Description:TECHNICAL FIELD
[0001] The embodiments of the present disclosure generally relate to a low voltage switchgear application. More particularly, the present disclosure relates to molded case circuit breakers (MCCB) using thermal magnetic releases for overload and short circuit protection.

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] Over-current protection devices provide electrical protection and/or isolation to electrical systems. Examples of over-current protection/isolation devices include but are not limited to circuit breakers, interrupters, switches, contactors and the like. Circuit breakers typically include one or more electrical contacts, and provide protection against persistent over-current conditions and short circuit conditions. As a motor circuit breaker, circuit breakers are known whose tripping behavior (up to several times the starting current) is adapted to the electric motor to be protected, or which serve as line circuit breakers to protect electric lines or systems against thermal overloads or short-circuit damage. The tripping behavior and thus the use of such circuit breakers are determined by the thermal and short-circuit tripping values.
[0004] Circuit breakers are generally used to protect any device from overload and short circuit faults. The molded case circuit breakers have the following subsystems: mechanism, contact system, and release.
[0005] The release can be either electronic or thermal magnetic releases. The thermal magnetic release uses electromagnetic coils to provide short circuit protection, and bimetal to provide overload protection. The overload condition can be explained in simple terms as higher current (not as high as short circuit) persisting for long time. The system will be designed to carry a specific rated current for a period based on its duty cycle. If higher current (overload current) flows in the system for longer periods, then the system will not be able to dissipate the excess heat generated because of the overload and ultimately the system will break down. 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.
[0006] Thermal and/or magnetic overload trip device is accomplished in a manner well known in the art and is described and shown US 2015/0035627 A1, US 2005/0007220 A1 and US 2009/0195346A1.
[0007] US 2015/0035627 A1 the invention relates to the magnetic release consist of a moving core and a fixed core whose reluctance is adjusted by means of a linear slotted slider. The moving core is connected to the slots provided in the slider. The slider is moved in a linear fashion, during which the moving core position is varied according to the slot in which it is connected thereby changing the magnetic coupling /overlap between moving core and fixed core. This way the reluctance is varied. The slider is adjusted by means of a gear arrangement. Whereas in present invention, the reluctance between moving core and fixed core is varied by changing the angle of air gap between the cores. The construction of the cores is hinged C-I type which is different from the above invention. The air gap angle change is achieved by means of cam profile on the rotary slider. The cam profile decides the position of moving core for different settings. The cam profile can be either integral or detachable.
[0008] US 2005/0007220 A1, the invention relates to the magnetic release consists of a moving core and a fixed core whose reluctance is adjusted by means of a linear slotted slider. The moving core is connected to the slots provided in the slider. The slider is moved in a linear fashion, during which the moving core position is varied according to the slot in which it is connected thereby changing the magnetic coupling /overlap between moving core and fixed core. This way the reluctance is varied. The slider is adjusted by means of a gear arrangement. Whereas in the present invention, the reluctance between moving core and fixed core is varied by changing the angle of air gap between the cores. The construction of the cores is hinged C-I type which is different from the above invention. The air gap angle change is achieved by means of cam profile on the rotary slider. The cam profile decides the position of moving core for different settings. The cam profile can be either integral or detachable.
[0009] US 2009/0195346A1, the invention relates to the magnetic system consists of a moving core (armature), trip shaft, slider (second transmission element) and a knob (adjusting element). The claim of this invention relates to the variation of gap between moving core and trip shaft. For different short circuit settings, when the knob is adjusted, the connected slider component rotates so that the gap between moving core and arm of the trip shaft is varied. Whereas in the present invention the reluctance of the magnetic system is varied by varying the air gap between the moving core and fixed core. The air gap angle change is achieved by means of cam profile on the rotary slider. The cam profile decides the position of moving core for different settings. The cam profile can be either integral or detachable.

SUMMARY
[0010] To overcome this observation, this invention is developed on cam-based mechanism for reluctance variation in magnetic trip unit of MCCB.
