Claims:1. A busway plug-in box assembly comprising:
a circuit breaker assembly;
a protective panel for said circuit breaker assembly;
an actuating mechanism to effect opening of said protective panel upon an opening actuation to allow access to said circuit breaker assembly and to effect closing of said protective panel upon an closing actuation to restrict access to said circuit breaker assembly; and
an interlock assembly to operatively couple the opening actuation and the closing actuation of said actuating mechanism with “OFF” and “ON” state of said circuit breaker assembly respectively;
wherein the interlock assembly effects locking of said protective panel to restrict access to said circuit breaker assembly when said circuit breaker assembly is in the “ON” state; and
wherein execution of said opening actuation of said actuation mechanism to effect the opening of said protective panel to allow access to said circuit breaker assembly urges the interlock mechanism to effect the “OFF” state of said circuit breaker assembly.
2. The busway plug-in box assembly of claim 1, wherein execution of the closing actuation of said actuation mechanism to effect the closing of said protective panel to restrict access to said circuit breaker assembly urges the interlock mechanism to effect the “ON” state of said circuit breaker assembly.
3. The busway plug-in box assembly of claim 1, wherein the interlock assembly comprises a circuit breaker actuating handle, a door lock link, a locking mechanism and a pip to operatively couple said locking mechanism with said circuit breaker actuating handle and said door lock link.
4. The busway plug-in box assembly according to claim 3, wherein said door lock link is an integral part of said circuit breaker actuating handle.
5. The busway plug-in box assembly according to claim 3, wherein the locking mechanism comprises a base link, a locking link and a biasing means.
6. The busway plug-in box assembly of claim 1, wherein the protective panel further comprises a locking latch.
7. The busway plug-in box assembly according to any of the preceding claims, wherein the door lock link is engaged with said locking latch of the protective panel when the circuit breaker assembly is in the “ON” state.
8. The busway plug-in box assembly according to any of the preceding claims, wherein execution of the opening actuation of said actuating mechanism effects disengagement of said door lock link from the locking latch of the protective panel and pivotal movement of said circuit breaker actuating handle to effect the “OFF” state of said circuit breaker assembly.
, Description:TECHNICAL FIELD
[0001] The disclosure generally relates to electrical power distribution systems. In particular, it pertains to a door interlock mechanism for plug-in box in electrical power distribution or busway housing to prevent accidents due to unintentional exposure to Moulded Case Circuit Breaker (MCCB) in a live condition when the plug-in box door is open.

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] Electrical power distribution or busway systems are used to distribute electrical power throughout buildings, particularly commercial or industrial type buildings. Generally, a busway includes a number of busway sections which are connected to one another by busway joints. Each busway section includes a housing that encloses a plurality of busbars which may be phase busbars, neutral busbars, or ground busbars depending on the particular application. The busbars are supported in side-by-side, spaced-apart relation within the metal housing, and suitable insulation is provided to ensure that each phase is electrically isolated from the other phases and from ground.
[0004] Plug-in units are used in busways as a means to tap power from the main conductors. Machines, lights, tools and other components requiring electricity are provided access to the power conducting busbars at such power tap-off locations disposed along the busway. These busways have provisions at spaced intervals for the convenient connection of removable metal units enclosing power tap-off devices such as safety switches, circuit breakers, fuses, or the like, the purpose of each tap-off unit being to control the supply of electric power to a particular utilization circuit. Such a tap-off unit is removably mounted on the busway housing, and the tap-off device enclosed therein is connected to the electric power source by means of suitable plug-in type disconnect contacts disposed to engage cooperating uninsulated portions of the respective bus bars.
[0005] Typically, a short-circuit protection device like a Moulded Case Circuit Breaker (MCCB) is placed inside of the plug-in box, and power is derived thereafter depending on the parity of the device viz. On, Off, Trip. The plug-in box requires to be operated externally; hence the actuation of the button of the MCCB needs to be derived from elements within the Plug-in box. Plug-in boxes can be tapped into the busway manually.
[0006] Access to the busbars within the busway is provided by a door assembly which covers a plurality of slots in the busway housing. If the plug-in box door is opened when the MCCB is charged, it may lead to hazardous situations. Electrical standards thus require an interlock mechanism to prevent the bus plug door from being opened when the MCCB is in the "power on" position and to prevent the power from being turned on when the door is open.
