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 CHANGE-OVER SWITCH
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 switching devices like switch assemblies, circuit breakers etc. The present invention particularly relates to a changeover switch or transfer switches assembly with mechanical interlock mechanism to interconnect power from two alternate power supplies. The present invention more particularly relates to a mechanism for providing complete electrical isolation between the two alternate power supplies.
B) BACKGROUND OF THE INVENTION
[0002] Transfer switches are well known in art. The transfer switches are used to vary source of electrical power to a load between a primary source, usually called "main" source, and a secondary source, usually called "emergency" source. The main source is most often a private or public supplier of electricity, generating electricity from a power station and supplying power to the load. The emergency source is most often a generator, an inverter, a fuel cell or a solar cell located nearby, designed to supply electrical power for relatively short period during event of power failure or instability at the main source. The transfer switch typically comprises a pair of circuit interrupters combined with a drive mechanism, a linkage mechanism and a selection mechanism.
[0003] The drive and linkage mechanisms are either mechanical or electrical in nature. In mechanical systems, usually motors are preferred, but at other times, there is a clear preference for manually operated drive mechanisms. The selection mechanism is either an automatic selection or manual selection. In manual selection, for example, to supply power from the emergency source to the load, an operator opens the main source circuit interrupter and closes the emergency source circuit interrupter. Moreover, the time involved in transferring power between failed main source and the emergency source must be short in the transfer switch applications.
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[0004] In current scheme, switchgear is provided with a double-decker switch disconnector, which sandwiches two mechanism modules connected with an interlock module. The mechanism includes a shaft connected to interlocking component. One end of connecting link is connected between an interlocking component and one end of a pivoted link. The pivoted link is pivotally moved at centre and the other end of the connecting link is connected to bridge. The bridge houses the moving contacts. A torsion spring is connected to the free end of the pivoted link. Thus the connecting link, the pivoted link and the torsion spring form an actuating mechanism which operates one switch disconnector. Accordingly there exists another actuating mechanism to operate a second switch disconnector. Further the operations of the two actuating mechanisms are interlocked using an interlock mechanism. However the two mechanisms that are arranged one above the other require depth wise more space during the installation. The single torsion spring used per switch leads to increase the spring stress and decrease the net spring force.
[0005] In light of the foregoing discussion, there exists a need to provide a mechanical interlock mechanism for complete electrical isolation between the main source and the emergency source for delivering power to the load. There is also a need to provide positive mechanical interlock mechanism between the two switches ensuring that one switch is in ON state while the other is in OFF state or vice versa, or both of the switches are in OFF state at a time. Also there exists a need to provide a mechanical interlock mechanism with two torsion springs leading to reduction in spring stress and increase in net spring force. Further there exists a need to provide the transfer switch with a single mechanism having two dead centres. Moreover there exists a need to provide a depth and width wise compact transfer switch design with reliable torque efficiency for mechanical interlocking between the two switches.
[0006] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
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C) OBJECT OF THE INVENTION
[0007] 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.
[0008] The primary object of the invention is to develop a mechanical interlock device and method for actuating a transfer switch to provide a complete electrical isolation between a main source and an emergency source for delivering power to the load.
[0009] Another object of the invention is to develop a mechanical interlock device and method for actuating a transfer switch to provide positive mechanical interlock mechanism between the two switches ensuring that one switch is in ON state while the other is in OFF state or vice versa, or both of the switches are in OFF state at a time.
[0010] Yet another object of the invention is to develop a mechanical interlock device and method for actuating a transfer switch, with a single mechanism having two dead centres.
[0011] Yet another object of the invention is to develop a mechanical interlock device which has depth and width wise compact transfer switch design for mechanical interlocking between the two switches.
[0012] Yet another object of the invention is to develop a mechanical interlock device and method for actuating a transfer switch to reduce the spring stress and to increase the net spring force during the actuation of transfer switch.
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[0013] Yet another object of the invention is to develop a mechanical interlock device and method for actuating a transfer switch to provide reliable torque efficiency.
D) SUMMARY OF THE INVENTION
[0014] The various embodiments of the present invention provide a mechanical interlock device and method for actuating a transfer switch to provide a complete electrical isolation between a main source and an emergency source. The device provides a positive mechanical interlock mechanism between the two switches ensuring that one switch is in ON state while the other is in OFF state or vice versa, or both of the switches are in OFF state at a time.
[0015] According to one embodiment of the present invention, an interlock mechanism is provided for a change over switch provided with two switches that are connected respectively to two different power supplies. The interlock mechanism has an operating handle connected to a driver. A rack is connected to the driver. A first switch is connected to the driver through the rack. A first slotted gear is connected to the first switch to engage with the rack. A first bridge pin is coupled to the first slotted gear. A first torsion spring is connected to the first slotted gear.
[0016] A second switch is connected to the driver through the rack. A second slotted gear is provided in the second switch to engage with the rack. A second bridge pin is coupled to the second slotted gear. A second torsion spring is connected to the second slotted gear. A mechanism plate is provided between the two switch housings provided with the first and the second switch components respectively. A first horizontal slot is provided below the rack on the mechanism plate to receive the first bridge pin. A second horizontal slot is provided below the rack on the mechanism plate to receive the second bridge pin.
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[0017] The operating handle is rotated in clock wise direction to operate the driver to move the rack in forward direction to rotate the first slotted gear in anti-clock wise direction to move the first bridge pin along the first horizontal slot to turn the first switch to ON position, when the first switch is turned to ON position and the second switch to OFF position. The operating handle is rotated in anti clock wise direction to operate the driver to move the rack in reverse direction to rotate the second slotted gear in clock wise direction to move the second bridge pin along the second horizontal slot to turn the second switch to ON position, when the second switch is turned to ON position and the first switch to OFF position.
