Claims:

1. A moulded case circuit breaker (MCCB) comprising:
an insulating housing provided with an incoming part and an outgoing part, said housing comprising:
an electronic release module;
a fixed contact assembly;
a dynamic mechanism;
a moving contact assembly;
a latch assembly; and
a slot motor with a solenoid assembly,
wherein, in an energised state, the solenoid assembly operates to latch the moving contact for a predetermined duration of time in order to provide a delayed action.
2. The MCCB as claimed in claim 1, wherein the electronic release module comprises:
an insulated enclosure;
three current sensors configured on an individual pole; and
a PCB module comprising a signal conditioning and amplification unit, a test trip and power up circuit, a switch for delay time setting, a main microcontroller and a secondary microcontroller.
3. The MCCB as claimed in claim 1, wherein the fixed contact assembly comprises:
a lower contact;
an upper contact placed opposite to the lower contact and to the moving contact; and
a return spring placed between the upper contact and the lower contact.
4. The MCCB as claimed in claim 1, wherein the dynamic mechanism assembly comprises:
an insulated knob; and
a moving contact assembly that is coupled with a terminal of the electronic release module via a braided copper wire.
5. The MCCB as claimed in claim 1, wherein the moving contact assembly comprises:
a moving contact;
a contact button; and
an arc runner.
6. The MCCB as claimed in claim 1, wherein the latch assembly comprises an insulated shaft connected to an extension spring mechanism and coupled to both moving contact assembly and fixed contact assembly, wherein rotation of the knob enables latching of the moving contact of the dynamic mechanism for the predetermined time duration, and wherein, upon de-latching, the insulated shaft rotates to allow the contacts to open.
7. The MCCB as claimed in claim 1, wherein the slot motor with solenoid assembly comprises:
a solenoid configured to, when energised, provide latching force to latch the moving contact for the predetermined time duration; and
a “U” shaped magnet configured to increase repulsive force between current carrying contacts to enable quick separation of the contacts.
8. The MCCB as claimed in claim 1, wherein operation of said MCCB comprises the steps of:
detecting, through a current transformer, a fault current flowing through one or more individual poles of the MCCB;
converting a secondary output of the current transformer from an AC output to a DC output, wherein at least a part of the DC output is utilised for self-power generation and the remaining DC output is conditioned and amplified;
providing the remaining DC output to the main microcontroller which is configured to generate a DIGITRIP;
generating an ANATRIP from an analogue signal conditioning circuit; and
providing DIGITRIP and ANATRIP to the secondary microcontroller which is configured to generate two outputs, wherein the first output is configured to enable the latching of the moving contact for the predetermined time duration to provide delay in opening of the contacts of the MCCB.
9. The MCCB as claimed in claim 1, wherein operation of said MCCB comprises the steps of:
disabling the first microcontroller output to disengage the latching of the moving contact; and
enabling the second microcontroller output to separate the contacts of the MCCB to trip the MCCB.
10. The MCCB as claimed in claim 1, wherein operation of said MCCB comprises the step of resetting the MCCB after tripping of the MCCB to retain self-power generation.
, Description:
TECHNICAL FIELD
[0001] The present disclosure relates to the field of safety of electrical circuits. In particular, the present disclosure relates to the construction and working of moulded case circuit breakers.

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] Most conventional moulded case circuit breakers (MCCBs) do not have a high short time withstand current capacity, and are suitable for utilisation category A. Such MCCBs are provided with a current limiting technology, in which the fixed contact profile is reversed with respect to the moving contact system. The current limiting action means that the contacts of the MCCB will open much before the peak short circuit current. This limiting action followed by opening operation is achieved by the repulsion force between the contacts, which is produced due to holms, Lorentz, slot motor and blast of high-pressure gas of the arc along with operating mechanism. The current reversal contact system contributes towards the repulsion force produced due to Lorentz and the holms repulsion force is contributed by the distribution of current across the contact, which further depends upon the hardness of contact material, true contact area and contact pressure.
[0004] However, selectivity plays a crucial role in a secondary distribution system, especially where zone wise protection is required at different level of branch circuits. Under such a situation, there is a need for a CAT AB MCCB, which demands CAT B operation for say 120-130 ms followed by CAT A operation, which will open the contact system after intended delay time due to current limiting action.