[0011] The invention relates to low voltage switchgear application and specifically to a molded case circuit breakers (MCCB) using thermal magnetic releases for overload and short circuit protection.
[0012] In the present invention the thermal magnetic release consists of thermal part and magnetic part. This invention mainly discusses on the mechanism for adjusting the reluctance of the magnetic circuit during the adjustment of different short circuit settings, especially the cam profile provided in the slider which ensures smooth variation of the air gap between the moving core and fixed core. When the user sets the magnetic knob at any of the setting between the minimum and maximum, the slider which is already engaged with the magnetic knob, rotates along and in turn rotates the moving core which is sliding on the cam profile of the slider. Hence for each short circuit setting, the cam profile facilitates the moving core to take a particular position thereby attaining the required reluctance in the magnetic circuit by changing the air gap. During the rotation of moving core, the magnetic spring force happens simultaneously. The other advantage in this invention is the variable reluctance and fixed reluctance principles can be combined in a magnetic circuit. This mechanism used for the adjustment of reluctance of magnetic circuit also helps in achieving higher degree of rotation of magnetic knob, helps in reducing backlash effects as there is always proper engagement between moving parts.
[0013] Aspects of the present invention relates a cam-based mechanism for reluctance variation in magnetic trip unit of MCCB. The proposed invention includes cam profile in the slider facilitates to effectively vary the reluctance and biasing spring force of the magnetic circuit simultaneously. The proposed invention includes cam profile in the slider can be either integral or detachable based on the ease of manufacturing or ease of assembly of a specific system. The proposed profile of the cam is provided such that the different short circuit settings are achieved either using variable reluctance or combining both variable and fixed reluctance. For example- Min to Max settings achieved by uniform variation in the reluctance or Min to Mid settings achieved by uniform variation in reluctance and fixed reluctance up to Max settings.
[0014] 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
[0015] The accompanying drawings, which are incorporated herein, and constitute a part of this invention, illustrate exemplary embodiments of the disclosed methods and systems in which like reference numerals refer to the same parts throughout the different drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Some drawings may indicate the components using block diagrams and may not represent the internal circuitry of each component. It will be appreciated by those skilled in the art that invention of such drawings includes the invention of electrical components, electronic components or circuitry commonly used to implement such components.
[0016] FIG. 1A illustrates a side view of magnetic part of thermal magnetic release, in accordance with an embodiment of the present invention.
[0017] FIG. 1B-1C illustrates a side view of the cam profile with two different settings, in accordance with an embodiment of the present invention.
[0018] FIG. 2 illustrates x-sectional view of magnetic release with housing as stopper for moving core, in accordance with an embodiment of the present invention.
[0019] FIG. 3A illustrates aside view of slider engagement with magnetic knob, in accordance with an embodiment of the present invention.
[0020] FIG. 3B illustrates latching mechanism components, in accordance with an embodiment of the present invention.
[0021] FIG. 4 illustrates a magnetic spring held between a slider and a moving core, in accordance with an embodiment of the present invention.
[0022] FIG. 5 illustrates the thermal and magnetic release components assembly without housing, in accordance with an embodiment of the present invention.
[0023] FIG. 6 illustrates gear teeth like arrangement in thermal part of thermal magnetic release, in accordance with an embodiment of the present invention.
[0024] FIG. 7 illustrates another isometric inside view of thermal magnetic release, in accordance with an embodiment of the present invention.
[0025] The foregoing shall be more apparent from the following more detailed description of the invention.

DETAILED DESCRIPTION
[0026] Various example embodiments will now be described more fully with reference to the accompanying drawings in which only some example embodiments are shown. Specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. The present invention, however, may be embodied in many alternate forms and should not be construed as limited to only the example embodiments set forth herein.
[0027] Accordingly, while exemplary embodiments of the invention are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments of the present invention to the particular forms disclosed. On the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the invention. Like numbers refer to like elements throughout the description of the figures.
