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Cisco AVS 3120 Application Velocity System Hardware Installation Guide
OL-11805-01
Chapter 5 Maintaining Your AVS 3120
Using Power Protection Devices
Using Power Protection Devices
A number of devices are available that protect against power problems such as power surges, transients,
and power failures. The following subsections describe some of these devices.
Surge Protectors
Surge protectors are available in a variety of types and usually provide a level of protection
commensurate with the cost of the device. Surge protectors prevent voltage spikes, such as those caused
during an electrical storm, from entering an AVS 3120 through the electrical outlet. Surge protectors,
however, do not offer protection against brownouts, which occur when the voltage drops more than
20 percent below the normal AC line voltage level.
Line Conditioners
Line conditioners go beyond the overvoltage protection of surge protectors. Line conditioners keep an
AVS 3120’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 AVS 3120 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 AVS 3120 for a limited amount of time—from 15 minutes to an hour or so—depending on the UPS
system.
Surge protectors should be used with all UPS systems, and the UPS system should be Underwriters
Laboratories (UL) safety-approved.