解説APC Back-UPS 550 Uninterruptible Power Supply Output Waveform.jpg
English: This image shows the non-sinusoidal nature of the AC power provided by some inexpensive consumer grade uninterruptible power supplies (in this case APC model "Back-UPS 550"). The UPS output is shown in yellow compared with a standard 120 VAC 60 Hz single phase waveform. This are actual waveforms measured by a dual trace digital oscilloscope.