FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
PROVISIONAL SPECIFICATION
(See Section 10 and rule 13)
TITLE OF THE INVENTION:

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

TECHNICAL FIELD
[0001] The present invention generally relates to the circuit breakers and particularly relates to a Bus Bar Trunking system for circuit breakers. The present invention more particularly relates to interlocking of tap off box with the Bus Bar Trunking system (BBT) in circuit breakers like Miniature Circuit Breakers (MCB), Molded Case Circuit Breaker (MCCB), Switch Disconnector Fuse (SDF), etc.
BACKGROUND OF THE INVENTION
[0002] The Bus Bar Trunking system (BBT) is the most efficient, safe and ideal system for supplying electricity to the industrial installations and high rise structures. The Bus Bar Trunking system performs the function of a cable by transporting the current from one system to another. The system has been designed specifically for the installations where there is a need for a rapid and quick availability of the power supply. It is used generally in commercial, industrial and agricultural buildings where the need to have many control switches is limited. The BBT is a simple product solely made up from the enclosures, conductors and insulation. In the Bus Bar Trunking system, the conductors are fitted inside the Trunking. The BBT are the enclosed systems for supplying the electric power to the loads safely and reliably. The system also eliminates the need for the distribution and panel boards.
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[0003] The bus bar Trunking systems are provided with Tap-off provisions at regular intervals. The Trunking systems are supplied with tap-off boxes and are fitted with components such as fuses, Miniature Circuit Breakers (MCB), Moulded Case Circuit Breakers (MCCB) for the protection and control of the loads.
[0004] The Tap off box (TOB) is a unit which houses either a MCCB or SDF in an enclosure that is provided with all safety interlocks from the point of view of user. The TOB is used in BBT. The rating of TOB is generally as per the usage of the MCCB. The currently available TOBs are provided with three interlocks. The TOB enclosure should be interlocked with the BBT, when the MCCB is ON. The door of the TOB enclosure should be restricted to open, when MCCB is switched ON. The conventional methods used for interlocking the Tap off Box with the Bus Bar system uses a pair of flat part projecting out of the TOB, this arrangement is prone to transit damage and many a times gives away the desire function.
[0005] The prior art patent No. US7311538 discloses a Tap-off Interlock. It includes an interlock movable between the first and second positions by operation of an operating handle that controls the OFF or OPEN and ON or CLOSED state of an electrical disconnect device located inside the tap-off device. The interlock allows busway tap off device to be installed or removed from busway section when electrical disconnect device is at open position and closed position.
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[0006] The prior art patent No. US4385214 discloses an interlock pushbutton assembly. It includes a pair of pushbutton switches with electrical contacts and an interlock mechanism between the switches. An interlock mechanism comprises an interlock plunger for contacting the shoulders of the pushbutton switches, and a return spring in contact with the interlock plunger for retaining the plunger in a predetermined position.
[0007] The earlier design of interlock for Tap off Box with Bus bar Trunking occupies more space and was costlier. Hence there is a need to develop a new improved design for interlocking of tap off box with Busbar Trunking system.
OBJECTS OF THE INVENTION
[0008] The primary object of the present invention is to provide an interlocking device for a Tap off box with Bus bar Trunking system.
[0009] Yet another object of the present invention is to prevent the plugging out of the Tap off Box with Bus bar straight length when the circuit breaker is in ON state.
[0010] Yet another object of the present invention is to provide an Interlock and plunger assembly for TOB with Bus bar Trunking system which uses push to the latch mechanism to interlock the TOB with Bus bar trunking.
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[0011] Yet another object of the present invention is to provide a Bus bar Interlock for Tap off Box which occupies less volume.
[0012] Yet another object of the present invention is to design an efficient, robust, compact and more reliable interlock for tap off box with bus bar trunking system.
[0013] Yet another object of the present invention is to provide an economical and cost effective interlocking device for Tap off box with bus bar trunking system.
[0014] Yet another object of the present invention is to provide a Bus Bar interlock for a tap off box, which can be used for interlocking of any standard switchgear products for basic purpose of interlocking.
SUMMARY OF THE INVENTION
[0015] The present invention provides an interlocking mechanism and plunger assembly for Tap of box (TOB) with Bus bar straight length so that the plugging out of the Tap off box in its energized state should be defeated in ON state of the Circuit breaker.
[0016] The embodiments of the present invention provides a new and improved design for interlocking of tap off box with Bus bar Trunking system. It includes a DIN rail type mounting for a TOB. The TOB assembly includes a push to de latch mechanism with intermediate rest or stay put thus allowing a TOB to be disconnected from Bus bar
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trunking system. When the latch is pushed inside the bus bar trunking system it helps to hold the TOB firmly onto Bus bar length (BBT), while holding onto BBT it also ensures an enclosure interlock is activated.
[0017] According to the embodiment of the present invention a link mechanism is provided to operate the tap off box with a MCCB inside it so that from outside it can be energized or de energized by a side operated handle. The link is designed in such a way that it can be used to operate on the competitors MCCB also, this is done by providing horizontal slot on it for adjustments required for competitors MCCB's. Further the interlock is designed in much easier way and it can be implemented in other switchgear standard products. The interlock is designed in such a way that the same interlock can be used for the other two different frames of tap off box which is of different current ratings.
BRIEF DESCRIPTION OF THE DRAWING
[0018] FIG. 1 shows the perspective view of the Bus bar interlock of the Tap off box with the bus bar length.
