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: INTERLOCK MECHANISM FOR SWITCHING DEVICES
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 present invention generally relates to electrical switchboards, particularly to motor control center switchboards. The present invention more particularly relates to switchboards with a short circuit protection device (SCPD) or switching device mounted in the module chassis.
B) BACKGROUND OF THE INVENTION
[0002] Generally, the draw-out feeders of a switchboard (particularly motor control center-MCC) comprises of three operating position (Service, Test, and Isolation). In service position, both the power circuit and the auxiliary circuit is connected, and in test position only power circuit is connected and auxiliary circuit is disconnected. Further in case of isolated position both power and auxiliary circuit is disconnected.
[0003] In normal operating condition, when the module is in service the switching device is in 'ON' condition. During this condition if the module position is changed from service to test, then there are chances of flash-over or arcing in both incoming and outgoing power contact.
[0004] Thus for preventing arcing during module operation, switching device should be is in 'OFF' condition. Thus to ensure that switching device should be is in 'OFF' condition the method of interlock is used. It also ensures that during draw-out of module from panel, switching device should be in 'OFF' position.
[0005] Hence there is a need to provide an interlock mechanism for switching devices to prevent unforced manual error and hazardous situation during withdrawals and insertion of module when switching device is in 'ON' condition.
[0006] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

C) OBJECTS OF THE INVENTION
[0007] The primary object of the present invention is to provide a switching device interlock mechanism in switchboard which ensures that withdrawal of module and operation of module take places only when the switching device is at 'OFF' condition
[0008] Another object of the present invention is to provide a switching device interlock mechanism in switchboard which avoids the possibility of arcing during module operation (i.e. Service to Test and Vice-versa) and withdrawal of module from panel.
[0009] Yet another object of the present invention is to provide a switching device interlock mechanism in switchboard where switching device handle shaft actuates when switching device handle rotates at specified angular rotation.
[0010] Yet another object of the present invention is to provide a switching device interlock mechanism in switchboard where a lever fixing bracket, fixed with interlock lever varies with shaft cross-section and shape. But interlock lever which is fixed with switching device handle shaft remains unchanged irrespective of shaft cross-section and shape.
[0011 ] 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.
D) SUMMARY OF THE INVENTION
[0012] The various embodiments of the present invention provide an interlock mechanism for switching device in switchboards comprising an interlock guiding plate, an interlock lever, a interlock lever fixing bracket, a interlock locking plate, a interlock plate, a control fascia slider, a switching device shaft and a switching device. The interlock lever is mounted in such a way that a 90° rotation of the shaft causes

the interlock lever to rotate at an angle of+45° to-45° and vice versa to provide for a linear rotation of the interlock plate.
[0013] According to an embodiment of the present invention, the module feeder position (i.e. Service, test, Isolation) is changed by the operating mechanism and module is drawn-out from the panel when the switching device is in 'OFF' condition. When the switching device is in ON condition the module position cannot be changed as the mechanism handle cannot be inserted in the control fascia. The switching device interlock bracket prevents the opening of control fascia slider. The switching device interlock plate is also inserted into tray fixed with the panel that prevents the withdrawal of the module from the panel.
[0014] According to an embodiment of the present invention, the interlock guiding plate is adapted to guide the the switching device interlock plate during an up-down movement of the plate. The interlock plate is inside a module and the interlock locking bracket is above the control fascia slider when the switching device is in OFF position. The interlock plate is inserted into a tray when the switching device is in ON position. The locking bracket comes to the front of the control fascia slider thereby preventing the opening of the control fascia slider. The interlock is actuated with a rotation of the switching device shaft.
E) BRIEF DESCRIPTION OF THE DRAWINGS:
[0015] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
[0016] FIG. 1 illustrates a front view of a switching device with the interlock mechanism in 'OFF' condition according to one embodiment of the present invention.
[0017] FIG. 2 illustrates an isometric view of the switching device interlock mechanism in 'OFF' condition according to one embodiment of the present invention.

