Voltage independent UPS or VI UPS

means a federally regulated UPS that produces an AC output within a specific tolerance band that is independent of under-voltage or over-voltage variations in the input voltage without depleting the stored energy source. The output frequency of a VI UPS is dependent on the input frequency, similar to a voltage and

frequency dependent system.

Note: VI input dependency may be verified by performing the steady state input voltage

tolerance test specified in 10 C.F.R. section 430.23(aa) 2.27.3. (Appendix Y to subpart B of

part 430 2.27.3.) and ensuring that the UPS remains in normal mode with the output voltage

within the specified output range when the input voltage is varied by ±10% of the rated

input voltage.