[0019] FIG. 2 shows the top perspective view of the Tap off box with its box hidden. It shows two assemblies plunger and interlocking assembly.
[0020] FIG. 3 shows the side view of the bus bar interlock of the tap off box.
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[0021] FIG. 4 shows the full side view of the Tap off box with its box being hidden. It shows the basic scheme of how the bus bar interlock is being implemented in Tap off box.
[0022] FIG. 5 shows the interlock plate assembly which is used for the purpose of interlocking of the tap of box with bus bar.
[0023] FIG. 6 illustrates a plunger assembly used for interlocking of the tap off box with Bus bar Trunking system..
[0024] FIG. 7 shows the rear view of the tap off box with Bus bar length showing an Interlock assembly and Plunger assembly.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The present invention provides a new improved design for interlocking of tap off box with Busbar Trunking system. It includes a DIN rail type mounting for a TOB. The TOB assembly includes a push to de latch mechanism with intermediate rest or stay put thus allowing a TOB to be disconnected from Busbar trunking system. When the latch is pushed inside the busbar trunking system it helps to hold the TOB firmly onto Bus bar length (BBT),while holding onto BBT it also ensures a enclosure interlock is activated.
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[0026] According to the embodiment of the present invention a link mechanism to operate the tap off box with a MCCB inside it so that from outside it can be energized or de energized by a side operated handle. The link is designed in such a way that it can be used to operate on the competitors MCCB also, this was done by providing horizontal slot on it for adjustments required for competitors MCCB's. Further the interlock is designed in much easier way and it can be implemented in other switchgear standard products. The interlock is designed in such a way that the same interlocked can be used for the other two different frames of tap off box which is of different current ratings.
[0027] The brief understanding of the invention can obtained from the following description of the drawings.
[0028] FIG. 1 shows Bus bar interlock of the Tap off box with the bus bar length (16). Where (17) is the arm of link mechanism which is pushing the plunger (11) downwards. This assembly is divided in two sub assemblies Plunger assembly and Interlock assembly. In Interlock assembly there is a interlock plate (12) which is been supported by the interlock plate guider (13) which is mounted on the rear side of the tap off box the required force to push interlock plate is given by the spring (15). The interlock plate (13) gets interlocked into the bus bar length of bus bar (16). In Plunger assembly there is a plunger (II) and its cap (10) which is guided into a plunger guider (8) with a compression spring. Whole plunger assembly is screwed onto side surface of MCCB support (18).
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[0029] FIG. 2 shows Tap off box with its box hidden and bus bar interlocking. On Top side of it is the cover (2) which is mounted onto Tap of box with the help of the two hinges (4), the MCCB is made to operate by side handle (5) with a grip (6) onto it. It includes two assemblies such as Plunger assembly and Interlock assembly assemblies for bus bar interlock.
[0030] FIG. 3 shows the side view of the bus bar interlock of the tap off box (18). It is locked to the length of the Bus bar (16) and (7) is the link assembly arm which is pushing a plunger (11) downwards which is getting engaged into a interlock plate (12) so that when the MCCB is in ON state the movement of the plunger is down so in that state no one can plug out the tap off box from bus bar which is the basic purpose of the bus bar interlock. Also whenever someone wants to plug out the Tap off box for service and maintenance there is a feature provided in this scheme, there is a stopper (14) which drops into slot created when interlock plate is pulled against the force of spring, detailed description of this feature is ahead.
[0031] FIG. 4 shows the full side view of the Tap off box with its box being hidden so it shows the basic scheme of how the bus bar interlock is being implemented in Tap off box.
[0032] FIG. 5 shows the interlock plate assembly in which there is interlock plate (12) which is used for the purpose of interlocking of the tap of box with bus bar and there is an interlock plate guider plate (13) which holds the interlock plate (12). There is a spring
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(15) against which force the interlock plate is being moved for defeating the interlocking of tap off box. In this assembly there is a stopper (14) also which is pivoted and used in condition of service and maintenance of tap off box.
[0033] FIG. 6 illustrates a plunger assembly. The plunger (11) has a cap (10) which is pushed by the arm of the link assembly. For movement of the plunger there is a plunger guider (8) provided so that the plunger moves always in vertical plane. The movement of the plunger is against the force of the plunger spring (10) which is used to reset the plunger back to its original position when the MCCB is in off state or at that time when the arm of link assembly is not pushing the plunger assembly downwards.
[0034] FIG. 7 shows the rear view of the tap off box. The bus bar interlock shows two assemblies such as Interlock assembly and Plunger assembly. Box (1) and the cover (2) of the tap off box is shown in the diagram. The whole tap off unit is energized by a side operated handle which turns the MCCB to either ON or OFF state. The main aim of the new improved bus bar interlock is to lock the tap off box with the bus bar straight length when the tap off box is in energized state.
[0035] The overall design of the bus bar interlock is easy and convenient it has several advantages like cost effective, less volume, more robust and rigid design. It is transit proof, simple, robust and economical. The interlock assembly is designed for almost 20000 number of operations. The bus bar interlock used in the scheme can also be implemented in the other standard switchgear products for basic purpose of interlocking
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of a device if need arises. The present interlocking scheme can be implemented for better interlocking of tap off box.
The detailed scope of the monopoly claimed for the invention shall be ascertained and provided at the time of filing of the Complete Specification.
Dated this 29th of August, 2008

Rakesh Prabhu,
Patent Agent, ALMT Legal,
No.2, Lavelle Road, Bangalore-560 001, INDIA

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

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