Abstract: The apparatus and methods of the invention provide conversion of a wide range of utility voltages found worldwide, to a fixed nominal voltage level. The invention therefore provides the ability to "plug in" to virtually any power source, and produce a desired nominal voltage for operation of electrical equipment either alone or in conjunction with a UPS device. The voltage selection apparatus provides standard nominal levels of electrical power to equipment while utilizing power sources of varying voltage and frequency. The device is dynamically adaptive to the input power source, and maintains its output within a nominal range even where the input source varies to a substantial degree. The voltage selection apparatus comprises an input for receiving input AC voltage from a power source, and a transformer to produce an output voltage which is coupled to the input.