FORM 2
The Patents Act 1970
(39 of 1970) &
The Patent Rules 2003 COMPLETE SPECIFICATION
(See Section 10 and rule 13)


TITLE OF THE INVENTION:
DOOR INTERLOCK AND STATUS INDICATOR SYSTEM FOR TAP-OFF BOX.
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai- 400 001, Maharashtra. INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED


A) TECHNICAL FIELD
[0001] The embodiments of the present invention generally relate to switching devices and particularly to tap off box in switching device. The embodiments more particularly relate to door interlocking and status indication system for tap off box.
B) BACKGROUND OF THE INVENTION
[0002] Tap-off box (TOB) is a protection device for branch circuits, in which the automatic switch will shut off electricity, when overloading or short circuit occurs. Where ever required, the tap-off box is installed and mounted with the required switchgear that is fed from the bus bars. The plug-in type tap-off boxes with protective devices can be relocated even when system is live. Tap-off box is simple to design and plan, quick to install using only a few tools, flexible for modifications and expansions.
[0003] The TOB is the unit that houses either a MCCB or SDF in an enclosure that is provided with all safety interlocks from the point of view of user. The rating of the TOB is generally as per the usage of the MCCB. The opening of the TOB door is restricted when the MCCB is switched on. During the ON condition of the MCCB, the operating handle of the TOB is pad lockable. The status of TOB can be indicated on the outside to indicate the ON, OFF or TRIP status of the enclosed switchgear device.

[0004] The currently available interlocking mechanisms are bulkier and complex in design. The door padlocks that are presently available include more number of components and springs that are damaged due to the frequent use. As a result of the wear and tear of the springs, the door interlock systems become non operational quickly and the frequency of failures are more.
[0005] Moreover the status indication of the tap off box is provided at only one side now. The operating status off the TOB is not indicated in other sides so that the user finds difficulty in inferring the status of the TOB when he is looking the TOB from other sides.
[0006] Hence, there is a need to provide a simple interlocking mechanism with less number of components and improved design. Further there is a need to make the status indication of the switchgear device in TOB visible from all the sides.
[0007] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
C) OBJECT OF THE INVENTION
[0008] A primary object of the present invention is to provide an improved door interlocking system with less number of components for a tap off box to prevent the accidental opening of the tape off box, when the switchgear is turned ON.

[0009] Another object of the present invention is to provide an improved locking system to lock the door of a top off box using less number of components thereby simplifying the design of the system and to reduce the cost of the system.
[0010] Yet another object of the present invention is to provide a three way status indication system for TOB to enable user to understand the operating status of the TOB from three different sides to improve the visibility.
[0011] Yet another object of the present invention is to develop a door interlocking and status indicating system for TOB with flexibility in design to facilitate effective door interlocking even when the TOB is used to store TOB with different ratings.
D) SUMMARY OF THE INVENTION
[0012] The above mentioned shortcomings, disadvantages and problems are address herein and which will be understood by reading and studying the following specification.
[0013] The various embodiments of the present invention provide a door interlocking and status indication system for a tap off box. The tap off box encloses switchgears. An operating handle is connected to the tap off unit through a rotary mechanism and moved to ON, TRIP and OFF positions, accordingly when the tap off unit is turned to ON, TRIP and OFF conditions. A first pad locking component is provided on the handle. A first door pad locking component may be attached to the handle or may be formed integrally with the handle. A second door pad lock component is attached to

the cover of the TOB. The second door pad lock component is attached to the surface of the cover or may be formed integrally with the cover surface.
[0014] In the de-energized state or when the tap off unit is turned to TRIP or OFF conditions, the first door pad lock component and the second door pad lock component do not interfere with each other so that the cover of the TOB may be opened easily by the user.
[0015] When the tap off unit is turned ON by moving the operating handle, the first door padlock component provided on the handle is arranged over the second door padlock component on the cover of the TOB to press down the second door padlock component of the cover to prevent the opening of the cover. Thus the door of the TOB is defeated from opening, when the TOB is in energized condition. The interlocking system is formed with two door padlock components to provide an effective door interlocking operation of the TOB even without the use of springs. The first door padlock component can be adjustably moved and fixed at any position along the handle so that the door locking may be done effectively even when the TOB is used with circuit breakers of different ratings.
[0016] Three operating status indicator system are provided on the front side surface and at the two side surfaces in the left and right sides so that the operating status is visible from all the three sides namely, the front side, the left side and the right side. The first status indicator system is provided on the front side of the TOB. The first status indicator system includes an arrow mark which is provided on the hand grip mounted over the operating handle so that the operating status of the switching device

