Claims:WE CLAIM:
1. A plug-in unit installed in a busway and having an enclosure, wherein said plug-in unit comprising:
at least one circuit breaker mounted within said enclosure and a knob of said circuit breaker engaged with a driving arm;
an operating handle adapted to operate said driving arm for switching of said breaker ON-OFF-RESET operation;
a flexible extension arm component fasten with said driving arm, wherein said flexible extension arm component comprises at least two flexi extension arm actuator fixed with walls of said enclosure respectively; and
a plunger assembly;
wherein, during operating said operating handle to operate said driving arm, plunger assembly pushed by said flexi extension arm actuator to engage/dis-engage said plunger with a busbar interlock plate provided on the plug-in unit to interlock/unlock it with busway before breaker switching from OFF to ON condition or ON to OFF condition, respectively.
2. The plug-in unit as claimed in claim 1, wherein a circuit breaker is mounted on a mounting plate of said enclosure and is fastened on a mounting bracket such that movement of said circuit breaker is fixed with respect to horizontal and vertical direction.

3. The plug-in unit as claimed in claim 1, wherein at least two said flexi extension arm actuator fastened to a flexi extension arm base respectively with one or more rivet so that movement of said actuator is smooth and free with respect to said flexi extension arm base.

4. The plug-in unit as claimed in claim 3, wherein said flexible extension arm component further comprises a flexi extension arm spring means being connected between said flexi extension arm base and said flexi extension arm actuator for integrating switching travel distance while switching of said breaker from one state to another state.

5. The plug-in unit as claimed in claim 1, wherein said operating handle fasten with a bush assembly connected said enclosure wall using hardware as external media for said switching of said breaker ON-OFF-RESET operations.

6. The plug-in unit as claimed in claim 1, wherein said plunger is dis-engaged from said busbar interlock plate once said knob cross a dead centre while operating the operating handle for switching of breaker from ON to OFF state.

7. A flexible extension arm component to accommodate different circuit breakers with an interlock feature for a Plug-in Unit as claimed in claims 1-6, wherein said component comprising:
a left and right flexi extension arm actuator fastened with at least two flexi extension arm base respectively;
a rotation limiting slot each on said flexi extension arm actuator, wherein said rotation limiting slot on said flexi extension arm actuator is riveted with a guide slot on said flexi extension arm base so as to limit the rotation of said flexi extension arm actuator such that switching of said circuit breakers while said plug-in unit is plugging or outing by an operator; and
a flexi extension arm spring connected between said flexi extension arm base and said flexi extension arm actuator for integral travel while switching of said circuit breaker from one state to another state.
Dated this 31st day of March 2018

Abhishek Sen
Of S. MAJUMDAR & CO.
(Applicant’s Agent)
, Description:
TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to a switching devices such as circuit breakers, and more particularly the invention relates to a common mechanism to accommodate any kind of circuit breaker inside plug-in box.

BACKGROUND

[002] Busways are installed in residential, commercial as well as industrial premises for the distribution purpose. Plug-in boxes are installed in the busways for the final distribution. Circuit breakers is heart of plug-in box. Protect of busways from the failure at the final distribution load is the prime objective of the circuit breaker. In such situations, safety of the working personnel in the vicinity the plug-in box is top most priority.

[003] The Plug-in box/units are installed in the busways to tap off the power from the main conductors. Typically, circuit breaker is placed inside the plug-in box and then power is derived depending on the parity of the devices, viz., ON, OFF, TRIP. Plug-in box is required to be operated through means of external medium. Thus, the activation of the knob of the circuit breakers is need to be derived within the plug-in box. Every circuit breaker knob is at different positions with respect to their working principle, operating condition, complexity of the construction, purpose and manufacturer. Travel of the circuit breaker knob while changing its position from one state of frame to another is also different for different circuit breaker or the different range of the circuit breaker. TRIP to RESET travel of the circuit breaker is another main concern while considering broad range of circuit breaker in plug-in box. TRIP to RESET force is also the major concern with its travel time while the design the PIB with mechanical linkages.

[004] There can be the possibility of try for removal of plug-in unit from busway without switching OFF breaker. This can lead to fault and in respect the hazardous condition. As plug-in units are inserted with busway manually, there is the possibility of insertion while the breaker is in the ON condition. This can cause the severe damage to the surrounding. Considering threats during manual operations, at most required to provide the safety as the part of the feature of the installation of the product. This cannot be solved through rigid extension arm.

[005] Another point is motive of the plug-in box that it is operated from ON to OFF and OFF to ON states when busway is charged during maintenance. Site where the busways are installed is full of contamination of dust, moisture. Generally, plug-in boxes are tapped in or out from busways manually. Therefore, it easily leads for unexpected possible short circuit due to development of arc in improper contacts.

