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:
MODULAR AUTOMATIC TRANSFER SWITCH WITH INTERCHANGEABLE INPUT AND OUTPUT POSITIONS
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 transfer switches and particularly relates to automatic transfer switches. The present invention more particularly relates to an automatic transfer switch with a facility to interchange input and output positions.
B) BACKGROUND OF THE INVENTION
[0002] Transfer switches control the switching of power between main and auxiliary power supplies to a load. Automatic transfer switches (ATS) switch between the power sources automatically to ensure continuous supply of power. In an electrical power transfer system sensors detect a power outage. During an outage, various actuating mechanisms are adopted to switch the power to an alternate source.
[0003] Currently, various mechanical switching mechanisms are used to move electrical transfer switch between two power sources. Solenoid plunger is moved by energizing solenoids to rotate contact bars causing movement of switches in an ATS.
[0004] At present all manufacturers of ATS provide switching mechanisms which lack the flexibility to interchange input and output terminals. The interchanging of terminals at onsite is cumbersome and is not cost effective.
[0005] In the current switching mechanisms, the transfer switch moves between fixed terminals of power sources. However, interchanging the positions among power terminals and load at onsite is required to accommodate different orientations of power input and output components. The currently available transfer mechanisms do not facilitate easy and economically viable interchange in terminals.


[0006] Hence there is a need to provide an easy switching mechanism with flexibility to interchange the positions among input and output terminals at onsite.
C) OBJECTS OF THE INVENTION
[0007] The primary object of the present invention is to develop an automatic transfer switch with a facility to interchange input and output positions at onsite.
[0008] Yet another object of the present invention is to develop a compact and cost effective automatic transfer switch to make and break power supply from alternate sources.
[0009] 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
[0010] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
[0011] According to one embodiment of the present invention, an automatic transfer switch device has a housing provided with three contact terminals which are arranged at equal distances. A moving contact is arranged between each of the two contact terminals. An insulation sheet is movably arranged between each of the two contact terminals and connected to a rotating drum provided inside the housing. The rotating drum has geometrical slots at the periphery and an interchanging slot at the top. The insulation sheet has a pin which is received in the slots of the rotating drum so that the insulation sheet is held with the drum and moved along with the drum during the

rotational and translational movement. The rotating drum is rotated to interpose and remove the insulation sheet between the moving contact and the respective two contact terminals to break and make an electrical contact between the respective two contact terminals.
[0012] The rotating drum is rotated outwardly to remove the insulation sheet between the moving contact and the respective two contact terminals to make the moving contact to establish an electrical contact between the respective two contact terminals to make the respective two contact terminals to act as input and output terminals. The rotating drum is rotated inwardly to interpose the insulation sheet between the moving contact and the respective two contact terminals to break the electrical contacts between any two terminals. The rotating drum is rotated by preset angle to switch the input sources.
[0013] The various embodiments of the present invention provide flexibility to interchange input and output positions onsite in a automatic transfer switch (ATS). The interchanging of positions provides a triangular arrangement of contact system.
[0014] Contact between fixed terminals and moving contacts are isolated by insertion of insulation sheets. The insulation sheets are connected to a pin which is slidably attached to slots provided on a cylindrical drum.
[0015] According to one embodiment of the present invention, moving contacts and contact terminals are enclosed in a housing assembly. The housing assembly comprises of cylindrical hole to mount a slidable cylindrical drum. The drum has geometrical slots on the surface. The shapes of the slots are different from each other to ensure specific movement of slidable pins.
[0016] Three movable contacts are placed between the terminals in the housing. Insulation sheets with connecting pins are arranged to be slidably placed between the moving contacts and the terminals. The connecting pins are slidably attached to the
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geometrical slots on the surface of the drum. Ah actuator rotates the drum which slides the connecting pins in the geometrical slots.
[0017] The input and load terminals may be interchanged onsite by pulling out and rotating the drum along an axis. The drum is displaced such that all the three pins fall into interchanging slots of the drum. The actuator rotates the drum by 120, 240 or 360 degrees to interchange the power and load terminals.
[0018] 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.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0019] 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:
[0020] FIG. 1 illustrates a top view of the multipole automatic transfer switch according to an embodiment of the present invention.
[0021] FIG. 1 illustrates a top view of the multipole automatic transfer switch according to an embodiment of the present invention.
[0022] FIG. 2 illustrates a perspective view of the insulation sheet in the automatic transfer switch according to one embodiment of the present invention.
