Claims:1. A safety interlock device (1) to achieve interlock between a short circuit protection device (SCPD), racking screw and a door of a withdrawable type feeder, wherein said device comprising
a housing (8) mounted on a rotary operating mechanism (ROM) (2) of said SCPD (6);
an operating handle fixed on said housing (8) and is connected to said ROM through an operating shaft (14);
a rotating plate (7) having plurality of grooves, adapted to be rotated by virtue of said operating handle (3) to switch ON said SCPD;
a racking lever (4) accommodate in one of said plurality of grooves, wherein said lever is capable of moving up/down according to rotation of said rotating plate (7) or according to SCPD’s ON & OFF position, so as to allow/restrict the access to said racking screw (5), when the SCPD is switched OFF/ON.
2. The device as claimed in claim 1, wherein said housing (8) includes a flange wherein a spring loaded stopper (9) fixed to restrict rotation of said rotating plate (7), thereby restricting said SCPD from being switched ON, when said door is open.
3. The device as claimed in claim 2, wherein said rotatory plate (7) includes at least one has groove profile (7a), in which said spring loaded stopper (9) is engaged and restrict the rotation of rotating plate (7) when door is open.
4. The device as claimed in claim 3, wherein said rotatory plate (7) includes at least a curved groove (7c) to accommodate said racking lever (4) so as to enable said lever to move up and down according to a rotating angle of said shaft through said rotating plate (7).
5. The device as claimed in claim 4, wherein said rotatory plate (7) includes at least circular groove (7d) to accommodate a door lever (11) so as to enable said plate (7) to rotate while switching ON the SCPD, with door of said feeder being closed.
6. The device as claimed in claim 5, wherein said rotating plate (7) further includes a groove (7b) through which said shaft (14) is fixed.
7. The device as claimed in claim 1, wherein said racking lever (4) is embraced with a lever guide (10) to restrict unwanted movement of said racking lever while rotating said rotary plate (7).
8. A withdrawable type feeder comprising:
a short circuit protection device (SCPD) (6);
a racking system with racking screw (5); and
a safety interlock device (1) to achieve interlock between said short circuit protection device (SCPD), said racking screw and a door of said feeder, wherein said device comprising
a housing (8) mounted on a rotary operating mechanism (ROM) (2) of said SCPD (6);
an operating handle fixed on said housing (8) and is connected to said ROM through an operating shaft (14);
a rotating plate (7) having plurality of grooves, adapted to be rotated by virtue of said operating handle (3) to switch ON said SCPD;
a racking lever (4) accommodate in one of said plurality of grooves, wherein said lever is capable of moving up/down according to rotation of said rotating plate (7) or according to SCPD’s ON & OFF position, so as to allow/restrict the access to said racking screw (5), when the SCPD is switched OFF/ON..
, Description:TECHNICAL FIELD OF THE INVENTION

[001] The present subject matter described herein, in general, relates to interlock mechanism of electrical feeder. More particularly, the invention relates to safety interlock mechanism for a feeder consisting of short circuit protection device (SCPD) to allow user to operate SCPD after closing door and to restrict any unwanted operation of racking in or racking out of feeder.

BACKGROUND OF THE INVENTION

[002] There are two types of the switchboards used to distribute the generated power; Power Control Centre (PCC) and Motor Control Centre (MCC). Power Control Centre distributes the power to different Motor Control Centre (MCC) and Motor Control Centre (MCC) distributes that power intelligently to different motor loads, lamp loads using feeders/modules.