[0005] To satisfy zone wise protection or selectivity criteria, there is required a variation in rating or setting of the MCCBs that are used in the incoming and outgoing branch circuit. A conventional MCCB with same rating, would not fulfil the selectivity criteria and would not support both CAT A and CAT B states of operation.
[0006] There is therefore a requirement in the art for an MCCB capable of zone protection that can perform both CAT A and CAT B operation.
[0007] 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.
[0008] In some embodiments, the numbers expressing quantities or dimensions of items, 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.
[0009] 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.
[0010] 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.
[0011] 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 groups used in the appended claims.

OBJECTS
[0012] A general object of the present disclosure is to provide an MCCB for CAT AB utilisation.
[0013] Another object of the present disclosure is to provide an MCCB that is capable of discrimination of actual fault condition at the different location of branch circuit.
[0014] Another object of the present disclosure is to provide an MCCB that is capable of zone wise short circuit fault protection.
[0015] Another object of the present disclosure is to provide an MCCB with a provision of short time withstand capacity for few milliseconds.

SUMMARY
[0016] The present disclosure relates to the field of safety of electrical circuits. In particular, the present disclosure relates to the construction and working of moulded case circuit breakers.
[0017] In an aspect, the present disclosure provides a moulded case circuit breaker (MCCB) comprising: an insulating housing provided with an incoming part and an outgoing part, said housing comprising: an electronic release module; a fixed contact assembly; a dynamic mechanism; a moving contact assembly; a latch assembly; and a slot motor with a solenoid assembly, wherein, in an energised state, the solenoid assembly operates to latch the moving contact for a predetermined duration of time in order to provide a delayed action.
[0018] In an embodiment, the electronic release module comprises: an insulated enclosure; three current sensors configured on an individual pole; and a PCB module comprising a signal conditioning and amplification unit, a test trip and power up circuit, a switch for delay time setting, a main microcontroller and a secondary microcontroller.
[0019] In another embodiment, the fixed contact assembly comprises: a lower contact; an upper contact placed opposite to the lower contact and to the moving contact; and a return spring placed between the upper contact and the lower contact.
[0020] In another embodiment, the dynamic mechanism assembly comprises: an insulated knob; and
[0021] a moving contact assembly that is coupled with a terminal of the electronic release module via a braided copper wire.
[0022] In another embodiment, the moving contact assembly comprises: a moving contact; a contact button; and an arc runner.
[0023] In another embodiment, the latch assembly comprises an insulated shaft connected to an extension spring mechanism and coupled to both moving contact assembly and fixed contact assembly, wherein rotation of the knob enables latching of the moving contact of the dynamic mechanism for the predetermined time duration, and wherein, upon de-latching, the insulated shaft rotates to allow the contacts to open.
[0024] In another embodiment, the slot motor with solenoid assembly comprises: a solenoid configured to, when energised, provide latching force to latch the moving contact for the predetermined time duration; and a “U” shaped magnet configured to increase repulsive force between current carrying contacts to enable quick separation of the contacts.
[0025] In another embodiment, operation of the MCCB comprises the steps of detecting, through a current transformer, a fault current flowing through one or more individual poles of the MCCB; converting a secondary output of the current transformer from an AC output to a DC output, wherein at least a part of the DC output is utilised for self-power generation and the remaining DC output is conditioned and amplified; providing the remaining DC output to the main microcontroller which is configured to generate a DIGITRIP; generating an ANATRIP from an analogue signal conditioning circuit; and providing DIGITRIP and ANATRIP to the secondary microcontroller which is configured to generate two outputs, wherein the first output is configured to enable the latching of the moving contact for the predetermined time duration to provide delay in opening of the contacts of the MCCB.
[0026] In another embodiment, operation of the MCCB comprises the steps of disabling the first microcontroller output to disengage the latching of the moving contact; and enabling the second microcontroller output to separate the contacts of the MCCB to trip the MCCB.
[0027] In another embodiment, operation of the MCCB comprises the step of resetting the MCCB after tripping of the MCCB to retain self-power generation.
[0028] 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
[0029] 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.
[0030] FIGs. 1 and 2 illustrate exemplary isometric view and sectional view of a CAT AB MCCB in accordance with embodiments of the present disclosure.
