What is computer grade power in Double Conversion Online UPS? Powercom website says "Computer Grade Power can be defined as AC power that has a stable ground reference with less than 0.5 volts of level change of the ground reference and less than 10 volts of noise on the AC waveform." What is this 10 volts referring to, in the above definition? How can this be seen on the power analyser? What would the THD(current) on the Online UPS OUTPUT be, for it to be called computer grade power? [THD-voltage] should be less than 5% on UPS output, I am aware of this.