[003] Each MCC panel has numbers of feeder, which comprises of short circuit protection device (SCPD), monitoring relays and controlling devices. This feeder may be draw out and fixed type. Draw out feeders are fixed in the panel compartment and these feeders are removable. Any feeders have three stages of operation while racking in: isolate, test and service. Since feeder is withdrawable, it will be operated in three stages as mentioned above while racking IN & OUT. It becomes mandatory to operate this feeder without impairing the safety of user. This safety should be maintained as in the following manner:
• Feeder should be ON only if door is properly closed.
• Once feeder is ON, Door should not be OPEN.
• If SCPD is ON then feeder should not be racked in & out and vice versa.
[004] Hence, while operating draw out feeder, there should be some interlocks to ensure safety of device as well as personnel. Another requirement is to optimize the design with less number of components.
[005] For existing patents related to safety interlock mechanism for feeder, a reference is made to US3999643A, entitled “Electrical interlock safety control to prevent operation of mower during reverse travel”. In this prior art, a transmission lever operated switch is incorporated in the electric control circuit for an electric clutch employed in the drive of a tractor mounted mower whereby the electric circuit is de-energized whenever the transmission control lever is placed in its reverse position. The control circuit for the electric clutch includes a seat operated switch whereby the electric circuit will be de-energized whenever the seat is unoccupied. The electric circuit further includes an on-off switch which is interconnected with an ignition circuit switch for an internal combustion engine whereby when the ignition switch is closed, the on-off switch for the electric clutch circuit will be open. Thus, during starting of the engine, the mower blade drive will be inoperative due to the de-energization of the electric clutch control circuit. The electrical interlock control prevents operation of the mower blade during starting of the engine, when the operator's seat is unoccupied and/or when the transmission control is in reverse
[006] Reference is made to US20120085628A1, entitled “Electrical apparatus, and racking assembly and coupling therefor”. In the prior art, a coupling is provided for a racking assembly for racking an electrical apparatus into and out of an enclosure with an actuator. The electrical apparatus includes a housing. The racking assembly includes a safety interlock, which is movable between a locked position, and an unlocked position corresponding to the racking assembly being operable to rack the electrical apparatus into or out of the enclosure. The coupling includes an adapter having a first portion coupled to the racking assembly, and a second portion coupled to the actuator. A sleeve is movably disposed on the adapter. The sleeve moves the safety interlock from the locked position to the unlocked position. When the safety interlock is disposed in the unlocked position, the adapter transfers movement of the actuator to the racking assembly to move the electrical apparatus.
[007] Reference is further made to CN201629511U, entitled “Interlocking mechanism of drawout medium and high voltage breaker”. This prior art relates to an interlocking mechanism of a drawout medium and high voltage breaker. The medium and high voltage breaker comprises a breaker body, a breaker operating panel provided with an operating hole and a hole sealing plate used for opening or closing the operating hole. The interlocking mechanism comprises an interlocking shaft, and one end of the interlocking shaft is fixed with the hole sealing plate. The utility model is characterized in that the interlocking mechanism also comprises a crankarm, a limit plate and an electromagnet, and the crankarm is arranged on the interlocking shaft; the limit plate is fixed on the breaker body for axially limiting the crankarm; the electromagnet is directly or indirectly arranged on the breaker body, and electrically connected with an electric wire on a switchgear; a telescopic movable iron core is arranged on the electromagnet, and the movable iron core corresponds to the crankarm and can come into contact with the crankarm. The utility model has the advantages of safe use, high motion reliability and no error operation. The mechanism capable of realizing electric interlocking has broad application range.
[008] Reference is also made to CN201196926Y, entitled “Interlocking apparatus of power distribution cabinet ground switch and breaker chamber cabinet door”. The prior art document discloses an interlocking device for a grounding switch of an electric power distribution cabinet and a cabinet door of a breaker room, which comprises a cam, a positioning board, a middle door bolt and a locking device which are connected with an operating shaft of the grounding switch, wherein the positioning board is provided with a plurality of longitudinal grooves which are respectively matched with corresponding positioning bolts on a cabinet body, the lower end of the positioning board is pressed against the outer profile of the cam, and the upper end of the positioning board is fixed with one end of the middle door bolt; and the other end of the middle door bolt is matched with a locking screw stem.
[009] In existing designs, SCPD handle is mounted on the door and handle itself has safety interlock features. However, as per requirement, this handle should not be mounted on the door and hence all interlocks get defeated. Further, feeders consists of various type of SCPD and handle location changes according to SCPD’s position. In such case, designing a separate and common mechanism to achieve interlocks is a challenge. Furthermore, it should be compact to allow users to access the terminals of SCPD because this interlock will be mounted exact in front of the SCPD.

[0010] Accordingly, there is a dire need to design a safety interlock mechanism for a SCPD integrated feeder, which would allow a user to access SCPD’s terminals, would be an integral part of SCPD itself and independent of SCPD mounting location. The mechanism should be not allow rack IN/OUT module without switching OFF SCPD and to switch ON the SCPD when the door is open.

SUMMARY OF THE INVENTION

[0011] 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.

[0012] An objective of the present invention is to provide a safety interlock device to allow user to operate SCPD after closing door and to restrict any unwanted operation of racking or racking out of feeder.

[0013] Another objective of the present invention is to provide a safety interlock mechanism for a withdrawable feeder having a SCPD, which is independent of the SCPD location within feeder and to optimize it with less number of components.

[0014] Yet another objective of the present invention is to a safety interlock mechanism for a withdrawable feeder having a SCPD, which comprises an arrangement for blocking racking screw of feeder when SCPD is ON.

