AN IMPROVED MECHANISM FOR TRANSFER SWITCH
Field of the invention
[0001] The present invention generally relates to transfer switch. More particularly embodiment of present invention relates to mechanism for transfer switch.
Prior Art [0002] Normally, all businesses receive the power supply from electric supply company. The supply company provides uninterrupted power supply to all the consumers round the clock. Some times due to unusual condition, the power supplies tails usually for short time period. However, consumers such as Hospitals cannot afford power failure. Hence, establishments where a continuity of power supply is essential need to have an alternate source for power supply such as generator.
[0003] Automatic transfer switches are known to be employed, in prior art, to switch between a primary source of electric power for a particular consumer between a primary source, generally referred to as "normal" source and a secondary source, generally referred to as "emergency" source. The transfer switch transfers the load from normal supply to emergency supply under circumstances where normal supply fails and returns to normal supply after it is restored. As mentioned above, the normal source is supplier of electricity while emergency source is most often a generator located at consumer's site. The power failure can have fatal consequences, and the reliability of the means for switching between power sources is of high importance. Moreover, because the time involved in transferring between the failed normal source and emergency source must be short in such applications, thus it is important that the switching means for transferring between normal and emergency is rapid. In a typical transfer switch, load from normal source to emergency source transfers before the emergency source has built up enough energy to sufficiently handle the load. To address this problem, a suitable timer mechanism is employed to delay the transfer. [0004] A typical transfer switch known to exist in the prior art, utilizes a linear actuator mechanism which has a single central solenoid with plunger. The actuating mechanism employed comprises of a transfer switch that is movable by

the actuator between the contact block of normal source and contact block of
emergency source. In this mechanism the actuator is placed in the neutral position
for the number of seconds until the proper voltage is achieved, which may range
from fraction of second to twenty seconds or more.
[0005]Hence there is a need of the transfer switch mechanism for transferring the
load from normal source to emergency source with minimum or without time
delay.
OBJECT OF THE INVENTION [0006] It is an object of the invention to provide an improved mechanism for transfer switch. More particularly, it is an object of the invention to provide a mechanism which eliminates the time delay introduced due to flux. It is also an object of the invention to provide an improved mechanism that advantageously utilizes the reduced time delay to toggle between the contacts provided for the normal supply and the contacts provided for the emergency supply. [0007] It is a further object of the invention to provide a positive interlock arrangement, within the mechanism itself, for a transfer switch.
BRIEF DESCRIPTION OF THE DRAWINGS [0008] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to various embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. [0009] Figure 1 shows outline diagram of the typical transfer switch according to an example of the embodiment of the invention.
[0010] Figure 2 shows outline drawing of the transfer switch according to an example of the embodiment of the invention.
[0011] Figure 3 shows outline of single solenoid operated mechanism according to an example of the embodiment of the invention according to an example of the

embodiment of the invention according to an example of the embodiment of the
invention.
[0012] Figure 4 shows outline diagram of contact system of transfer switch
according to an example of the embodiment of the invention.
[0013] Figure 5 shows outline diagram of contact system of transfer switch
according to an example of the embodiment of the invention.
[0014] Figure 6 shows outline diagram of mechanism in position 1 of transfer
switch according to an example of the embodiment of the invention.
[0015] Figure 7 shows outline diagram of mechanism in position 2 of transfer
switch.
[0016] Figure 8 shows outline diagram of mechanism according to Figure 6
according to an example of the embodiment of the invention.
[0017] Figure 9 shows outline diagram of mechanism according to Figure 7
according to an example of the embodiment of the invention.
[0018] Figure 10 shows outline diagram of disc assembly according to an example
of the embodiment of the invention.
[0019] Figure 11 shows outline diagram of disc according to an example of the
embodiment of the invention.
DETAILED DESCRIPTION OF INVENTION [0020] The invention provides a transfer switch. More particularly embodiments of the invention provides an improved mechanism for transfer switch, which comprises of two sets of moving contacts which transfer the load from normal power supply to emergency power supply.
[0021] Figure 1 shows an outline diagram of the typical transfer switch according to an example of the embodiment of the invention. The transfer switch (10) switches between of normal power source (1) and emergency power source (2) to supply electrical power to a load (3). Figure I shows load (3) via transfer switch (10) that draws power from normal source (1) under normal operating condition. In case of a fluctuation arising from altered voltage supply, the transfer switch (10) detects such an altered condition and transfer the load (3) from normal source (1) to emergency source (2). Further, the transfer switch (10) upon restoration of the

normal source, transfers the load (3) from emergency source (2) to norma! source (1) automatically according to an example of the embodiment of the invention. [0022] Figure 2 shows the single solenoid operated mechanism (11) according to an example of the embodiment of the invention. The solenoid mechanism (11) comprises of solenoid (18) mounted on the casing of a transfer switch. A plunger (20) is coupled to the solenoid and is configured to toggle between two predetermined positions. A rotating disc (17) is mounted on the casing and is configured to rotate between two slotted groove situated at diametrically opposite positions on the disc as shown in Figure 11. Further, the single solenoid operated mechanism also comprises of a shaft lever (14) and a main lever (16) which connects the rotating disc (17) and shaft lever (14). The single solenoid operated mechanism is also provided with a compression spring for driving the shaft lever beyond the dead center of the lever and a torsion spring coupled to the plunger and configured to restore the plunger from one predetermined position to another position in the transfer switch mechanism.
[0023] Figure 3 shows the contact system of transfer switch having modular assembly (4) according to an example of the embodiment of the invention. It comprises of a normal source (I), an emergency source (2), a load contact (3) and a plurality of moving contacts (22) which is driven by driving shaft (23). The load is connected to the alternate source (2) by moving contacts (22) which are driven by the driving shaft (23). Driving shaft (23) is connected by the main shaft (12) which couples the mechanism (11) and switching contacts (4). Figure 4 shows the contact system of a transfer switch having modular assembly (4) according to an example of the embodiment of the invention. The load is connected to the normal source (1) by moving contacts (22) which is driven by driving shaft (23), whereas the emergency source (2) is isolated from the load (3).
[0024] Figure 5 shows the mechanism which is in normal source (1) position of transfer switch (10) according to an example of the embodiment of the invention. When the solenoid (18) is energized, the plunger (20) will be drawn into the coil of the solenoid (18). The drawing in of the plunger due to the solenoid being energized causes the disc (17) to rotate in anti clock wise direction. The main lever