[0007] To the best of our knowledge, none of the prior art disclosed interlocking mechanisms and methods to operate the same provides adequate safety to the personnel working on plug-in boxes. Typical plug-in box designs use a pad-lock to hold the door in a closed condition. Further, the earlier designs of interlock for Tap off Box with Bus bar Trunking occupied more space and were costlier. There is therefore a need in the art to overcome one or more problems associated with existing interlock systems and methods of operation thereof. Accordingly, it would be advantageous to provide a plug-in box door interlock mechanism that may not be bulky and costly while at the same time prevents the possibility of a hazardous condition due to accidental exposure of users to live parts, thereby ensuring their safety.

OBJECTS OF THE INVENTION
[0008] An object of the present disclosure is to overcome disadvantages associated with conventional interlocking mechanisms for plug-in boxes of electrical power distribution or busway systems.
[0009] Another object of the present disclosure is to provide an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that minimizes the accidents due to unintentional exposure to MCCB in a live condition when the plug-in box door is open and thus ensures safety of personnel.
[0010] Another object of the present disclosure is to provide an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that minimizes the use of associated hardware.
[0011] Another object of the present disclosure is to provide an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that is easy to operate.
[0012] Another object of the present disclosure is to provide an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that is economical to produce.
[0013] Another object of the present disclosure is to provide an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that is aesthetic in appearance.

SUMMARY
[0014] Aspects of present disclosure relate to a busway plug-in box assembly including: a circuit breaker assembly; a protective panel for said circuit breaker assembly; an actuating mechanism to effect opening of said protective panel upon an opening actuation to allow access to said circuit breaker assembly and to effect closing of said protective panel upon a closing actuation to restrict access to said circuit breaker assembly; and an interlock assembly to operatively couple the opening actuation and the closing actuation of said actuating mechanism with “OFF” and “ON” state of said circuit breaker assembly respectively; wherein the interlock assembly effects locking of said protective panel to restrict access to said circuit breaker assembly when said circuit breaker assembly is in the “ON” state and wherein execution of said opening actuation of said actuation mechanism to effect the opening of said protective panel to allow access to said circuit breaker assembly urges the interlock mechanism to effect the “OFF” state of said circuit breaker assembly.
[0015] In an embodiment, execution of the closing actuation of said actuation mechanism to effect the closing of said protective panel to restrict access to said circuit breaker assembly urges the interlock mechanism to effect the “ON” state of said circuit breaker assembly.
[0016] In an embodiment, the interlock assembly comprises a circuit breaker actuating handle, a door lock link, a locking mechanism and a pip to operatively couple said locking mechanism with said circuit breaker actuating handle and said door lock link. In an embodiment, said door lock link is an integral part of said circuit breaker actuating handle. In another embodiment, said door lock link is fixedly coupled to said circuit breaker actuating handle using a suitably locking means such that rotational degree of freedom for said door lock link in relation to said circuit breaker actuating handle is minimal. In an embodiment, the locking mechanism comprises a base link, a locking link and a biasing means. In an embodiment, the protective panel further comprises a locking latch.
[0017] In an embodiment, the door lock link is engaged with said locking latch of the protective panel when the circuit breaker assembly is in the “ON” state.
[0018] In an embodiment, execution of the opening actuation of said actuating mechanism effects disengagement of said door lock link from the locking latch of the protective panel and pivotal movement of said circuit breaker actuating handle to effect the “OFF” state of said circuit breaker assembly.
[0019] 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
[0020] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0021] FIG. 1 illustrates an exemplary perspective view of an assembly of busway plug-in box including a door having interlocking mechanism in accordance with embodiments to the present disclosure.
[0022] FIG. 2 illustrates an enlarged view of the locking mechanism in accordance with embodiments to the present disclosure.
[0023] FIG. 3 illustrates an exploded view of the locking mechanism in accordance with embodiments to the present disclosure.
[0024] FIG. 4 illustrates an exemplary perspective lateral view of a busway plug-in box including an assembled MCCB in ‘on’ position in accordance with embodiments to the present disclosure.
[0025] FIG. 5 illustrates an exemplary lateral view of a busway plug-in box including an assembled MCCB in ‘off’ position in accordance with embodiments to the present disclosure.
[0026] FIG. 6 illustrates an exemplary lateral view of differential position of door interlocking assembly of a busway plug-in box in accordance with embodiments to the present disclosure.
[0027] FIG. 7 illustrates an exemplary view of a busway plug-in box including a door in ‘opened’ position in accordance with embodiments to the present disclosure.
[0028] FIG. 8 illustrates a perspective lateral view of a busway plug-in box including a door in ‘closed’ position in accordance with embodiments to the present disclosure.

DETAILED DESCRIPTION
[0029] 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.
[0030] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0031] 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.
[0032] 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.