[0018] FIG. 3 illustrates a front view of the switching device interlock mechanism in 'ON' condition according to one embodiment of the present invention.
[0019] FIG. 4 illustrates an isometric view of the switching device interlock mechanism in 'ON' condition according to one embodiment of the present invention.
[0020] FIG. 5 illustrates an isometric view of interlock guiding plate used in the operation of the switching device interlock mechanism according to one embodiment of the present invention.
[0021] FIG. 6 illustrates an isometric view of interlock lever used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0022] FIG. 7 illustrates an isometric view of the interlock lever fixing bracket used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0023] FIG. 8 illustrates an isometric view of interlock locking plate used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0024] FIG. 9 illustrates an isometric view of interlock plate used in the operation of switching device interlock mechanism device according to one embodiment of the present invention.
[0025] FIG. 10 illustrates an isometric view of control fascia slider used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0026] FIG. 11 illustrates an isometric view of switching device shaft used in the operation of switching device interlock mechanism according to one embodiment of the present invention.

[0027] FIG. 12 illustrates an isometric view of short circuit protection device which is interlocked with the switchboard according to one embodiment of the present invention.
[0028] 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
[0029] 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.
[0030] The various embodiments of the present invention provide an interlock mechanism for switching device in switchboards. The interlock mechanism comprising of an interlock guiding plate, interlock lever which is fixed firmly with the switching device shaft. The interlock mechanism further comprises of interlock lever fixing bracket which changes according to the changes of switching device shaft cross-section and shape, a interlock locking plate which prevents the opening of control fascia slider during Switching Device 'ON' condition, a interlock plate which moves vertically (up-down), a control fascia slider where moving this mechanism handle is introduced into mechanism shaft, a switching device shaft and a short circuit protection device (SCPD) or switching device.
[0031 ] When the switching device is in 'OFF' condition, the module feeder position (i.e. Service, test, Isolation) can be changed by operating mechanism and module can be drawn-out from the panel. When Switching Device is in 'ON' condition (Fig.3)

module position cannot be changed, because the mechanism handle at this particular position can't be inserted in the control fascia. This is due to switching device interlock bracket which prevents the opening of control fascia slider. More over the switching device interlock plate is also inserted into tray (fixed with panel), that prevent pull out (withdrawal) of module from the panel.
[0032] The interlock lever rotates with switching device ROM shaft. At least one interlock plate is connected with interlock lever with the interlock plate and a locking bracket is fixed. The interlock lever is mounted in such a way that, with the 90° rotation of switching device handle shaft, lever rotation will be +45° to-45° and vice versa in 360° quadrant system for almost linear rotation of interlock plate.
[0033] When the switching device is in 'OFF' position the interlock plate is inside the module and interlock locking bracket is above the mechanism control fascia slider. During this period the module can be removed from panel or the mechanism can be operated by opening the mechanism control fascia slider.
[0034] When switching device is in 'ON' position the interlock plate is moved towards downward direction and inserted into tray which is fixed with panel. During this condition the module cannot be removed from the panel. With the movement of interlock plate, locking bracket is also moved towards downward direction which further comes to the front of the control fascia (mechanism) slider. This prevents the opening of the slider.
[0035] FIG. 1 illustrates a front view of the switching device interlock mechanism in 'OFF' condition according to one embodiment of the present invention. With respect to FIG. 1, the switching device interlock mechanism comprises, a interlock guiding plate 101 which guides switching device interlock plate during the up-down movement, a interlock lever 102 which is fixed with switching device shaft, a interlock lever fixing bracket 103 which changes according to changes of switching device shaft cross-section and shape, a interlock locking plate 104 which prevents the opening of control fascia slider during switching device in 'ON' condition. The switching device interlock mechanism further comprises of a interlock plate 105which

moves vertically (up-down) and during switching device is in 'ON' condition the interlock plate is inserted into module tray, a control fascia slider 106, wherein by moving control fascia slider mechanism handle is inserted into mechanism shaft, a switching device shaft 107 and a short circuit protection device (SCPD) 108 or switching device which is interlocked in the switching board using the interlock mechanism.
[0036] When switching device is in 'OFF' condition, the module feeder position (i.e. Service, test, Isolation) can be changed by operating mechanism and module can be draw-out from the panel. The interlock lever 102 rotates with switching devices ROM shaft. An interlock plate 105 is connected with interlock leverl02and with the interlock plate 105 a locking bracket 104 is fixed. Interlock lever 102 is mounted in such a way that, with the 90° rotation of switching device handle shaft 107, lever rotation will be +45° to-45° and vice versa in 360° quadrant system for almost linear rotation of interlock plate J 05. Whern the switching device is in 'OFF' the position of the interlock plate 105 is inside the module and interlock locking bracket 103 is above the mechanism control fascia slider 106. During this the module can be removed from panel or mechanism can be operated by opening the mechanism control fascia slider 106.
[0037] FIG. 2 illustrates an isometric view of the switching device interlock mechanism in 'OFF' condition according to one embodiment of the present invention.
[0038] FIG. 3 illustrates a front view of the switching device interlock mechanism in 'ON' condition according to one embodiment of the present invention. When switching device is in 'ON' condition module position cannot be change, because during this period mechanism handle can't be inserted in the control fascia 106. This is due to switching device interlock bracket prevents the opening of control fascia slider 106. More over the switching device interlock plate 104 is also inserted into tray (fixed with panel), that prevent pull out (withdrawal) of module from panel. When switching device is in 'ON' position interlock plate 104 is moved downward direction and inserted into tray which is fixed with panel. This condition prevents the module to be removed (Draw-out) from panel. With the movement of the interlock plate 104, the

