Editing Data center (section)

===Electrical power===
[[File:Datacenter Backup Batteries.jpg|thumb|right|A bank of batteries in a large data center, used to provide power until diesel generators can start]]
[[File:Power generator of a hospital data center.jpg|thumb|Diesel-powered generator of a hospital data center]]

Backup power consists of one or more [[uninterruptible power supply|uninterruptible power supplies]], battery banks, and/or [[Diesel generator|diesel]] / [[gas turbine]] generators.<ref>Detailed explanation of UPS topologies {{cite web|url=http://www.emersonnetworkpower.com/en-US/Brands/Liebert/Documents/White%20Papers/Evaluating%20the%20Economic%20Impact%20of%20UPS%20Technology.pdf|title=EVALUATING THE ECONOMIC IMPACT OF UPS TECHNOLOGY|url-status=dead|archive-url=https://web.archive.org/web/20101122074817/http://emersonnetworkpower.com/en-US/Brands/Liebert/Documents/White%20Papers/Evaluating%20the%20Economic%20Impact%20of%20UPS%20Technology.pdf|archive-date=2010-11-22 }}</ref>

To prevent [[single point of failure|single points of failure]], all elements of the electrical systems, including backup systems, are typically given [[Redundancy (engineering)|redundant copies]], and critical servers are connected to both the ''A-side'' and ''B-side'' power feeds. This arrangement is often made to achieve [[N+1 redundancy]] in the systems. [[Transfer switch#Static transfer switch|Static transfer switches]] are sometimes used to ensure instantaneous switchover from one supply to the other in the event of a power failure.