[0018] The driver is provided with a gear mechanism to engage with the rack
to transmit the rotary motion of the operating handle to the rack. The rack is provided with a first gear mechanism to engage with the driver through the gear in the driver. The rack is provided with a second gear mechanism to engage with the first slotted gear to rotate the first slotted gear to move the bridge pin along the first horizontal slot, when the first switch is turned from ON to OFF position or vice versa. The rack is provided with a third gear mechanism to engage with the second slotted gear to rotate the second slotted gear to move the bridge pin along the second horizontal slot, when the second switch is turned from ON to OFF position or vice versa.
[0019] Both the first bride pin and the second bride pin are at the centre of the
mechanism plate, when both the first switch and the second switch are in OFF position. The first bridge pin is moved along the first horizontal slot from the left end of the first horizontal slot to the right end of the first horizontal slot and vice versa, accordingly when the first switch is moved from the OFF to ON position and vice versa. The second bridge pin is moved along the second horizontal slot from the right end of the second horizontal slot to the left end of the second horizontal slot and vice versa, accordingly when the second switch is moved from the OFF to ON position and vice versa.
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[0020] The first slotted gear and the second slotted gear are arranged in a
vertical direction. The first slotted gear has an arm provided with a slot to receive the first bridge pin so that the rotary motion of the first slotted gear is transformed into the translational motion of the first bridge pin along the first horizontal slot. The second slotted gear has an arm provided with a slot to receive the second bridge pin so that the rotary motion of the second slotted gear is transformed into the translational motion of the second bridge pin along the second horizontal slot.
[0021] The torsion spring is connected to the first slotted gear and to the
mechanism plate. The second torsion spring is connected to the second slotted gear and to the mechanism plate. The first and second torsion springs are charged continuously respectively during the movement of the first and second switches from the ON/OFF position to the dead center position and releases the stored energy during the movement of the first and second switches from the dead center position to OFF/ON positions. Both the first and the second torsion springs are helical springs. Both the first and the second torsion springs have maximum potential energy at the dead center position. The first and the second torsion springs are said to be pre-compressed in OFF or ON position of the first and second switches. The speeds of the helical springs are manually dependent during the movement of the switches from the ON/OFF position to the dead center position. The speeds of the helical springs are manually independent during the movement of the switches from the dead center position to ON/OFF position.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0022] 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:
[0023] FIG. 1 illustrates a top side perspective view of a transfer switch according to one embodiment of the present invention.
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[0024] FIG. 2 illustrates an exploded perspective view of a transfer switch according to one embodiment of the present invention.
[0025] FIG. 3 illustrates a top view of an interlock mechanism of a transfer switch in different orientation according to one embodiment of the present invention.
[0026] FIG. 4 illustrates a top view of an interlock mechanism when both the top switch (switch I) and the bottom switch (switch II) of transfer switch are in OFF state according to one embodiment of the present invention.
[0027] FIG. 5 illustrates a bottom view of an interlock mechanism showing the meshing and de-meshing of a rack when both the top switch (switch I) and the bottom switch (switch II) of a transfer switch are in OFF state according to one embodiment of the present invention.
[0028] FIG. 6 illustrates a top view of an interlock mechanism, with the intermediate position of the mechanism between OFF state and dead centre while turning the top switch (switch I) of transfer switch from OFF state to ON state according to one embodiment of the present invention.
[0029] FIG. 7 illustrates a bottom view of an interlock mechanism showing the position of the rack when the mechanism attains an intermediate position between OFF state and dead centre while turning the top switch (switch I) of transfer switch from OFF state to ON state, according to one embodiment of the present invention.
[0030] FIG. 8 illustrates a top view of an interlock mechanism at the dead centre position while turning the top switch (switch I) of transfer switch from OFF state to ON state according to one embodiment of the present invention. [0031] FIG. 9 illustrates a bottom view of an interlock mechanism showing the position of rack when the mechanism attains dead centre position while turning the
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top switch (switch I) of transfer switch from OFF state to ON state, according to one embodiment of the present invention.
[0032] FIG. 10 illustrates a top view of an interlock mechanism, with the intermediate position of the mechanism between the dead centre and ON state while turning the top switch (switch I) of transfer switch from OFF state to ON state according to one embodiment of the present invention.
[0033] FIG. 11 illustrates a bottom view of an interlock mechanism indicating the position of rack when the mechanism attains an intermediate position between the dead centre and ON state while turning the top switch (switch I) of transfer switch from OFF state to ON state, as shown in FIG. 10 according to one embodiment of the present invention.
[0034] FIG. 12 illustrates a top view of an interlock mechanism with the top switch (switch I) of transfer switch at ON state and bottom switch (switch II) of transfer switch at OFF state according to one embodiment of the present invention.
[0035] FIG. 13 illustrates a bottom view of an interlock mechanism indicating the position of rack, when the top switch (switch I) of transfer switch is at ON state and the bottom switch (switch II) of transfer switch is at OFF state, according to one embodiment of the present invention.
[0036] FIG. 14 illustrates a top view of an interlock mechanism, with the intermediate position of the mechanism between the OFF state and dead centre while turning the bottom switch (switch II) of transfer switch from OFF state to ON state according to one embodiment of the present invention.
[0037] FIG. 15 illustrates a bottom view of an interlock mechanism indicating the position of rack when the mechanism attains an intermediate position between OFF
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state and dead centre while turning bottom switch (switch II) of transfer switch from OFF state to ON state, according to one embodiment of the present invention.
[0038] FIG. 16 illustrates a top view of an interlock mechanism at dead centre position while turning the bottom switch (switch II) of transfer switch from the OFF state to ON state according to one embodiment of the present invention.
[0039] FIG. 17 illustrates a bottom view of an interlock mechanism indicating the position of rack when the mechanism attains a dead centre position while turning the bottom switch (switch II) of transfer switch from OFF state to ON state, according to one embodiment of the present invention.
[0040] FIG. 18 illustrates a top view of an interlock mechanism, with the intermediate position of the mechanism between dead centre and ON state while turning bottom switch (switch II) of transfer switch from OFF state to ON state, according to one embodiment of the present invention.
