THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

UNINTERRUPTED POWER SWITCH
A) TECHNICAL FIELD
[0001] The present invention generally relates to power supply controllers used to supply continuous power to electronic and electrical appliances and particularly relates to the powering scheme of a Digital Generator Control Unit (DGCU). The DGCU controls the operation of a starter/generator in an aircraft. The DGCU gets power primarily from the starter/generator which it controls, and from the battery in the event of starter/generator failure. The present invention may be used in any electrical or electronic product which requires battery or any backup power supply continuously.
B) BACKGROUND OF THE PRESENT INVENTION
[0002] The systems currently used to supply an uninterrupted power to any electronic and electrical appliances which require continuous back up power supply or emergency supply are classified into uninterrupted power supply system, transfer switch, network switch, inverter, emergency power system, programmable logic controller, etc.
[0003] An uninterruptible power supply (UPS), also known as an uninterruptible power source or a battery backup is a device which maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility

power is not available. There are three distinct types of UPS: off-line, line-interactive and on-line.
[0004] When a power failure occurs, the off-line type of UPS effectively switches from utility power to its own power source, almost instantaneously. The on-line type of UPS, which is continuously connected to the protected load, draws energy from its reserves, usually stored in lead-acid batteries, converting it to AC power,
[0005] The on-line type of UPS, in addition to providing protection against complete failure of the utility supply, provides protection against all common power problems, and for this reason it is also known as a power conditioner and a line conditioner.
[0006] The Transfer switches allow switching from a primary power source to a secondary or tertiary power source and are employed in some electrical power distribution systems. Most often transfer switches can be seen where emergency power generators are used to back up power from the utility source. The transfer switch allows switching from utility power to emergency generator power. The switch is a manual switch or an automatic switch or a combination of manual and automatic. During a power outage, the transfer switches isolate the emergency circuits from the utility line allowing for efficient operation of the generator without back feeding onto the utility.

[0007] The Transfer switches continually monitor the incoming utility power. Any anomaly such as voltage sags, brownouts, spikes or surges will cause the internal circuitry to command a generator startup and then a transfer to the emergency generator when additional switch circuitry determines the generator has the proper voltage and frequency. When utility power returns, or no other anomalies have occurred for a set time, the transfer switch will then transfer, back to utility power and command the generator to turn off after another specified amount of "cool down" time.
[0008] The US Patent number 5886561 discloses a backup battery switch. The switch has a switching circuit to switch the power supply between a main power supply and a battery power supply. The switching circuit is provided with a comparator, a p-channel battery power transfer transistor, a p-channel main power transfer transistor and an inverter. The comparator which is operated on the main power supply is connected on input to the main power supply and to the battery power supply. The comparator analyzes the voltage level of the main power supply and the voltage level of the battery power supply to provide a selection signal. The p-channel battery power transfer transistor is controlled by the selection signal to transfer the battery supply signal to a switched power supply node. The p-channel main power transfer transistor is controlled by the inverter to transfer the main power supply to the switched power supply node.
[0009] The US Patent number 4327298 discloses a battery backup system for a microcomputer. The battery back-up system for microcomputer senses a line voltage and

supplies battery power to microcomputer, when there is a large reduction of voltage in the main supply line.
[0010] Thus the currently available products supply power from a battery or a generator. These products switch to secondary source as soon as the primary power falls below the secondary power source (In 28V system, as soon as primary power falls below 28V, the switch over to secondary source takes place). Some of these products use relays thereby resulting significant delay in switching operation, and higher volume of products,
[0011] Hence there is a need to develop an uninterrupted power switch which will draw power from the primary source (generator) until the primary source reaches its lower limit (8V lower limit during 28V operation) and is not capable of sourcing power. Also there is a need to enable quick switching operation from one source to another and to assign priority to power supply from generator than the power supply from the battery. Also there is a need to isolate the battery when the power supply from the generator is available. Also there is a need to assign a priority to a power supply source to supply electrical power to a load, when multiple power supply sources are available to supply electrical power to the load.
C) OBJECTS OF THE INVENTION
[0012] The primary object of the present invention is to develop an uninterrupted power switch to assign priority to any one of the two sources of power and to allow the primary power source to supply the electrical power to the load until a preset lower voltage limit is reached.

