What is a UPS Static Bypass?

An on-line UPS has a static bypass built-into its design. The UPS inverter is always ‘on-line’ and its output waveform, voltage and frequency are monitored. If the output wave starts to collapse due to an overload and the overload is greater than the overload rating or there is an internal fault, the load is automatically transferred via the static bypass from the output of the inverter to the UPS bypass line. When the fault clears or the overload is reduced, the load us automatically transferred back to the output of the inverter. Some smaller on-line UPS below 10kVA may state in their specifications that they have an automatic bypass which will be relay rather than static technology based.