[0041] FIG. 19 illustrates a bottom view of an interlock mechanism indicating the position of a rack when the mechanism attains an intermediate position between the dead centre and ON state while turning the bottom switch (switch II) of transfer switch from OFF state to ON state, according to one embodiment of the present invention.
[0042] FIG. 20 illustrates a top view of an interlock mechanism with the bottom switch (switch II) of transfer switch at ON state and top switch (switch I) of transfer switch at OFF state according to one embodiment of the present invention.
[0043] FIG. 21 illustrates a bottom view of an interlock mechanism indicating the position of a rack, when the bottom switch (switch II) of transfer switch is at ON state and top switch (switch I) of transfer switch is at OFF state, according to one embodiment of the present invention.
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[0044] Although the 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
[0045] In the following detailed description, a 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.
[0046] The various embodiments of the present invention provide a mechanical interlock device and method for transfer switch for providing a complete electrical isolation between a main source and an emergency source. The device provides a positive mechanical interlock mechanism between the two switches ensuring that one switch is in ON state and the other is in OFF state or vice versa, or both of the switches are in OFF state at a time.
[0047] According to one embodiment of the present invention, an interlock mechanism is provided for a change over switch provided with two switches that are connected respectively to two different power supplies. The interlock mechanism has an operating handle connected to a driver. A rack is connected to the driver. A first switch is connected to the driver through the rack. A first slotted gear is connected to the first switch to engage with the rack. A first bridge pin is coupled to the first slotted gear. A first torsion spring is connected to the first slotted gear.
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[0048] A second switch is connected to the driver through the rack. A second slotted gear is provided in the second switch to engage with the rack. A second bridge pin is coupled to the second slotted gear. A second torsion spring is connected to the second slotted gear. A mechanism plate is provided between the two switch housings provided with the first and the second switch components respectively. A first horizontal slot is provided below the rack on the mechanism plate to receive the first bridge pin. A second horizontal slot is provided below the rack on the mechanism plate to receive the second bridge pin.
[0049] The operating handle is rotated in clock wise direction to operate the driver to move the rack in a forward direction to rotate the first slotted gear in anticlock wise direction to move the first bridge pin along the first horizontal slot to turn the first switch to ON position, when the first switch is turned to ON position and the second switch to OFF position. The operating handle is rotated in anti clock wise direction to operate the driver to move the rack in reverse direction to rotate the second slotted gear in clock wise direction to move the second bridge pin along the second horizontal slot to turn the second switch to ON position, when the second switch is turned to ON position and the first switch to OFF position.
[0050] The driver is provided with a gear mechanism to engage with the rack
to transmit the rotary motion of the operating handle to the rack. The rack is provided with a first gear mechanism to engage with the driver through the gear in the driver. The rack is provided with a second gear mechanism to engage with the first slotted gear to rotate the first slotted gear to move the bridge pin along the first horizontal slot, when the first switch is turned from ON to OFF position or vice versa. The rack is provided with a third gear mechanism to engage with the second slotted gear to rotate the second slotted gear to move the bridge pin along the second horizontal slot, when the second switch is turned from ON to OFF position or vice versa.
[0051 ] Both the first bride pin and the second bride pin are at the centre of the
mechanism plate, when both the first switch and the second switch are in OFF
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position. The first bridge pin is moved along the first horizontal slot from the left end of the first horizontal slot to the right end of the first horizontal slot and vice versa, accordingly when the first switch is moved from the OFF to ON position and vice versa. The second bridge pin is moved along the second horizontal slot from the right end of the second horizontal slot to the left end of the second horizontal slot and vice versa, accordingly when the second switch is moved from the OFF to ON position and vice versa.
[0052] The first slotted gear and the second slotted gear are arranged in a
horizontal direction. The first slotted gear has an arm provided with a slot to receive the first bridge pin so that the rotary motion of the first slotted gear is transformed into the translational motion of the first bridge pin along the first horizontal slot. The second slotted gear has an arm provided with a slot to receive the second bridge pin so that the rotary motion of the second slotted gear is transformed into the translational motion of the second bridge pin along the second horizontal slot.
[0053] The torsion spring is connected to the first slotted gear and to the
mechanism plate. The second torsion spring is connected to the second slotted gear and to the mechanism plate. The first and second torsion springs are charged continuously respectively during the movement of the first and second switches from the ON/OFF position to the dead center position and releases the stored energy during the movement from the dead center position to OFF/ON positions. Both the first and the second torsion springs are helical springs. Both the first and the second torsion springs have maximum potential energy at the dead center position. The first and the second torsion springs are said to be pre compressed in OFF or ON position of the first and second switches. The speeds of the helical springs are manually dependent during the movement of the switch from the ON/OFF position to the dead center position. The speeds of the helical springs are manually independent during the movement of the switch from the dead center position to ON/OFF position.
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[0054] FIG. 1 illustrates a top side perspective view of a transfer switch according to one embodiment of the present invention. With respect to FIG. 1, the transfer switch is provided with two switches such as a top switch (switch I) 1 and a bottom switch (switch II) 2. For example a main power source is fed at the input of top switch (switch I) 1 and an emergency power supply is fed at the input of bottom switch (switch II) 2. An interlock device is provided in the transfer switch to provide a complete electrical isolation between a main source and an emergency source for delivering power to load. The transfer switch provides complete isolation between the main source supply and the emergency power supply such that only one power supply gets connected to the load at a time.
[0055] The transfer switch provides a positive mechanical interlock mechanism between the two switches ensuring switch (I) 1 is in ON state and the switch (II) 2 is in OFF state or switch (I) 1 is in OFF state and the switch (II) 2 is in ON state, or both of the switches 1, 2 are in OFF state at a time. The top switch 1 is provided with an assembly of terminals, bridge, housing and cover mounted on top of the mechanical interlock mechanism. The bottom switch 2 is provided with an assembly of terminals, bridge, housing and cover mounted on bottom side of the mechanical interlock mechanism.