[0028] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments of the present invention. As used herein, the term “and/or,” includes any and all combinations of one or more of the associated listed items.
[0029] It will be understood that when an element is referred to as being “connected,” or “coupled,” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected,” or “directly coupled,” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between,” versus “directly between,” “adjacent,” versus “directly adjacent,” etc.).
[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments of the invention. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the terms “and/or” and “at least one of” include any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
[0031] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0032] Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, term such as “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein are interpreted accordingly.
[0033] Following reference numerals and the associated components are used in drawings and to explain the working of the invention:
1. LATCH
2. TRIPPER
3. MAGNETIC KNOB
4. SLIDER
4a. DETACHABLE CAM PROFILE
5. MOVING CORE
6. FIXED CORE
7. MAGNETIC SHAFT
8. HEATER
9. MAGNETIC SPRING
10. OVERLOAD SHAFT
11. AMBIENT TEMPERATURE COMPENSATION (ATC) BIMETAL
12. THERMAL KNOB
13. KNOB HOLDER
14. HOUSING
15. BIMETAL
16. THERMAL CALIBRATION SCREW
[0034] FIG. 1A illustrates a side view of magnetic part of thermal magnetic release, in accordance with an embodiment of the present invention.
[0035] FIG. 1B-1C illustrates a side view of the cam profile with two different settings, in accordance with an embodiment of the present invention.
[0036] FIG. 2 illustrates x-sectional view of magnetic release with housing as stopper for moving core, in accordance with an embodiment of the present invention.
[0037] FIG. 3A illustrates aside view of slider engagement with magnetic knob, in accordance with an embodiment of the present invention.
[0038] FIG. 3B illustrates latching mechanism components, in accordance with an embodiment of the present invention.
[0039] FIG. 4 illustrates a magnetic spring held between a slider and a moving core, in accordance with an embodiment of the present invention.
[0040] FIG. 5 illustrates the thermal and magnetic release components assembly without housing, in accordance with an embodiment of the present invention.
[0041] FIG. 6 illustrates gear teeth like arrangement in thermal part of thermal magnetic release, in accordance with an embodiment of the present invention.
[0042] FIG. 7 illustrates another isometric inside view of thermal magnetic release, in accordance with an embodiment of the present invention.
[0043] As discussed above, the thermal magnetic release uses electromagnetic coils to provide short circuit protection, and bimetal to provide overload protection. The overload condition can be explained in simple terms as higher current (not as high as short circuit) persisting for long time. The system will be designed to carry a specific rated current for a period based on its duty cycle. If higher current (overload current) flows in the system for longer periods, then the system will not be able to dissipate the excess heat generated because of the overload and ultimately the system will break down.
[0044] 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.
[0045] The thermal part of the thermal magnet release usually consists of a heater (8), a bimetal (15), a thermal calibration screw (16), an overload shaft (10), and latching mechanism (1 and 2).
[0046] Deflection of bimetal under high temperature is the phenomenon used in thermal magnetic release to protect the circuit from overload current. A heater (8) element is used, which will carry current and will provide the necessary heat to bimetal either by passing current through the bimetal (direct heating) or by thermally conducting the heat to the bimetal (Indirect heating). The bimetal (15) in turn will deflect and gives a signal to the overload shaft (10) and in turn to ambient temperature compensation (ATC) bimetal (11) and finally to the latch mechanism (1 & 2).
[0047] Similarly, a fixed core (6) and a moving core (5) are used for short circuit protection. A pre-determined air gap is maintained between fixed and the moving core with the help of a biasing spring force named as magnetic spring (9). The air gap and the core materials determine the reluctance of the magnetic circuit. The magnetic spring (9) is held between moving core (5) and slider (4). Slider (4) enables to vary the biasing spring force and air gap for different settings in coordination with the magnetic knob (3). The magnetic knob (3) is the one which is accessed by the user for adjusting the short circuit settings. During higher currents (short circuit), the magnetic energy due to higher currents helps to overcome the reluctance of the magnetic circuit. The moving core in turn will give signal to the magnetic shaft (7) meant for short circuit and then to the latching mechanism (1, 2 and 11). During fault, latching mechanism issues the trip command to the circuit breaker. After the fault is cleared the circuit breaker can be reset for normal operation.