(16) connected to the rotating disc (17) will compress the main spring (15). Further, when the plunger (20) is fully drawn, the main spring (15) will cross the dead center resulting in rotation of the shaft lever (14) as well as rotating disc (17) and then it will reach to second position of the transfer switch. By the same time the pin which connects the plunger (20) and rotating disc (17) will follow circular path of groove which is in rotating disc (17). When the solenoid (18) is de energized the pin (17e) will follow linear path of the groove and then latches for next operation.
[0025] Figure 6 shows the mechanism which is in emergency source (2) position of the transfer switch (10) according to an example of the embodiment of the invention. When the solenoid (18) is energized, the plunger (20) will be drawn into the coil of the solenoid (18). The rotating disc (17) will start rotating in anti clock wise direction. The main lever (16) connected to the rotating disc (17) will compress the main spring (15). Further when the plunger (20) is fully drawn, the main spring (15) will cross the dead center resulting in rotation of the shaft lever (14) as well as rotating disc (17) and then it will reach to second position of the transfer switch. By the same time the pin which connects the plunger (20) and rotating disc (17) will follow circular path of groove which is in rotating disc (17). When the solenoid (18) is de energized the pin (17e) will follow linear path of the groove and then latches for next operation.
[0026] Figure 7 shows mechanism according to figure 5. The main shaft (12) is connected to the shaft lever in mechanism and switch modular assembly (4) according to an example of the embodiment of the invention. [0027] Figure 8 shows mechanism according to figure 6. The main shaft (12) is connected to the shaft lever in mechanism and switch modular assembly (4) according to an example of the embodiment of the invention. [0028J Figure 9 shows the rotating disc assembly (17) according to an example of the embodiment of the invention. When the solenoid (18) is activated, the rotating disc (17) will rotate in anti clockwise direction say for about 100 degree after that due to main compression spring it will rotate in the same direction about 80 degree. At the same time the pin (17e) which connects the solenoid (18), plunger (20) and

rotating disc (17) will follow circular path of the groove. When the solenoid (18) is
de energized it will follow the linear path of the groove.
[0029] Figure 10 shows the rotating disc according to an example of the
embodiment of the invention which has grooves (17c and 17d), linear and circular
path for the pin (17e) which connects the solenoid (18) and plunger (20). These
two grooves (17c and 17d) are placed exactly 180 degree opposite direction. So
when the disc (17) rotates about 180 degree due to solenoid (18) and main
compression spring pin (17e) will latch in the other groove (17c).
[0030] The invention, as described herein and as illustrated by diagrams provide
an improved mechanism for a transfer switch.
[0031] The foregoing description of the invention has been set for merely to
illustrate the invention and is not intended to be limiting. Since modifications of
the disclosed embodiments incorporating the spirit and substance of the invention
may occur to person skilled in the art, the invention should be construed to include
everything within the scope of the appended claims and equivalents thereof.

We claim:
1. An improved mechanism for a transfer switch comprising of i. a casing;
ii. a single solenoid mounted on the casing of a transfer switch iii. a plunger coupled to the solenoid and configured to toggle
between two predetermined positions; iv. a disc mounted on the casing and configured to rotate between two slotted groove situated at diametrically opposite positions on the disc; v. a main lever having two ends with one end mounted on to the disc and at the other end pivotingly coupled to a shaft lever; vi. a compression spring coupled to the shaft lever and adapted
for driving the shaft lever beyond me dead centre; and vii. a tension spring coupled to the plunger and configured to restore the plunger from one predetermined position to another. 1. An improved mechanism according to claim 1, wherein the single solenoid is operated to enhance the forward stroke of the single solenoid.
3. An improved mechanism according to claim 1, wherein the enhanced forward stroke of the single solenoid is advantageously utilized to eliminate the time delay of the operation of the single solenoid.
4. An improved mechanism according to claim 1, wherein during the operation of the solenoid the movement of the plunger coupled to the solenoid, is controlled by the tension spring.
5. An improved mechanism according to claim 1, wherein the disc is configured to rotate unidirectionally between two grooves positioned at diametrically opposing positions on the disc.
6. An improved mechanism according to claim 1, further wherein the unidirectional rotation of the disc is achieved by the enhanced forward stroke operation of the solenoid.

7. An improved mechanism according to claim 1, wherein the unidirectional rotation of the disc causes bi-directional rotation of the shaft lever coupled to the disc.
8. A transfer switch for transferring load from one power source to another, comprising
i. an improved mechanism as claimed in claims 1 -7; ii. a normal source contact; iii. a emergency source contact; iv. a load contact; and
v. a moving contact assembly driven by the shaft of the mechanism as claimed in claims 1 -7.
9. A Transfers switch of claim 8, wherein the switch is a multi pole transfer
switch.