Uninterruptible Power Supplies: A Critical Power Play
Part 4: Standby Online Hybrid UPS Improve Energy Efficiency
Standby Online Hybrid UPS Improve Energy Efficiency
By Greg Livengood - February 2010 - Power & Communication
Standby online hybrid UPS, also referred to as double conversion on demand, are similar to true online UPS, but with higher energy efficiency. The significant difference is standby online hybrid UPS loads are served directly from utility power as long as the power is within acceptable tolerances. Once the power exceeds the set tolerances, the UPS switches to standard true online operation.
Typical applications include server rooms, and the typical size ranges from 15 kVA units up to 75 kVA per rack.
Advantages include: grater reliability because of redundant systems; energy efficiency that can be more than 97 percent; greater power quality because the power output is isolated from power input; and a smaller footprint than line-interactive systems.
Disadvantages include higher initial and operating cost; batteries that require replacement every five years; and greater maintenance requirements because components have shorter service lives than line-interactive UPS.