Claims:1. A thermal-magnetic release of a moulded case circuit breaker, said thermal-magnetic release comprising:
a fixed magnet;
a moving magnet adapted to move towards the fixed magnet, separated from the fixed magnet by a predetermined air gap, said moving magnet held in position by springs;
a magnetic knob provided with a groove;
a magnetic shaft coupled with the springs such that rotation of the magnetic shaft causes change in extension of the springs; and
a shaft holder coupled with the magnetic shaft and coupled with the magnetic knob at the groove of the magnetic knob,
wherein, the magnetic knob and the magnetic shaft are perpendicular and non-intersecting with one another, and
wherein rotation of the magnetic knob causes rotation of the shaft holder and consequently the magnetic shaft enabling change in extension of the spring to change the spring force holding the moving magnet.
2. The thermal-magnetic release as claimed in claim 1, wherein a clockwise rotation of the magnetic knob reduces the spring force holding the moving magnet.
3. The thermal-magnetic release as claimed in claim 1, wherein an anti-clockwise rotation of the magnetic knob increases the spring force holding the moving magnet.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general to tripping of an MCCB. In particular, the present disclosure relates to a means to vary the overload current threshold of the MCCB.

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 generally used to protect any device from overload and short circuit. Moulded case circuit breakers (MCCB) have the following subsystems,
• Mechanism
• Contact system
• Release
[0004] The release can be a thermal-magnetic release. The thermal-magnetic release uses electromagnetic coils to provide short circuit protection, and bimetal to provide overload protection. A circuit is designed to carry a particular rated current for a period of time based on its duty cycle. Overload condition is when a higher current (not as high as short circuit) persists for an extended period of time. If higher current (overload current) flows in the circuit for longer periods, then the circuit will not be able to dissipate the excess heat generated because of the overload and ultimately the circuit will break down.
[0005] A fixed magnet or C core and a moving magnet or I core are used for short circuit protection. A pre-determined air gap is maintained between fixed and the moving magnet. During higher currents (short circuit), the magnetic energy due to higher currents helps to overcome the pre-determined gap. The moving magnet, in turn, will give signal to the magnetic shaft meant for short circuit and then to the latching mechanism.
[0006] During any fault, overload or short circuit, the thermal-magnetic release issues the break command and the circuit breaker trips to protect the connected device. After the fault is cleared the circuit breaker can be reset for normal operation.
[0007] However, in many cases, it will be desired that the overload current for a circuit be varied. Generally, to vary the overload current limit in the MCCB, the MCCB is required to be disassembled and the spring force is required to be manually changed to that required, which can be a tedious and time-consuming process.
[0008] There is, therefore, a requirement in the art for a means to quickly vary the overload current threshold of a thermal-magnetic release of an MCCB.
[0009] 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.

OBJECTS OF THE INVENTION
[0010] A general object of the present invention is to provide a thermal-magnetic release of an MCCB which can be configured for different overload current thresholds.
[0011] Another object of the present invention is to provide a thermal-magnetic release of an MCCB whose overload current threshold can be changed easily without significant effort.
[0012] Another object of the present invention is to provide a thermal-magnetic release of an MCCB whose overload current threshold can be changed quickly.

SUMMARY
[0013] The present disclosure relates, in general to tripping of an MCCB. In particular, the present disclosure relates to a means to vary the overload current threshold of the MCCB.
[0014] In an aspect, the present disclosure provides a thermal-magnetic release of a moulded case circuit breaker, said thermal-magnetic release comprising: a fixed magnet; a moving magnet adapted to move towards the fixed magnet, separated from the fixed magnet by a predetermined air gap, said moving magnet held in position by springs; a magnetic knob provided with a groove; a magnetic shaft coupled with the springs such that rotation of the magnetic shaft causes change in extension of the springs; and a shaft holder coupled with the magnetic shaft and coupled with the magnetic knob at the groove of the magnetic knob, wherein, the magnetic knob and the magnetic shaft are perpendicular and non-intersecting with one another, and wherein rotation of the magnetic knob causes rotation of the shaft holder and consequently the magnetic shaft enabling change in extension of the spring to change the spring force holding the moving magnet.
