Modular UPS systems are usually presented as having an extremely low failure rate when considering the UPS output. In fact, the best modular UPS systems are designed to increase the global system’s reliability and availability with minimum downtime due to their hot-swappable parts and cost-effective redundancy, the complete independence of each module and no fault propagation if one of the modules fails.

However, the biggest concern is their internal reliability: having a high number of modules increases the failure rate of the UPS system.

Consequently, to avoid this problem, the module’s MTBF value should be much higher than the typical MTBF of a standard UPS.

The aim of this guide is to help users understand and quantify the strong impact of the power module’s MTBF value on the internal reliability of the Modular UPS System, as well as the associated costs of substituting the failed modules, and the possible impact on the supplied equipment’s downtime.