is indicated by the arrow mark. The arrow mark is made to point towards ON, TRIP and OFF labels provided on the top side of the cover, when the operating handle is moved to ON, TRIP and OFF positions.
[0017] The second status indicator system is provided on the left side surface of the TOB. The second status indicator system has a cap provided with notch and an indicator unit. The circular cap is directly coupled to the mechanism and moved with respect to the operating status of the TOB. The indicator unit has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch of the cap is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the cap is moved.
[0018] The third operating status indicator system is provided on the right hand side of the TOB. The third operating status indicator system has a cap mounted on the handle unit, a notch and an indicator unit. The notch is attached to the operating handle and moved with respect to the operating status of the TOB. The indicator unit has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the operating handle is moved.
[0019] Thus the various embodiments of the invention provide an effective door interlocking system using two components and without the use of springs thereby reducing the cost and simplifying the system. Three operating status indicator systems are provided at front, left and right side surfaces of TOB to show the operating status of the TOB from any of the three sides.

E) BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 illustrates a left side plan view of tap off box provided with door interlock and operating status indicator system according to one embodiment of the present invention.
[0021] FIG. 2 illustrates a top side perspective view of the tap off box provided with door interlock and operating status indicator system according to one embodiment of the present invention.
[0022] FIG. 3 illustrates an enlarged view of door interlock and operating status indicator system according to one embodiment of the present invention.
[0023] FIG. 4 illustrates a side perspective view of tap off box provided with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state.
[0024] FIG. 5 illustrates a partial top side plan view of the top off box with door interlock and operating status indicator system according to one embodiment of the present invention, when the TOB is in ON state.
[0025] FIG. 6 illustrates a top side view of top off box with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state.

[0026] FIG. 7 illustrates an enlarged view of padlock and first operating status indicator system in door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state.
[0027] FIG. 8 illustrates a right side view of TOB provided with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state.
[0028] FIG. 9 illustrates the enlarged view of third operating status indicator system in door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state.
[0029] FIG. 10 illustrates a left side view of tap off box provided with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state.
[0030] FIG. 11 illustrates the enlarged view of the second operating status indicator system in a door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state.
[0031] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF THE INVENTION

[0032] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0033] The various embodiments of the present invention provide a door interlocking and status indication system for a tap off box. The tap off box encloses switchgears. An operating handle is connected to the tap off unit through a rotary mechanism and moved to ON, TRIP and OFF positions, accordingly when the tap off unit is turned to ON, TRIP and OFF conditions. A first pad locking component is provided on the handle. A first door pad locking component may be attached to the handle or may be formed integrally with the handle. A second door pad lock component is attached to the cover of the TOB. The second door pad lock component is attached to the surface of the cover or may be formed integrally with the cover surface.
[0034] In the de-energized state or when the tap off unit is turned to TRIP or OFF conditions, the first door pad lock component and the second door pad lock component do not interfere with each other so that the cover of the TOB may be opened easily by the user.
[0035] When the tap off unit is turned ON by moving the operating handle, the first door padlock component provided on the handle is arranged over the second door

padlock component on the cover of the TOB to press down the second door padlock component of the cover to prevent the opening of the cover. Thus the door of the TOB is defeated from opening, when the TOB is in energized condition. The interlocking system is formed with two door padlock components to provide an effective door interlocking operation of the TOB even without the use of springs. The first door padlock component can be adjustably moved and fixed at any position along the handle so that the door locking may be done effectively even when the TOB is used with circuit breakers of different ratings.
[0036] Three operating status indicator system are provided on the front side surface and at the two side surfaces in the left and right sides so that the operating status is visible from all the three sides namely, the front side, the left side and the right side. The first status indicator system is provided on the front side of the TOB. The first status indicator system includes an arrow mark which is provided on the hand grip mounted over the operating handle so that the operating status of the switching device is indicated by the arrow mark. The arrow mark is made to point towards ON, TRIP and OFF labels provided on the top side of the cover, when the operating handle is moved to ON, TRIP and OFF positions.
[0037] The second status indicator system is provided on the left side surface of the TOB. The second status indicator system has a cap provided with notch and an indicator unit. The circular cap is directly coupled to the mechanism and moved with respect to the operating status of the TOB. The indicator unit has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch

