What is “MTBF”?
“MTBF” stands for “Mean Time Between Failures”. To calculate MTBF:

8760 hours (= 1 year)
——————————————–
No. of power disturbances in 1 year

MTBF, for most UPS systems, is 25,000 hours and higher. When deciding whether to use one facility UPS or multiple smaller systems keep in mind the following: If one UPS has an MTBF of 25,000, then two UPSs will have a combined MTBF of 12,500 hours. Extending this logic to a medium size data center with 10 UPSs, they will have a combined MTBF of 2,500 hours (or 2 months) between failures. The failure may only become apparent when utility power is lost and the supported system crashes.