[0033] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0034] Embodiments of the present disclosure relate to a door interlocking mechanism for a plug-in box in electrical power distribution or busway housing. In an aspect, the disclosed interlocking mechanism overcomes deficiencies of the conventional plug-in box door interlocking mechanisms wherein, it provides a means to hold the plug-in door in the closed position when the MCCB is in ‘ON’ state and also to prevent the charging of a MCCB when the plug-in box door is open.
[0035] An aspect of present disclosure relates to a busway plug-in box assembly including: a circuit breaker assembly; a protective panel for said circuit breaker assembly; an actuating mechanism to effect opening of said protective panel upon an opening actuation to allow access to said circuit breaker assembly and to effect closing of said protective panel upon an closing actuation to restrict access to said circuit breaker assembly; and an interlock assembly to operatively couple the opening actuation and the closing actuation of said actuating mechanism with “OFF” and “ON” state of said circuit breaker assembly respectively; wherein the interlock assembly effects locking of said protective panel to restrict access to said circuit breaker assembly when said circuit breaker assembly is in the “ON” state and wherein execution of said opening actuation of said actuation mechanism to effect the opening of said protective panel to allow access to said circuit breaker assembly urges the interlock mechanism to effect the “OFF” state of said circuit breaker assembly.
[0036] In an embodiment, a circuit breaker assembly can be a fuse, a miniature circuit breaker (MCB), a moulded case circuit breaker (MCCB), a residual current device (RCD), residual current breaker with overload protection (RCBO), an earth leakage circuit breaker (ELCB), a recloser, a polyswitch, a magnetic circuit breaker, or any circuit breaker assembly known to a person skilled in the art. In a preferred embodiment, a circuit breaker assembly is a moulded case circuit breaker (MCCB).
[0037] In an embodiment, a protective panel for said circuit breaker assembly can be a door or any other type of a barrier known to a person skilled in the art. In a preferred embodiment, a protective panel for said circuit breaker assembly is a door.
[0038] In an embodiment, an actuating mechanism to effect opening and closing of said protective panel can be rotary handle operator, a push/pull handle operator or any other type of a handle mechanism known to a person skilled in the art. In a preferred embodiment, an actuating mechanism to effect opening and closing of said protective panel is a rotary handle operator.
[0039] In an embodiment, execution of the closing actuation of said actuation mechanism to effect the closing of said protective panel to restrict access to said circuit breaker assembly urges the interlock mechanism to effect the “ON” state of said circuit breaker assembly.
[0040] In an embodiment, the interlock assembly comprises a circuit breaker actuating handle, a door lock link, a locking mechanism and a pip to operatively couple said locking mechanism with said circuit breaker actuating handle and said door lock link. In an embodiment, said door lock link is an integral part of said circuit breaker actuating handle. In another embodiment, said door lock link is fixedly coupled to said circuit breaker actuating handle using a suitably locking means such that rotational degree of freedom for said door lock link in relation to said circuit breaker actuating handle is minimal. In an embodiment, the locking mechanism comprises a base link, a locking link and a biasing means. In an embodiment, the protective panel further comprises a locking latch.
[0041] In an embodiment, the door lock link is engaged with said locking latch of the protective panel when the circuit breaker assembly is in the “ON” state.
[0042] In an embodiment, execution of the opening actuation of said actuating mechanism effects disengagement of said door lock link from the locking latch of the protective panel and pivotal movement of said circuit breaker actuating handle to effect the “OFF” state of said circuit breaker assembly.
[0043] One embodiment of the invention provides a busway plug-in box assembly 100 that can include a circuit breaker 102 (hereinafter referred to as a MCCB), a circuit breaker actuating handle assembly 104, a protective panel (e.g. a door) 106, a locking mechanism 108 and a mounting plate 110 as illustrated in FIG. 1. The MCCB 102 of the plug-in box assembly 100 can be fitted on to the mounting plate 110 and can further be engulfed by the MCCB actuating handle assembly 104. The MCCB actuating handle assembly 104 of the plug-in box assembly 100 can include a MCCB actuating handle, a door lock link 114 which can be mounted on the MCCB actuating handle assembly 104 and can further include a pip 116, protruding from a surface of the door lock link 114, as illustrated in FIG. 1. However, it should be appreciated by a person skilled in the art that the door lock link 114 can also be an integral part of the MCCB actuating handle 104. The door 106 of the plug-in box assembly 100 can include a door lock latch 118 for its engagement with the door lock link 114, when the door 106 is closed. The locking mechanism 108 of the plug-in box assembly 100, as illustrated in FIG. 2 and FIG. 3, can include a locking link 204, which can further include a pivot of the locking link 208, a cam of the locking link 312, a spring hole 304 and a door cam 202; a base link 112, which can further include support holes 310 and 314, a pivot hole 308 and a spring hole 316; an extension spring 206; and a pivot pin 306. The locking link 204 can be pivotably attached on the base link 112. The connection between the locking link 204 and the base link 112 can be established by an extension spring 206. The locking link 204 and base link 112 are illustrated in more detail in FIG. 2 and FIG. 3.