[0048] For different settings of short circuit protection, the adjusting knob is rotated to a specific setting, the slider in turn slides on a rigid support in housing so that the air gap and biasing spring force are varied simultaneously. The slider consists of a triangular shaped slope on which the moving core rests. Whenever the slider moves the moving core rotates along.
[0049] Generally, in such systems high reaction force is seen by the adjusting knob which makes it difficult to rotate and there is a chance of the slider to move back to its initial position due to the biasing spring force.
[0050] This invention facilitates overcoming such limitations and provides a more rigid mechanism for varying the reluctance of the magnetic circuit.
[0051] In the existing systems, the magnetic circuit consists of a linearly moving slider. The moving core slides on the angular slope portion of the slider. As the slider moves the angle of slope varies which in turn varies the angle of air gap between moving core and fixed core. As a result, the reluctance of the magnetic circuit is adjusted for a particular short circuit setting. A significant change in reluctance is required while adjusting every short circuit setting (say 6 to 12 times the rated current) especially in the Thermal magnetic release units with high rated currents. The main limitation in this system is, the linear movement of slider within the available space, the degree of rotation of magnetic knob can be 180 degrees max. the angle of slope profile of the slider becomes very steep to provide wider short circuit settings.
[0052] In the existing arrangement there is only change in biasing spring force and the reluctance of magnetic circuit is fixed for different short circuit settings
[0053] While changing the short circuit settings, the shaft position may not be as per the design intended position due to backlash effect which might affect the performance.
[0054] The existing system has very low mechanical stability and transfers high stress on connecting components due to high reaction force
[0055] The present invention facilitates overcoming such limitations and provides a more rigid mechanism for varying the reluctance of the magnetic circuit.
[0056] According to the present invention, the slider (4) and magnetic knob (3) are engaged together by means of cam arrangement. The magnetic knob (3) consists of a spiral feature on which the cam profile in slider (4) comes in contact. When the magnetic knob (3) is rotated / adjusted to different settings, the cam facilitates the slider (4) to rotate correspondingly. The slider also consists of a detachable cam profile (4a) for varying the position of moving core (5)
[0057] In the present invention, the slider (4) is a rotating component and the detachable cam profile (4a) which acts as the slope for moving core. The moving core slides very smoothly on the profile and helps to change the reluctance according to the setting without occupying more space. Therefore, for a given space, change in reluctance between the two extreme settings (minimum and maximum) is significantly higher than the existing system. Hence wider settings can be achieved say up to 7 discrete settings in this invention.
[0058] To elaborate, according to the present invention the thermal magnetic release consists of thermal part and magnetic part.
[0059] The thermal part comprises a heater, bimetal, thermal calibration screw, overload shaft, thermal knob (12). The bimetal deflects according to the current flowing through the heater. When overload current flows through the heater, which is generally 1.3 times the rated current, the bimetal deflects more. It issues a trip signal to the overload shaft which then makes the latch system to de-latch and the circuit breaker trips. When the thermal knob is adjusted, the gear teeth in the thermal knob drives the overload shaft by engaging with the rack profile. The overload shaft is set in different settings seamlessly without any backlash. The thermal knob (12) is held in its position by a knob holder (13).
[0060] The magnetic part comprises a moving core, fixed core, magnetic shaft (7), magnetic spring, slider, and magnetic knob as in fig (5). The moving core is held in its position by means of a magnetic spring with a pre-determined air gap from fixed core. The other end of magnetic spring is connected to the slider which facilitates to maintain the biasing spring force for discrete short circuit settings as shown in fig (3). The fixed core is assembled in its position along with the heater and housing. When the rated current flows through the heater, the magnetic force generated is not enough to overcome the reluctance of the air gap between fixed & moving core and the biasing magnetic spring force. When the short circuit current flows, the magnetic force generated overcomes the reluctance as well as the magnetic spring force and issues the trip signal to the magnetic shaft (7) which then releases the latch mechanism to trip the circuit breaker.
