FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: AN IMPROVED TWO WAY INTERLOCKING
MECHANISM OF TAP OFF BOX WITH BUS BAR STRAIGHT LENGTH
2. Applicant(s):
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY: An Indian Company
(c) ADDRESS: L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
The present invention relates to an improved two way interlocking mechanism of tap off box with bus bar straight length. More particularly, the invention relates an improved two way interlocking mechanism, with two states viz engaged state and disengaged state to provide foolproof locking of the tap off box with bus bar straight length.
BACKGROUND OF THE INVENTION
Bus bar trunking system is a fabricated enclosed structure, which is having many components like straight length, T sections, elbows, Joints, Tap Off Boxs etc. L&T imports the BBT scheme from its company Tamco from Malaysia through ESE. All the design of BBT are 10 to 15 years old which uses lots of copper in their design and their design is not cost efficient.
US 2,984,769 discloses an electric power distribution systems. Particularly it relates to an electric power busway having plug-in type power take-off devices or plugs which interlock with the busway to prevent insertion and/or removal while the plug is in a predetermined condition.
US 4,496.916 discloses a modular switch-fuse box is provided which can be engaged via terminals 26 with a busbar supply system. The box is divided into a switch compartment 14 and a fuse compartment 16. the latter having an access door 36 which is normally blocked by operating handle 38 when in the "on" position. Handle 38 is provided with a semi-concealed latch 64 allowing access to the fuses 32 when live.
US 5,192.217 discloses The improved plug-in base assembly of the present invention provides a means for complying with European Health and Safety requirements and

particularly the requirement of IEC 439-1 paragraph 7.4.2.2. Subparagraph 7.4.2,2.3 generally requires that live parts be shielded such that they cannot be contacted when a door or cover normally protecting them is opened or removed. This requirement provides additional protection to the installer of a tap-off device against unintentional contact with the uninsulated edges of bus bars exposed through the plug-in openings. The additional protection is provided by a finger barrier which covers the normally exposed uninsulated edge of a bus bar. The finger barrier perrmits the electrical connectors of a tap-off box to pass through the plug-in opening and make an electrical connection while preventing any unintentional contact of the installers fingers with the uninsulated edge of the bus bar.
US 3007016 discloses an electric power distribution systems and more particularly it relates to an interlocking mechanism for power tap-off boxs in connection with low-voltage plug-in type bus bar distribution systems. Bus bar distribution systems, commonly referred to as busways, are used For the safe and efficient distribution of multiphase electric power in industrial plants, office buildings and the like. In essence a busway comprises a plurality of elongated electrical conductors or bus bars connected for energization to respective phases of a polyphase electric power source and enclosed in a grounded metal box or housing.
The drawbacks of the above mentioned prior art is that the prior art mechanism is not safe because it can be defeated from customers by changing the spring position. The operating force and mechanical life of the prior art were less. The operations had more number of states thus showing malfunctioning of the mechanism. The interlocking mechanism uses a torsion spring for the interlocking, which is not foolproof and sometimes malfunctions in its operation. The operating force of the mechanism is also low which do not provide the customer a feel when being operated. The interlocking mechanism by the torsion spring in the prior art provided unstable operations.

Thus there is a need to provide an improved interlocking mechanism of the tap off box (TOB) with a busbar. The improved mechanism which will provide foolproof locking of the TOB and operating is also on a higher side so that it can provide the customer a feel when it is operated. The improved mechanism should further provide a more safer as all critical mechanism part are not accessible to the customer outside. The improved mechanism would provide a higher operating force and good mechanical life and it will replace the existing mechanism as it is a more robust design and provide stable operations.
OBJECTS OF THE INVENTION
The main object of the present invention is to overcome the disadvantages of the prior an.
Another object of the present invention is to provide an improved interlocking mechanism for fully integrated mechanism which is not accessible for the customer.
Yet another object of the present invention is to provide an improved interlocking mechanism for higher operating force and good mechanical life so that the customer while operating gets a feel of operation.
Yet another object of the present invention is to provide an improved interlocking mechanism that is more robust, reliable and stable in its operation.
Yet another object of the present invention is to provide an improved interlocking mechanism that is a two state operation viz engaged state and disengaged state for foolproof locking of the tap off box with bus bar straight length.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided an improved two way interlocking mechanism of Tap off Box with Bus bar so as to provide foolproof

locking of said tap off box with the said bus bar in ON state, said mechanism comprising:
(i) an interlocking means adapted to operate in engaged and/or
disengaged state with said bus bar; (ii) plurality of support means operativeiy connected with said interlocking means by screw and nut means adapted to hold the said interlocking means in a substantially vertical position; (iii) a spring arrangement comprising:
(a) a spring means fixed with said support means adapted to provide force to provide two way interlocking of Tap off Box with said Bus bar;
(b) a spring support means disposed inside said spring means; and
(c) a spring support guide means comprising:
two standard threaded holes inside which spring support screw and spring support nut is placed adapted to fix said interlocking means with it;
a rectangular slot on top of said spring support means adapted to control the motion/deflection of said spring support means to a predefined degree.
DETAILED DESCRIPTION OF THE INVENTION
The improved interlocking mechanism for Tap Off Box (TOB) with the busbar straight length. This is used engagement of the TOB with the length when the box is in On state. This mechanism has only two state in which it can rest which are:
• Engaged state
• Disengaged state
Therefore the rest position comprises of the engaged state and the disengaged state.

