electromagnet to pick up and sustain in hold-on condition. Output signal from the microcontroller 116 can be received at the gate of the MOSFET 120 through the opto coupler 122. When microcontroller PWM signal is high, MOSFET 120 can allow electromagnetic coil 118 to be connected to input supply. On the other hand when the microcontroller PWM signal is low electromagnetic coil 118 can be disconnected. Thus by varying the pulse width of microcontroller output, load voltage can be varied and pick-up/hold-on/drop-off of the electromagnetic can be maintained.
[0048] In an embodiment, when under voltage condition appears, microcontroller 116 can wait for a period of electromagnet response time for allowing sample voltage to recover to its normal voltage condition. If under voltage condition sustains even after the wait period, the PWM signal can be stopped thereby causing electromagnet to go to drop-off condition. In an embodiment the delay can avoid misinterpreting momentary dips in supply voltage as under voltage condition.
[0049] In shunt release, when electronic circuit is energized PWM signal can be issued and electromagnet can go to hold on condition and simultaneously trip signal can be issued to the circuit breaker.
[0050] FIG. 2 illustrates an exemplary flow diagram 200 for logic followed by the microcontroller in accordance with embodiments of the present disclosure. In an embodiment the flow diagram 200 can comprise of three loops such as an electromagnet pick up loop 202, a hold on loop 204 and a delatch loop 206. Further the flow diagram 200 can use variables such as a time control variable ‘t’, a response time delay variable ‘d’, a trigger variable ‘trigger’ and a flag variable ‘i’. The ‘trigger’ can take values 0 or 1 wherein 0 indicates a high microcontroller output and 0 indicates a low microcontroller output. The flag ‘i’ can take values o indicating pick up and 1 indicating hold on.
[0051] In an embodiment, the program logic can begin at step 208 with a delay for allowing other circuit components to be able to respond. In the exemplary flow diagram a delay of 25 msec is provided. After the start up delay, at step 210 input signal voltage (Vin) can be compared with predefined threshold voltage level (Vthr). If Vin > Vthr, then flag ‘i’ can be checked to select between pick up condition or hold on condition. At start up, flag ‘i’ is set to zero, therefore the logic flows into electromagnet pick up loop 202. During pick up, microcontroller output is set high (trigger=1) for duration of the electromagnet pick up loop 202. In the exemplary flow diagram duration of the electromagnet pick up loop 202 is kept as 20 msec. On completion of pick up loop 202, flag ‘i’ can be set to “1” at step 216 and program control transferred to the start of the program. During each msec of pick up loop 202 under voltage condition can be rechecked at step 214. If under voltage occurs before completion of pick up loop, then program can break out of the loop and microcontroller output set to low (trigger=0) at step 218 and program control transferred to the start of the program.
[0052] In an embodiment, if at step 210 Vin > Vthr & flag =1 then program can flow into hold on loop 204. In hold on loop, microcontroller output can be set on high (trigger=1) for 1msec after a preset time period. In the exemplary flow diagram 200, the preset time period is kept as 9 msec. The program control stays in hold on loop 204 until under voltage condition appears. After each 9 msec, under voltage condition is rechecked at step 220. To avoid tripping from momentary under voltage condition during hold on, the program remains in the hold on loop 204 after detection of under voltage condition for a period equal to electromagnet response time which in the exemplary flow diagram is 5msec. The delay in response can be achieved by response time delay variable ‘d’. If under voltage situation persists above this electromagnet response time, then program control can break out of hold on loop 204 and can flow to delatch loop 206. Whenever under voltage condition persists the program control comes to the delatch loop 206. Program control can remain within the delatch loop 206 until there is continuous 20msec of normal voltage. This delay is provided to avoid the momentary voltage fluctuation and to allow the electromagnet to work in stable condition. Once voltage regains to normal level, program control can flow to start of the program with flag ‘i’ = 0.
[0053] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0054] The present disclosure overcomes problems associated with conventional under voltage and shunt release.
[0055] The present disclosure provides a single electronic circuit for both under voltage and shunt release.
[0056] The present disclosure provides a single coil for both pick up and hold on.
[0057] The present disclosure provides a single electronic circuit for both under voltage and shunt release that uses PWM technique for achieving higher force output from a single coil even with low Volt-Ampere.
[0058] The present disclosure provides a self-resetting type, continuous duty under voltage and shunt release.
[0059] The present disclosure provides a under voltage and shunt release that incorporates means to avoid release due to momentary fluctuations of voltage.