[0031] FIGs. 3 and 4 illustrate exemplary isometric view and front view of the housing of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0032] FIG. 5 illustrates an exemplary isometric view of the insulated top cover of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0033] FIG. 6 illustrates an exemplary isometric view of an add on cover of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0034] FIGs. 7 and 8 illustrate exemplary side view and isometric view of an electronic release of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0035] FIG. 9 illustrates an exemplary current carrying part retainer of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0036] FIG. 10 illustrates an exemplary fixed contact assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0037] FIGs. 11 and 12 illustrate exemplary representations of lower fixed contact and upper fixed contact respectively of the fixed contact assembly, in accordance with embodiments of the present disclosure.
[0038] FIG. 13 illustrates an exemplary dynamic mechanism assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0039] FIG. 14 illustrates an exemplary insulated knob attached to the dynamic mechanism assembly, in accordance with embodiments of the present disclosure.
[0040] FIG. 15 illustrates an exemplary moving contact assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0041] FIG. 16 illustrates an exemplary insulated shaft along with the moving contact assembly, in accordance with embodiments of the present disclosure.
[0042] FIG. 17 illustrates the exemplary insulated shaft, in accordance with embodiments of the present disclosure.
[0043] FIG. 18 illustrates an exemplary slot motor with solenoid assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0044] FIGs. 19 and 20 illustrate exemplary sectional view of the solenoid assembly in closed condition and open condition respectively, in accordance with embodiments of the present disclosure.
[0045] FIG. 21 illustrates an exemplary insulated enclosure of a slot motor assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0046] FIG. 22 illustrates an exemplary sectional view of the solenoid assembly, in accordance with embodiments of the present disclosure.
[0047] FIG. 23 illustrates an exemplary plunger assembly, in accordance with embodiments of the present disclosure.
[0048] FIG. 24 illustrates an exemplary functional block diagram for the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0049] FIG. 25 illustrates an exemplary additional circuit requirement for CAT AB operation for the proposed MCCB, in accordance with embodiments of the present disclosure.
[0050] FIG. 26 illustrates an exemplary schematic arrangement for CAT B operation, in accordance with embodiments of the present disclosure.
[0051] FIG. 27 illustrates an exemplary test trip circuit with FSD interface used to test the trip functionality of the electronic release of the proposed CAT AB MCCB.
[0052] FIG. 28 illustrates an exemplary communication and test connector circuit for feeding voltage from the function generator through the test port.
[0053] FIG. 29 illustrates an exemplary test setup for testing the trip functionality of the electronic release of the proposed CAT AB MCCB.
[0054] FIG. 30 illustrates exemplary view of sequential operation of input and output signal from the microcontroller.
[0055] FIG. 31 illustrates exemplary view of sequential operation of output signal fed to AC solenoid and FSD.
[0056] FIG. 32 illustrates an exemplary flow diagram for sequential operation between solenoid and the FSD, in accordance with embodiments of the present disclosure.
[0057] FIG. 33 illustrates an exemplary sequential time diagram for operation of the proposed CAT AB MCCB.

DETAILED DESCRIPTION
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] In an aspect, the present disclosure provides an MCCB with CAT AB operation that comprises a mechanical latch system to provide an intended short time delay in current limiting action. The entire latch system is suitably placed inside an enclosure (shell) holding the reversal fixed contact assembly and slot motor. It essentially consists of a solenoid, whose plunger under CAT A state is magnetically latched by a permanent magnet. However, when a CAT B requirement is needed, after sensing the critical (limiting) current, a microcontroller is programmed so as to generate an output, which is fed to signal conditioning circuit followed by a solid-state device to actuate the solenoid so that its plunger pops out and get interlocked at the other end of enclosure along with return spring. The plunger resting upon the moving contact of MCCB holds it firmly for the intended delay time (120 – 130 ms), after which, power supply to the solenoid is switched off by the microcontroller. The plunger retracts back to its rest state due to the restraining spring at the other end of housing. This state of the latch system satisfies the requirement of CAT B operation.
[0064] FIGs. 1 and 2 illustrate exemplary isometric view and sectional view of a CAT AB MCCB in accordance with embodiments of the present disclosure. In an embodiment, the CAT AB moulded case circuit breaker comprises an insulated housing (1), a cover (2), an add on cover (3), an electronic release (4), a fixed contact assembly (5), a quenching unit (6), a dynamic mechanism assembly (7) and a slot motor assembly (8).