of the cap is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the cap is moved.
[0038] The third operating status indicator system is provided on the right hand side of the TOB. The third operating status indicator system has a cap mounted on the handle unit, a notch and an indicator unit. The notch is attached to the operating handle and moved with respect to the operating status of the TOB. The indicator unit has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the operating handle is moved.
[0039] Thus the various embodiments of the invention provide an effective door interlocking system using two components and without the use of springs thereby reducing the cost and simplifying the system. Three operating status indicator systems are provided at front, left and right side surfaces of TOB to show the operating status of the TOB from any of the three sides.
[0040] FIG. 1 illustrates a left side plan view of tap off box provided with a door interlock and operating status indicator system according to one embodiment of the present invention. With respect to FIG. 1, a TOB is mounted on a rail. Operating handle 3 is connected to the tap off unit through a rotary mechanism and moved to ON, TRIP and OFF positions, accordingly when the tap off unit is turned to ON, TRIP and OFF conditions. First pad locking component 1 is provided on handle 3 attached with hand grip 4. First door pad locking component 1 may be attached to handle 3 or may be formed integrally with handle 3. Second door pad lock component

2 is attached to the cover of the TOB. Second door pad lock component 2 is attached to the surface of the cover or may be formed integrally with the cover surface.
[0041] In the de-energized state or when the tap off unit is turned to TRIP or OFF conditions, first door pad lock component 1 and second door pad lock component 2 do not interfere with each other so that the cover of the TOB may be opened easily by the user.
[0042] The second status indicator system is provided on the left side surface of the TOB. The second status indicator system has cap 6 provided with notch and indicator unit 7. Circular cap 6 is directly coupled to the mechanism and moved with respect to the operating status of the TOB. Indicator unit 7 has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch of the cap is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the cap is moved.
[0043] FIG. 2 illustrates a top side perspective view of the tap off box provided with door interlock and operating status indicator system according to one embodiment of the present invention. With respect to FIG. 2, a TOB is mounted on a rail. Operating handle 3 is connected to the tap off unit through a rotary mechanism and moved to ON, TRIP and OFF positions, accordingly when the tap off unit is turned to ON, TRIP and OFF conditions. First pad locking component 1 is provided on handle 3. First door pad locking component 1 may be attached to handle 3 or may be formed integrally with handle 3. Second door pad lock component 2 is attached to the cover

of the TOB. Second door pad lock component 2 is attached to the surface of the cover or may be formed integrally with the cover surface.
[0044] In the de-energized state or when the tap off unit is turned to TRIP or OFF conditions, first door pad lock component 1 and second door pad lock component 2 do not interfere with each other so that the cover of the TOB may be opened easily by the user.
[0045] The first status indicator system is provided on the front side of the TOB. The first status indicator system includes an arrow mark which is provided on the hand grip mounted over operating handle 3 so that the operating status of the switching device is indicated by the arrow mark. The arrow mark is made to point towards ON, TRIP and OFF labels 11 provided on the top side of the cover, when operating handle 3 is moved to ON, TRIP and OFF positions.
[0046] FIG. 3 illustrates an enlarged view of door interlock and operating status indicator system according to one embodiment of the present invention. With respect to FIG. 3, operating handle 3 is connected to the tap off unit through a rotary mechanism and moved to ON, TRIP and OFF positions, accordingly when the tap off unit is turned to ON, TRIP and OFF conditions. First door pad locking component 1 is provided on handle 3. First door pad locking component 1 may be attached to handle 3 or may be formed integrally with handle 3. Second door pad lock component 2 is attached to the cover of the TOB. Second door pad lock component 2 is attached to the surface of the cover or may be formed integrally with the cover surface.