[0013] Another object of the present invention is to enable quick switching of power supply from available sources to ensure a continuous power supply to the load.
[0014] Another object of the present invention is to develop an uninterrupted power ' switch to assign priority to a generator to supply power to a load when both a battery power supply and the generator power supply are available.
[0015] Yet another object of the present invention is to develop an uninterrupted power switch to isolate the battery, when the power is supplied to the load from the generator.
[0016] Yet another object of the present invention is to develop an uninterrupted power switch to select a power supply from the battery, when the generator does not produce sufficient power for a load.
[0017] Yet another object of the present invention is to develop an uninterrupted power switch to ensure a sharp cut-off for transition from one power supply to another power supply.
[0018] Yet another object of the present invention is to develop an uninterrupted power switch to prevent unnecessary draining of the battery, when power is supplied to the load from the generator.
[0019] 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 PRESENT INVENTION
[0020] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification
[0021] According to one embodiment of the present invention, an uninterrupted power switch has a power supply switching device connected to a battery power supply, a generator power supply and to a load to supply electrical power to the load either from the battery or from the generator. The power supply switching device is electrically connected between the battery power supply and the generator through a switching controller. The power supply switching device is connected to the load through a diode. The switching controller activates the power supply switching device based on a preset threshold level to select the battery power supply or the generator power supply. When the voltage of the supplied electrical power from the generator is more than the preset threshold value, the electrical power from the generator is supplied to the load. The power supply from the generator to the load is continued until the voltage of electrical power supplied from the generator falls below the threshold level. The electrical power from the battery is supplied to the load, when the voltage of the electrical power supplied from the battery is less than the preset threshold value.
[0022] According to one embodiment of the present invention, the uninterrupted power switch includes two power supplies as the inputs and a load supply as output. The battery supply and its ground are connected as the first input while the generator power supply and its ground are connected as the second input. The output of the switch is connected to the load. The load voltage must be present always irrespective of whether one or both

the inputs to the switch are present. When both the inputs ate present, then the priority is assigned to the generator to supply electrical power to the load and the battery supply is isolated. This results in effective usage of the battery, thereby enhancing the life of the battery.
[0023] Thus the preferred embodiments of the present invention enable to switch power supply from one source to another source quickly to ensure continuous power to the load. A priority is assigned to the generator to supply an electrical power to the load when both the battery supply and the generator supply are available. The battery power supply is isolated, when the electrical power is supplied to the load from the generator. The battery is selected to supply electrical power to the load, when the generator does not produce sufficient power for a load. The number of components used in the uninterrupted power switch is reduced thereby reducing the cost and size of the switch.
[0024] The unnecessary draining of the battery is prevented, when the electrical power from the generator is supplied to the load, thereby resulting in effective usage of onboard battery and hence increasing the life of the battery. A continuous power supply to the load is ensured in minimum switching time thereby preventing the hang up operation of a processor. The circuit is formed with a few components, thereby reducing the cost and size of the switch device-
[0025] 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
[0026] 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:
[0027] FIGURE.l illustrates a block diagram of an uninterrupted power switch according to one embodiment of the present invention.
[0028] FIGURE.2 illustrates a functional block diagram of an uninterrupted power switch according to one embodiment of the present invention.
[0029] FIGURE.3 illustrates a schematic block circuit diagram of an uninterrupted power switch according to one embodiment of the present invention.
[0030] FIGURE.4 illustrates a schematic block circuit diagram of an uninterrupted power switch according to one embodiment of the present invention.
[0031] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

F) DETAILED DESCRIPTION OF THE INVENTION
[0032] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments which 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.
[0033] According to one embodiment of the present invention, an uninterrupted power switch has a power supply switching device connected to a battery power supply, a generator power supply and to a load to supply electrical power to the load either from the battery or from the generator. The power supply switching device is electrically connected between the battery power supply and the generator through a switching controller. The power supply switching device is connected to the load through a diode. The switching controller activates the power supply switching device based on a preset threshold level to select the battery power supply or the generator power supply. When the voltage of the supplied electrical power from the generator is more than the preset threshold value, the electrical power from the generator is supplied to the load. The power supply from the generator to the load is continued until the voltage of electrical power supplied from the generator falls below the threshold level. The electrical power from the battery is supplied to the load, when the voltage of the electrical power supplied from the battery is less than the preset threshold value.