[0023] FIG. 3 illustrates a perspective view of the drum in the automatic transfer switch according to one embodiment of the present invention.
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[0024] FIG. 4 illustrates planar view of the position of insulation sheets in initial position of automatic transfer switch according to one embodiment of the present invention.
[0025] FIG. 5 illustrates a top view of automatic transfer switch in of switched condition according to one embodiment of the present invention.
[0026] FIG. 6 illustrates planar view of the position of connecting pins in the switched condition of automatic transfer switch according to one embodiment of the present invention.
[0027] FIG. 7 illustrates a side perspective view of contacts and insulation and drum assembly in initial condition in the automatic transfer switch according to one embodiment of the present invention.
[0028] FIG. 8 illustrates the side perspective view of contacts, insulation and drum assembly in displaced outward condition of drum in the automatic transfer switch according to one embodiment of the present invention.
[0029] FIG. 9 illustrates the side perspective view of contacts, insulation and drum assembly in rotated condition of drum in the automatic transfer switch during the interchanging of input and output positions according to one embodiment of the present invention.

[0030] FIG. 10 illustrates the side perspective view of the automatic transfer switch after the interchanging of input and output positions and drum displaced inwards i.e. final position according to one embodiment of the present invention.
[0031] FIG.l 1 illustrates planar view of the position of insulation sheets during the interchanging operation of input and output terminals in an automatic transfer switch according to one embodiment of the invention.
[0032] 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 ail of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF INVENTION
[0033] 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.
[0034] The various embodiments of the present invention provide flexibility to interchange input and output positions at onsite in an automatic transfer switch (ATS).
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[0035] According to one embodiment of the present invention, an automatic transfer switch device has a housing provided with three contact terminals which are arranged at equal distances. A moving contact is arranged between each of the two contact terminals. An insulation sheet is movably arranged between each of the two contact terminals and connected to a rotating drum provided inside the housing. The insulation sheet comprises a flat portion and a pin attached to the flat portion. The rotating drum has three geometrical slots formed at the periphery and an interchanging slot formed at the top. The insulation sheet has a pin which is guided by the slots of the rotating drum so that the insulation sheet is held with the drum and moved along with the drum during the rotational and translational movement. The rotating drum is rotated to interpose and remove the insulation sheet between the moving contact and the respective two contact terminals to break and make an electrical contact between the respective two contact terminals.
[0036] The rotating drum is rotated to remove the insulation sheet between the moving contact and the respective two contact terminals to make the moving contact to establish an electrical contact between the respective two contact terminals to make the respective two contact terminals to act as input and output terminals. The rotating drum is rotated to interpose the insulation sheet between the moving contact and the respective two contact terminals to break the electrical contacts between any two terminals. The rotating drum is rotated by preset angle to switch the input sources.
[0037] The contact between fixed terminals and moving contacts are isolated by insertion of insulation sheets. The insulation sheets are connected to a pin which is


slidably attached to slots provided on a cylindrical drum. The slots are provided for holding the pin of each insulation sheet.
[0038] According to one embodiment of the present invention, moving contacts and contact terminals are enclosed in a housing assembly. The housing assembly comprises of cylindrical hole to mount a slidable cylindrical drum. The drum has geometrical slots on the surface. The shapes of the slots are different from each other to ensure specific movement of slidable pins.
[0039] Three movable contacts are placed between the terminals in the housing. Insulation sheets with connecting pins are arranged to be slidably placed between the moving contacts and the terminals. The connecting pins ate slidably attached Vo the geometrical slots on the surface of the drum. An actuator rotates the drum which slides the connecting pins in the geometrical slots. When an insulation sheet is to be moved away from the moving contact the connecting pin attached to the respective insulation sheet is moved in the geometrical slot to displace the insulating sheet away from the terminals thereby establishing an electrical contact between moving contact and two terminals to make the two terminals act as input and output terminals.
[0040] The input and load terminals may be interchanged onsite by pulling out and rotating the drum along an axis. The drum is displaced such that all the three pins fall into interchanging slots of the drum. The actuator rotates the drum by 120, 240 or 360 degrees to interchange the power and load terminals.
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[0041] 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.