it provide foolproof locking of the TOB and the operating is also on the higher side
so it provide the customer a feel when it is operated
The new mechanism is much safer as all the critical mechanism part are not
accessible to the customer from outside
The new mechanism is having a higher operating force and good mechanical life and
it replaces the existing mechanism as it is a more robust design
The features can be described as follows:-
• Fully integrated mechanism which is not accessible for the customer
• Good mechanical life, which is up to 10000 number of operations
• Two state operation of the mechanism which removes possibility of the malfunctioning of the mechanism
• Better operating force so that customer while operating get a feel of operation
• The new mechanism if more robust, reliable and sturdy in its operation
• This mechanism uses a compression spring for the operation so better operation.
The improved two way interlocking mechanism of Tap off Box with Bus bar straight length to provide foolproof locking of said tap off box with bus bar straight length in ON state, said mechanism comprising an interlocking means which is adapted to operate in engaged and/or disengaged state with said bus bar, plurality of interlock supports operatively connected with said interlocking means by interlock plate screw means and interlock nut means adapted to hold the said interlock means in vertical position and a spring arrangement means .
The plurality of interlock support is two in number interlock plate support 1 and interlock plate support 2

The spring assembly comprising a spring means fixed with interlock support means to provide force to implement two way interlocking mechanism of Tap off Box with Bus bar straight length, a spring support means spring support means comprises holder rod means being disposed inside said spring means so as to hold said spring means intact in its position.
The spring support guide comprising two standard threaded holes inside which spring support screw and spring support nut in placed adapted to fix said interlocking means with it and a rectangular slot on top of said spring support means adapted to control the motion/deflection of said spring support means to about 29 degrees.
The two way interlocking mechanism comprises of engaged/engaging state and disengaged/disengaging state. The interlock plate is adapted to be rotated in clockwise direction to disengage said tap off box with said bus bar straight length and rotated in anticlockwise direction to engage said tap off box with said bus bar straight length.
The spring means comprises of the compression spring. The compression spring is adapted to get compressed generating a force opposite in direction to that of the force applied to interlocking plate at its rest position such that after each half cycle of rotation of interlocking plate spring crosses its dead centre transferring the force of the spring into reversed direction leading to operation of the interlock plate in other state. The rest position comprises of engaged position and disengaged position. The engaged position is the position in which the interlock plate is in engagement with the bus bar and the disengaged position is the position is which the interlock plate is in disengagement with the bus bar.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates mechanism and its assembly in engagement position (Bus bar section hidden).
Figure 2 illustrates mechanism and its assembly in disengagement position (Bus bar section hidden).
Figure 3 illustrates front view of the whole mechanism in engaged state (Bus bar section hidden).
Figure 4 illustrates disengaged state.
Figure 5 illustrates engaged state.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Following diagrams are marked. Each number corresponds to a part, component or some section.
They can be listed as follows:-
1 Tap off Box section
2 Interlock Plate
3 Interlock plate support 1
4 Interlock plate support 2
5 Mechanism spring
6 Mechanism spring support
7 Mechanism spring support guide
8 Screw (Interlock plate)
9 Nut (Interlock plate)
10 Screw (mechanism spring support)

11 Nut (mechanism spring support)
12 Screw (Interlock plate support)
] 3 Nut (Interlock plate support)
14 Screw (spring support guide)
15 Bus bar trunking section
Fig. 1 shows the mechanism and its assembly. Tap off box is represented by its section (1) which is in L shape. There is an interlock plate (2) which is used for the engagement of the TOB with the bus bar. The Interlock plate is supported by the two supports which are Interlock support 1 (3) and interlock plate support 2 (4). These two supports (3) and (4) are used to hold the interlock plate (2) in perfectly vertical position for the engagement. There is mechanism spring (5) , which provide the necessary force to the whole mechanism. Interlock plate (2) is fixed by the Screw (8).
The mechanism further comprises of the spring assembly. The spring assembly consists of mechanism spring (5), mechanism spring support (6), mechanism spring support guide. The mechanism spring is the compression spring used. There is mechanism spring support (6) which holds the compression spring (5). When the whole mechanism is operated mechanism spring support (6) is left free to deflect in the mechanism spring support guide (7) that is having a rectangular slot in it so that the mechanism spring support (6) can deflect by a certain degree which is predefined. Again mechanism spring support is held on its position by screw and nut which are (10) and (11) in the figure. Mechanism spring support guide (7) is having two standard threaded holed in it so that it can be fixed on to the interlock plate (2) with the help of the standard screw which is shown as (14) in the Fig. 1.
There is also a arrow which shows the direction in which the interlock plate (2) is going to be operated with circular motion and the motion of the interlock plate is