[0065] FIGs. 3 and 4 illustrate exemplary isometric view and front view of the housing of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. The insulated housing (1) is meant for holding the MCCB comprising the components and sub–assemblies as shown in FIGs. 1 and 2. The housing has three rectangular shaped slots (9, 10) provided at an incoming and an outgoing to accommodate respective terminals resting upon a metallic retainer. A hexagonal shaped groove, provided in the respective slot, aids in holding the retainer along with the terminal. Hexagonal groove is further extended with circular holes (20), through which the retainer is held by the housing using a fastener such as slotted cheese head screw.
[0066] In another embodiment, along the individual central axis of each pole, two vertical circular holes (12) are provided in the housing to hold the fixed contact assembly (5). The protruded part consists of rectangular grooves with a cut (13), inside which the perforated insulated sheets retaining the quenching unit Deion plates are inserted. The perforated sheet with circular holes, aids in improving the aerodynamic behaviour of the ionized blast of gas passing through, thereby enabling faster cooling of the hot gases. A “T” shaped rectangular cut (14) provided at both the top and bottom surface of the housing is configured to accommodate insulated phase barrier between the individual poles. The dynamic mechanism main shaft is cylindrical in shape, is adapted to rest and swivel along the semi-circular opening (15) in the housing.
[0067] In another embodiment, in the central pole of the housing, four rectangular protruded parts with circular holes (16) are provided to hold the dynamic mechanism assembly (7) using the vertical and horizontal plates. In order to firmly retain the protruded part of the slot motor within the housing, in each pole, a “C” shaped rectangular cut (17) is provided. The electronic release (4) outgoing terminal in each pole consists of rectangular current carrying parts (41), which is suitably placed along the cut (11) and firmly fixed with the housing by a screw passing through the hole (19).
[0068] FIG. 5 illustrates an exemplary isometric view of the insulated top cover of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the insulated top cover, at both its top and bottom surfaces, has rectangular slots to match with the housing, along with adequate creepage and clearance requirements. Suitable openings (23, 24) with ergonomically geometrical structure, at the top surface of the insulated top cover, accommodates the under voltage and shunt release device to be assembled with the MCCB. Additionally, an opening (25) at the central axis of the middle pole allows the knob to project out from the dynamic mechanism assembly such that it can be operable. The electronic release resting inside the housing projects out through the rectangular cut (26) provided in the top cover.
[0069] In another embodiment, a “T” shaped rectangular opening (27) is provided in the top cover that matches with the cut marks (14) provided in the housing to accommodate an insulated phase barrier. The insulated phase barrier can be made of an insulating material such as polyvinyl based compounds.
[0070] In another embodiment, along the convex surface of the insulated top cover, a cut mark (29) is present in the cover that can allow an insulated label to be firmly gripped to its surface. Circular holes (30), along with inserts and fasteners, aid in connecting add on cover (3) with the top cover (2).
[0071] FIG. 6 illustrates an exemplary isometric view of an add on cover of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the add on cover is a rectangular part (31) with a projected convex (33) protruded part. Along the four corners are provided holes (32) through which screws can be inserted to connect with the main cover. At its central axis, a rectangular opening (34) is provided so that the knob of the MCCB, can be projected out through it.
[0072] In another embodiment, for ease of identification of different states and types of MCCB, a provision (35) for suitable pad printing is provided. The fixed contact terminal assembly (5) of the moulded case circuit breaker rests upon the retainer (43).
[0073] FIGs. 7 and 8 illustrate exemplary side view and isometric view of an electronic release of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the electronic release module comprises an insulated enclosure (36) with three current sensors placed on an individual pole, a PCB module comprising a signal conditioning unit along with an amplification circuit, a voltage follower, a dip switch for current and delay time setting, a microcontroller, a test trip condition and power up circuit, a flux shift tripping device (39) and a test kit. The difference in construction of a conventional CAT A MCCB with that of the proposed MCCB is an additional circuit, which receives both analogue and digital trip signal from an existing MCCB and then operates the solenoid of the MCCB and that of FSD with an intended delay programme provided by the microcontroller along with opto-isolator.