[0044] As illustrated in FIG. 4, when the MCCB 102 is in ‘on’ state, an actuation force created by the rotation of the door handle assembly 402 brings the extension spring 206 in an expanded position. The locking link 204 rotates about its pivot axis upon rotation of the door handle assembly 402 and disengages the cam of the locking link 312 from the pip of the door lock link 116. The locking link 204 is held in a pushed/backward position with respect to the MCCB actuating handle assembly 104. The MCCB actuating handle assembly 104 thus relatively becomes free to move on its motion axis. The door cam 202 now engages with the door lock latch 118, attached to the interior of the door 106 of the plug-in box assembly 100. The door thus cannot be opened when the MCCB 102 is in ‘on’ position.
[0045] As illustrated in FIG. 5, when the MCCB 102 is in ‘off’ state, the actuation force created by the rotation of the door handle assembly 402 acts on the extension spring 206 and the extension spring 206 compresses/comes back to its original position. The locking link 204 moves about a pivot axis and comes back to its original position. The cam of the locking link 312 engages the pip of the door lock link 116. This restricts the motion of the MCCB actuating handle assembly 104. The door cam 202 disengages from the door lock latch 118, attached to the interior of the door 106 of the plug-in box assembly 100. The door 106 is thus opened when the MCCB is in ‘off’ position.
[0046] As illustrated in FIG. 6, when the door 106 is partially opened upon rotation of the door handle assembly 402 along a motion axis, the interlocking assembly is in a differential position. The extension spring 206 is partially acted upon by the actuation force created by the rotation of the door handle assembly 402. The locking link 204 starts to move about a pivot axis in forward direction. The cam of the locking link 312 moves forward to engage with the pip of the door lock link 116. The door cam 202 partially disengages with the door lock latch 118, attached to the interior of the door 106 of the plug-in box assembly 100.
[0047] As illustrated in FIG. 7 and FIG. 8, when the door 106 is being opened, the extension spring 206 compresses upon rotation of the door handle assembly. The locking link 204 moves about a pivot axis in forward direction. The cam of the locking link 312 engages with the pip of the door lock link 116. This restricts the motion of the MCCB actuating handle assembly 104. The MCCB 102 is put in an ‘off’ state. The door cam 202 disengages with the door lock latch 118, attached to the interior of the door 106 of the plug-in box assembly 100. The door is thus opened. Alternatively, when the door 106 is being closed by rotating the door handle assembly 402 about a motion axis, an actuation force acts on the extension spring 206. The locking link 204 rotates about a pivot axis upon the rotation of the door handle assembly 402 and disengages the cam of the locking link 312 from the pip of the door lock link 116. The locking link 204 is held in a pushed/backward position with respect to the MCCB actuating handle assembly 104. The MCCB actuating handle assembly 104 thus relatively becomes free to move. The MCCB 102 is put in an ‘on’ position. The door cam 202 engages with the door lock latch 118, attached to the interior of the door 106 of the plug-in box assembly 100. The door is thus closed.
[0048] Although a rotational operation of the door handle assembly 402 has been disclosed, it is within the scope of the invention that a back and forth linear operation of the handle assembly will produce the intended function of the invention. In a linear operation of the door handle assembly 402 it is understood that the handle will not rotate about the motion axis, but will move in a linear direction.
[0049] At this point it should be appreciated that the exemplary embodiments describe a plug-in box door interlocking mechanism that defines a means to hold the plug-in door in the closed position when the MCCB is ‘on’. The mechanism also provides a means to use the locking link as an inhibitor to the movement of the handle assembly for restricting the turning ‘on’ of the MCCB when the door is open.
[0050] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0051] The present disclosure overcomes disadvantages associated with conventional door interlocking mechanisms in plug-in boxes of electrical power distribution or busway systems.
[0052] The present disclosure provides for an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that minimizes the accidents due to unintentional exposure to MCCB in a live condition when the plug-in box door is open and thus ensures safety of personnel.
[0053] The present disclosure provides for an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that minimizes the use of associated hardware.
[0054] The present disclosure provides for an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that is economical to produce.
[0055] The present disclosure provides for an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that is easy to operate.
[0056] The present disclosure provides for an interlocking mechanism for plug-in box doors of electrical power distribution or busway systems that is aesthetic in appearance.