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Arrangement for controlling an A.C. voltage

  • US 4,714,870 A
  • Filed: 10/23/1986
  • Issued: 12/22/1987
  • Est. Priority Date: 11/07/1985
  • Status: Expired due to Fees
First Claim
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1. In an arrangement for controlling on A.C. voltage for supplying a load wherein the load is connected to the secondary winding of a transformer, the primary winding of the transformer has a number of taps which are selectively connectable to an external A.C. voltage source, an electronic control device is responsive to the magnitude of the terminal voltage of the external A.C. voltage source for stepwise connecting the different taps automatically to thereby connect that tap which causes the voltage supplied to the load to be of a predetermined value, the electronic control device comprising controllable two-way electronic switches, the number of which corresponds to the number of said taps, the improvement wherein the electronic control device further comprises means connected to control the operation of the electronic control device so as to close the switch to be activated next before the switch then conducting is opened whereby the last two mentioned switches are only momentarily closed at the same time to short circuit a portion of the secondary winding and the phase shift between the voltage and current therein is momentarily eliminated.

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