[0074] In another embodiment, at the top surface is a space available (37) for label and dip switches along with socket for connection with the test kit. Using a slotted cheese head screw, the housing (1) is fit with the cover (2) through the holes (21, 28) provided in the respective insulated parts.
[0075] In another embodiment, the moulded insulated electronic release is provided with rectangular protruded parts (40), which are adapted to slide along a cut (18) provided in the housing. Other terminal (38) of the electronic release (4), is connected to the retainer (43) resting upon the slot (10) by means of screw fitment through the hole (42).
[0076] FIG. 9 illustrates an exemplary current carrying part retainer of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, on its surface are provided two threaded holes (44) for connection with the insulated housing using screw fitments. Another hole (45) is adapted for entry of the main terminal screw.
[0077] FIG. 10 illustrates an exemplary fixed contact assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the fixed contact assembly (5) comprises an upper and a lower current carrying part made out of ETP copper and a restraining spring (48) holding the upper current carrying part. The upper current carrying part (46) is placed opposite to the lower current carrying part (47) and the moving contact so that current reversal can occur. The lower fixed contact (47) is a sigmoid shaped part and has two vertical threaded holes (51) at its top surface, through which screw can pass to connect it with the housing (1).
[0078] In another embodiment, two other horizontal threaded holes (50) are adapted for screw fitment with a slot motor. Centrally located hole (52) with no threading is provided for ease of entry of the return spring (48) between the upper and lower fixed contact. At a bottom end and front surface, a threaded hole (49) is provided, which is meant for the termination of external conductor. The top end of the part (47) is orthogonally bent (53) for connection with the upper fixed contact (46).
[0079] FIGs. 11 and 12 illustrate exemplary representations of lower fixed contact and upper fixed contact respectively of the fixed contact assembly, in accordance with embodiments of the present disclosure. In an embodiment, counter-shank holes (54) are provided on the lower contact. The upper fixed contact (46), at its extreme end, is provided with through hole (55) upon the circular protruded part (59), which is adapted to mate with the counter shank holes (54) of lower contact. At its bottom surface, is a projected rectangular protrusion (57), which is meant to retain the restraining spring (48). At its top surface, rectangular protruded part (56) is the contact button which is suitably bonded with the base material using conventional technique such as brazing (flame, Induction, spot) and welding (spot) or other suitable means. Beside the rectangular protruded part (56), is a projected part (58) of current carrying part, which retains the arc runner.
[0080] FIG. 13 illustrates an exemplary dynamic mechanism assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the dynamic mechanism assembly (7) comprises an insulated knob (60), a moving contact assembly (61), a braided copper wire (62) linking the moving contact with the terminal (41) of the electronic release, an insulated common shaft drive (63), an insulated bush (64), a pin (66) and a mechanism (65) constituting vertical and horizontal plates, a set of lever, a bracket and a set of extension springs.
[0081] FIG. 14 illustrates an exemplary insulated knob attached to the dynamic mechanism assembly, in accordance with embodiments of the present disclosure. In an embodiment, the insulated knob (60) comprises a convex protruded part (70), which at its bottom, is suitably scooped (69) so as to provide a dampening action (or, dynamic resiliency) against impact and has “L” shaped protruded parts (68) at its four corners. The knob is guided by a metallic bracket of the mechanism using the part (68). Its top surface is provided with a wedge-shaped protruded part, which is meant for manual operation of the device.
[0082] FIG. 15 illustrates an exemplary moving contact assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the moving contact assembly (61) comprises a moving contact (71), a contact button (73) and an arc runner (74). The initial portion of the moving contact is rectangular in shape, which further projects out in a triangular shape of thin cross-section (72) in order to be trapped between the jaws of an insulated bush (64). A rectangular opening (76) ensures right mating with the bush. The moving contact, along with the bush and main shaft drive, is assembled using a common pin (66) that is adapted to enter a hole (75). The moving contact assembly (61) is connected to the contact terminal (5) via the electronic release contact system (41, 42) using a copper braided wire (62). The braided wire is a flexible twisted conductor suitable to carry the current under both normal and abnormal condition.
