An uninterruptible power supply, also called an uninterruptible power source, or UPS, is an electrical device that provides emergency fail-over power when the regular input power source, typically 110VAC, fails. The on-battery runtime of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment.
A UPS is typically used to protect hardware such as PC’s, servers, firewalls, routers, ethernet switches, telephone systems, or other electrical equipment where an unexpected power disruption could cause serious business disruption or data loss. UPS units range in size from units designed to protect a single computer without a video monitor (around 200 VA rating) to large units powering entire data centers or buildings.
A UPS:
• Should be placed between the electrical power receptacle and your electronic piece of equipment.
• Isolates your equipment from a power outage.
• Switches to battery backup when the unit senses a power outage or change in voltage.
• Gives you time to save information and shut down your equipment.
Recommendations:
• Use a UPS with any piece of electronic equipment that could be adversely affected by power problems. (these include PCs, networking appliances, phone systems, etc.)
• If a piece of computer equipment is critical, choose an on-line UPS.
• For less critical equipment, choose a standby or line-interactive UPS.
Line-interactive:
• Features an internal circuit that attempts to maintain normal voltage levels.
• Regulates the voltage without resorting to battery power.
• Helps the batteries last longer.
• Assures batteries are only used during a power outage.
On-line:
• Powers the computer or other equipment from an internal power supply 100% of the time.
• AC power from the incoming line is converted to DC, converted back to AC and then fed to the electronic equipment.
• Incoming power is continually filtered and recreated.
• Provides the highest level of protection.