[0056] In various embodiments of the present invention, it is imperative that not more than one switch that is either switch (I) 1 or switch (II) 2 is in ON state and either both of the switches the switch (I) 1 and the switch (II) 2 are in OFF state. Means of ensuring that switch (I) 1 is ON state and the switch (II) 2 is in OFF state OR switch (I) 1 is in OFF state and the switch (II) 2 is in ON state at a given time is known as "switch interlocking".
[0057] FIG. 2 illustrates an exploded perspective view of a transfer switch according to one embodiment of the present invention. With respect to FIG. 2 the transfer switch includes a handle 3 made of plastic which acts as an actuating mechanism during the turning of switch I or switch II from ON state to OFF state or
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from OFF state to ON state. A top switch housing 4 is a thermo set plastic part of top switch (the switch I) which guides a bridge from top side to prevent the exposure of internal parts of the switch I by covering the internal parts of switch I. A bottom switch housing 5 is a thermo set plastic part of the top switch. The bottom switch housing 5 guides terminals, bridge from bottom side and mechanical interlock mechanism device from top face. A top switch housing 6 is a thermo set plastic part of bottom switch (the switch II) which guides terminals, bridge from bottom side and mechanical interlock mechanism device from bottom face.
[0058] A bottom switch housing 7 is a thermo set plastic part of the switch II (bottom switch) which guides the bridge from the bottom side to prevent exposure of the internal parts of the switch II by covering the internal parts. A terminal shroud 8 is a plastic housing which covers a box clamp assembly of the transfer switch. Bridge 9 is an assembly of plastic component supporting eight moving contacts made of copper. The bridge 9 reciprocates in the housing due to the force exerted by a bridge pin present in the interlock mechanism. The reciprocation of the bridge 9 in the housing causes the closing or opening of the switch I and switch II making the switches either OFF or ON during the transfer switch actuation. A terminal 10 is a copper component forming the fixed contact of the switch I and the switch II. Both the top switch (switch I) and the bottom switch (switch II) have 8 terminals.
[0059] FIG. 3 illustrates a top view of an interlock mechanism of a transfer switch in different orientation according to one embodiment of the present invention. With respect to FIG. 3, the interlock mechanism is mounted on a mechanism plate 17. The mechanism plate 17 houses or guides driver 11, slotted gears 13a and 13b, bridge pins 14a and 14b, torsion springs 15a and 15b and rack 12. The interlock mechanism provides a complete electrical isolation between a main power source and an emergency power source while transferring the power to a load. Positive interlock mechanism is provided by the interlock mechanism such that at a time only one switch i.e. either switch I (top switch) or switch II (bottom switch) is turned from ON state to OFF state or from OFF state to ON state while transferring power to load, or
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both the switches are at OFF state. The driver 11 made of metal is provided with an operating handle mounted at the top of the mechanical interlock mechanism. The driver 11 is guided to rotate in the bottom switch housing and top switch housing. The driver 11 transmits the rotary motion of the handle to the rack. 12. The rack 12 is a cast component provided in the interlock mechanism to transmit the motion from the driver 11 to the slotted gears 13a and 13b of respective switches, the switch I (top switch) and the switch II (bottom switch).
[0060] The slotted gear 13a and the slotted gear 13b are cast component provided with small number of gear teeth called pinion, are helpful in engaging (meshing) or disengaging (demeshing) with the rack 12. The slotted gear 13a and 13b each are provided with a single slot to accommodate the bridge pin 14a and 14b respectively. The bridge pin 14a and 14b are metallic components provided in the interlock mechanism which translates the motion from the slotted gears 13a and 13b to bridges of respective switches (switch I and switch II). The bridge pin 14a and 14b makes the bridges to translate in respective switches (switch I and switch II). The bridge pin 14a and 14b moves in the single slot provided in the slotted gears 13a and 13b respectively during the transfer of the switch actuation. The bridge pins 14a and 14b translate in the single slot provided in the slotted gear 13a and 13b and the housing of the transfer switch simultaneously. The torsion springs 15a and 15b having helical turns with two arms are provided in the interlock mechanism. One end of the arm of the torsion spring 15a and 15b is fixed to the slotted gear 13a and 13b respectively, whereas the other end of the arm of the torsion spring 15a and 15b are left free. As angle between the two arms of the torsion spring 15a and 15b deviate from its natural free condition, the torsion springs 15a and 15b exert force on the interlock mechanism which is proportional to the angle of deflection. A mechanism spacer 16 is provided in the interlock mechanism to maintain specified a space between the mechanism plates 17.
[0061] In various embodiments of the present invention, a dead centre is a position of the interlock mechanism at which the torsion spring 15a and 15b has maximum
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stored potential energy and ready to release the stored potential energy. When the maximum allowable angle of the torsion spring 15a or 15b mounted in the interlock mechanism is less than the free angle of the torsion spring 15a or 15b, then the torsion spring 15a or 15b is said to be in pre-compressed state.
[0062] In various embodiments of the present invention, output speed or velocity of the bridge pin 14a or 14b is proportionate to the speed with which an operator rotates an operating handle mounted in an interlock mechanism is known as "manual dependent" interlock mechanism. The output speed or velocity of the bridge pin 14a or 14b is disproportionate to the speed with which an operator rotates the operating handle mounted in an interlock mechanism is known as "manual independent" interlock mechanism.
[0063] FIG. 4 illustrates a top view of an interlock mechanism when both the top switch (switch I) and the bottom switch (switch II) of transfer switch are in OFF state according to one embodiment of the present invention. With respect to FIG. 4, the, two slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of the two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are left free. Two bridge pins 14a and 14b are provided in slot present in the slotted gears 13a and 13b respectively, when the switch I and the switch II are in OFF state. In that position, no power is supplied to load, bridge pin 14a, 14b and slotted gear 13a, 13b come towards the centre of the interlock mechanism. Two torsion springs 15a, 15b are in released condition. Teeth provided in driver 11 are engaged with the rack 12.
