Cisco Systems 474, 274 manual Line Conditioners, Uninterruptible Power Supplies

Appendix B Maintaining the Wide Area Virtualization Engine

Using Power Protection Devices

Line Conditioners

Line conditioners go beyond the overvoltage protection of surge protectors. Line conditioners keep a system’s AC power source voltage at a fairly constant level and therefore can handle brownouts. Because of this added protection, line conditioners cost more than surge protectors—up to several hundred dollars. However, these devices cannot protect against a complete loss of power.

Uninterruptible Power Supplies

Uninterruptible power supply (UPS) systems offer the most complete protection against variations in power because they use battery power to keep the system running when AC power is lost. The battery is charged by the AC power while it is available, so once AC power is lost, the battery can provide power to the system for a limited amount of time—from 15 minutes to an hour or so—depending on the UPS system.

UPS systems range in price from a few hundred dollars to several thousand dollars, with the more expensive units allowing you to run larger systems for a longer period of time when AC power is lost. UPS systems that provide only

5 minutes of battery power let you conduct an orderly shutdown of the system but are not intended to provide continued operation. Surge protectors should be used with all UPS systems, and the UPS system should be Underwriters Laboratories (UL) safety-approved.

	Cisco Wide Area Virtualization Engine 274 and 474 Hardware Installation Guide
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