[0083] FIG. 16 illustrates an exemplary insulated shaft along with the moving contact assembly, in accordance with embodiments of the present disclosure. In an embodiment, the insulated shaft (63) is connected to the extension spring loaded mechanism via two sets of bar systems (77, 78) coupled through a metallic pin (80). Latching and de-latching of the mechanism is done by the latching bracket (79), which is driven by the two set of bars. Rotation of the knob will latch the bracket against the vertical plate (81). Upon de-latching, the stored energy of the extension spring causes the set of bars to rotate, leading to rotation of the common shaft to open the contacts. Two side plates (82) connect the vertical plate and the plate (83) holding the knob of the MCCB.
[0084] FIG. 17 illustrates the exemplary insulated shaft, in accordance with embodiments of the present disclosure. In an embodiment, the insulated shaft is cylindrical in shape and consists of evenly distributed protruded parts (85) for each pole to accommodate a bush (64) to hold the moving contact assembly. At its central axis, the part (85) has holes (86) through which a common pin enters to connect the shaft (63), the bush (64) and the moving contact (61). In order to satisfy the condition of utilisation category B, it is required that a delay of about 120 ms be present for the opening operation, which is achieved by mechanically holding the moving contact of the dynamic mechanism for such a duration against repulsion force created due to holms, Lorentz and slot motor. This is achieved by the solenoid assembly which is part of the slot motor assembly.
[0085] FIG. 18 illustrates an exemplary slot motor with solenoid assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the assembly comprises an insulated enclosure (87), a holding the solenoid assembly (89) and a “U” shaped magnet assembly (88). The “U” shaped magnet assembly surrounds the upper fixed contact and provides the desired repulsion effect to aid the current limiting action during CAT “A” state of the MCCB. The solenoid assembly under its energized state, mechanically holds the moving contact, thereby providing the intended delayed action to satisfy the CAT “B” condition.
[0086] FIGs. 19 and 20 illustrate exemplary sectional view of the solenoid assembly in closed condition and open condition respectively, in accordance with embodiments of the present disclosure. In an embodiment, when the solenoid is energized, a plunger (90) pops out of a bobbin (92) and enters the hole provided in the opposite side of the enclosure against the restraining force provided by the return spring (91). In doing so, it overlaps the moving contact (94), thereby holding the contact system in closed condition.
[0087] In another embodiment, upon de-energization of the solenoid, the plunger (90) retracts back due to the restraining stored energy (91) and is further driven back by the permanent magnet (95).
[0088] In another embodiment, the insulated enclosure (87) consists of a shallow slanted part (96) to support the upper fixed contact, which is held at its rest position by the helical spring (48) positioned inside the opening (98). The enclosure further consists of two hollow rectangular cuts (97) provided to support the “U” shaped magnet known as slot motor which is adapted to increase repulsion force created between the current carrying contacts. Above this cut (97), on one of the rectangular protruded part (100), is provided rectangular openings (101) to place the solenoid assembly.
[0089] FIG. 21 illustrates an exemplary insulated enclosure of a slot motor assembly of the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the slot motor assembly has a shell (99) with a nut to firmly fit the enclosure with the housing of the moulded case circuit breaker. Opposite to the rectangular cut (101) is present another circular hole (102), which holds the return spring (91).
[0090] FIG. 22 illustrates an exemplary sectional view of the solenoid assembly, in accordance with embodiments of the present disclosure. In an embodiment, the assembly comprises an insulated bobbin (103) with a rectangular upper flange and lower flange to accommodate the coil winding, a hollow cylinder to hold the plunger (90) and a cylindrical permanent magnet (95) attached at an extreme left hand.
[0091] FIG. 23 illustrates an exemplary plunger assembly, in accordance with embodiments of the present disclosure. In an embodiment, the plunger assembly (90) consists of an insulated part (104), inserted inside the ferromagnetic core (105). The solid insulated part is cylindrical (111) in shape with a protrusion (110) at its bottom surface meant for entry into the helical return spring. At its top surface, is a hole (109) through which the ferromagnetic core is inserted. This core consists of a two-step solid cylinder (106, 107). Part (107) of the core is provided with counter shank chamfer (108) for ease of entry of the core inside the hole (109).
[0092] In an aspect, the present disclosure provides a modified CAT A MCCB with an extension, where a CAT B functionality is additionally obtained by intentionally delaying the opening operation of the MCCB by 120 to 130 ms in the event of an abnormal condition such as short circuit fault etc., and thereby providing a suitable short time withstanding capability. This functionality can be achieved by means of mechanically latching the moving contact of the MCCB for the intended duration, using a solenoid along with slot motor assembly. In order to achieve this in existing MCCB architecture, the frame size needs to be increased along the width so as to accommodate the solenoid assembly in each pole of the MCCB without violating the insulation co-ordination requirement such as creepage and clearance etc under abnormal condition.