[0064] FIG. 5 illustrates a bottom view of an interlock mechanism indicating the meshing and demeshing of the rack when both the top switch (switch I) and bottom switch (switch II) of transfer switch are in OFF state according to one embodiment of the present invention. With respect to FIG. 5 & 6 two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two
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torsion springs 15a and 15b are left free. Two bridge pins 14a and 14b are provided in slot present in the slotted gears 13a and 13b respectively, when the switch I and the switch II are in OFF state; no power is supplied to the load, bridge pin 14a, 14b and slotted gear 13a, 13b come towards the centre of the interlock mechanism. Two torsion springs 15a, 15b are in released condition. Gear teeth provided in the slotted gear 13a and 13b are disengaged from rack 12 as shown in the figure.
[0065] FIG. 6 illustrates a top view of an interlock mechanism, with intermediate position of the mechanism between the OFF state and dead centre while turning the top switch (switch I) of the transfer switch from the OFF state to ON state according to one embodiment of the present invention. With respect to FIG. 6, two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of the two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are left free. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in clockwise direction as indicated in the figure. The clockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13b in anticlockwise direction as indicated in the figure. The torsion spring 15b gets charged and potential energy is stored in the torsion spring 15b simultaneously, due to anticlockwise rotation of the slotted gear 13b.
[0066] During the charging process of the torsion spring 15b, the torsion spring 15b gets deflected and angle between the two arms of the torsion spring 15b is reduced. The bridge pin 14b is moved in a direction as shown in figure due to anticlockwise rotation of the slotted gear 13b. Thus the slotted gear 13b of the interlock mechanism attains an intermediate position between the OFF state and dead centre while turning the top switch (switch I) from the OFF state to ON state. Further, the velocity of the bridge pin 14b depends on the manual speed of rotation of the handle in clockwise direction, while the slotted gear 13b of the interlock mechanism attains an
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intermediate position between OFF state and dead centre. The bridge pin 14b motion is lost in a bridge slot provided in the slotted gear 13b, while the slotted gear 13b of the interlock mechanism attains an intermediate position between OFF state and dead centre.
[0067] FIG. 7 illustrates a bottom view of an interlock mechanism indicating the position of a rack, when the mechanism attains an intermediate position between OFF state and dead centre while turning the top switch (switch I) of transfer switch from OFF state to ON state according to one embodiment of the present invention. With respect to FIG. 7, two slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are connected to the mechanism plate. Two bridge pins 14a and 14b are provided in the slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in clockwise direction as indicated in the figure. The slotted gear 13b of the interlock mechanism attains an intermediate position between the OFF state and dead centre, while turning the top switch (switch I) from OFF state to ON state. The teeth of the rack 12 are partially meshed with the gear teeth of the slotted gear 13b causing anticlockwise rotation of the slotted gear 13b.
[0068] FIG. 8 illustrates a top view of the interlock mechanism at a dead centre position while turning the top switch (switch I) of the transfer switch from the OFF state to ON state according to one embodiment of the present invention. With respect to FIG. 8, two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are left free. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in clockwise direction as indicated in the figure. The clockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the
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rack 12 leads to rotation of the slotted gear 13b in anticlockwise direction as indicated in the figure. The torsion spring 15b gets charged and potential energy is stored in the torsion spring 15b simultaneously, due to anticlockwise rotation of the slotted gear 13b. The bridge pin 14b is moved in a direction as shown in figure due to anticlockwise rotation of the slotted gear 13b. The torsion spring 15b gets completely charged until the angle between two arms of the torsion spring 15b reaches to lowest possible value at the dead centre. Hence, maximum potential energy gets stored in the torsion spring 15b. Thus, the slotted gear 13b of the interlock mechanism attains a dead centre position while turning the top switch (switch I) of the transfer switch from OFF state to ON state.
[0069] FIG. 9 illustrates a bottom view of an interlock mechanism showing position of rack, when the mechanism attains dead centre position while turning the top switch (switch I) of transfer switch from OFF state to ON state, according to one embodiment of the present invention. With respect to FIG. 9, two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are connected to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in clockwise direction as indicated in the figure. The slotted gear 13b of the interlock mechanism attains dead centre position, while turning the top switch (switch I) of transfer switch from OFF state to ON state as illustrated in FIG. 8. The teeth in the rack 12 are altogether meshed with gear teeth of the slotted gear 13b causing anticlockwise rotation of the slotted gear 13b.
[0070] FIG. 10 illustrates a top view of an interlock mechanism, with the intermediate position of the mechanism between dead centre and ON state while turning the top switch (switch 1) of transfer switch from OFF state to ON state according to one embodiment of the present invention. With respect to FIG. 10, two
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slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are connected to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on driver 11 is manually rotated in clockwise direction as indicated in the figure. The clockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13b in anticlockwise direction as indicated in the figure.
[0071] The torsion spring 15b gets completely charged until the angle between two arms of the torsion spring 15b reaches to lowest possible value and attains dead centre position as illustrated in FIG. 8. Once the slotted gear 13b attains a dead centre position, stored energy from the torsion spring 15b is released gradually. The two arms of the torsion spring 15b tend to move away from each other to acquire free condition. The bridge pin 14b tends to move towards right side as indicated by an arrow. Thus the slotted gear 15b attains an intermediate position between the dead centre and ON state while turning the top switch (switch I) of transfer switch from OFF state to ON state. Further, the velocity of the bridge pin 14b is manually independent of the speed of rotation of the handle in clockwise direction, while the slotted gear 15b attains an intermediate position between dead centre and ON state. The velocity of the bridge pin 14b is decided by the released force of the torsion spring 15b while the slotted gear 15b attains an intermediate position between dead centre and ON state.
