Soft Switching Technologies Corporation

William R Kranz

Deepakraj M Divan

Robert S Schneider

William E Brumsickle

Glen Luckjiff

Dual feed power supply system provides high reliability of a dual utility feed, with minimal interruptions in power supplied to critical loads during switching, and compensation for voltage sags occurring on the primary power feed. AC input buses are connected through a transfer switching apparatus to phase lines of a distribution bus. The transfer switching apparatus has a first input terminal connected to one of the phase lines of the first input bus and a second input terminal connected to one of the phase lines of the second input bus, and an output terminal connected to one of the phase lines of the distribution bus. Input switches allow switching from one or the other of the AC input buses to the distribution bus, with a fast transfer switch used to interrupt the supply of power from the input buses to the distribution bus during switching of the input switches.

Dual feed power supply systems with enhanced power quality

A low cost, small size, light weight, and highly effective system and method for providing dynamic power line voltage sag correction is provided. A dynamic voltage sag corrector includes a static bypass switch and a regulator/storage module connected together in parallel between input terminals and output terminals. Under normal operating conditions, the static bypass switch is closed, and a normal line voltage level is provided directly from the input terminals to the output terminals via the static bypass switch. When a voltage sag condition is indicated, the static bypass switch is opened, and the regulator/storage module is controlled to provide a near normal output voltage signal to the output terminals. The regulator/storage module includes a power conversion circuit which is controlled to provide the desired output voltage signal by adding a voltage level on storage capacitors to the available input line voltage signal. The components of the dynamic voltage sag corrector are selected to provide voltage sag correction for a duration sufficient to provide correction of 90-95% of voltage sag/drop conditions which are likely to be encountered. The size, cost, and weight of the dynamic voltage sag corrector is thereby reduced. The dynamic voltage sag corrector may also provide surge condition correction, may be configured to provide extended duration voltage sag correction to a priority portion of a load, may provide support to a load even if there is a complete break in an input power line, and may be employed in single or multi-phase applications.

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Madison, WI, United States of America

William R Kranz