A couple of months ago, I addressed the increased acceptance of shorter runtimes for UPS in data centers and other mission critical applications, but what was not discussed is why this trend is gaining steam.

Customer runtime requirements for UPS systems have decreased from 15 minutes or longer a decade ago to one minute or less today. So why the change? Why are customers asking for less and less energy storage for their critical facilities? What has changed in the data center environment that is driving down runtime requirements? 

Customers generally articulate three reasons for the reduction in runtime requirements:

• Extra runtime is unnecessary.
  Multi-minute UPS runtimes are a byproduct of an era when backup generators were slow to start or unreliable, or when generators were not present and the UPS had to carry the load as long as possible until utility power returned.
  By contrast, most modern on-site backup generators today can start and support an entire critical load in 10 seconds or less. For sites with backup generators, having multiple minutes of UPS stored energy is now completely redundant. Further, with the evolution of cloud computing and IT virtualization, in the event of a power disturbance, loads can be switched to an alternate site or cloud environment very rapidly — often in less than one minute.
   
• Extra runtime costs too much.
  Extended ride-through times are generally achieved through attaching large quantities of valve regulated lead acid (VRLA) batteries to the UPS. These extra batteries increase costs in multiple ways: at first purchase, increased maintenance and monitoring costs, and in periodic (4 to 6 year) battery replacements. Since the extra runtime is no longer valuable, this equipment represents an unnecessary and unjustifiable expense for owners and operators of mission critical facilities. In this post-recession era of doing more with less, customers simply are not going to spend more money than is required.
   
• Extra runtime takes up too much room.
  Not only are customers constantly looking for ways to save money, but floor space as well. In data centers and other mission critical facilities, square footage is at a premium, and with shorter runtimes, fewer bulky battery cabinets are needed, freeing up floor space for other applications and hardware.

You wouldn’t attach a sports car engine to your lawn mower because that much horsepower is not needed to cut the grass. This same principle can be applied to UPS equipment. Customers are increasingly willing to only purchase and install the amount of runtime necessary to get the job done right, nothing more!

While runtimes have diminished in recent years, overall system reliability and availability requirements have increased. Put simply, customers want critical power products that are more reliable, redundant, and efficient, but take up less space and cost less money.