Pressure to substantially reduce energy demand by data centers while they provide increased capacity for data processing is creating a perfect storm for the mission-critical industry. Optimizing efficiency is widely accepted as the first step in the quest for energy demand reduction. The popular metric is power usage effectiveness or PUE. PUE is calculated by dividing the amount of power in kilowatts entering a data center by the power in kilowatts used to run the computer infrastructure within it. PUE is therefore expressed as a ratio, with overall efficiency improving as the quotient decreases toward 1.
Members of the Green Grid, an industry group focused on data center energy efficiency, created PUE. Data center infrastructure efficiency (DCIE) is the reciprocal of PUE and is expressed as a percentage that improves as it approaches 100 percent.
Since you can’t manage what you can’t measure, the first step to gaining control is to specify and install power monitoring/measuring hardware throughout a facility’s electrical backbone that is connected to intelligent software and integrated into a globally accessible network for users with “the need to know.”
Since everything we do is aimed at making the entire machine we call the data center as efficient and reliable as possible, surviving the perfect storm means meeting availability requirements. Downtime can be planned or unplanned; however, all downtime detracts from efficiency. An arc flash is the last thing we want in such a setting.
Arc flash from a failed bus joint or cable connection is the most egregious cause of unplanned downtime, so much of what we do while maintaining mission-critical electrical infrastructure is intended to avoid unplanned downtime as a result of this problem.
Arc flash is literally a ball of fire caused by an electrical fault. Ralph Lee’s technical paper entitled “The Other Electrical Hazard; Electric Arc Blast Burns” (1985) provides the following graphic definition, “Current passing through a vapor of the arc terminal conductive metal.” Recognition of arc flash has put emphasis on increased safety standards and changed the traditional approach to maintenance and repair. However, serious workplace injuries and fatalities from electrical arc-flash incidents continue to occur each year.
The traditional approach to designing, building, and maintaining mission-critical electrical infrastructure includes the following elements: