Preface
Power Protection
The greatest threats to a system’s supply of power are power loss, power spikes,
and power surges caused by electrical storms, which interrupt system operation
and/or damage system components. To protect your system, always properly
ground power cables and one of the following devices.
Surge Protector
Surge protectors are available in a variety of types and usually provide a level
of protection proportional with the cost of the device. Surge protectors prevent
voltage spikes from entering a system through the AC power cord. 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 Conditioner
Line conditioners go beyond the over voltage 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. However, line conditioners
cannot protect against a complete loss of power.
Uninterruptible Power Supply
Uninterruptible power supply (UPS) systems offer the most complete protection
against variations on power because they use battery power to keep the server
running when AC power is lost. The battery is charged by the AC power while it
is available, so when AC power is lost, the battery can provide power to the
system for a limited amount of time, depending on the UPS system.
UPS systems range in price from a few hundred dollars to several thousand
dollars, with the more expensive unit s 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.