[006] Most of the accessories in the busways installation are bound for customization as per available space for the route and the customer demand. Circuit breaker in the plug-in box is dependent on the application of the load requirements in the distribution and some cases customer choice. Some of the cases customers are particular with choice of manufacturer for the breaker inside the plug-in box. These variations are need to be taken care while executing the projects and developing the business.

[007] Currently available technology has the feature such as door interlock, interlock the plug-in with busways and provision to accommodate different makes of MCCBs using rigid arm. Rigid arm has a limitations of distance which can be travelled while switching from one state to another. Therefore, existing technology needs adjustment in their mechanism as per the demand of the different makes of the MCCBs (breaker) Considering from the point of manufacturer of the plug-in boxes, manufacturer need to develop verities of instances to fulfil the criteria. Locking of interlock with the busways only ignited when the breaker gets completely switched ON or else when knob of the breaker crosses the dead centre.

[008] Plug-in boxes can be with MCCB or MCB thus instead of specific MCCB or MCB breaker is the most suitable nomenclature

[009] Reference is made to US3657606A which discloses a plug-in unit is hooked into notches in the upper flange of a bus duct, plugged into the duct by swinging it down against the side of the duct wherein stab connectors enter a duct opening to engage the bus bars therein, and latched to the side of the duct by spring biased latches which engage the bottom flange of the duct. An interlock between the unit operator and one of the latches blocks movement of that latch wherein it interferes with the bottom flange to prevent plugging in or removal of the unit with the enclosed switch thereof in the ''''ON'''' condition. Indicators are provided on the sides of the bus duct to assist in positioning the unit into the notches when the upper flange is not visible.

[0010] Reference is further made to 201621011431 which discloses a mechanism to interlock a Plug in unit with a busway.

[0011] Reference is still made to 201621011348 which discloses a door interlock mechanism for a plug-in units used in busways.

[0012] Reference is further made to 201621011429 which discloses a Plugin Unit Mechanism to accommodate any make of MCCB.

[0013] However, the following are the problems of the prior art which is addressed by the present invention:
1. Focus on the interlock with the busways during charged condition.
2. Focus on the door closure and safety in that respect for the operating personnel in the surrounding.
3. MCCB only is considered as the preferable circuit breaker.
4. Currently available mechanism focuses on the rigid structure for the application of the force on the circuit breaker knob. Rigid arm has a limitations of distance which can be travelled while switching from one state to another.
5. Focus is to utilization of the own switchgear product by the manufacturer. Less scope available for the customization of the product mix based on the other manufacturers product.
[0014] Thus, there exists a dire need for the provision of the mechanism which can accommodate different modes (ON-OFF-TRIP-RESET) of different circuit breaker and engagement of interlock before crossing the dead center of the circuit breaker knob from OFF to ON state which can be availed the safety first before switching of breaker.

SUMMARY OF THE INVENTION

[0015] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[0016] An objective of the present invention is to provide a mechanism common for the different circuit breaker change without making the verities of components.

[0017] Another objective of the present invention is to provide a flexible extension arm which engages and locks the interlock with busways before it is crossing the dead centre of the circuit breaker operating knob so that enhanced safety can be achieved.

[0018] Yet another objective of the present invention is to reduce the need of development of different rigid arm based on larger and shorted travel distance while switching of circuit breaker from one state to another state.

[0019] Accordingly, to one aspect, the present invention provides a plug-in unit installed in a busway and having an enclosure, wherein said plug-in unit comprising:
at least one circuit breaker mounted within said enclosure and a knob of said circuit breaker engaged with a driving arm;
an operating handle adapted to operate said driving arm for switching of said breaker ON-OFF-RESET operation;
a flexible extension arm component fasten with said driving arm, wherein said flexible extension arm component comprises at least two flexi extension arm actuator fixed with walls of said enclosure respectively; and
a plunger assembly;
wherein, during operating said operating handle to operate said driving arm, plunger assembly pushed by said flexi extension arm actuator to engage/dis-engage said plunger with a busbar interlock plate provided on the plug-in unit to interlock/unlock it with busway before breaker switching from OFF to ON condition or ON to OFF condition, respectively.

[0020] In another aspect, the present invention provides a flexible extension arm component to accommodate different circuit breakers with an interlock feature for a Plug-in Unit as mentioned above, wherein said component comprising:
a left and right flexi extension arm actuator fastened with at least two flexi extension arm base respectively;
a rotation limiting slot each on said flexi extension arm actuator, wherein said rotation limiting slot on said flexi extension arm actuator is riveted with a guide slot on said flexi extension arm base so as to limit the rotation of said flexi extension arm actuator such that switching of said circuit breakers while said plug-in unit is plugging or outing by an operator; and
a flexi extension arm spring connected between said flexi extension arm base and said flexi extension arm actuator for integral travel while switching of said circuit breaker from one state to another state.