[0061] The latching mechanism consists of a latch (1) and a tripper (2) as shown in FIGs. 3B-3C. Initially the latch and tripper are in engaged or latched condition and the tripper gets released or de-latched when trip signal emerges either from a thermal or magnetic system due to overload or short circuit current. In this invention the trip system offers a high delivering force with lesser latching force which increases the efficiency of the system. It has a tripper which gets actuated linearly through a stored energy when de-latched and trips the circuit breaker. The linear motion aids in no loss of force delivered by the tripper to the circuit breaker mechanism. Also, the trip system offers very less reaction forces or opposing force to the bimetal and moving core. This helps in reducing the biasing spring forces and thereby making the handling of assembly with ease.
[0062] This invention mainly discusses on the mechanism for adjusting the reluctance of the magnetic circuit during the adjustment of different short circuit settings, especially the cam profile provided in the slider which ensures smooth variation of the air gap between the moving core and fixed core. When the user sets the magnetic knob at any of the setting between the minimum and maximum, the slider which is already engaged with the magnetic knob, rotates along and in turn rotates the moving core which is sliding on the cam profile of the slider. Hence for each short circuit setting, the cam profile facilitates the moving core to take a particular position thereby attaining the required reluctance in the magnetic circuit by changing the air gap. During the rotation of moving core, the magnetic spring force happens simultaneously.
[0063] The other advantage in this invention is the variable reluctance and fixed reluctance principles can be combined in a magnetic circuit. The cam profile (4a) will be used for varying the position of moving core (5) for certain settings (say min to mid settings) and from then on, the remaining settings will be achieved by fixed reluctance principle. In the fixed reluctance portion, the moving core (5) takes a fixed position by providing a stopper (14a) in the housing (14). In other words, the moving core (5) rests on the cam profile (4a) up to certain settings and rests on the housing stopper (14a) for remaining settings (say, Mid to Max). The resting point of moving core is different when its slides on the cam profile (4a) and when it rests on the housing stopper (14a). This mechanism used for the adjustment of reluctance of magnetic circuit also helps in achieving higher degree of rotation of magnetic knob, helps in reducing backlash effects as there is always proper engagement between moving parts.
[0064] Accordingly, the present invention provides a reluctance varying mechanism such that the air gap and biasing spring force are varied simultaneously during different short circuit settings.
[0065] The cam-based arrangement facilitates in providing tripping at 100% of set short circuit current which is the mean position.
[0066] The cam-based arrangement eliminates the backlash error and reduces the need for calibration of the system.
[0067] The cam profile in the slider facilitates to effectively vary the reluctance and biasing spring force of the magnetic circuit simultaneously.
[0068] The cam profile in the slider can be either integral or detachable based on the ease of manufacturing or ease of assembly of a specific system.
[0069] The profile of the cam can be provided such that the different short circuit settings are achieved either using variable reluctance or combining both variable and fixed reluctance. For example- Min to Max settings achieved by uniform variation in the reluctance or Min to Mid settings achieved by uniform variation in reluctance and fixed reluctance up to Max settings.
[0070] Accordingly, in an embodiment, a circuit breaker with a thermal magnetic release mechanism is disclosed. The circuit breaker includes a slider (4) engaged with a magnetic knob (3) by a cam arrangement, wherein the magnetic knob (3) having a spiral feature adapted to connect with a cam profile of the slider (4), such that a movement of the magnetic knob (3) facilitates the slider (4) to move correspondingly.
[0071] In this embodiment, the slider (4) further comprises a detachable cam profile (4a) for varying a position of a moving core (5) of the circuit breaker.
[0072] In this embodiment, the slider (4) is adapted to rotate, and the detachable cam profile (4a) is adapted to provide a slope for a moving core (5) of the circuit breaker, such that the moving core slides on the detachable cam profile to change a reluctance.
