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. - POSITION LOCKING SYSTEM FOR DRAW OUT
TYPE SWITCHGEAR
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:

TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to switchgear arrangement and more particularly to a position locking system for draw out type switchgear to lock and unlock movement of switchgear within the drawing space. The invention makes use of wire driven latches to lock and unlock the movement of the switchgear within the drawing space. This technology is used in the switchgear industry and allied areas.
BACKGROUND AND THE PRIOR ART
While racking the breaker into a cradle, the position of the breaker needs to be indicated for safety purposes. This is achieved using a position indicator. The position indicator may be neglected by the user, or he/she may be unaware of the positions and their related safety instructions. The safety of the operation may be jeopardized in case of an unintended motion of the switchgear within the drawing space. To facilitate a simpler indication to the user about the position of the breaker, single or plural defeatable latches are introduced in the current invention. Each -latch may be wire driven, and engages with slots within the rails corresponding to the intended positions of the switchgear. The position is thus successfully indicated to the user by the engagement of the latches.
In most draw-out type switchgear, there are no provisions to indicate the intended positions of the switchgear, or the indication is in visual or audio form. This indication may not be legible at times depending on the environments that the switchgear is used in, for example in loud and/or dusty places. In such a condition, the switchgear position is not easily intimated to the user. This calls for the use of a new range of mechanism to intimate the user about the true position of the switchgear

in a novel way. A physical indication is independent of audio or visual indications and is more prominent than the latter.
In conventional switchgear, the switchgear position is locked by means of halting the motion of the racking screw depending on the motion it has traversed. Hence, the position of the switchgear is determined by the position and/or motion of the racking screw/rack. However, due to tolerances the real position of the switchgear may not match with its intended position. Hence, there is a strong possibility of false position locking. This is eliminated by deriving the real displacement of the switchgear and its engagement at the rail itself.
In US 2010/0263995 by Jian Sheng Bi et al, a position locking device is made using a screw rod, a catching plate, a positioning plate, a locking plate, and a push rod. The screw rod has key ways. The catching plate has a hole and a protrusion that can be inserted into the keyways. Positioning notches for limiting the positions are farmed on the surface of the positioning plate, and corresponding protruding platforms are disposed on the bottom surface One end of the locking plate bears against the bottom surface of the positioning plate, and the other end is locked to or unlocked from an outward protruding platform of the catching plate. One end of the push rod passes through the catching plate hole, and has an inclined surface. When the push rod is pushed, the inclined surface makes the catching plate leave the key ways.
CN1402397 (A) discloses a locking device for a draw-out circuit breaker, which provides a device capable of locking under the three different states of off, test, and on. In the patent, this function is achieved through a cooperation of a plurality of members, that is, a fork shaft and an unlocking shaft, a locking sheet and a roller thereon, a slot and a roller slot on a square shaft, and a locking trench on a catching plate.

These inventions rely on the position of the racking mechanism rather than the actual position of the breaker. There may be a lag between the actual breaker position and the intended position of the breaker due to tolerances. This may hinder the safety of the operation and may lead to an inaccurate intimation of the breaker position.
The present invention takes care of this problem by engaging latches into the rails, which eliminates the possibility of a mismatch in the intended locking position of the breaker and the actual locking position.
OBJECTS OF THE INVENTION
A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
Other object of the present invention is to provide a position locking system for use in draw out type switchgear units.
Yet another object of the present invention is to use a means to defeat the engagement of the latch with the rail which is achieved by the displacement of the wire manually by the user.
These and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION
According to one embodiment of the present invention, there is provided position locking system for draw out type switchgear to lock and unlock movement of switchgear within the drawing space, said system comprising a plurality of wire driven latches, said latch having movement defined by a latch plate ; a plurality of slots for engaging said latches within the rails; a shaft having coupling arrangement on its sides; an actuation means to defeat engagement of said latch with said rail; a latch spring configured to push said latch plate in said slot; an audio indication means to indicate engaging and disengaging of said latch in said slot.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig 1 illustrates the assembly cut view at the bottom end.
Fig 2 illustrates the general assembly of the system.
Fig 3 illustrates outer view of the system.
Fig 4 illustrates latch engagement with one of the slots.
Fig. 5 illustrates assembly of the wire and the latch.
Fig 6 illustrates top view of the arrangement.
Fig. 7 illustrates the top view of the arrangement when the button is in pressed condition.

Fig. 8 illustrates rear view of the assembly with plural latches in the system.
Fig. 9 illustrates side view of the system with plural slots on the rail.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
Reference is first invited to Fig 1 where the assembly cut view at the bottom end is shown. A position locking system for draw out type switchgear to lock and unlock movement of switchgear within the drawing space is shown.
Fig. 2 shows general assembly of the system.
Fig. 3 shows outer view of the system in accordance with the present invention.
Fig. 4 shows that the user is required to press the button 2 which juts out from the face of the facia 5 to disengage the latch 2 from the rail 1 and continue the racking operation till a desired position is reached.
Fig. 5 shows the sides of the shaft with coupling arrangement provided therein.
Fig. 6 shows the eye of the wire at the facia-side 33 of the wire pulls the button 42 because of the hook in the button 421.