[0093] FIG. 24 illustrates an exemplary functional block diagram for the proposed CAT AB MCCB, in accordance with embodiments of the present disclosure.
[0094] In a conventional CAT A MCCB, during a short circuit fault, the ANALOG and DIGITAL trip signal obtained from the signal conditioning circuit is directly fed to the flux shift trip device to de-latch the mechanism and trip the MCCB so as to break the electrical branch circuit with adequate mechanical isolation requirement. It shall not provide any short time withstand capability.
[0095] In an embodiment, the proposed technology reveals an additional circuit (Dash line block), that is incorporated in the existing electronic release so as to achieve the CAT AB requirement. In the event of a short circuit, high fault current flowing through the individual poles of the MCCB will be sensed by the current transformer (CT), whose secondary output is suitably rectified to convert the AC to a DC output signal. The DC output obtained from the rectified circuit is partly utilized for self-power generation to drive the control circuit and the remaining is fed to the signal conditioning circuit so as to reject any high frequency noise and spurious signal, and then to amplify along with voltage follower circuit, current zero crossing detection circuit, test trip circuit, thermal memory circuit using operational amplifier etc. The reference of the digital circuit is set by a dip switch.
[0096] In another embodiment, the sensor output after signal conditioning, is fed to a main microcontroller, which is an integral component of the electronic release. The differential output is fed to the main microcontroller (PIC18LF4420), which is programmed in such a way that it produce DIGITRIP output. An ANATRIP output is directly obtained from analogue signal conditioning circuit using operational amplifiers.
[0097] In another embodiment, the ANATRIP and DIGITRIP signals are fed to a second microcontroller (MSP430G2231), which is programmed to produce two outputs. A first output is fed to the base of the transistor Q1 through a resistor, which can vary between minimum to any suitable value as per requirement. When the base voltage is high, Q1 is turned ON to forward bias the photodiode of optocoupler U2, which, on conduction, emits photons to optically couple it with the photo-triac. When the optocoupler turns ON, its output drives the solenoid through the AC supply, and provides the desired galvanic isolation between the AC supply and DC output from microcontroller and transistor.
[0098] FIG. 25 illustrates an exemplary additional circuit requirement for CAT AB operation for the proposed MCCB, in accordance with embodiments of the present disclosure. In an embodiment, the first output is retained for a duration that is sufficient to keep the solenoid in energized condition for 120 to 130 milliseconds. The plunger pops out of the coil and overlaps the moving contact so as to mechanically latch the contact system. During this time period, the second output is in disabled state so that there is no chance of mal-operation of the mechanism due to FSD. Once the first output is disabled, a second output from U1 is enabled, which is fed to the branch circuit consisting of R4-D1-R6-C1. When the diode D1 is forward biased, this branch starts conducting thereby driving the trigger circuit of MOSFET M1B, which turns ON to operate the FSD and hence trip the MCCB. This causes a break of the branch circuit with adequate mechanical isolation and hence no current flows through the circuit. There is no self-power available as it is obtained from the current sensor output. Since there is no power available to both microcontrollers, there is no output further available to cause any mal-operation of solenoid and FSD.
[0099] In order to retain self-power generation, the MCCB is required to be RESET and then switched ON manually.
[0100] FIG. 26 illustrates an exemplary schematic arrangement for CAT B operation, in accordance with embodiments of the present disclosure. In a CAT A state, the coil is de-energized, and the plunger is held by the permanent magnet, such that it does not overlap the moving contact. During a fault condition, the MCCB operates in conventional way by the repulsion effect. However, in CAT B state, the coil is energized for a short time period so that plunger pops out and overlaps the moving contact, thereby firmly holding the moving contact for the short time period to provide delay in opening operation due to repulsion effect. After the intended period, the plunger retracts back to original state thereby releasing the moving contact.
