Cisco 7541 - Power Source Interruptions; Using Power Protection Devices; Surge Protectors

B-5
Cisco Wide Area Virtualization Engine 7541, 7571, and 8541 Hardware Installation Guide
Appendix B Maintaining the WAVE-7541, WAVE-7571, and WAVE-8541
Using Power Protection Devices
Power Source Interruptions
Systems are especially sensitive to variations in voltage supplied by the AC power source. Overvoltage,
undervoltage, and transients (or spikes) can erase data from memory or even cause components to fail.
To protect against these types of problems, power cables should always be properly grounded and one
or both of the following methods should be used:
• Use one of the power protection devices described in Using Power Protection Devices.
• Place the system on a dedicated power circuit (rather than sharing a circuit with other heavy
electrical equipment). In general, do not allow the system to share a circuit with any of the
following:
– Copier machines
– Air conditioners
– Vacuum cleaners
– Space heaters
– Power tools
– Teletype machines
– Adding machines
– Laser printers
– Facsimile machines
– 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
• Line Conditioners
• Uninterruptible Power Supplies
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
20 percent below the normal AC line voltage level.