[0034] According to one embodiment of the present invention, the uninterrupted power switch includes two power supplies as the inputs and a load supply as output. The battery supply and its ground are connected as the first input while the generator power supply and its ground are connected as the second input. The output of the switch is connected to the load. The load voltage must be present always irrespective of whether one or both the inputs to the switch are present. When both the inputs are present, then the priority is assigned to the generator to supply electrical power to the load and the battery supply is isolated. This results in effective usage of the battery, thereby enhancing the life of the battery.
[0035] According to one embodiment of the present invention, the uninterrupted power switch is provided with a transistor such as a P-channel MOSFET in the supply path of a battery. The MOSFET is connected to a load through a diode such as a Schottldiy diode. A PNP type transistor is connected to the base of the MOSFET. The base of the PNP type transistor is connected to a generator power supply through a resistor. A Zener diode is connected to the collector of the PNP type transistor and to a ground.
[0036] When the MOSFET is switched on, the electrical power from the battery is supplied to the load through the diode. When the battery supplies the required current to the load, the voltage at the load terminal is equal to the voltage of the battery minus the diode drop value. The diode is a Schottky power diode. The Schottky diode has a lower voltage drop and hence power loss in the Schottky diode is less, when compared with the power loss in the regular power diode. The MOSFET is switched on, when the PNP type transistor is switched on. The PNP type of transistor is connected to the base of the MOSFET. The transistor derives its base voltage from the generator power supply. Whenever the generator voltage is less than the preset threshold voltage value (lower

limit), the transistor is switched on and the gate of the MOSFET is connected to the ground in the absence of Zener diode. As a result, a negative voltage is provided across the gate-to-source of MOSFET, thereby turning on the MOSFET, and connecting the battery to the load. The zener diode is provided to limit the gate-to-source voltage to a pre set value, for example to about 12V, to prevent the breakdown of the gate of MOSFET. In the absence of the Zener diode, the gate -to-source voltage builds to a value, for example, to -28V, thereby resulting in the breakdown of gate capacitance. Another main usage of the Zener diode is to set a threshold voltage for the generator so that the battery gets connected to the load, when the voltage of the generator power supply is less than the preset threshold value. For example, the generator threshold for the current circuit is set to about 23 Volts. When the generator voltage falls below the preset threshold level, then the battery is connected to the load. In another embodiment of the present invention, the Zener diode is connected between the collector of the PNP type transistor and gate of MOSFET to reduce the threshold value to a given voltage such as 8 volts. The resistor connected to the base of the transistor is used to ground the base of transistor, when the power supply wire from the generator is physically removed. The resistor is connected to the base of the transistor to ensure that the transistor is switched on to connect the battery to the load, when the electrical power supply wire is physically removed. A diode is provided between the base and the emitter of the PNP type transistor to prevent generation of negative spikes across the base-to-emitter junction of the transistor. This diode also helps to prevent the breakdown of the junction capacitance. The Schottky diodes are provided between the MOSFET and the load to prevent the current from flowing in the reverse direction, when any one of the two power sources is not available. Whenever the generator power supply becomes greater than 23 volts (or 8 volts), the MOSFET does not conduct, as its gate-to-source voltage is

more than -5 volts. Under these conditions, the generator supplies electrical power to the load and the battery is isolated.
[0037] Thus the preferred embodiments of the present invention enable to switch power supply from one source to another source quickly to ensure continuous power to the load. A priority is assigned to the generator to supply an electrical power to the load when both the battery supply and the generator supply are available. The battery power supply is isolated, when the electrical power is supplied to the load from the generator. The battery is selected to supply electrical power to the load, when the generator does not produce sufficient power for a load. The number of components used in the uiainterrupted power switch is reduced thereby reducing the cost and size of the switch.
[0038] Thus the uninterrupted power switch of the present invention prevents the unnecessary draining of the battery, when the electrical power from the generator is supplied to the load. As a result, the effective usage of on-board battery and hence the life of the battery are increased. A continuous power supply to the load is ensured with a minimum switching time thereby preventing the hang up operation of a processor. The circuit is formed with a few components, thereby reducing the cost and size of the switch device.
[0039] The FIG.l shows a block diagram of an uninterrupted power switch according to one embodiment of the present invention. With reference to FIG. 1, the switch is connected to two power supply sources at the input side. For example, the two power supply sources are a battery and a generator supply. A load is connected to the output side of the switch. The switch has two inputs. The battery and its ground are connected as the first input, while the generator power supply and its ground are connected as the