[0042] FIG. 1 illustrates a top perspective view of initial condition of automatic transfer switch according to one embodiment of the invention. Auxiliary power source terminal Tl, main power source terminal T3 and output terminal T2 are separated by 120 degrees and partially enclosed.in the housing 1. Moving contact M12 is mounted between terminals Tl and T2. Insulation sheet 112 is displaced between the moving contact M12 and terminals Tl and T2. Insulation sheet 112 isolates the auxiliary terminal from output terminal switching off the auxiliary power source. Moving contact M13 is mounted between terminals Tl and T3. Insulation sheet 113 is displaced between the moving contact Ml3 and terminals Tl and T3. Insulation sheet 113 isolates the auxiliary terminal from main power source to prevent shorting. Moving contact M23 is mounted between terminals T2 and T3. Insulation sheet 123 is displaced away from moving contact M23 and terminals T2 and T3. Main power source terminal T3 is connected to output terminal T2 by moving contact M23.
[0043] A drum 2 is inserted in the centre of the moving contact and terminal assembly. Geometrical slots are made on the surface of drum 2. Connecting pins attached to insulation sheets are slidably fixed to the slots.
[0044] FIG. 2 illustrates the bottom perspective view of the insulation sheet according to one embodiment. Insulation sheet 112 may slide between the moving contact and input or output terminals to break the contact. The insulation sheet 112 moves away from the moving contact and input or output terminals to make the
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contact. The insulation sheet [12 has a connecting pin P12 on one surface which is slidably attached to geometrical slots in drum 2. Insulation sheets 113 and 123 are identical to insulation sheet 112 with connecting pins PI 3 and P23 respectively.
[0045] FIG. 3 illustrates a perspective view of the drum according to one embodiment of the invention. Drum 2 comprises of a cylindrical drum with geometrical slots. An interchanging slot 3 along the circumference of drum 2 is slidably connected to the geometrical slots on the surface of drum 2.
[0046] FIG. 4 illustrates planar view of the position of insulation sheets in initial position of automatic transfer switch according to one embodiment of the invention. In the initial condition, connecting pin P12 is in OFF condition displacing insulation sheet 112 between moving contact M12 and contact terminals Tl, T2 to switch off the auxiliary power source. Connecting pin P13 is in OFF condition displacing insulation sheet 113 between moving contact M13 and contact terminals Tl and T3 to isolate main and auxiliary power. Connecting pin P23 is in ON condition displacing insulation sheet 123 away from moving contact M23 and contact terminals T 2, T3 to switch on main power supply.
[0047] FIG. 5 illustrates a top perspective view of switched condition of automatic transfer switch according to one embodiment of the invention. The actuator rotates drum 2 by X° in the clockwise direction. The connecting pins slide in the slots to displace the insulation sheets towards or away from moving contacts. The rotation of the drum 2 displaces two insulation sheets simultaneously from initial condition to switch off main power supply and switch on auxiliary power supply. Insulation sheet
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112 is displaced away from the moving contact M12 and terminals TI and T2. Auxiliary power source terminal Tl is connected to output terminal T2 by moving contact M12 to switch on the auxiliary power.
[0048] Moving contact M13 is mounted between terminals Tl and T3. Insulation sheet 113 is displaced between the moving contact M13 and terminals Tl and T3. Insulation sheet 113 isolates the auxiliary terminal from main power source to prevent shorting of power. Insulation sheet 123 is displaced between moving contact M23 and terminals T2 and T3. Insulation sheet 123 isolates the main terminal from output terminal switching off the main power source.
[0049] FIG. 6 illustrates planar view of the position of connecting pins in the switched condition of automatic transfer switch according to one embodiment of the invention. In the switched condition, the actuator rotates drum 2 by X° in the clockwise direction. The connecting pins slide along the slots by rotation of drum 2. Connecting pin P12 is in ON condition displacing insulation sheet 112 away from moving contact M12 and contact terminals Tl, T2 to switch on the auxiliary power source. Connecting pin P13 is in OFF condition with insulation sheet 113 between moving contact Ml3 and contact terminals T3, Tl to isolate main and auxiliary power. Connecting pin P23 is in OFF condition displacing insulation sheet 123 between moving contact M23 and contact terminals T2, T3 to switch off main power supply.
[0050] The automatic transfer switch switches off auxiliary power and switches on main power supply to load when main power supply is restored as illustrated in FIG. 1. The actuator rotates drum 2 by X° in anticlockwise direction. The connecting pins
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slide along the slots by rotation of drum 2. Moving contact Ml 2 is mounted between terminals Tl and T2. Insulation sheet 112 is displaced between the moving contact M12 and terminals Tl and T2. Insulation sheet 112 isolates the auxiliary terminal from output terminal switching off the auxiliary power source. Moving contact Ml 3 is mounted between terminals Tl and T3. Insulation sheet 113 is displaced between the moving contact M13 and terminals Tl and T3. Insulation sheet 113 isolates the auxiliary terminal from main power source to prevent shorting of power. Moving contact M23 is mounted between terminals T2 and T3. Insulation sheet 123 is displaced away from moving contact M23 and terminals T2 and T3. Main power source terminal T3 is connected to output terminal T2 by moving contact M23.
