Reliability and availability estimation of DC Uninterruptible Power Supply systems using Monte-Carlo simulation

The purpose of this paper is to describe the method used to calculate the Reliability and Availability estimations of the Uninterruptible Power Supply (UPS) systems using Monte-Carlo simulation method. In this method, the failure rates (λ), and availability (A) of the major components in the UPS are simulated by the use of random number generators. The main objective of this method is to produce, artificially, reliability data for use in statistical analysis and to compare with the results that would be obtained from field trials. Reliability parameters such as the system's Failure Rates (λ), Mean Time Between Failures (MTBF), System Availability (A), and System Unavailability (W), can be achieved and thus can be used as an indication of the reliability level of the UPS systems. In this paper, the method are applied to two DC UPS configurations (with and without generator), and comparisons on the results obtained from this method were made to the results from other reliability estimation method such as the Reliability Block Diagram (RBD), Boolean Truth Table and Field Data estimation method.