second input. The output of the switch is connected to the load. The load voltage is always supplied, irrespective of whether one or both of the power supply sources are connected to the two inputs. When both the inputs are available, then priority is given to the generator power supply to supply the electrical power to the load and the battery supply is isolated. Thus the battery is used effectively to increase the life of the battery efficiendy and effectively.
[0040] The FIG. 2 indicates a functional block circuit diagram of an uninterrupted switch according to one embodiment of the present invention. With respect to FIG.2, the uninterrupted power switch has a power supply switching device to supply an electrical power to a load from a battery power supply or from a generator power supply. A switch control circuit is connected to the power supply switching device to output a control signal to the switching device based on a preset threshold value to supply the electrical power from the battery or from the generator. The power supply switching device is connected to the load through a diode circuit.
[0041] The power supply switching device is electrically connected between the battery power supply and the generator through a switching controller. The power supply switching device is connected to the load through a diode circuit. The switching controller activates the power supply switching device based on a preset threshold level to select the battery power supply or the generator power supply. The switching controller compares the voltage of the generator power supply with the preset threshold level to supply the electrical power to the load from the generator or from the battery. When the voltage of the supplied electrical power from the generator is more than the preset threshold value, the electrical power from the generator is supplied to the load. The power supply from the generator to the load is continued until the voltage of

electrical power supplied from the generator falls below the threshold level. The electrical power from the battery is supplied to the load, when the voltage of the electrical power supplied from the battery is less than the preset threshold value. The diode circuit is provided between the load and the switching device to prevent the current from flowing in the reverse direction, when one of the two power sources is not available for power supply.
[0042] The FIG. 3 indicates a schematic circuit diagram of an uninterrupted power switch according to one embodiment of the present invention. With respect to the FIG. 3, the switch consists of a P-channel MOSFET provided in the supply path of a battery. The MOSFET is connected to a load through a Schottky diode Dl, A Schottky diode D2 is connected between the load and the diode Dl. When the MOSFET is switched on, the electrical power from the battery is supplied to the load via diode Dl and a required current is supplied to the load. The voltage at the load terminal due to the supply of power from the battery is equal to that of the battery minus the diode Dl drop. The diode Dl is a Schottky power diode. The voltage drop in the Schottky power diode is less than the voltage drop in a regular power diode, A transistor Ql is connected to the base of the MOSFET. The MOSFET is switched on, when the transistor Ql is switched on. The Transistor Ql is a PNP type of transistor connected to the base of the MOSFET. The transistor Ql derives its base voltage from the generator power supply. When the generator does not produce a nominal power, for example 28 volts or a preset lower threshold voltage, the transistor is switched on. As a result, the gate of the MOSFET gate is connected to ground in the absence of zener diode D4 that is connected between the collector of the transistor Ql and the ground. Hence a negative voltage is generated across the gate-to-source of MOSFET, thereby switching on the MOSFET to connect the battery to the load. The zener diode is provided to limit the

gate-to-source voltage to a given voltage, such as about 12V, to prevent the breakdown of the gate capacitance of the MOSFET. In the absence of zener diode, the gate-to-source voltage builds to a voltage level of -28V, thereby resulting in breakdown of gate capacitance. The second and crucial purpose of the zener is to set a threshold voltage for the generator so that the generator supply is disconnected and the power from the battery is connected to the load, when the voltage of the generator power supply is less than the threshold voltage. In one example, the threshold value for the generator power supply is set as 23 volts. When the generator voltage falls below the preset threshold value, then the battery is connected to the load. When the threshold voltage is to be reduced, for example to 8 Volts, the zener diode D4 may be connected between the collector of transistor Ql and the gate of MOSFET Ml as shown in FIG. 4. As a result, the threshold voltage of the generator is reduced for example to around 8 Volts. A resistor R2 is connected between the base of the transistor and the generator power supply to ground the base of transistor Ql, when the generator wire is physically disconnected. This ensures that the transistor Ql is switched on, to connect the battery to load. A fast response Diode D3 is connected between the emitter and the base of the transistor to prevent generation of negative spikes across the base-to-emitter junction of the transistor Ql. The diode D3 prevents the break down of the transistor junction. A diode D2 is connected between the diode Dl and the ground through a resistor R3. The diodes Dl and D2 are provided to prevent current from flowing in the reverse direction, when one of the power sources is not available for power supply.
[0043] When the voltage of the generator power supply is more than the preset threshold value, for example 23 volts, the MOSFET does not conduct, as the gate-to-source voltage of MOSFET is more than -5 volts. Under these conditions, the generator supplies the electrical power to the load and the battery is isolated. Thus the