[0051] FIG. 7 illustrates a side perspective view of contacts, insulation and drum assembly in initial condition according to one embodiment of the invention. Insulation sheet 112 is displaced between the moving contact M12 and terminals Tl and T2. Insulation sheet 112 isolates the auxiliary terminal from output terminal switching off the auxiliary power source. Insulation sheet 113 is displaced between the moving contact M13 and terminals Tl and T3. Insulation sheet 113 isolates the auxiliary terminal from main power source to prevent shorting of power. Moving contact M23 is mounted between terminals T2 and T3. Insulation sheet 123 is displaced away from moving contact M23 and terminals T2 and T3. Main power source terminal T3 is connected to output terminal T2 by moving contact M23. The actuator displaces the drum 2 along the axis of the drum.
[0052] FIG. 8 illustrates the side perspective view of according to one embodiment of the invention. Connecting pins P12 and P13 move to interchanging slot 3 when drum 2 is displaced by distance "P". Connecting pin P23 moves to interchanging slot 3 when actuator displaces drum 2 by distance "P+Q". The actuator may rotate the drum freely when all three connecting pins are in interchanging slot. The drum 2 may be rotated freely interchanging input and output positions by 120 .
[0053] FIG. 9 illustrates the side perspective view of contacts, insulation and drum assembly in rotated condition of drum in automatic transfer switch during the interchanging of input and output positions according to one embodiment of the


invention. The actuator rotates drum 2 by 120° in clockwise direction to change the slots of insulating sheets. Insulating sheet 112 moves from slot S3 to S2, insulating sheet 123 moves from slot S2 to SI and insulating sheet 113 moves from slot SI to S3. The main power supply terminal is changed from T3 in initial position to T2 in interchanged position. The auxiliary power supply terminal is changed from Tl in initial position to T3 in interchanged position. The output terminal is changed from T2 in initial position to Tl in interchanged position.
[0054] The drum 2 is displaced by distance P along its axis towards the contact terminals. The connecting pins and insulating sheets slide in the interchanged slots by distance P. Insulating sheets 123 slides along slot SI, 112 slides along slot S2 and 113 slides along slot S3.
[0055] FIG. 10 illustrates the side perspective view of interchanged input and output positions and drum displaced inwards i.e. final position according to one embodiment of the invention. The drum 2 is displaced by distance Q along its axis towards the contact terminals. The connecting pins and insulating sheets slide in the interchanged slots by distance Q. Insulating sheets 113 and 123 slide by distance Q along with drum 2. Insulating sheet 112 slides along slot S2 by distance Q. The interchanged positions of insulating sheets in slots of drum 2 interchanges the input terminals to T2 and T3, and output terminal to Tl.
[0056] The actuator may rotate the drum by 240° or 360 ° in clockwise directions to interchange the input and output terminals. The drum may be rotated in anticlockwise direction to interchange the input and output terminals according to another embodiment of the present invention.
[0057] FIG. 11 illustrates planar view of the position of insulation sheets in initial and interchanged positions of automatic transfer switch according to one embodiment of the invention. Step A illustrates the initial condition of the drum 2. Connecting pin P12 is in OFF condition displacing insulation sheet 112 between moving contact M12 and contact terminals Tl and T2 to switch off the auxiliary power source. Connecting pin P13 is in OFF condition displacing insulation sheet 113 between
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moving contact M13 and contact terminals T3 and Tl to isolate main and auxiliary power supplies. Connecting pin P23 is in ON condition displacing insulation sheet 123 away from moving contact M23 and contact terminals T 2, T3 to switch on main power supply.
[0058] In Step B, the connecting pins slide along the slots by movement of drum 2. The actuator moves drum 2 along the axis of the drum by distance P. Movement of slots S1 and S3 along with drum 2 slides connecting pins P12 and P13 into the interconnecting slot 3. Movement of slot S2 by distance P displaces the connecting pin P23 by distance P in the slot.