[0047] In the de-energized state or when the tap off unit is turned to TRIP or OFF conditions, first door pad lock component 1 and second door pad lock component 2 do not interfere with each other so that the cover of the TOB may be opened easily by the user.
[0048] The first status indicator system is provided on the front side of the TOB. The first status indicator system includes arrow mark 5 which is provided on the hand grip mounted over operating handle 3 so that the operating status of the switching device is indicated by arrow mark 5. Arrow mark 5 is made to point towards ON, TRIP and OFF labels 11 provided on the top side of cover 10, when operating handle 3 is moved to ON, TRIP and OFF positions.
[0049] FIG. 4 illustrates a side perspective view of tap off box provided with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state. With respective FIG. 4, first door padlock component 1 provided on handle 3 is arranged over second door padlock component 2 on the cover of the TOB to press down second door padlock component 2 of the cover to prevent the opening of the cover, when the tap off unit is turned ON by moving operating handle 3. Thus the door of the TOB is defeated from opening, when the TOB is in energized condition. The interlocking system is formed with two door padlock components to provide an effective door interlocking operation of the TOB even without the use of springs. First door padlock component 1 can be adjustably moved and fixed at any position along handle 3 so that the door locking may be done effectively even when the TOB is used with circuit breakers of different ratings.

[0050] The second status indicator system is provided on the left side surface of the TOB. The second status indicator system has cap 6 provided with notch and indicator unit 7. Circular cap 6 is directly coupled to the mechanism and moved with respect to the operating status of the TOB. Indicator unit 7 has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch of the cap is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the cap is moved.
[0051] FIG. 5 illustrates a partial top side plan view of the top off box with door interlock and operating status indicator system according to one embodiment of the present invention, when the TOB is in ON state. With respect to FIG. 5, first door padlock component 1 provided on handle 3 is arranged over second door padlock component 2 on cover 10 of the TOB to press down second door padlock component 2 of cover 10 to prevent the opening of cover 10, when the tap off unit is turned ON by moving operating handle 3. Thus the door of the TOB is defeated from opening, when the TOB is in energized condition. The interlocking system is formed with two door padlock components 1, 2 to provide an effective door interlocking operation of the TOB even without the use of springs. First door padlock component 1 can be adjustably moved and fixed at any position along handle 3 so that the door locking may be done effectively even when the TOB is used with circuit breakers of different ratings.
[0052] FIG. 6 illustrates a top side view of top off box with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state. The first status indicator system is provided on

the front side of the TOB. The first status indicator system includes an arrow mark which is provided on the hand grip mounted over the operating handle so that the operating status of the switching device is indicated by the arrow mark. The arrow mark is made to point towards ON, TRIP and OFF labels provided on the top side of the cover, when the operating handle is moved to ON, TRIP and OFF positions.
[0053] FIG. 7 illustrates an enlarged view of padlock and first operating status indicator system in door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state. The first status indicator system is provided on the front side of the TOB. The first status indicator system includes arrow mark 5 which is provided on the hand grip mounted over operating handle 3 so that the operating status of the switching device is indicated by arrow mark 5. Arrow mark 5 is made to point towards ON, TRIP and OFF labels 11 provided on the top side of the cover, when operating handle 3 is moved to ON, TRIP and OFF positions.
[0054] FIG. 8 illustrates a right side view of TOB provided with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state. With respect to FIG. 8, the third operating status indicator system is provided on the right hand side of the TOB. The third operating status indicator system has cap 9 mounted on handle 3, a notch and an indicator unit. The notch is attached to operating handle 3 and moved with respect to the operating status of the TOB. The indicator unit has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch is moved to indicate any one of

the three positions to reveal the actual operating condition of the TOB, as the operating handle 3 is moved.
[0055] FIG. 9 illustrates the enlarged view of third operating status indicator system in door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state. With respect to FIG.9, the third operating status indicator system is provided on the right hand side of the TOB. The third operating status indicator system has a cap 9 mounted on the handle unit, a notch 8 and an indicator unit 7. Notch 8 is attached to the operating handle and moved with respect to the operating status of the TOB. Indicator unit 7 has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. Notch 8 is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the operating handle is moved.
[0056] FIG. 10 illustrates a left side view of tap off box provided with door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state. With respect to FIG. 10, the second status indicator system is provided on the left side surface of the TOB. The second status indicator system has a cap provided with notch and an indicator unit. The circular cap is directly coupled to the mechanism and moved with respect to the operating status of the TOB. The indicator unit has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. The notch of the cap is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as the cap is moved.