[0072] FIG. 11 illustrates a bottom view of an interlock mechanism showing the position of rack when the mechanism attains intermediate position between dead centre and ON state while turning top switch (switch I) of transfer switch from OFF state to ON state, as shown in FIG. 10 according to one embodiment of the present invention. With respect to FIG. 11, two slotted gears 13a and 13b are fixed to a
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rack 12 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are connected to a mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in clockwise direction as indicated in the figure. The slotted gear 13b of the interlock mechanism attains an intermediate position between the dead centre and ON state, while turning the top switch (switch I) of transfer switch from OFF state to ON state as illustrated in FIG. 10. The teeth in the rack 12 are partially meshed with gear teeth of the slotted gear 13b causing anticlockwise rotation of the slotted gear 13b.
[0073] FIG. 12 illustrates a top view of an interlock mechanism with top switch (switch I) of transfer switch at ON state and bottom switch (switch II) of transfer switch at OFF state according to one embodiment of the present invention. With respect to FIG. 12, two slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of the two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a ■ and 15b are left free. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in clockwise direction as indicated in the figure. The clockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13b in anticlockwise direction as indicated in the figure.
[0074] The torsion spring 15b gets completely charged until angle between two arms of the torsion spring 15b reaches to lowest possible value and attains dead centre position as illustrated in FIG. 8. Once the slotted gear 13b attains a dead centre position, stored energy from the torsion spring 15b is released gradually as illustrated in the FIG. 10. Following the gradual release of potential energy stored in the torsion
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spring 15b, the slotted gear 13b crosses the dead centre position. The released force from the spring 15b tends to move the slotted gear 13b in anticlockwise direction. The bridge pin 14b is moved to its right most position with a greater velocity by virtue of the force released from the torsion spring 15b. Thus the top switch (switch I) is turned to ON state and the bottom switch (switch II) is kept in OFF position. Once the slotted gear 13b crosses the dead centre position, the bridge associated with the top switch (switch I) is moved along with the bridge pin 14b, ensuring the motion of bridge and contacts housed in the bridge to be manually independent and dependent on the torsion spring 15b release force.
[0075] FIG. 13 illustrates a bottom view of an interlock mechanism showing the position of rack, when top switch (switch I) of transfer switch is at ON state and bottom switch (switch II) of transfer switch is at OFF state, according to one embodiment of the present invention. With respect to FIG. 13, two slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the top switch from OFF state to ON state, a handle mounted on driver 11 is manually rotated in clockwise direction as indicated in the figure. The clockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13b in anticlockwise direction as indicated in the figure. The top switch (switch I) attains ON state and the bottom switch (switch II) remains in OFF position. The teeth in the rack 12 are partially meshed with gear teeth of the slotted gear 13b causing anticlockwise rotation of the slotted gear 13b, and making the top switch ON.
[0076] In various embodiments of the present invention, to change top switch (switch I) from ON state to OFF state, handle mounted on the driver 11 is manually rotated in anticlockwise direction. The anticlockwise rotation of the handle causes
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rack 12, slotted gear 13b, and bridge pin 14b to be moved exactly in opposite direction as that while turning the top switch (switch I) from OFF state to ON state. Thus the bridge pin 14b is moved to its left most position from right most position (as shown in FIG. 12). During turning of the top switch from ON state to OFF state, the torsion spring 15b gets charged from ON to dead centre position and the charged energy is released from dead centre to OFF position. The bridge pin 14b loses its motion in a bridge slot provided in the slotted gear 13b, while the slotted gear 13a reaches from ON to dead centre position. Bridge associated with the top switch is moved along with the bridge pin 14b, ensuring motion of the bridge and contacts housed in the bridge to be manually independent and dependent of the torsion spring 15b release force, while the slotted gear 13a reaches from dead centre to OFF state.
[0077] FIG. 14 illustrates a top view of an interlock mechanism, with intermediate position of the mechanism between OFF state and dead centre while turning the bottom switch (switch II) of transfer switch from OFF state to ON state according to one embodiment of the present invention. With respect to FIG. 14 two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state a handle mounted on driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The clockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13a in clockwise direction as indicated in the figure. The torsion spring 15a gets charged and potential energy is stored in the torsion spring 15a simultaneously, due to clockwise rotation of the slotted gear 13a.
[0078] During the charging process of the torsion spring 15a, the torsion spring 15a gets deflected and the angle between the two arms of the torsion spring 15a is reduced. The bridge pin 14a is moved in a direction as shown in figure due to
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clockwise rotation of the slotted gear 13a. Thus the slotted gear 13a of the interlock mechanism attains an intermediate position between the OFF state and dead centre, while turning the bottom switch (switch II) from OFF state to ON state. Further, the velocity of the bridge pin 14a depends on the manual speed of rotation of the handle in anticlockwise direction, when the slotted gear 13a of the interlock mechanism attains intermediate position between OFF state and dead centre. The motion of the bridge pin 14a is lost in a bridge slot provided in the slotted gear 13a, while the slotted gear 13a of the interlock mechanism attains an intermediate position between OFF state and dead centre.
[0079] FIG. 15 illustrates a bottom view of interlock mechanism showing position of rack when the mechanism attains an intermediate position between OFF state and dead centre, while turning the bottom switch (switch II) of transfer switch from OFF state to ON state, according to one embodiment of the present invention. With respect to FIG. 15, two slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The slotted gear 13a of the interlock mechanism attains an intermediate position between OFF state and dead centre while turning the bottom switch (switch II) from OFF state to ON state as illustrated in FIG. 14. The teeth in the rack 12 are partially meshed with gear teeth of the slotted gear 13a causing clockwise rotation of the slotted gear 13a.
