A flywheel driven rotary UPS is used for applications requiring ride-through of short duration power system outages, voltage dips, etc. The flywheel driven rotary UPS typically does not include batteries, and support times are usually on the order of a few seconds to a few minutes. The use of a generator driven rotary UPS can provide extended power for an indefinite power outage and also supply air-conditioning and lighting loads. Data processing equipment rooms will typically overheat within a 15- to 30-minute period if the ventilation system is not working, making the generator set a near necessity for outages in excess of this time. Analysis of battery cost will often justify a generator set at lower cost than choosing a long battery support time with an accompanying restriction of eventually implementing an orderly critical load shutdown. A battery support time of as little as a few minutes may be specified with generator set backup; however, longer support times in the range of 15 minutes are more typical.
1) Diesel engine
3) Electromagnetic clutch
6) Synchronous motor /alternator
4) Flywheel
Some of rotary UPS systems consists of an AC Motor Generator (M-G) set with a flywheel, as well as a rectifier, storage batteries, inverter, static switch and solid state circuitry. Both the motor generator set and the rectifier/battery/
