FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
PROTECTION MECHANISM FOR A REMOVABLE PART OF SWITCHGEAR AND CONTROL-GEAR ASSEMBLIES;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to a protection mechanism for removable part of switchgear and control-gear assemblies. More particularly, the mechanism is provided to prevent operation when short circuit protection device is in ON state.
BACKGROUND OF THE INVENTION
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 is the device which distributes the power to different Motor Control Centre (MCC) and Motor Control Centre (MCC) is the device which is used to distribute that power intelligently to different types of electrical loads like motor loads, lamp loads etc using feeders. Feeders are nothing but a semi enclosed housing consisting of chassis used for mounting electrical devices and a door. These feeders are again classified as Full Width Modules and Fractional Modules depending on the current ratings and the switching devices inside it.
When electric power is distributed in locations accessible to the public in a loop feeder system, the fuses and switches are housed in a metal enclosure to which access can be had only by authorized personnel. It is essential that such personnel be prevented from coming into contact with energized circuits including loop feeder switches and drawer-mounted fuses connected thereby to the energized loop feeder circuit and also inadvertent feeding to load. The contacts are not designed for making and braking of electrical current online. Hence, it is essential to ensure the load is disconnected during operation of removable device.

In one of the existing arrangements, a common operating knob / handle is used to operate the SCPD and changing the state of module. In this system, the operating handle of product and associated accessories cannot be used. Also, it is not convenient to use for all sizes of switches.
In another existing arrangement, mechanical solid linkages are used to interlock the SCPD and removable part of switchgear and control-gear assemblies. As a result, position of SCPD with respect to interlocking parts loses flexibility and requires more variety of components.
In yet another existing arrangement, clutch cables are used to achieve interlocks. The clutch has metallic parts. Also, can transfer force only in pulled mode so for return travel spring or other means are required.
Accordingly, it is required to devise a solution to overcome the aforementioned problems.
SUMMARY OF THE INVENTION
The present invention provides a protection mechanism for a removable part of switchgear and control-gear assemblies comprising a cam adapted on a shaft to sense position of the device, a blocking bracket rotating about a pivot point, a cable free to move in an outer sleeve and connecting the cam with the blocking bracket, wherein depending upon condition of the protection device the cable is pulled by the cam for rotating the blocking bracket about the pivot point to block an opening for preventing a handle from being inserted in the opening.

BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments. Fig. 1 shows a short circuit protection device in OFF state. Fig. 2 shows the short circuit protection device in ON state.
DESCRIPTION OF THE INVENTION
According to an embodiment the present invention provides a protection mechanism for removable part of switchgear and control-gear assemblies comprising a cam adapted on a shaft to sense position of the device; a blocking bracket rotating about a pivot point; a cable free to move in an outer sleeve and connecting the cam with the blocking bracket; wherein depending upon condition of the protection device the cable is pulled by the cam for rotating the blocking bracket about the pivot point to block an opening for preventing a handle from being inserted in the opening.
In an embodiment of the present invention the device further comprises a lug adapted on the cam for enabling the cam to pull the cable.
In an embodiment of the present invention the outer sleeves are rigidly fixed on the device by using a pair of guides.
As per an embodiment, the device of the present invention further comprises a tensile spring connecting the cable to the blocking bracket.

In an embodiment, the device further comprises a tensile spring holder adapted to hold the spring.
In an embodiment, the blocking bracket blocks the opening when the device is in ON position.
As per an embodiment, the blocking bracket unblocks the opening when the device is in OFF position.
Referring to Fig 1, the present invention shows the short circuit protection device 100 in OFF state. The protection device 100 comprises a cam 110 adapted on a shaft 120 to sense position of the device 100; a blocking bracket 130 rotating about a pivot point 130a; a cable 140 free to move in an outer sleeve 150 and connecting the cam 110 with the blocking bracket 130. Depending upon condition of the protection device 100 the cable 140 is pulled by the cam 110 for rotating the blocking bracket 130 about the pivot point 130a to block an opening 160 for preventing a handle (not shown) from being inserted in the opening 160.
According to an embodiment cam 110 is fitted on short circuit protection device shaft 120. Cam 110 is coupled to clutch cables 140. A Lug 170 is fitted on Cam 110. On the other end of lug 170, cable 140 is fixed. Cable 140 is free to move in outer sleeve 150. Both ends of sleeve 150 are rigidly fixed with the device using guides 180 (180a, 180b). On the other side of cable 140, a tensile spring holding part 190 is attached. A fixed bracket 135 is set on base of the device. On fixed bracket 135, blocking bracket 130 is fixed as pin joint. It can rotate about pivot point 130a as shown in the Figure (1) & Figure (2). At free end of blocking bracket 130, spring holding part 190 having tensile spring 195 is attached.

As per an embodiment rotation of shaft 120 is prevented when short circuit protection device (S.C.P.D) is in ON position as shown in Fig. 2. When shaft 120 is rotated it operates engaging power contact with conductor called dropper. Power contacts are designed only for carrying current and not designed to be used for making or breaking current.
In absence of the protection mechanism, power contact can be engaged or disengaged by rotating the shaft 120 with the handle (not shown) when S.C.P.D is in ON position, this may lead to arcing.
When S.C.P.D is in OFF position, the handle (not shown) can be inserted through opening 160 and shaft 120 can be rotated to operate mechanism as shown in Fig. 1.
When S.C.P.D is made ON, cable 140 is pulled which in turn operates blocking bracket 130. Blocking bracket 130 is moved about pivot point thereby blocking opening 160 for handle insertion as shown in Fig 2. So, with S.C.P.D ON, the handle (not shown) cannot be inserted and operation is prevented.
In draw-out modules, it is required that when the short circuit protection device is in ON condition, one should not be able to operate the mechanism of the module i.e. change of state of the module is to be restricted. This is an additional feature provided to the current carrying feeder modules. When the short circuit protection device is in ON condition, one cannot insert the handle into the module thereby preventing the operation.
This invention will serve in solving the problems arising out of operating the module with short circuit protection in ON condition. Further, spring is used for compensating tolerances.

Spring will prevent damage to any component in protection mechanism if short circuit protection is made ON with handle inserted inside.
The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since, modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the appended claims.

We Claim:
1. A protection mechanism for removable part of switchgear and control-gear assemblies
comprising:
a cam adapted on a shaft to sense position of the device;
a blocking bracket rotating about a pivot point;
a cable free to move in an outer sleeve and connecting the cam with the blocking
bracket;
wherein depending upon condition of the protection device the cable is pulled by the cam for rotating the blocking bracket about the pivot point to block an opening for preventing a handle from being inserted in the opening.
2. The protection mechanism as claimed in claim 1, wherein the device further comprises a lug adapted on the cam for enabling the cam to pull the cable.
3. The protection mechanism as claimed in claim 1, wherein the outer sleeves are rigidly fixed on the device using a pair of guides.
4. The protection mechanism as claimed in claim 4, wherein the device further comprises a tensile spring connecting the cable to the blocking bracket.
5. The protection mechanism as claimed in claim 1, wherein the device has a tensile spring holder adapted to hold the spring.
6. The protection mechanism as claimed in claim 1, wherein the blocking bracket blocks the opening when the device is in ON position.

7. The protection mechanism as claimed in claim 1, wherein the blocking bracket unblocks the opening when the device is in OFF position.