Pfizer needed to replace their existing site UPS system with a more robust system giving better redundancy and back-up supply to the plant critical loads. As the plant is a cGMP API site, process control & DCS systems need reliable uninterrupted power 24/7. A new N+1 UPS system was designed to replace the existing single UPS, which would fit within the confines of the existing building.
In addition, the design needed to provide for a ‘doomsday’ scenario so that emergency power can be switched directly to the plant critical load in the event of catastrophic failure of the N+1 UPS system. The resulting design is a resilient configuration featuring an automatic transfer switch on the UPS inputs (with diesel generator back-up), a coupling cabinet with wrap-around bypass capability on the UPSs themselves and a manual changeover switch on the UPS output with a raw mains supply (with generator back-up).