One way to make fail-safe production lines and manufacturing processes is to use a redundant power supply system. A well-planned system includes not only multiple power supplies, but also several redundant ac input power lines. This white paper from Acopian describes a redundant arrangement, in which more than one power supply feeds a single voltage rail. If one power supply fails, the other continues to provide the entire power needs of that rail. Furthermore, a separate feed to each power supply input helps to stem failure on the primary side.