In addition to a UPS system, a back-up generator is an important component of protecting buildings with critical facilities or distributed computing. The UPS system will only support the critical load for the duration of the battery supply. This is typically five to 20 minutes, depending on the application. After the batteries are depleted, the load will crash. Very often, companies are so concerned with electrical reliability that the mechanical plant is overlooked.
Most critical systems require temperature control to maintain reliable operations.
Some equipment may also be water-cooled which requires a reliable, if not uninterruptible power source. Redundancy is equally important on the mechanical side. Redundancy needs to be evaluated for the HVAC, refrigeration plant, air-handling system, fuel oil system, building automation system, and water service. Failure of any of these components can bring a facility to its knees. Maintenance is critical.