[0101] In an embodiment, the performance of the slot motor along with solenoid assembly of the CAT AB MCCB is checked as follows,

Solenoid details
Coil voltage supply : 130V, 50 Hz
No. of turns (N) : 1250 – 1350
SWG : 42
Resistance R : 113 – 116 ohms
Diameter of conductor : 0.1016 mm
Cross-sectional Area : 0.00811 mm²

Permanent magnet
O. D : 4.7 mm
Thickness : 1.6 mm
Material : NdFeB or equivalent rare earth

Test results
Test voltage applied to coil : 130 V, 50Hz
Test current @130V, 50Hz : 1.016 Amp while switching (pick – up) for 120 – 130 ms

Condition of plunger
Without energization of coil : inside the bobbin in rest condition due to permanent magnet
With energization of coil : positive forward movement to overlap the moving contact

[0102] FIG. 27 illustrates an exemplary test trip circuit with FSD interface used to test the trip functionality of the electronic release of the proposed CAT AB MCCB.
[0103] FIG. 28 illustrates an exemplary communication and test connector circuit for feeding voltage from the function generator through the test port.
[0104] FIG. 29 illustrates an exemplary test setup for testing the trip functionality of the electronic release of the proposed CAT AB MCCB. 3V is fed to the test trip connector from the function generator through the test port. The FSD is replaced with 1.2 K ohm connected in parallel to diode D5; and a 15V source supply is obtained from separate regulated voltage DC source.
[0105] In an embodiment, to check the performance of the microcontroller (MSP430G2231) programme, the following output at P1.5 and P1.6 are captured, which are fed to the FSD and solenoid respectively. The ANATRIP signal of 2.2V is fed to the pin P1.0. As per the intended programme, when ANATRIP is fed to the input pin, P1.6 gets enabled first and after a delay of 120 -130 ms, P1.5 gets enabled and then P1.6 gets disabled.
[0106] FIG. 30 illustrates exemplary view of sequential operation of input and output signal from the microcontroller.
[0107] FIG. 31 illustrates exemplary view of sequential operation of output signal fed to AC solenoid and FSD. The overall performance of both the output pin with a triac output opto-isolator driving AC load is shown.
[0108] FIG. 32 illustrates an exemplary flow diagram for sequential operation between solenoid and the FSD, in accordance with embodiments of the present disclosure. In an embodiment, an algorithm can be used to programme the microcontroller (MSP430G2231), given as,

? declare the header files and variables
? define the WDT and set the clock cycle
? configure the various pins for the intended function
? under normal condition, set the FSD and solenoid at low state
? convert the analogue signal into 10-bit digital signal using an analogue to digital convertor. ADC10 module is configured with user software
? enable the core with ADC10ON bit. Configure it by two control register ADC10CTL0 and ADC10CTL1 for turning ON the ADC function and setting the sampling of the input signal
? once sensing and ADC conversion is done, pause the programme execution by enabling the interrupt programme so as to operate it in low power mode. This will reduce µC consumption to 0.1 µA
? store the sampled data in ADC10MEM and compare it with reference to decide for any abnormal condition
? if any abnormal condition is sensed, then enable the pin for operation of solenoid and FSD with the intended delay
? do few no operation before ending the Programme and continue the iteration to run the programme.

[0109] FIG. 33 illustrates an exemplary sequential time diagram for operation of the proposed CAT AB MCCB.
[0110] Thus, the proposed MCCB satisfies the requirement of a CAT AB MCCB, for its suitability in zone wise protection of the branch circuit in the event of an abnormal condition such as short circuit fault. This is accomplished by providing an intentional delay in the operation of the MCCB while protecting the branch circuit against short circuit fault, thereby enabling CAT AB utilisation criteria. The proposed CAT AB MCCB has the following advantages,

? discrimination of actual fault condition at the different location of branch circuit
? zone wise short circuit fault protection
? mechanical latch – de-latch arrangement along with microcontroller program for CAT AB operation
? provision of short time withstand capacity for few milliseconds.

[0111] 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 patient 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.
[0112] 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
[0113] The present disclosure provides an MCCB for CAT AB utilisation.
[0114] The present disclosure provides an MCCB that is capable of discrimination of actual fault condition at the different location of branch circuit.
[0115] The present disclosure provides an MCCB that is capable of zone wise short circuit fault protection.
[0116] The present disclosure provides an MCCB with a provision of short time withstand capacity for few milliseconds.