Patent ID: 6989613

Claim:
Apparatus for automatically providing electrical voltage output in three different magnitudes responsive to three ranges of source voltage values, comprising: a transformer including first and second primary windings and a secondary winding; a voltage sensor interconnected with the source voltage and energized to provide a first signal on the source voltage being within the range 90–130 VAC, a second signal when the source voltage is within the range 90–108 VAC, a third signal when the source voltage is within the range 108–116 VAC, a fourth signal when the source voltage is within 116–130 VAC, and a fifth signal when the source voltage is outside the range 90–130 VAC; an in-range control is actuated by each of the first, second, third and fourth signals to energize a first relay having contacts that interconnect the source voltage with the transformer and the in-range control is actuated by the fifth signal to deenergized the first relay disconnecting the source voltage from the transformer; the voltage sensor second signal is connected to a boost control and a high-low control energizing second and third relays closing contacts that interconnect the primary windings in parallel providing maximum transformer output added to the source voltage; the voltage sensor third signal is connected to the boost control and high-low boost energizing the second relay to close contacts interconnecting source voltage to the transformer primary and dropping out the third relay to connect the primary windings in series providing a low boost to the source voltage; and the voltage sensor fourth signal also acts on the boost control to drop out the second relay which drops out the third relay and provides a direct connection between the source voltage and the apparatus output.