[0015] Accordingly, in one implementation, the present invention discloses a safety interlock device to achieve interlock between a short circuit protection device (SCPD), racking screw and a door of a withdrawable type feeder, wherein said device comprising
a housing mounted on a rotary operating mechanism (ROM) of said SCPD;
an operating handle fixed on said housing and is connected to said ROM through an operating shaft;
a rotating plate having plurality of grooves, adapted to be rotated by virtue of said operating handle to switch ON said SCPD;
a racking lever accommodate in one of said plurality of grooves, wherein said lever is capable of moving up/down according to rotation of said rotating plate or according to SCPD’s ON & OFF position, so as to allow/restrict the access to said racking screw, when the SCPD is switched OFF/ON.

[0016] In another aspect, there is provided a withdrawable type feeder comprising:
a short circuit protection device (SCPD);
a racking system with racking screw; and
a safety interlock device to achieve interlock between said SCPD, said racking screw and a door of said feeder, wherein said device comprising
a housing mounted on a rotary operating mechanism (ROM) of said SCPD;
an operating handle fixed on said housing and is connected to said ROM through an operating shaft;
a rotating plate having plurality of grooves, adapted to be rotated by virtue of said operating handle to switch ON said SCPD;
a racking lever accommodate in one of said plurality of grooves, wherein said lever is capable of moving up/down according to rotation of said rotating plate or according to SCPD’s ON & OFF position, so as to allow/restrict the access to said racking screw, when the SCPD is switched OFF/ON.

[0017] 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

[0018] 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:

[0019] Figure 1 shows the assembly view of the withdrawable type feeder comprising the safety interlock device, according to one implementation of the present invention.

[0020] Figure 2 shows the safety interlock device fixed on rotary operating mechanism of short circuit protection device, according to one implementation of the present invention.

[0021] Figure 3 shows the exploded view of safety interlock device, according to one implementation of the present invention.

[0022] Figure 4 shows the design of housing accommodating whole safety interlock device, according to one implementation of the present invention.

[0023] Figure 5 shows the detailed view of rotary plate, according to one implementation of the present invention.

[0024] Figure 6 shows the profile of lever, according to one implementation of the present invention.

[0025] Figure 7 shows the assembly of lever with lever guide, according to one implementation of the present invention.

[0026] Figure 8 shows the exploded view of the whole assembly of safety interlock mechanism with door lever, stopper, additional guide, lever and rotary plate, according to one implementation of the present invention.

[0027] Figure 9 shows (a) a state when the door is closed and SCPD is in between ON & OFF position, (b) a state when the authorized person can defeat the door lock by rotating door lever, 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] In one implementation, the present invention discloses a safety interlock mechanism for a withdrawable feeder having a short circuit protection device SCPD. In new design, interlocking between the door & SCPD is again obtained. Through the design of new interlock mechanism, interlocking between the door of the enclosure of feeder & SCPD is obtained and the following safety features are achieved:
1. SCPD can be ON only after door is securely closed.
2. Door can be opened only after SCPD is OFF and this is defeatable so that an authorized person can open the door even if SCPD is ON.
3. A lever blocks access to racking screw when SCPD is ON.
4. No one can rack IN/OUT module without switching OFF SCPD.
[0037] In one implementation, in the interlock mechanism, one circular plate having circular & smiley shaped cutouts and one “i” shaped lever are provided. These two plates are assembled within a housing and this housing gets fixed on MCCB or SCPD. “i” shape lever move straight up & down according to the rotation of circular plate which is engaged with SCPD handle. Smiley shaped cutout is made to allow blocking lever to move up & down to restrict & allow the access to racking screw to enable the racking the feeder in and out of its enclosure. This interlock design is made in such a way that it can be mounted on MCCB and so independent of SCPDs variants.
[0038] In one implementation, referring to figure 1, the assembly view of a feeder comprising the safety interlock mechanism as disclosed in the present invention is shown. The feeder comprises a short circuit protection device (SCPD) (6), a racking system with racking screw (5), safety interlock mechanism (1) with handle (3) mounted on interlock housing (8) fixed on rotary operating mechanism (ROM) (2) of SCPD (6) with lever (4).

[0039] In one implementation, referring to figure 2, the safety interlock mechanism (1) fixed on rotary operating mechanism (2) of short circuit protection device (SCPD) is shown. Here, the interlock mechanism comprises housing (8), rotating plate (7) and lever (4). Operating handle (3) gets fixed on housing (8).