[0015] In an embodiment, a clockwise rotation of the magnetic knob reduces the spring force holding the moving magnet.
[0016] In another embodiment, an anti-clockwise rotation of the magnetic knob increases the spring force holding the moving magnet.
[0017] 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 DRAWINGS
[0018] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.
[0019] FIG. 1 illustrates an exemplary representation of a moulded case circuit breaker, in accordance with an embodiment of the present disclosure.
[0020] FIG. 2 illustrates an exemplary representation of a thermal magnetic release assembly of a moulded case circuit breaker, in accordance with an embodiment of the present disclosure.
[0021] FIG. 3 illustrates an exemplary representation of mechanical linkages, in accordance with an embodiment of the present disclosure.
[0022] FIG. 4 illustrates an exemplary representation of magnetic mechanical linkages, in accordance with an embodiment of the present disclosure.
[0023] FIG. 5 illustrates an exemplary representation of a magnetic knob, in accordance with an embodiment of the present disclosure.
[0024] FIG. 6 illustrates an exemplary representation of a magnetic shaft, in accordance with an embodiment of the present disclosure.
[0025] FIG. 7 illustrates an exemplary representation of a release assembly, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0026] 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.
[0027] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0028] 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.
[0029] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[0030] 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.
[0031] The present disclosure relates, in general to tripping of an MCCB. In particular, the present disclosure relates to a means to vary the overload current threshold of the MCCB.
[0032] In an aspect, the present disclosure provides a thermal-magnetic release of a moulded case circuit breaker, said thermal-magnetic release comprising: a fixed magnet; a moving magnet adapted to move towards the fixed magnet, separated from the fixed magnet by a predetermined air gap, said moving magnet held in position by springs; a magnetic knob provided with a groove; a magnetic shaft coupled with the springs such that rotation of the magnetic shaft causes change in extension of the springs; and a shaft holder coupled with the magnetic shaft and coupled with the magnetic knob at the groove of the magnetic knob, wherein, the magnetic knob and the magnetic shaft are perpendicular and non-intersecting with one another, and wherein rotation of the magnetic knob causes rotation of the shaft holder and consequently the magnetic shaft enabling change in extension of the spring to change the spring force holding the moving magnet.
[0033] In an embodiment, a clockwise rotation of the magnetic knob reduces the spring force holding the moving magnet.
[0034] In another embodiment, an anti-clockwise rotation of the magnetic knob increases the spring force holding the moving magnet.
[0035] FIG. 1 illustrates an exemplary representation of a moulded case circuit breaker, in accordance with an embodiment of the present disclosure.
[0036] FIG. 2 illustrates an exemplary representation of a thermal magnetic release assembly of a moulded case circuit breaker, in accordance with an embodiment of the present disclosure.
[0037] FIG. 3 illustrates an exemplary representation of mechanical linkages, in accordance with an embodiment of the present disclosure.
[0038] FIG. 4 illustrates an exemplary representation of magnetic mechanical linkages, in accordance with an embodiment of the present disclosure.
[0039] FIG. 5 illustrates an exemplary representation of a magnetic knob, in accordance with an embodiment of the present disclosure.
[0040] FIG. 6 illustrates an exemplary representation of a magnetic shaft, in accordance with an embodiment of the present disclosure.
[0041] FIG. 7 illustrates an exemplary representation of a release assembly, in accordance with an embodiment of the present disclosure.

[0042] As shall appear in the embodiments described herein, numerals, as they appear in the associated drawings, shall be used to designate the following components,
1. Heater
2. Bimetal
3. Calibration Screw
4. C core
5. I core
6. Tripper
7. Latch link
8. Compensation bimetal
9. Magnetic knob
10. Magnetic shaft
11. TM shaft
12. Trip Spring
13. Magnetic spring
14. Knob holder
15. Calibration Groove
16. Calibration Slot
17. Knob stopper
18. Spring hook hole
19. Shaft holder
20. Follower
21. I core spring hole
22. Contact system
23. Operating Mechanism
24. Release
[0043] Circuit breakers are generally used to protect any device from overload and short circuit. Moulded case circuit breakers (MCCB) have the following subsystems,
• Mechanism (23)
• Contact system (22)
• Release (24)
[0044] The release (24) can be either an electronic release or a thermal-magnetic release. The thermal-magnetic release uses electromagnetic coils to provide short circuit protection, and bimetal to provide overload protection. A circuit is designed to carry a particular rated current for a period of time based on its duty cycle. Overload condition is when a higher current (not as high as short circuit) persists for an extended period of time. If higher current (overload current) flows in the circuit for longer periods, then the circuit will not be able to dissipate the excess heat generated because of the overload and ultimately the circuit will break down.