[0057] FIG. 11 illustrates the enlarged view of the second operating status indicator system in a door interlock and operating status indicator system according to one embodiment of the present invention, with the TOB in ON state. With respect to FIG. 11, the second status indicator system is provided on the left side surface of the TOB. The second status indicator system has cap 6 provided with notch and indicator unit 7. Circular cap 6 is directly coupled to the mechanism and moved with respect to the operating status of the TOB. Indicator unit 7 has three positions coded with different colors to indicate the ON, TRIP and OFF conditions. Notch of the cap 6 is moved to indicate any one of the three positions to reveal the actual operating condition of the TOB, as cap 6 is moved.
G) ADVANTAGES OF THE INVENTION
[0058] Thus the various embodiments of the present invention provide an improved locking system with a first locking component coupled to the cover of the tap off box and an adjustable second locking component in the handle. The variability of operating distance of second locking component provides flexibility of the tap off box to accommodate switchgear with varying sizes. The minimum locking components reduce the cost and improve operability of the locking mechanism. The locking components are engaged when the switchgear is energized by moving the handle to ON position preventing any inadvertent intervention. Three indictors are provided to indicate the ON, OFF or TRIP status of enclosed switchgear in a tap off box. The external indicators are placed in separate pane of enclosure with different facing directions to increase visibility of the status indication.

[0059] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.
[0060] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.
Date: December 24, 2008. RAKESH PRABHU
Place: Bangalore. Patent Agent

CLAIMS
What is claimed is:
1. A door interlock and status indication system for a tap off box including a
cover and an operating handle, the system comprising:
a first door pad lock component mounted on the operating handle of the tap off box;
a second door pad lock component mounted on the cover of the tap off box ; a fist status indication system provided on the front side of the tap off box; a second status indication system provided on the left side surface of the tap off box;
a third status indication system provided on the right side of the tap off box; wherein the first door pad lock component and the second door pad lock component interfere with each other in energized state to prevent the opening of the tap off box in energized state while the first door pad lock component and the second door pad lock component do not interfere with each other in non-energized state.
2. The system according to claim 1, wherein the first and the second and the
third status indication systems enable the user to view the true operating status
of the tap off box from the front, left and the right sides of the tap off box.

3. The system according to claim 1, wherein the first door pad locking component is adjustably mounted on the operating handle to provide effective door locking operation, even when the tap off box is used to accommodate the circuit breakers of different ratings.
4. The system according to claim 1, wherein the first status indication system mounted on the front side of the tap off box, includes an arrow mark provided on the handle grip mounted on the operating handle of the tap off box.
5. The system according to claim 1, wherein the first status indication system mounted on the front side of the tap off box, includes label indicator comprising three labels provided on the cover of the tap off box to indicate the ON, TRIP and OFF conditions of tap off box.
6. The system according to claim 1 wherein the arrow mark in the first status indicator system is moved with respect to the movement of the operating handle to point one label in the label indicator to show the true operating status of the tap off box from the front side.
7. The system according to claim 1, wherein the second status indication system mounted on the left side of the tap off box, includes circular cap with a beep and a status indicator.

8. The system according to claim 1, wherein the status indicator in the second status indication system has three color coded labels to indicate the ON, TRIP and OFF conditions of the tap off box.
9. The system according to claim 1, wherein the beep in the circular cap is moved based on the movement of the operating handle to point one of the three color coded labels in the status indictor to show the true operating condition of the tap off box from the left side.
10. The system according to claim 1, wherein the third status indication system mounted on the right side of the tap off box, includes a cap mounted on the operating handle of the tap of box and another status indicator.
11. The system according to claim 1, wherein the status indicator in the third status indication system has three color coded labels to indicate the ON, TRIP and OFF conditions of the tap off box.
12. The system according to claim 1, wherein the third status indication system
mounted on the right side of the tap off box, includes a notch mounted on the
operating handle of the tap off box.
13. The system according to claim 1, wherein the notch in the third status
indication system is moved based on the movement of the operating handle to

indicate one of the three color coded labels in the status indictor to show the true operating condition of the tap off box from the left side.

To,
The Controller of Patents,
The Patent office, Mumbai