The choice of using UPS eco mode operation for critical systems is a widely debated topic in the industry today, as energy costs rise and corporations seek to enhance their green image by showing improved power usage effectiveness (PUE) in their annual reports. As with almost all new energy-saving technology, there are pros and cons, which this article will look to explore. We will focus on typical large-scale data center UPS systems, 3-phase, 300 kVA and larger. We will examine a number of salient issues that one must investigate fully before considering implementation of eco mode in a critical system environment.
Before exploring the functionality of eco mode, we must understand the infrastructure within the data center itself—from the IT load to the mechanical equipment. To do this, we must answer important questions, such as:
What are the power limitations on the critical load being supported by the UPS?
Is the IT load older style equipment or later technology? Older technology, due to its generally oversized and robust construction, is generally more resilient to power disturbances.
What is the ride-through time of the individual power supplies of the critical equipment compared to UPS transfer schemes?
What is the response of the non-IT loads to power disturbances and how can they affect the IT loads?
What is the site’s raw power-quality history?
What is the utility’s history of power surges and sags?