[0080] FIG. 16 illustrates a top view of an interlock mechanism at dead centre position, while turning the bottom switch (switch II) of transfer switch from OFF state to ON state according to one embodiment of the present invention. With respect to FIG. 16, two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of the two torsion springs 15a and 15b are connected to the
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slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The anticlockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear J 3a in clockwise direction as indicated in the figure. The torsion spring 15a gets charged and potential energy is stored in the torsion spring 15a simultaneously, due to clockwise rotation of the slotted gear 13a. The bridge pin 14a is moved in a direction as shown in figure due to clockwise rotation of the slotted gear 13a. The torsion spring 15a gets completely charged until the angle between the two arms of the torsion spring 15a reaches to lowest possible value at dead centre. Hence, maximum potential energy gets stored in the torsion spring 15a. Thus, the slotted gear 13a of the interlock mechanism attains a dead centre position while turning bottom switch (switch II) of transfer switch from OFF state to ON state.
[0081] FIG. 17 illustrates a bottom view of an interlock mechanism showing the position of rack, when the mechanism attains dead centre position while turning the bottom switch (switch II) of transfer switch from OFF state to ON state, according to one embodiment of the present invention. With respect to FIG. 17, two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism, one end of the two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state, a handle mounted on driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The slotted gear 13a of the interlock mechanism attains dead centre position while turning bottom switch (switch II) of transfer switch from OFF state to ON state as illustrated in FIG. 16. The teeth in the rack 12 are altogether meshed with gear teeth of the slotted gear 13a causing clockwise rotation of the slotted gear 13a.
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[0082] FIG. 18 illustrates a top view of an interlock mechanism, with an intermediate position of the mechanism between dead centre and ON state while turning bottom switch (switch II) of transfer switch from OFF state to ON state according to one embodiment of the present invention. With respect to FIG. 18, two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state, a handle mounted on driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The anticlockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13a in clockwise direction as indicated in the figure.
[0083] The torsion spring 15a gets completely charged until the angle between two arms of the torsion spring 15a reaches to lowest possible value and attains dead centre position as illustrated in FIG. 16. Once the slotted gear 13a attains a dead centre position, the stored energy from the torsion spring 15a is released gradually. The two arms of the torsion spring 15a tend to move away from each other to acquire a free condition. The bridge pin 14a tends to move towards the right side as indicated by an arrow. Thus the slotted gear 15a attains an intermediate position between the dead centre and ON state, while turning the bottom switch (switch II) of transfer switch from OFF state to ON state. Further, the velocity of the bridge pin 14a is manually independent of speed of the rotation of the handle in anticlockwise direction, while the slotted gear 15a attains an intermediate position between dead centre and ON state. The velocity of the bridge pin 14a is decided by the released force of the torsion spring 15a while the slotted gear 13a attains an intermediate position between the dead centre and ON state.
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[0084] FIG. 19 illustrates a bottom view of an interlock mechanism showing the position of rack, when the mechanism attains an intermediate position between the dead centre and ON state while turning bottom switch (switch II) of transfer switch from OFF state to ON state, according to one embodiment of the present invention. With respect to FIG. 19, two slotted gears 13a and 13b are fixed to a rackl2 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to a compression plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The slotted gear 13a of the interlock mechanism attains an intermediate position between a dead centre and ON state while turning bottom switch (switch II) of transfer switch from OFF state to ON state as illustrated in FIG. 18. The teeth in the rack 12 are partially meshed with gear teeth of the slotted gear 13b causing the clockwise rotation of the slotted gear 13b.
[0085] FIG. 20 illustrates a top view of an interlock mechanism with bottom switch (switch II) of transfer switch at ON state and top switch (switch I) of transfer switch at OFF state according to one embodiment of the present invention. With respect to FIG. 20, two slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The anticlockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13a in clockwise direction as indicated in the figure.
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[0086] The torsion spring 15a gets completely charged until the angle between the two arms of the torsion spring 15a reaches to lowest possible value and attains a dead centre position as illustrated in FIG. 16. Once the slotted gear 13a attains a dead centre position, the stored energy from the torsion spring 15a is released gradually as illustrated in the FIG. 18. Following the gradual release of potential energy stored in the torsion spring 15a, the slotted gear 13a crosses the dead centre position. The released force from the spring 15a tends to move the slotted gear 13a in clockwise direction. The bridge pin 14a is moved to its left most position with a greater velocity by virtue of the released force of the torsion spring 15a. Thus the bottom switch (switch II) attains ON state and the top switch (switch I) remains in OFF position. Once the slotted gear 13a crosses the dead centre position bridge associated with the bottom switch is moved along with the bridge pin 14a, ensuring motion of bridge and contacts housed in the bridge to be manually independent and dependent on the torsion spring 15a release force.
[0087] FIG. 21 illustrates a bottom view of an interlock mechanism showing position of rack when bottom switch (switch II) of transfer switch is at ON state and bottom switch (switch II) of transfer switch is at OFF state, according to one embodiment of the present invention. With respect to FIG. 21, two slotted gears 13a and 13b are fixed to a rack 12 of the interlock mechanism. One end of two torsion springs 15a and 15b are connected to the slotted gears 13a and 13b respectively. Other end of the two torsion springs 15a and 15b are fixed to the mechanism plate. Two bridge pins 14a and 14b are provided in a slot present in the slotted gears 13a and 13b respectively. In order to change the bottom switch from OFF state to ON state, a handle mounted on the driver 11 is manually rotated in anticlockwise direction as indicated in the figure. The anticlockwise rotation of the handle leads rack 12 to translate in linear direction as indicated in the figure. Translating motion of the rack 12 leads to rotation of the slotted gear 13a in clockwise direction as indicated in the figure. The bottom switch (switch II) attains ON state and the top switch (switch I) remains in OFF position as illustrated in the FIG. 20. The teeth in the rack 12 are
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partially meshed with gear teeth of the slotted gear 13b causing clockwise rotation of the slotted gear 13a, and making the bottom switch ON.
