Cisco Systems 274 Manuale Utente
B-7
Cisco Wide Area Virtualization Engine 274 and 474 Hardware Installation Guide
OL-17739-01
Appendix B Maintaining the Wide Area Virtualization Engine
Using Power Protection Devices
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Teletype machines
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Adding machines
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Laser printers
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Facsimile machines
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Any other motorized equipment
Besides these appliances, the greatest threats to a system’s supply of power are
surges or blackouts caused by electrical storms. Whenever possible, turn off the
system and any peripherals and unplug them from their power sources
during thunderstorms.
surges or blackouts caused by electrical storms. Whenever possible, turn off the
system and any peripherals and unplug them from their power sources
during thunderstorms.
If a blackout occurs—even a temporary one—while the system is turned on, turn
off the system immediately and disconnect it from the electrical outlet. Leaving
the system on may cause problems when the power is restored; all other
appliances left on in the area can create large voltage spikes that can damage
the system.
off the system immediately and disconnect it from the electrical outlet. Leaving
the system on may cause problems when the power is restored; all other
appliances left on in the area can create large voltage spikes that can damage
the system.
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:
power surges, transients, and power failures. The following subsections describe
some of these devices:
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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 a
system through the electrical outlet. Surge protectors, however, do not offer
protection against brownouts, which occur when the voltage drops more than
protection commensurate with the cost of the device. Surge protectors prevent
voltage spikes, such as those caused during an electrical storm, from entering a
system 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.