How important is the UPS output waveform?
That’s a good question, and one is worthy of some debate. One school of thought holds that one should always run equipment on the best approximation of sinusoidal input that one can, and that deviations produce harmonics which may either be interpreted as signal if they get through a power supply, or may actually damage the equipment. Another school holds that since almost all computers use switching-type power supplies, which only draw power at or near the peaks of the waveforms, the shape of the input power waveform is not important. Who’s right? I don’t know. My opinion is that sinusoidal output is worth the extra money, especially for on-line UPS systems that continually provide their waveform to the computer. Also, if you don’t know that your equipment has a switching-type power supply, you might want to think twice before buying a low quality UPS. [ Some of this information from a great article in the October 1994 issue of LAN Magazine, check it out.
