Under-load switching device particularly adapted for voltage regulation and balance
AssigneeTRW Inc.
InventorRichard E. Stewart
Life of this patent
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Abstract
An under-load switching device particularly adapted for use with a transformer having voltage taps for voltage regulation and for balancing the phase voltages in a multi-phase AC power system includes a pair of rotary tap selectors connected in parallel to the voltage taps, and a pair of switches for alternately connecting the tap selectors to an AC line, such that load current flows through only one tap selector and an associated switch at a time. A control unit monitors the voltage on the AC line, determines the tap required to be selected to compensate for voltage variations, causes the tap selector which is not carrying load current to select the required tap, and operates the switches at a zero-current point to transfer the AC line to the selected tap.
Claims14
A device for switching, under load, between transformer taps and the like, there being a plurality of such taps, comprising first and second selector means adapted to be connected in parallel to said plurality of taps, each selector means being capable of independently selecting any tap of said plurality, means for operating the first and second selector means, first and second switch means connected to said first and second selector means, respectively, and operable for alternately connecting a tap selected by the first selector means and a tap selected by the second selector means to a conductor, means for operating the first and second switch means such that only one selected tap is connected to the conductor at a time, and means for determining which selector means selects the tap that is connected to the conductor to enable operation of the other selector means, thereby permitting tap selection under no-load conditions.
Dependencies are inferred from the claim text.