uninterrupted power switch of the present invention supplies a continuous power to a load quickly and efficiently.
[0044] The FIG. 4 indicates a schematic circuit diagram of an uninterrupted power switch according to one embodiment of the present invention. With respect to the FIG. 4, the switch consists of a P-channel MOSFET provided in the supply path of a battery. The MOSFET is connected to a load through a Schottky diode Dl. A Schottky diode D2 is connected between the load and the diode Dl. When the MOSFET is switched on, the electrical power from the battery is supplied to the load via diode Dl and a required current is supplied to the load. The voltage at the load terminal due to the supply of power from the battery is equal to that of the battery minus the diode Dl drop. The diode Dl is a Schottky power diode. The voltage drop in the Schottky power diode is less than the voltage drop in a regular power diode, A transistor Ql is connected to the base of the MOSFET. The MOSFET is switched on, when the transistor Ql is switched on. The Transistor Ql is a PNP type of transistor connected to the base of the MOSFET. The transistor Ql derives its base voltage from the generator power supply. When the generator does not produce a nominal power, for example 28 volts or a preset lower threshold voltage, the transistor is switched on. As a result, the gate of the MOSFET gate is connected to ground in the absence of Zener diode D4 that is connected between the emitter of the transistor Ql and the base of the MOSFET. Hence a negative voltage is generated across the gate-to-source of MOSFET, thereby switching on the MOSFET to connect the battery to the load. The Zener diode is provided to limit the gate-to-source voltage to a given voltage, such as about 12V, to prevent the breakdown of the gate capacitance of the MOSFET. In the absence of Zener diode, the gate-to-source voltage builds to a voltage level of -28V, thereby resulting in breakdown of gate capacitance- The second and crucial purpose of the Zener is to set a

threshold voltage for the generator so that the generator supply is disconnected and the power from the battery is connected to the load, when the voltage of the generator power supply is less than the threshold voltage. In one example, the threshold value for the generator power supply is set as 23 volts. When the generator voltage falls below the preset threshold value, then the battery is connected to the load. When the threshold voltage is to be reduced, for example to 8 Volts, the Zener diode D4 may be connected between the collector of transistor Ql and the gate of MOSFET Ml as shown in FIG. 4. As a result, the threshold voltage of the generator is reduced for example to around 8 Volts. A resistor R2 is connected between the base of the transistor and the generator power supply to ground the base of transistor Ql, when the generator wire is physically disconnected. This ensures that the transistor Ql is switched on, to connect the battery to load. A fast response Diode D3 is connected between the emitter and the base of the transistor to prevent generation of negative spikes across the base-to-emitter junction of the transistor Ql. The diode D3 prevents the break down of the transistor junction. A diode D2 is connected between the diode Dl and the ground through a resistor R3. The diodes Dl and D2 are provided to prevent current from flowing in the reverse direction, when one of the power sources is not available for power supply.
[0045] When the voltage of the generator power supply is more than the preset threshold value, for example 23 volts, the MOSFET does not conduct, as the gate-to-source voltage of MOSFET is more than -5 volts. Under these conditions, the generator supplies the electrical power to the load and the battery is isolated. Thus the uninterrupted power switch of the present invention supplies a continuous power to a load quickly and efficiently.

G) ADVANTAGES OF THE INVENTION
[0046] Thus the preferred embodiments of the present invention allow the primary power source to supply the load until the preset lower threshold voltage is reached and the secondary power source (such as battery) to supply the electrical power to the load, when the voltage of the primary power source is less than the preset lower threshold voltage.
[0047] The present invention also enables to switch the power supply from one source to another source quickly to ensure continuous power supply to the load. A priority is assigned to the generator to supply an electrical power to the load when both the battery supply and the generator supply are available. The battery power supply is isolated, when the electrical power is supplied to the load from the generator. The battery is selected to supply electrical power to the load, when the generator does not produce sufficient power for a load. The switch provides a sharp cut off for transition to switch power supply between different sources. The number of components used in the uninterrupted power switch is reduced thereby reducing the cost and size of the switch.
[0048] The unnecessary draining of the battery is prevented, when the electrical power from the generator is supplied to the load, thereby resulting in effective usage of onboard battery and hence increasing the life of the battery. A continuous power supply to the load is ensured in minimum switching time thereby preventing the hang up operation of a processor.