[0021] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0022] Figure 1 illustrates the flexible extension arm component when circuit breaker is in OFF condition, according to one implementation of the present invention.

[0023] Figure 2 shows the flexible extension arm component little force applied on the operating handle to change its position but not crossed the dead centre of the knob, according to one implementation of the present invention.

[0024] Figure 3 illustrates a flexible extension arm component when circuit breaker is in ON condition, according to one implementation of the present invention.

[0025] Figure 4 illustrates a plunger pin out when circuit breaker is in ON condition, according to one implementation of the present invention.

[0026] Figure 5 illustrates a plunger pin out when circuit breaker is in OFF condition, according to one implementation of the present invention.

[0027] Figure 6 illustrates the exploded view of flexible extension arm component, according to one implementation of the present invention.

[0028] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0029] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0030] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0031] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0032] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0033] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0034] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0035] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0036] It is also to be understood that the term “module” is used in the specification to indicate an apparatus, unit, component and the like. The term “means” when used in the specification is taken to specify the mode by which desired result is achieved.

[0037] The present invention can be implemented with an electrical switching system that may include but not limited to, circuit breakers or thermo-magnetic breaker, molded case circuit breaker (MCCB) residual circuit breaker (RCB), earth leakage circuit breaker (ELCB) and the like.

[0038] In one implementation, the present invention consists of flexible extension arm assembly, circuit breaker, driver link and plunger assembly and busway. Flexible extension arm assembly is fixed with the walls of the plug-in box enclosure and free to rotate. Once the breaker is mounted on the circuit breaker mounting plate, knob of the circuit breaker is engaged by the slot on the driving arm, which is fasten with the flexible extension arm assembly. While operating the operating handle provided on the plug-in box to operate the driving arm, plunger is pushed by the flexi extension arm actuator to engage it with the busbar interlock plate provided on the plug-in box to interlock it with busway before breaker get switched ON. Once the plunger is reached up to its maximum allowable position, flexible extension arm integrated its travel distance till the breaker will get switched ON. While operating the operating handle for switching of breaker from ON to OFF state, once the MCCB knob crossed the dead centre then only plunger pin is dis-engaged from busbar interlock plate.

[0039] In the implementation, when the busbar interlocks are pulled outside then there is no engagement of busbar interlock plate with the plunger pin at all and for that period plunger pin freezes at its position. Therefore, movement of flexible extension arm is stopped by the plunger pin. Thus, large obstruction to the force on driving arm not allow to change the circuit breaker knob position. And circuit breaker cannot be switched ON into the ON state. Thus, said invention provides safety with its universal mechanism.

[0040] Reference is made to figure 1 which illustrates the flexible extension arm component when circuit breaker is in OFF condition, according to one implementation of the present invention. The figure 2 shows the flexible extension arm component little force applied on the operating handle to change its position but not crossed the dead centre of the knob, according to one implementation of the present invention.

[0041] Reference is made to figure 3 which illustrates a flexible extension arm component when circuit breaker is in ON condition, according to one implementation of the present invention.

[0042] Reference is made to figure 4 which illustrates a plunger pin out when circuit breaker is in ON condition, according to one implementation of the present invention.

[0043] Reference is made to figure 5 which illustrates a plunger pin out when circuit breaker is in OFF condition, according to one implementation of the present invention.

[0044] Reference is made to figure 6 illustrates the exploded view of flexible extension arm component, according to one implementation of the present invention.

[0045] The components of the present invention as shown in the figures 2-6 are listed below:
1. Busway
111. Top housing busway
2. Plug-in Box
21. Enclosure wall
22. Enclosure door
3. Flexible extension arm assembly
31. Flexi extension arm actuator-left
32. Flexi extension arm actuator -Right
33. Flexi extension arm base
34. Flexi extension arm spring
35. Rotation limiting slot
36. Guide slot
4. Bush assembly
41. Driver Link
42. Bush
5. Driving Arm
6. Operating Handle
7. Plunger Assembly
71. Plunger Cap
72. Plunger Pin
8. Busbar Interlock
81. Busbar Interlock Plate
811. Alignment circular slot
9. Circuit breaker
91. Knob
10. Mounting plate
11. Mounting bracket
12. Rivet
13. Hardware

[0046] In one implementation, the assembly include one unit of busway 1 and the plug-in box 2 is inserted in it. Busbar interlock 8 is locked with top housing busway 111 to indicate that without use of specific feature plug-out of the plug-in box is not possible. A circuit breaker 9 is mounted on the mounting plate 10 of the plug-in box and it is fastening on the mounting bracket 11 such that movement of the circuit breaker 9 mounted on the mounting plate 10 is fixed with respect to horizontal and vertical direction.