[0088] In various embodiments of the present invention, to change bottom switch (switch II) from ON state to OFF state, a handle mounted on the driver 11 is manually rotated in clockwise direction. The clockwise rotation of the handle causes rack 12, slotted gear 13 a, and bridge pin 14a to be moved exactly in opposite direction as that while turning the bottom switch (switch II) from OFF state to ON state. Thus the bridge pin 14a is moved to its right most position from left most position (as shown in FIG. 20). During the turning of the bottom switch from ON state to OFF state, the torsion spring 15a gets charged from ON to dead centre position and the charged energy is released from dead centre to OFF position. The bridge pin 14a loses its motion in a bridge slot provided in the slotted gear 13a, while the slotted gear 13a reaches from ON to dead centre position. Bridge associated with the bottom switch is moved along with the bridge pin 14a, ensuring motion of the bridge and contacts housed in the bridge to be manually independent and dependent on the torsion spring 15a release force, while the slotted gear 13a reaches from dead centre to OFF state.
G) ADVANTAGES OF THE INVENTION
[0089] Thus the various embodiments of the present invention provides a mechanical interlock device and method for a transfer switch to providing a complete electrical isolation between a main source and an emergency source for delivering power to load. The transfer switch has single mechanism which attains two dead centres. The transfer switch design provides depth and width wise compactness for mechanical interlocking between two switches. The device leading to reduction in spring stress and increase in net spring force during transfer switch actuation. The transfer switch provides reliable torque efficiency.
[0090] 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
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modifications. However, all such modifications are deemed to be within the scope of the claims.
[0091] 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.
Date: September 16 2009 RAKESH PRABHU
Place: Bangalore. Patent Agent
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CLAIMS
WHAT IS CLAIMED IS:
1. An interlock mechanism for change over switch including two
switches connected to two power supplies, the system comprising:
An operating handle;
A driver connected to the operating handle;
A rack connected to the driver;
A first switch connected to the driver through the rack;
A first slotted gear connected to the first switch to engage with the rack;
A first bridge pin coupled to the first slotted gear;
A first torsion spring connected to the first slotted gear;
A second switch connected to the driver through the rack;
A second slotted gear provided in the second switch to engage with the rack;
A second bridge pin coupled to the second slotted gear;
A second torsion spring connected to the second slotted gear;
A mechanism plate provided between the two switch housings provided with
the first and the second switch components respectively; and
A first horizontal slot provided below the rack on the mechanism plate to
receive the first bridge pin;
A second horizontal slot provided below the rack on the mechanism plate to
receive the second bridge pin;
Wherein the operating handle is rotated in clock wise direction to operate the
driver to move the rack in forward direction to rotate the first slotted gear in
anticlock wise direction to move the first bridge pin along the first horizontal
slot to turn the first switch to ON position, when the first switch is turned to
ON position and the second switch to OFF position.
2. The mechanism according to claim 1, wherein the operating handle is rotated in anti clock wise direction to operate the driver to move the rack in reverse direction to rotate the second slotted gear in clock wise direction to
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move the second bridge pin along the second horizontal slot to turn the second switch to ON position, when the second switch is turned to ON position and the first switch to OFF position.
3. The mechanism according to claim 1, wherein the driver is provided with a gear mechanism to engage with the rack to transmit the rotary motion of the operating handle to the rack.
4. The mechanism according to claim 1, wherein the rack is provided with a first gear mechanism to engage with the driver through the gear in the driver.
5. The mechanism according to claim 1, wherein the rack is provided with a second gear mechanism to engage with the first slotted gear to rotate the first slotted gear to move the bridge pin along the first horizontal slot, when the first switch is turned from ON to OFF position or vice versa.
6. The mechanism according to claim 1, wherein the rack is provided with a third gear mechanism to engage with the second slotted gear to rotate the second slotted gear to move the bridge pin along the second horizontal slot, when the second switch is turned from ON to OFF position or vice versa.
7. The mechanism according to claim 1, wherein both the first bride pin and the second bride pin are at the centre of the mechanism plate, when both the first switch and the second switch are in OFF position.
8. The mechanism according to claim 1, wherein the first bridge pin is moved along the first horizontal slot from the left end of the first horizontal slot to the right end of the first horizontal slot and vice versa, accordingly when the first switch is moved from the OFF to ON position and vice versa.
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9. The mechanism according to claim 1, wherein the second bridge pin is
moved along the second horizontal slot from the right end of the second
horizontal slot to the left end of the second horizontal slot and vice versa,
accordingly when the second switch is moved from the OFF to ON position
and vice versa.
10. The mechanism according to claim 1, the first slotted gear and the second slotted gear are arranged in a vertical direction.
11. The mechanism according to claim 1, wherein the first slotted gear has an arm provided with a slot to receive the first bridge pin so that the rotary motion of the first slotted gear is transformed into the translational motion of the first bridge pin along the first horizontal slot.
12. The mechanism according to claim 1, wherein the second slotted gear has an arm provided with a slot to receive the second bridge pin so that the rotary motion of the second slotted gear is transformed into the translational motion of the second bridge pin along the second horizontal slot.
13. The mechanism according to claim 1, wherein the torsion spring is connected to the first slotted gear and to the mechanism plate.
14. The mechanism according to claim 1, wherein the second torsion spring is connected to the second slotted gear and to the mechanism plate.
15. The mechanism according to claim 1, wherein the first torsion spring
and the second torsion springs are charged continuously during the movement
of the respective first and second switches from the ON/OFF position to the
dead center position and releases the stored energy during the movement from
the dead center position to OFF/ON positions.

16. The mechanism according to claim 1, wherein both the first torsion spring and the second torsion spring are helical springs.
17. The mechanism according to claim 1, wherein both the first torsion spring and the second torsion spring have maximum potential energy at the dead center position.
18. The mechanism according to claim 1, wherein both the first torsion spring and the second torsion springs are said to be pre compressed in OFF or ON position of the first and second switches.
19. The mechanism according to claim 1, wherein the speeds of the torsion springs are manually dependent during the movement of the switch from the ON/OFF position to the dead center position.
20. The mechanism according to claim 1, wherein the speeds of the torsion springs are manually independent during the movement of the switch from the dead center position to ON/OFF position.
Dated this the 16 day of September, 2009

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

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

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