MTechnology, Inc. (MTech) performed a quantitative reliability analysis of the APC Symmetra MW UPS. The study used techniques of Probabilistic Risk Assessment (PRA) to calculate the likelihood of over 680,000 potential failure modes. The mathematical method accounts for uncertainty in failure rates and component performance, and provides detailed guidance as to the contribution of each system component to the overall risk of failure. The results allow APC to focus its engineering, manufacturing, and field service resources where they will be most effective in further improving system reliability. The study included an exhaustive analysis of the system’s architecture, component selection, control system, manufacturing practices, and response to internal and external faults. The study also included a detailed review of APC’s delta conversion online topology.

The study showed that system mean time between failures (MTBF) can exceed 1 million hours when operated with a redundant power section. This figure includes all equipment failures, including those attributable to causes beyond APC’s control, such as failures in the battery plant or electric utility.