How does a parallel redundant UPS configuration improve data center reliability compared to a distributed redundant configuration?

A parallel redundant UPS (Uninterruptible Power Supply) configuration improves data center reliability compared to a distributed redundant configuration primarily by providing increased capacity and instantaneous failover protection. In a parallel redundant setup, multiple UPS modules are connected in parallel to supply power to the critical load. Each UPS module is sized to carry a portion of the total load, but the combined capacity exceeds the actual load requirement. If one UPS module fails, the remaining modules can instantly take over the entire load without any interruption in power supply. This immediate failover is a key advantage. In contrast, a distributed redundant UPS configuration involves multiple UPS units each supplying power to a separate section or zone of the data center. While this approach offers redundancy in the sense that the failure of one UPS doesn't affect all sections, it typically requires manual intervention or a transfer switch to redirect power from a functional UPS to the affected zone. This switchover process introduces a brief interruption in power, which can be detrimental to sensitive equipment and applications. Furthermore, parallel redundant systems offer better scalability. Adding capacity in a parallel system is simpler because you just add another UPS module in parallel, whereas adding capacity in a distributed system requires redesigning the power distribution architecture. The inherent instantaneous failover and increased capacity of parallel redundant systems make them more reliable for critical data center operations where any power interruption is unacceptable.