[0059] In Step C, the actuator moves the drum 2 by distance Q. The slot S2 moves by distance Q to slide connecting pin P23 into the interconnecting slot 3. The connecting pins P12, P23 and P13 are in the interconnecting slot 3 by the movement of the drum 2 by a distance P+Q.
[0060] In Step D, the actuator rotates the drum by 120°. The connecting pin P12 is rotated by 120° in the interconnecting slot 3 to the threshold of slot S2. Connecting pin P23 is rotated by 120° in the interconnecting slot 3 to the threshold of slot SI. Connecting pin P13 is rotated by 120° in the interconnecting slot 3 to the threshold of slot S3. The main power supply terminal is changed from T3 in initial position to T2 in interchanged position. The auxiliary power supply terminal is changed from Tl in initial position to T3 in interchanged position. The output terminal is changed from T2 in initial position to Tl in interchanged position.
[0061] In Step E, the actuator displaces drum 2 by distance P along the axis towards the contacts. Connecting pins are slid into the interchanged slots by distance P. Connecting pins P13 is slid into slot S3, P12 is slid into slot S2 and P23 is slid into slot S1.
[0062] In Step F, the actuator displaces drum 2 by distance Q along the axis of the drum towards the contacts. Connecting pin P12 slides by distance P+Q in slot S2. The
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interchanged positions of insulating sheets in slots of drum 2 interchanges the input terminals to T2 and T3, and output terminal to Tl.
G) ADVANTAGES OF THE INVENTION
[0063] Thus the various embodiments of the present invention provide a compact automatic transfer switch. The switch has a compact design and easily operable to transfer power to output contact between main power supply and auxiliary power supply. A drum with geometrical slots is operated to move insulation sheets to make or break a contact. Connecting pins of insulation sheets slide in the geometrical slots by linear and rotational movement of the drum. The insertion slots of the connecting pins can be interchanged by simple linear and rotational motion of the drum. The terminal positions are interchanged by the interchanging the insertion slots of connecting pins. The simple design of the transfer switch is cost effective with minimal usage of copper.
[0064] 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.

RAKESH PRABHU
Patent Agent
[0065] 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: March 30, 2009 Place: Bangalore.

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CLAIMS
What is claimed is:
1. An automatic transfer switch device comprising:
a housing;
three contact terminals arranged inside the housing;
a moving contact arranged between each of the two contact terminals;
an insulation sheet movably arranged between each of the two contact
terminals; and
a rotating drum arranged at the housing;
wherein the rotating drum is moved to interpose and remove the insulation
sheet between the moving contact and the respective two contact terminals to
break and make an electrical contact between the respective two contact
terminals.
2. The switch device according to claim 1, wherein the rotating drum is rotated to remove the insulation sheet between the moving contact and the respective two contact terminals to make the moving contact to establish an electrical contact between the respective two contact terminals to make the respective two contact terminals to act as input and output terminals.
3. The switch device according to claim 1, wherein the rotating drum is rotated to interpose the insulation sheet between the moving contact and the respective two contact terminals to break the electrical contacts between any two terminals.
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4. The switch device according to claim 1. wherein the rotating drum is rotated by preset angle to switch the input sources.
5. The switch device according to claim 4, wherein the rotating drum is rotated by 120 degrees.
6. The switch device according to claim 4, wherein the rotating drum is rotated by 240 degrees.
7. The switch device according to claim 4, wherein the rotating drum is rotated by 360 degrees.
8. The switch device according to claim 1, wherein the rotating drum has three geometrical slots and an interchange slot.
9. The switch according to claim 1, wherein the insulation sheet is connected to
the rotating drum so that the drum is moved in or moved out to interpose and
remove the insulation sheet between the moving contact and the respective
two contact terminals to break and make an electrical contact between the
respective two contact terminals.
10. The switch according to claim 1, wherein the insulation sheet comprises a flat portion and a pin attached to the flat portion.
11. The switch according to claim 10, wherein the pin in the insulation sheet is inserted into any one of the three geometrical slots to connect the insulation
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sheet with the rotating drum so that the insulation sheet is inserted between the moving contact and the two contact terminals or removed to break or make the electrical contacts between the two contact terminals.
12. The switch according to claim 1, wherein the pin in the insulation sheet is moved to interchange slot from the geometrical slot to hold the insulation sheet during the rotation of the rotating drum to interchange the input and the output terminals between any two contact terminals.
RAKESH PRABHU
Patent Agent,
ALMT Legal,
#2, Lavelle Road, Bangalore-560 001
Dated this the 30th day of March 2009

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