DESC:TECHNICAL FIELD
[0001] The present disclosure relates to the field of protection devices used in low voltage power supply systems. In particular, the present disclosure relates to a novel embodiment that achieves a damper arrangement in a voltage sensing device/arrangement to avoid over-travel of tripping shaft.

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] Circuit breakers are switching devices that provide means to connect, carry, disconnect, and protect equipment connected in an electrical circuit as and when required. Circuit breakers can be designed to either manually interrupt the power supply circuit or automatically trip to discontinue the power supply under certain undesirable conditions Circuit breakers thus carry out an important function of protecting equipment connected in an electrical circuit from damage caused by overload, under-voltage, or short circuit. Typically, solenoid based voltage sensing devices are used to detect abnormalities in voltage supply and give tripping signals to the circuit breaker. Under normal voltage condition, sensing devices are inactive and do not interfere with the functioning of circuit breakers.
[0004] The solenoids typically incorporate a plunger that under drop-off condition of the solenoid, gets actuated to travels and trip a tripping shaft. To cause the tripping, the plunger typically drives the tripping shaft by pressing an actuator attached to the tripping shaft. During this travel the plunger may over travel and the resultant impact from the plunger can damage the connected and interacting components. Since most switchgear manufacturers provide a voltage sensing arrangement with fixed actuation length (plunger travel), they have to maintain other manufacturing and assembly parameters to avoid any damage to the connected and interacting components from the impact due to over travel of the plunger which may be tedious process and may not be cost effective solution to the problem.
[0005] There is therefore a need in the art to provide means so that over-travel of the plunger is taken care of and damage to the connected and interacting components due to such over travel is avoided.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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
[0011] An object of the disclosure is to overcome problems associated with conventional configuration of solenoid plunger in circuit breakers.
[0012] Another object of the disclosure is to provide a solenoid plunger that does not cause damage to connected and interacting components in spite of over travel.
[0013] Yet another object of the disclosure is to provide a solenoid plunger that absorbs the extra travel thus prevents damage to connected and interacting components in spite of over travel.

