U.P.S

AH = Amps x Hours. Determine the Amps, them multiply it by the number of hours you want the UPS to supply power.

Load{kW} * Time{hr} / System_Efficiency{no units ; 0<value<1 ; suggest 0.5} = Battery_Voltage{V} * Battery_Capacity{A-hr} / 1000{VA/kW} = Battery_Energy{kW-hr}

Example:

890{kW} * 1{hr} / 0.5 * 1000{VA/kW} / 12{V} = 148333 {A-hr}

BIG Battery ;-)

I have a good article on it. Give me your mail address. If u don,t want to post your address here, send a private message to me.

See this thread (especially the "Battery AH calculation" of comment # 9) for detail:

http://cr4.globalspec.com/thread/38821/KVA-of-UPS

- MS