Reliability estimation of uninterruptible power supply using reliability block diagram method

The aim of this paper is to investigate the reliability estimation technique for the Uninterruptible Power Supply (UPS) systems. A new methodology in estimating the reliability parameters of the AC Uninterruptible Power Supply (AC UPS) using the Reliability Block Diagram (RBD) method is proposed. In contrast with the existing UPS reliability prediction methods that requires more input data and computationally tedious, this approach provides useful and fast method to evaluate the system’s Failure Rates, Mean Time Between Failures, Availability and Unavailability. Reliability parameters obtained from five major UPS configurations were compared and discussed in detail. Equations for calculating the MTBF and Unavailability were presented along with component reliability estimates. Sensitivity analysis on the major components of the AC UPS was performed to investigate the effect on the overall system reliability. Finally, the actual field data from industrial best practice were used to validate the results obtained