SUMMARY
[0014] Aspects of the present disclosure relate to a circuit breaker that incorporates a solenoid based voltage sensing device to detect abnormalities in voltage supply and give tripping signals. In particular the disclosure provides a solenoid plunger that does not require adopting the manufacturing and assembly parameters such that the damage to the connected and interacting components from impact due to over travel of the plunger is avoided.
[0015] In an aspect the plunger can incorporate feature that absorbs/buffers the excess travel thus preventing the damage to connected parts due to excess travel.
[0016] In another aspect, the plunger can be made of two parts that are configured in a telescopic arrangement with a compression spring configured between them. The two parts can move telescopically to buffer/absorb any excess travel of the plunger.
[0017] In another aspect the compression spring can be configured such a way that normal force required to move an attached actuator does not compress the spring thus enabling transfer of tripping signal from the solenoid to the actuator. However, the moment the actuator has moved to trip the breaker, the increased force requirement cannot be sustained by the spring and it gets compressed thus absorbing the excess travel.
[0018] 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
[0019] 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.
[0020] FIG. 1 illustrates an exemplary representation of a voltage sensing device in accordance with an embodiment of the present disclosure.
[0021] FIG. 2 illustrates an exemplary representation of a plunger damping arrangement in accordance with an embodiment of the present disclosure.
[0022] FIG. 3 illustrates an exemplary representation of tripping arrangement in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0023] 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.
[0024] 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.
[0025] 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.
[0026] Aspects of the present disclosure relate to a circuit breaker that incorporates a solenoid based voltage sensing device to detect abnormalities in voltage supply and give tripping signals. In particular the disclosure provides a solenoid plunger that incorporates feature that absorbs/buffers the excess travel thus preventing the damage to connected parts due to excess travel.
[0027] In another aspect, the plunger can be made in two parts that are configured in a telescopic arrangement with a compression spring configured between them. The two parts can move telescopically to buffer/absorb any excess travel of the plunger.
[0028] In another aspect the compression spring can be configured such a way that normal force required to move an attached actuator does not compress the spring thus enabling transfer of tripping signal from the solenoid to the actuator. However, the moment the actuator has moved to trip the breaker, the increased force requirement cannot be sustained by the spring and it gets compressed thus absorbing the excess travel.
[0029] Referring now to FIG. 1 where a voltage sensing device 100 is illustrated. The voltage sensing device typically incorporates a plunger that on detection of occurrence of an abnormal voltage condition can travel to transmit a trip signal to an actuating mechanism. In an aspect of the disclosure, the voltage sensing device 100 can include a plunger 102 that includes a spring holder 106. The plunger 102 and the spring holder 106 together are in telescopic arrangement such that the spring holder 106 can move relative to the plunger 102 in longitudinal direction along the axis of the plunger 102. The spring holder 106 can be fitted over the plunger 102 with a plastic snap fit arrangement such that it stays with the plunger 102 but is free to telescopically travel longitudinally along the axis of the plunger 102.
[0030] In an aspect the amount of movement of the spring holder 106 relative to the plunger 102 upon installation can depend on the over travel of the plunger 102 as against requirement to actuate the trip mechanism. Therefore the two can be dimensioned and configured such that the relative movement between the two is more than the expected over travel.
[0031] FIG. 2 illustrates an exemplary schematic view 200 of the disclosed arrangement of the plunger 102 and spring holder 106 in accordance with an embodiment of the present disclosure. As shown there can be spring 104 configured between the plunger 102 and the spring holder 106 such that the plunger holder 106 can moves longitudinally along the axis of the plunger 102 under an applied force that is greater than compression force of the spring 104. The telescopic/longitudinal travel of the spring holder 106 can result in reduction in overall effective length of the plunger.
[0032] In an embodiment, the spring 104 can be chosen and configured between the plunger 102 and the spring holder 106 such a way that the spring 104 does not get compressed under a force required to actuate the trip mechanism. Therefore, the effective length of the plunger can remain unaltered during the tripping action thus enabling tripping without any adverse effect. However, if plunger continues to travel after the tripping is over, the higher force at the spring holder 106 can result in compression in the spring 104 reducing the effective length of the plunger and avoiding adverse effect on of the excess travel. Thus the disclosed arrangement works as a buffer or damping arrangement for extra travel of the plunger 102 than is necessary to actuate the trip mechanism.
[0033] According to one embodiment, the voltage sensing device 100 can be mounted on the operating mechanism of a circuit breaker as shown in FIG.3 where the plunger 102 can push an actuator 108 such that when the actuator 108 is pressed, it drives tripping shaft 110 through trip shaft actuator 112 that is positively fixed on the shaft 110. The damping arrangement as shown in FIG.2 can allow the spring 104 to damp/absorb/buffer the over-travel taking care of variation in plunger length and other parameters which are unavoidable considering process variations & assembly constraints.
[0034] The present disclosure helps overcome the limitation of variations in dimensions and position of parts of sensing and tripping arrangement when mounted on the switchgear interface. Also there is no need to critically controlling the output of sensing device since any over travel can now be damped avoiding ill effects of the over-travel of the plunger 102 on the tripping shaft 110.
[0035] According to one embodiment, plunger 102 with damping arrangement comprising spring holder 106 &spring 104can be housed in the voltage sensing arrangement such that when overload voltage is sensed, the plunger 102 can travel longitudinally and press the actuator 108. Actuator 108 can drive the latched trip shaft 110 by pressing trip shaft actuator 112. During this travel, effect of released force of the sensing device on the trip mechanism can be dampened by the spring 104 and it avoids over-travel of the actuator 108 and of the trip shaft 112. The disclosed dampening of the plunger travel can cater all dimensional variations in the assembly.
[0036] The present disclosure therefore enables self-controlled plunger length of voltage sensing arrangement and enhances the reliability in transmission of forces. The present arrangement also enhances the reliability of operation and dampens the impact of the plunger on switchgear interacting member.
[0037] According to another embodiment, the present disclosure provides a voltage sensing device that can include a plunger with a spring 104 and a spring holder 106, wherein the voltage sensing device can be operatively coupled with a damper arrangement for absorbing shocks and avoiding damage of interacting component due to plunger’s impact. In an aspect, the damper can be configured to have controlled feed of release actuation, achieving reliable force output and can also help avoid over-travel of tripping shaft member of switchgear.
[0038] 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 DISCLOSURE
[0039] The disclosure overcomes problems associated with conventional configuration of solenoid plunger in circuit breakers.
[0040] The disclosure provides a solenoid plunger that does not cause damage to connected and interacting components in spite of over travel.
[0041] The disclosure provides a solenoid plunger that absorbs the extra travel thus prevents damage to connected and interacting components in spite of over travel of the voltage sensing mechanism.
,CLAIMS:1. A voltage sensing mechanism (100) in a circuit breaker configured to sense an abnormal voltage condition and send a trip signal; the sensing mechanism comprising:
a plunger (102) configured to travel longitudinally on detection of the abnormal voltage condition and actuate a tripping mechanism;
a spring holder (106) attached with the plunger and configured to travel relative to the plunger (102) in longitudinal direction along axis of the plunger; and
a spring (104) configured between the plunger (102) and the spring holder(106) in compressed condition; wherein the spring(104) and the spring holder (106) are configured to dampen force due to over travel of the plunger(102).

2. The voltage sensing mechanism of claim 1, wherein the spring holder (106) is attached with the plunger (102) with help of plastic snap fit.

3. The voltage sensing mechanism of claim 1, wherein the travel of the spring holder (109) relative to the plunger (102) is more than the over travel of the plunger (102).

4. The voltage sensing mechanism of claim 1, wherein the spring (104) does not get compressed under a force required to actuate the trip mechanism.

5. The voltage sensing mechanism of claim 1, wherein an increased force after tripping compresses the spring (104).