[0047] As shown in figure 3, the Flexi extension arm actuator-left 31 is fastened with the flexi extension arm base 33 with the rivet 12 such that after the riveting the movement of the flexi extension arm actuator left 31 is smooth and free with respect to flexi extension arm base 33. Rotation limiting slot 35 on the flexi extension arm left 31 is riveted with the guide slot 36 of the flexi extension arm base 33 to limit the rotation of the flexi extension arm actuator 31 such that it will not allow switching of the circuit breaker 9 while plug-in box 2 in plugging or outing by the operator. Flexi extension arm spring is connected between the flexi extension arm base and the actuator for the integral travel while switching of breaker from one state to another state. Same is done using flexi extension arm actuator right 32 to develop flexi extension arm assembly 3 to be connected from the right side of the breaker.

[0048] Flexi extension arm assembly 3 is fixed with the bush 42 and the driver link 41 using hardware 13 (as shown in figure 2) and bush assembly 4 has been developed. Bush assembly 4 is connected on either side on the enclosure walls 21 of the plug-in box 2. Circuit breaker knob 91 is engaged with slot provided on driving arm 5. Operating handle 6 is fasten with bush assembly 4 connected on the left side enclosure wall 21 using hardware 13 as external media of switching of breaker ON-OFF-RESET operations.

[0049] In the implementation, when the enclosure door 22 is in closed conditioned and busbar interlock plates 81 on either sides are released, force is given on the operating handle to change the state of the circuit breaker 9 from the OFF to ON, the force experienced by the driving arm 5 through bush assembly 4. This lead to change the knob 91 from its existing position. As soon as, the flexi extension arm actuator (31 and 32) reached to plunger assembly 7, plunger cap 71 is pushed by the flexi extension arm actuator (31 and 32) on either sides of the enclosure walls 21. Therefore, alignment circular slot 811 on the busbar interlock plate 81 is engaged with plunger pin 72. When the force applied on the operating handle 6 is sufficiently larger to overcome the force needed to change the state of the knob 91, dead centre of the knob mechanism is crossed and state of the circuit breaker 9 is changed into ON.

[0050] In the implementation, when circuit breaker 9 is in ON condition and the force is applied on the operating handle 6 to switch OFF the circuit breaker 9, driving arm 5 experiences the force and once this force is sufficient enough to overcome the force applied by the knob 91 mechanism, dead centre of the knob mechanism crossed and it changes from state of ON to OFF. Once contact between the plunger cap 71 and the flexi extension arm actuator no longer exist then there is a disengagement between plunger pin 72 and alignment circular slot 811 on the busbar interlock plate 81.

[0051] In the implementation, for the ejection of the plug-in box 2 from the busway 1, Circuit breaker 9 is switched into OFF state and busbar interlock plate 81 is pulled outside on the either sides of plug-in box 2. Now in this situation force applied on the operating handle 6 to change the state of the breaker 9 from OFF to the ON state, but plunger pin 72 is not engaged with the alignment circular slot 811 on the busbar interlock plate 81. But it was hitting on the flat portion of the busbar interlock plate 81. Thus forward motion of the plunger pin is restricted and application of the force on the plunger cap 71 by the flexi extension arm actuator (31 & 32) is not effective. Therefore, there is an obstruction for the knob 91 to cross its dead centre. Thus, circuit breaker cannot be switched ON. In this condition only, plug-in box 2 can be inserted or ejected from the busways 1.

[0052] Some of the non-limiting advantaged of the present invention, are mentioned below:
• Universality of the flexible extension arm mechanism across the different verities of the circuit breakers in the plug-in box
• Universality of the flexible extension arm mechanism across the different configurations based on the phase-neutral and earth conductor
• Integrated switching travel distance of the mechanism during switching of different verities of circuit breaker within the specified boundaries as same as given for the rigid extension arm
• Locking of busbar interlock movement with respect to busways before switching from OFF to ON condition
• Unlocking of the busbar interlock movement with respect to busways after the switching from ON to OFF condition
• Simplified construction and reduction of variants while dealing with customization

[0053] Although a flexible extension arm component to accommodate circuit breakers with interlock feature for plug-in unit have been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of the flexible extension arm component to accommodate circuit breakers with interlock feature for plug-in unit.