Some aspects on the improvement of the MTBF of the power supplied to computers and related apparatus

The MTBF, mean time between failure, is an attempt to express mathematically the reliability of systems or components. A failure of a UPS system is defined as any unexpected deviation of output voltage parameters outside specified limits. The authors show the effect of the reliability of the public electricity network on the MTBF of uninterruptible power supply systems, and the difference in MTBF between UPS systems connected in series with the mains and those connected in parallel with the mains. Some statements are also made as to the real value of MTBF data and the importance thereof to end users