[0040] In one implementation, referring to figure 3, the exploded view of interlock mechanism (1) is shown. The housing (8) has a flange (8a) where stopper (9) is fixed and this stopper (9) is spring loaded which restricts the smiley shaped rotary plate (7) from being rotated when door is opened. Generally, ROM (2) is fixed on each SCPD and this ROM is connected with operating handle (3) through a shaft. When stopper is free and gets engaged in cutout (7a) of rotary plate (7), it cannot be rotated and thereby user cannot operate the SCPD until the door is closed. When Door is closed then a door lever (11) mounted in the door push the stopper (9) until rotary plate (7) is free to rotate.

[0041] In one implementation, referring to figure 4, the design of the housing (8) which accommodate whole interlock mechanism is shown. The housing has flange (8a) for stopper (9), rectangular cutout (8c) to pass door lever (11) through it when door is closed and has provision for SCPD operating handle (3).

[0042] In one implementation, referring to figure 5, a detailed view of rotary plate (7) is shown. This plate is designed in such a way that it is compact and can be accommodated for any SCPD feeder, so a user has sufficient space to access I/C & O/G parts of SCPD (6). Rotary plate (7) has rectangular cutout (7a), in which stopper (9) is engaged and restrict the rotation of plate (7) when the door is open. If door is closed, then door lever (11) press the stopper and gets engaged with plate. Now the plate (7) has circled cutout (7d) which can accommodate door lever (11), so if the plate (7) is rotated while switching ON the SCPD, it allows it to rotate when the door is closed. Plate (7) has cutout (7b) through which operating shaft (14) is fixed. These cutouts (7a & 7b) are so designed that SCPD can be ON after rotating plate through operating shaft (14) without dislocating the position of stopper (9) and door lever (11). Stopper (9) is spring loaded which continuously pushes the door lever (11) in opposite direction it means as soon as door is opened after switching OFF SCPD, stopper (9) retain its position inside rotary plate cutout (7a) & locks the movement of plate (7) and door lever comes out of plate. Another Smiley type cutout (7c) is made to accommodate racking lever (4). The profile of smiley cutout has been made to allow lever (4) to move Up & Down according to the rotating angle of SCPD’s shaft through plate (7).

[0043] In one implementation, referring to figure 6, profile of the lever (4) is shown, which always hangs on a pin (4a) in cutout (7c) and passes through (8d) of housing (8), this lever moves up and down according to rotation of plate (7) or according to SCPD’s ON & OFF position. This lever blocks the racking screw (5) of feeder from access. When SCPD is OFF, this lever stay UP and user can access to screw (5) and feeder can be racked in & out. Vice versa, if SCPD is ON, then it moves down and blocks the racking screw.

[0044] In one implementation, referring to figure 7, the assembly of lever (4) with lever guide (10) is shown. Lever (4) moves up & down and this movement is supported by additional guide (10), which embraces the lever and restrict the unwanted movement of lever while rotating rotary plate (7). Guide (10) has two arms which guides the lever (4) and holes (12) for fixing it with feeder tray plate (13) which is exactly above the racking screw (5).

[0045] In one implementation, figure 8 shows exploded view of the whole assembly of safety interlock mechanism with door lever (11), stopper (9), additional guide (10), lever (4) and rotary plate (7).

[0046] In one implementation, figure 9 shows two states: (a) When door is closed, the stopper is pushed by the door lever and SCPD is in between ON & OFF position, then door cannot be opened because surface (15) of door lever (11) gets locked on the surface (16) of rotary plate (7). It means door cannot be opened until the SCPD is OFF; (b) when the authorized person can defeat the door lock by rotating door lever (11) for an angle of 90 deg by a tool and then surface (15) of door lever will come out through cutout (7d). In this state, door can be opened even if SCPD is off and in that case stopper will remain on the surface (16) of plate (7). Door lever (11) is designed that it can be fixed to door and can be rotated by 90 deg angle.

[0047] Some of the noteworthy features of the present invention are as follows:
• Design of “rotary plate” with curved and smiley cutout for lever and stopper.
• Method of obtaining interlock feature without introducing any mounting plate to be mounted on feeders.
• SCPD mounted interlock, which eliminates the varieties depends on SCPD location within feeder.
• Design of lever and its links with plate and arrangements for blocking racking screw of feeder without using any cord.

[0048] Some of the non-limiting advantages of the present invention are:
• No use of cord to link shaft rotation into linear displacement of plate like other interlock.
• A common design suitable for all SCPD, which reduces the burden of more components variants.
• Due to mounting on ROM, this interlock occupies less area and so direct access to terminals of SCPD is possible.
• Simple design to achieve interlock between SCPD, Racking screw and Door with defeat feature.

[0049] Although a short circuit protection device integrated safety interlock device for withdrawable feeder, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific methods or devices described herein. Rather, the specific features are disclosed as examples of implementations of the short circuit protection device integrated safety interlock device for withdrawable feeder.