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US 7,064,458 B2Granted
Method and system for transferring a load between AC voltage sources
AssigneeTarget Hi-Tech Electronics Ltd.
InventorLupu Wittner
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AssigneeTarget Hi-Tech Electronics Ltd.
InventorLupu Wittner
Estimating the term…
Term ended 7 Jul 2024 (estimated)
A method and system for transferring a load from a first AC voltage source to a second AC voltage source. A temporary voltage source is connected to the load and to the first voltage source via a resistor. The first voltage source is disconnected from the load. The second voltage source is connected to the load. Finally, the temporary voltage source is disconnected from the load. The temporary voltage source may be independent of the first and second voltage sources, or may obtain voltage from the first or second voltage sources. The connecting and disconnecting is done by mechanical switches, by thyristors, or by mechanical switches and thyristors in parallel or in series.
A method of transferring a load from an initial voltage source to a final voltage source, the load being initially connected to the initial voltage source, comprising the steps of:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
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From the US filing history. Foreign family members aren’t listed.
The present invention relates to a method of transferring an electrical load from one AC voltage source to another with no interruption of voltage during the switch.
There are several circumstances in which a load must be transferred from one AC voltage source to another. One example of such a circumstance is transferring a load from an electrical power grid to a generator in case of an anticipated power outage. Another example of such a circumstance is phase balancing, in which a load is transferred from one phase to another.
Prior art methods of transferring a load from one AC voltage source to another all entail an interruption of voltage for at least a short time interval. The duration of this time interval depends on the speed of the switching circuit used. In high current applications, the switching circuits are mechanical devices that are capable of withstanding high currents and very high short-circuit currents.
The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:
FIG. 1 is a circuit diagram of a first embodiment of a system of the present invention;
FIGS. 2A through 2E illustrate waveforms that are useful in understanding the present invention
The present invention is of a method and system for transferring a load from one AC voltage source to another AC voltage source. Specifically, the present invention can be used for phase balancing.
The principles and operation of electrical load transfer according to the present invention may be better understood with reference to the drawings and the accompanying description.
The basic principle of the present invention is that, in transferring a load from a first AC voltage source to a second AC voltage, source, a temporary voltage source, which may be a separate third voltage source or which may obtain its voltage from the second voltage source, provides voltage to the load during the time interval between the disconnection of the first voltage source from the load and the connection of the second voltage source to the load.