locking bracket 103 is also moved in downward direction and comes to the front of control fascia (mechanism) slider 106. This further prevents the opening of the slider.
[0039] FIG. 4 illustrates an isometric view of the switching device interlock mechanism in 'ON' condition according to one embodiment of the present invention.
[0040] FIG. 5 illustrates an isometric view of interlock guiding plate used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0041] FIG. 6 illustrates an isometric view of interlock lever used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0042] FIG. 7 illustrates an isometric view of interlock lever fixing bracket used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0043] FIG. 8 illustrates an isometric view of interlock locking plate used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0044] FIG. 9 illustrates an isometric view of interlock plate used in the operation of switching device interlock mechanism device according to one embodiment of the present invention.
[0045] FIG. 10 illustrates an isometric view of control fascia slider used in the operation of switching device interlock mechanism according to one embodiment of the present invention.
[0046] FIG. 11 illustrates an isometric view of switching device shaft used in the operation of switching device interlock mechanism according to one embodiment of the present invention.

[0047] FIG. 12 illustrates an isometric view of short circuit protection device which is interlocked with the switchboard according to one embodiment of the present invention.
G) ADVANTAGES OF THE INVENTION
[0048] The various embodiments of the present invention provide an interlock mechanism for switching device in switchboards. The present invention ensures that withdrawal of module and operation of module will be take place only when switching device is in 'OFF' condition. It also avoids the possibility of arcing during module operation (i.e. Service to Test and Vice-versa) and withdrawal of module from panel.
[0049] The interlock operation depends upon the switching device handle shaft and it actuates when the switching device handle rotates. Switching device handle rotation is angular rotation, but this interlock move in linear direction. For achieving almost linear rotation of the interlock plate with angular rotation of switching device handle, the shaft fixing lever is made in such way that with the rotation of 90° rotates switching device handle which further rotates lever to +45° to -45° in 360° quadrant and vice-versa during 'ON' and 'OFF' operation of switching device.
[0050] The present invention also provides a mechanism where the interlock lever is fixed with switching device handle shaft and unchanged irrespective of shaft shape. The variation of lever is minimized by making unique lever, only changing one simple bracket which depends upon the shaft shape. The present invention also solves the problem of inventory of different types of complicated lever according to various shaft designs.
[0051] 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.

[0052] 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.

CLAIMS
What is claimed is:
1. An interlock mechanism for switching devices, the mechanism comprising:
a shaft;
a interlock lever attached to the shaft;
a interlock locking plate connected to the interlock lever;
a interlock guiding plate;
a interlock lever fixing bracket; and
a control fascia slider;
wherein the interlock lever is mounted in such a way that a 90° rotation of the
shaft causes the interlock lever to rotate at an angle of +45° to-45° and vice
versa to provide for a linear rotation of the interlock plate.
2. The mechanism according to claim 1, wherein the switching device interlock plate is inserted into a tray which is fixed with a panel.
3. The mechanism according to claim 1, wherein the interlock guiding plate is adapted to guide the the switching device interlock plate during an up-down movement of the plate.
4. The mechanism according to claim 1, wherein the interlock plate is inside a
module and the interlock locking bracket is above the control fascia slider when
the switching device is in OFF position.
5. The mechanism according to claim 1, wherein the interlock plate is inserted into a tray when the switching device is in ON position.
6. The mechanism according to claim 1, wherein the locking bracket comes to the front of the control fascia slider thereby preventing the opening of the control fascia slider.

7. The mechanism according to claim 1, wherein the interlock is actuated with a rotation of the switching device shaft.