Editing Uninterruptible power supply (section)

===Hybrid topology/double conversion on demand===

These hybrid rotary UPS<ref name="Rotary UPS">{{cite web|url=http://www.pscpower.com/site/wp-content/uploads/2013/06/Hybrid-Rotary-UPS.pdf|title=Hybrid Rotary UPS|archive-url=https://web.archive.org/web/20141204152131/http://www.pscpower.com/site/wp-content/uploads/2013/06/Hybrid-Rotary-UPS.pdf|archive-date=December 4, 2014|url-status=dead}}</ref> designs do not have official designations, although one name used by UTL is "double conversion on demand".<ref name="HPman">{{cite web|url=http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01173322/c01173322.pdf <!-- originally http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01173322/c01173322.pdf--> |archive-url=https://ghostarchive.org/archive/20221009/http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01173322/c01173322.pdf |archive-date=2022-10-09 |url-status=live |title=Increasing energy efficiency with modular HP three-phase power distribution|publisher=[[HP Inc.|HP]]}}</ref> This style of UPS is targeted towards high-efficiency applications while still maintaining the features and protection level offered by double conversion.

A hybrid (double conversion on demand) UPS operates as an off-line/standby UPS when power conditions are within a certain preset window. This allows the UPS to achieve very high efficiency ratings. When the power conditions fluctuate outside of the predefined windows, the UPS switches to online/double-conversion operation.<ref name="HPman" /> In double-conversion mode the UPS can adjust for voltage variations without having to use battery power, can filter out line noise and control frequency.