[0045] The thermal part of the thermal-magnet release usually consists of a heater (1), a bimetal (2), a calibration screw (3), a thermal shaft (11), and latching mechanism, as shown in FIG. 3.
[0046] A fixed magnet or C core (4) and a moving magnet or I core (5) are used for short circuit protection. A pre-determined air gap is maintained between fixed and the moving magnet. During higher currents (short circuit), the magnetic energy due to higher currents helps to overcome the pre-determined gap. The moving magnet, in turn, will give signal to the magnetic shaft (8) meant for short circuit and then to the latching mechanism (5).
[0047] During any fault, overload or short circuit, the thermo-magnetic release issues the break command and the circuit breaker trips to protect the connected device. After the fault is cleared the circuit breaker can be reset for normal operation.
[0048] The working of the thermal-magnetic release (24) is based on the mechanical linkages, as shown in FIG. 3. When a fault is sensed by release, it trips the operating mechanism (23) with tripper (6). The tripper (6) is latched to a latch link (7), which is loaded with trip spring (12).
[0049] For any temperature rise issues, the bimetal (2) of thermal assembly, as shown in FIG. 2, is fixed with heater (1) through fasteners. As current flow crosses the desired limit, the heater temperature increases. Further, this increase in temperature of heater produces heat, which is transferred to the bimetal through convection. Due to heating, the bimetal, which is a combination of two metals with different coefficient of expansion, bends thus deflecting the TM shaft (11) through the calibration screw (3). The TM shaft further deflects the compensation bimetal (8), which de-latches the tripper through latch link.
[0050] In case of overload condition, the C core (4), which is a fixed magnet, induces flux, due to which the I core, which is moving magnet, is pulled against the magnetic calibration spring (13) .The I core hits the TM shaft (11), which further rotates the compensation bimetal to de-latch the tripper through latch link (7).
[0051] The magnetic spring (13) is connected in between the I core (5) at I core hole (21) and the magnetic shaft with hole (18). The magnetic shaft has a rotary movement with a follower limb (20). The axial movement of magnetic shaft is addressed by a shaft holder (19), which is held in a release housing (24). The follower is inserted in the groove (15) of magnetic knob (9). Both knob and magnetic shaft are perpendicular to each other, but their axes are not intersecting each other. Knob is held in release housing, which is holder portion (14) and the vertical slot (16) on the knob is used to calibrated magnetic rating with the help of an engineer’s tool. The magnetic shaft (10) is adjusted with its follower limb wherein the limb is connected to the magnetic knob to the groove which is engraved on the magnetic knob. The magnetic knob and the groove in magnetic knob are designed with friction angle such that follower will be only moving with the rotation of knob. The groove in knob acts like cam connection with follower of shaft. Thus, with the manual operation of knob we can rotate the shaft in order to extent spring based on overload setting required.
[0052] As the knob is rotated through its slot (16), its groove also rotates. The slope of the groove further rotates the follower with respect to its axis of rotation. With the rotation of shaft, the extension of magnetic spring (13) changes. Thus, the load pulling I core varies with respect to rotation on magnetic knob (9). Hence, the rating for overload failure condition can be changed with respect to the extension of magnetic spring (13) with respect to magnetic linkages.
[0053] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive patent matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “includes” and “including” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practised with modification within the spirit and scope of the appended claims.
[0054] 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
[0055] The present invention provides a thermal-magnetic release of an MCCB which can be configured for different overload current thresholds.
[0056] The present invention provides a thermal-magnetic release of an MCCB whose overload current threshold can be changed easily without significant effort.
[0057] The present invention provides a thermal-magnetic release of an MCCB whose overload current threshold can be changed quickly.