Fig. 7 shows that the user is required to push the button 42 back to its original position, hence defeating the latch spring 21.
Fig. 8 shows the wire 3 connected to the latch 2 at the latch pin 23 by the eye of the wire at the latch side 32.
Fig. 9 shows a user unable to perform the racking operation while the latch 2 is engaged into the slot in the rail 11,12,13. This serves as a physical indication to the user. Horseplay and unintended racking are avoided by this setup.
The invented system is thus a position locking system for draw out type switchgear to lock and unlock movement of switchgear within the drawing space.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly the present invention consists of a manually actuated latch 2 that engages with a corresponding slot 11,12,13 on the rails 1 of the draw out type switchgear. The actuation is achieved in this invention using wires 3. These are covered with an industrial sheath 31. The facia end of the wire is connected to a button 42 which egresses from its slot 51 when the latch 2 engages with its corresponding slots 11,12,13 on the rails 1. On pressing of this button 42, the wires 3 are displaced away from the facia 5. This displacement makes the latch 2 to disengage with the slot 11, 12, 13 in the rail 1. Without the disengagement the switchgear motion is halted.
This collusion sends an indication about the position reached by the switchgear. The user is thus acknowledged about the position in a physical manner. The user must

then press the button 42, thus disengaging from the slot 11,12,13 and further continue the switchgear motion.
Constructional components/parts:
1. Rail
11. Slot for position 1
12. Slot for position 2
13. Slot for position 3
2. Latch
21. Latch spring 22.Latch plate 23.Latch pin
3.Wire
31. Wire sheath
32.Eye of wire at latch side
33. Eye of wire at facia side
41 .Pin for wire
42. Button
421. Hook on button
5. Facia
51. Slot in facia for button
The rail motion brings the slot 11,12,13 closer to the position of the latch 2 as shown in figure no. 9. The latch 2 can move only vertically defined by the latch plate 22. As the latch plate 22 aligns with the slot 11,12,13 in the rail 1, it is pushed into the slot

by the latch spring 21 as shown in figure no. 2 and figure no.3. The engagement of the latch 2 with the corresponding slot 11,12,13 in the rail 1 may create a distinct sound. This can be used as an audio indication for the user.
This motion also pulls the wire 3 connected to the latch 2 at the latch pin 23 by the eye of the wire at the latch side 32 as shown in figure no 8. The wire 3 also pulls the button 42 which is turned around the groove in the wire-pin 41. The eye of the wire at the facia-side 33 of the wire pulls the button 42 because of the hook in the button 421 as shown in figure no 6. This pushes the button 42 which is residing in a slot made in the facia 51 outside the facia 5. This leads to a visual indication for the user.
The user will be unable to perform the racking operation while the latch 2 is engaged into the slot in the rail 11,12,13 as shown in figure no 9. This serves as a physical indication to the user. Horseplay and unintended racking are avoided by this setup. The user is required to push the button 42 back to its original position, hence defeating the latch spring 21 as shown in figure no 7. The user is required to press this button 42 and continue with the racking operation of the switchgear. The same procedure is followed for every slot i.e. every position of the switchgear 11,12,13.
Hence, a physical, audio and visual indication are presented to the user, and successful locking.
The user is required to press the button 2 which juts out from the face of the facia 5 to disengage the latch 2 from the rail 1 and continue the racking operation till a desired position is reached as shown in figure no 6 and figure no 4.

Advantages:
This invention gives audio, visual and physical indication of the position of switchgear. It also provides locking of the position of the switchgear at multiple locations.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:
1. A position locking system for draw out type switchgear to lock and unlock
movement of switchgear within the drawing space, said system comprising:
a plurality of wire driven latches, said latch having movement defined by a latch plate;
a plurality of slots for engaging said latches within the rails;
a shaft having coupling arrangement on its sides;
an actuation means to defeat engagement of said latch with said rail;
a latch spring configured to push said latch plate in said slot;
an audio indication means to indicate engaging and disengaging of said latch in said slot.
2. System as claimed in claim 1 wherein said latch engage with said slot within the said rails corresponding to the actual position of said switchgear.
3. System as claimed in claim 1 wherein said actuation means is manually operated to defeat engagement of said latch with said rail.
4. System as claimed in claim 1 wherein said actuation means further connected to a button configured to engage and disengage said latch from said slot.

5. System as claimed in claim 4 wherein said button provides a visual indication for said engaging and disengaging of said latch.
6. System as claimed in claim 1 for locking at multiple locations, said location depending on position of said slot.
7. A position locking system for draw out type switchgear to lock and unlock movement of switchgear within the drawing space as herein described and illustrated with reference to the accompanying drawings.