Cisco Systems 274, 474 Using Power Protection Devices

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.

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.

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, page B-7

• Line Conditioners, page B-8

• Uninterruptible Power Supplies, page B-8

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

20 percent below the normal AC line voltage level.