The circuit is formed with a few components, thereby reducing the cost and size of the switch device. The present invention tends to reduce the usage of bulkier relays, thereby achieving faster switching speeds and compact product packaging.
[0049] The priority based Un-Interrupted Power Switch according to the present invention maintains a continuous power supply to the load, when the load is powered from multiple sources. The present invention relates to the powering scheme of Digital Generator Control Unit which controls the functioning of starter/generator. The generator control unit regulates the operation of a starter/generator in an aircraft. The starter/generator first takes supply from 28V battery, and after attaining a certain speed operates as a generator thereby producing power. The unit is powered initially by a battery and then by the generator. The power switch ensures smooth transition from battery to generator mode with minimum switching time, thereby ensuring a continuous power supply to the unit electronics. In the event of insufficient power generation by the generator (when the voltage of the generator is less than the lower threshold voltage limit), the switch connects the load to the battery. Under normal operating conditions of generator supplying power to unit, the battery is cut-off, thereby avoiding the unnecessary discharge of the battery power. The priority is always given to generator to supply power to the load provided the generator is capable of producing the required electrical power.
[0050] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.

CLAIMS
What is claimed is:
1. A priority based uninterrupted power switch, comprising:
a switching device connected to plurality of power sources supplying electrical power and to a load; and
a switching controller connected to said switching device to provide a control signal to said switching device to selectively supply electrical power from said plurality of power sources to load.
2. The uninterrupted power switch according to claim 1, wherein the switching controller to provide priority to one of the multiple power sources to supply power to the load, when all of the multiple sources are available for supplying power to the load.
3. The uninterrupted power switch according to claim 1, wherein said switching controller compares the output voltage of power source with threshold level of prioritized power source to permit or prevent the prioritized power source from supplying electrical power to said load.
4. The uninterrupted power switch according to claim 1, wherein the switching controller provides a control signal to the switching device to supply electrical power to the load from an alternate source from the plurality of the power

sources when the prioritized power source is unable to supply required electrical power to said load,
5. The uninterrupted power switch according to claim 1, wherein the plurality power sources may be 2.
6. The uninterrupted power switch according to claim 5, wherein one of the plurality of the power sources is a battery power supply.
7. The uninterrupted power switch according to claim 5, wherein one of the plurality of the power supply sources is a generator.
8. The uninterrupted power switch according to claim 2, wherein the switching controller provides a priority to the generator to supply electrical power to said load, when both the battery and the generator are available for supplying electrical power to said load.
9. The uninterrupted power switch according to claim 3, wherein the switching controller provides a preset threshold value for the voltage of the generator power supply to supply electrical power to said load.
10. The uninterrupted power switch according to claim 9, wherein the generator is
permitted to supply an electrical power to said load, when voltage of generator
power supply is more than the preset threshold value.

11. The uninterrupted power switch according to claim 9, wherein the switching controller outputs a control signal to switching device to supply electrical power from said battery to said load, when voltage of generator power supply is less than threshold value.
12. The uninterrupted power switch according to claim 1, wherein the switching device is a transistor.
13. The uninterrupted power switch according to claim 1, wherein the switching device is a MOSFET.
14. The uninterrupted power switch according to claim 1, wherein the switching device is a p-channel MOSFET.
15. The uninterrupted power switch according to claim 1, wherein the switching
controller is a transistor,
16. The uninterrupted power switch according to claim 1, wherein the switching controller is a PNP type transistor.
17. The uninterrupted power switch according to claim 1, wherein the PNP type transistor is switched on to turn on the MOSFET to supply power to said load from the battery.

18. The uninterrupted power switch according to claim 1, further comprises a Zener
diode connected to the PNP type transistor to set a threshold level for the
generator power supply voltage to connect said battery power supply to said load.
19. The uninterrupted power switch according to claim 17, wherein the Zener diode
is connected to the PNP type transistor to prevent the break down of the
junction gate capacitance of the MOSFET.
20. The uninterrupted power switch according to claim 1, further comprises a
Schottky diode circuit connected between the MOSFET and said load to prevent
the back flow of the current, when any one of the power sources is available for
supplying power to said load.