[0073] In this embodiment, the slider (4) is a linearly moving slider, and wherein a movement of the slider is adapted to move an angle of slope varies that varies an angle of air gap between a moving core and a fixed core of the circuit breaker.
[0074] In this embodiment, a movement of the magnetic knob (3) is a rotatory movement or a non-rotatory movement.
[0075] In this embodiment, in a fixed reluctance portion, the moving core is fixed at a fixed position by providing a stopper (14a) in a housing (14) of the circuit breaker.
[0076] In this embodiment, in a fixed reluctance portion, the moving core rests on the cam profile (4a) for a first setting and rests on a housing stopper (14a) for a second setting such that the resting point of moving core is different when its slides on the cam profile (4a) and when it rests on the housing stopper (14a).
[0077] What are described above are merely preferred embodiments of the present invention, and are not to limit the present invention; any modification, equivalent replacement and improvement within the principle of the present invention should be included in the protection scope of the present invention.
[0078] The example embodiment or each example embodiment should not be understood as a restriction of the invention. Rather, numerous variations and modifications are possible in the context of the present disclosure, in particular those variants and combinations which can be inferred by the person skilled in the art with regard to achieving the object for example by combination or modification of individual features or elements or method steps that are described in connection with the general or specific part of the description and are contained in the claims and/or the drawings, and, by way of combinable features, lead to a new subject matter or to new method steps or sequences of method steps, including insofar as they concern production, testing and operating methods.
[0079] References back that are used in dependent claims indicate the further embodiment of the subject matter of the main claim by way of the features of the respective dependent claim; they should not be understood as dispensing with obtaining independent protection of the subject matter for the combinations of features in the referred-back dependent claims. Furthermore, with regard to interpreting the claims, where a feature is concretized in more specific detail in a subordinate claim, it should be assumed that such a restriction is not present in the respective preceding claims.
[0080] Since the subject matter of the dependent claims in relation to the prior art on the priority date may form separate and independent inventions, the applicant reserves the right to make them the subject matter of independent claims or divisional declarations. They may furthermore also contain independent inventions which have a configuration that is independent of the subject matters of the preceding dependent claims.
[0081] Further, elements and/or features of different example embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims.
[0082] Example embodiments being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

, Claims:1. A circuit breaker with a thermal magnetic release mechanism, the circuit breaker comprising:
a slider (4) engaged with a magnetic knob (3) by a cam arrangement, wherein the magnetic knob (3) having a spiral feature adapted to connect with a cam profile of the slider (4), such that a movement of the magnetic knob (3) facilitates the slider (4) to move correspondingly.

2. The circuit breaker as claimed in claim 1, wherein the slider (4) further comprises a detachable cam profile (4a) for varying a position of a moving core (5) of the circuit breaker.

3. The circuit breaker as claimed in claim 2, wherein the slider (4) is adapted to rotate, and the detachable cam profile (4a) is adapted to provide a slope for a moving core (5) of the circuit breaker, such that the moving core slides on the detachable cam profile to change a reluctance.

4. The circuit breaker as claimed in claim 1, wherein the slider (4) is a linearly moving slider, and wherein a movement of the slider is adapted to move an angle of slope varies that varies an angle of air gap between a moving core and a fixed core of the circuit breaker.

5. The circuit breaker as claimed in claim 1, wherein a movement of the magnetic knob (3) is a rotatory movement or a non-rotatory movement.

6. The circuit breaker as claimed in claim 2, wherein in a fixed reluctance portion, the moving core is fixed at a fixed position by providing a stopper (14a) in a housing (14) of the circuit breaker.

7. The circuit breaker as claimed in claim 2, wherein in a fixed reluctance portion, the moving core rests on the cam profile (4a) for a first setting and rests on a housing stopper (14a) for a second setting such that the resting point of moving core is different when its slides on the cam profile (4a) and when it rests on the housing stopper (14a).