limited to predefined degree with the help of rectangular slot provided in the in the TOB section (1)
Fig.2 shows the same assembly which is shown in fig. 1. But the only difference is that the mechanism is operated in to a different state which is a disengaged state, In this state the TOB is free for disengagement from the bus bar straight length.The interlock plate (2) has come to this state by rotating it to clockwise direction in fig. 1. All the other assembly components remains the same but the position of the interlock plate with respect to TOB section (1) is changes.
If a customer wants to operate the interlock plate into the same position earlier shown in the fig. 1 it has to operate the interlock plate (2) in counter clockwise direction and again it will come to the same position which is shown in the fig. 1. When the Interlock plate ( 2) is operated against its rest position the mechanism spring (5) get compressed and develops a force in other direction so after half of the total mechanism rotation the spring crosses its dead centre and the force is transferred into reversed direction leading to operation of the interlock plate (2) in other state. That is how this mechanism comes in to two positions.
This mechanism has a unique feature that it can rest in only two positions which are shown in fig.] and fig. 2, because in any other position the forces would be higher to force the interlock plate (2) into its rest positions
Fig. 3 shows the side view of the whole mechanism. The mechanism is in engaged state in this figure. The interlock plate (2) is in perfectly vertical position and L shape bend which is provided in the interlock plate (2) is in perfectly horizontal plane
The nut (9) and screw (8) which is used to hold the interlock plate (2). Both (8) and (9) are used as a hardware to hold the interlock plate in vertical position.

Also there is screw (10) and nut (11) used for holding up the mechanism spring support in its position (14) is a standard screw used for the fixing of the mechanism spring support guide (7) which is having 2 threaded holes for its fixing with the interlock plate.
Fig. 4 is basically used to show how the mechanism is used for the engagement of the TOB with the bus bar straight length. In this figure there is bus bar section represented by (1 5) and interlock plate (2) is used for the engagement of the TOB. In the current position mechanism is in disengaged position in which there is no intersection of the interlock plate (2) with the bus bar straight length (15).To disengage the TOB with bus bar customer has to apply the force in the direction of the arrow shown in the fig. In the current position of the mechanism if a customer wants to disengage the TOB from Bus bar it will come out because while disengaging there will not be any intersection between the interlock plate (2) and the bus bar straight length section (15) So this is disengaged position of the mechanism
Fig. 5 the interlock plate (20 is engaged with the bus bar section (15) so when a customer wants to disengage the TOB with the bus bar section it will apply the force in the direction of the arrow and because of the intersection he will fail to disengage the TOB from the bus bar section.
So this way this mechanism will ensure foolproof locking of the TOB with the bus bar when the TOB is in ON state. By having only two positions of the mechanism it will ensure that the mechanism will not malfunction in any condition. This task was given to us to improve the bus bar interlocking of the TOB.
The invention has been described in a preferred form only and many variations may be made in the invention depending upon the elements/components used in the

mechanism, which will still be comprised within its spirit. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.

WE CLAIM
1. An improved two way interlocking mechanism of Tap off Box with Bus bar
so as to provide foolproof locking of said tap off box with the said bus bar in
ON state, said mechanism comprising:
(i) an interlocking means adapted to operate in engaged and/or disengaged state with said bus bar;
(ii) plurality of support means operatively connected with said interlocking means by screw and nut means adapted to hold the said interlocking means in a substantially vertical position;
(iii) a spring arrangement comprising:
a. a spring means fixed with said support means adapted to provide
force to provide two way interlocking of Tap off Box with said
Bus bar;
b. a spring support means disposed inside said spring means; and
c. a spring support guide means comprising:
two standard threaded holes inside which spring support screw and spring support nut is placed adapted to fix said interlocking means with it;
a rectangular slot on top of said spring support means adapted to control the motion/deflection of said spring support means to a predefined degree.
2. Mechanism as claimed in claim I wherein said interlocking means comprises
interlocking plate,

3. Mechanism as claimed in claims 1 and 2 wherein said interlock plaie is adapted to be rotated in clockwise direction to disengage said tap off box with said bus bar straight length,
4. Mechanism as claimed in claims 1 and 2 wherein said interlock plate is adapted to be rotated in anticlockwise direction to engage said tap off box with said bus bar straight length.
5. Mechanism as claimed in claims 1 to 4 wherein said interlocking plate is substantially L shaped.
6. Mechanism as claimed in claim I wherein said spring means comprises of compression spring.
7. Mechanism as claimed in claim 6 wherein said compression spring is adapted to get compressed generating a force opposite in direction to that of the force applied to said interlocking plate at its rest position such that after each half cycle of rotation of said interlocking plate said spring crosses its dead centre transferring the force of the spring into reversed direction leading to operation of the interlock plate in other state.
8. Mechanism as claimed in claim 7 wherein said rest position comprises of engaged position and disengaged position.
9. Mechanism as claimed in claim 1 wherein said spring support means comprises holder rod means being disposed inside said spring means so as to hold said spring means intact in its position.
10. Mechanism as claimed in claim 1 wherein said spring support means gets deflected to 29°.
11. An improved two way interlocking mechanism of Tap off Box with Bus bar so as to provide foolproof locking of said tap off box with the said bus bar in

ON state as substantially described hereinbefore with reference to accompanying drawings.