Figure 4-45.—Basic block diagram of a microcomputer’s power supply.
EXTERNAL COMPUTER PROTECTION
DEVICES
Most computer systems are equipped with some
sort of external protective device(s) that may include
backup power. They are provided in-line with the input
power source.
We discuss protection devices and
backup power.
Protection Devices
Protection devices are placed in-line with the power
source. Compensators are connected to a power panel;
compensators and line conditioners use an outlet as their
source.
COMPENSATORS.— Electrical compensators
provide ac input voltage regulation to ensure reliable
operation during voltage changes because of brownouts
(where the voltage may dip below the level needed to
run the computer) and transient voltage spikes.
Electrical compensators do not contain batteries or a
power invertor and, therefore, do not regulate or control
the frequency of the ac line voltage. Variations in input
frequency of the electrical compensator have a direct
effect on output voltage regulation.
LINE CONDITIONERS.— Line conditioners
filter the input power, bridge brownouts, suppress
over-voltage and over-current conditions, and generally
act as a buffer between the power source and the
computer. It is a real “surge suppressor.” The line
conditioner is an active device as opposed to a passive
surge-protector device. It contains circuits that bridge
brownouts or low-voltage situations temporarily.
SURGE PROTECTORS.— These devices are
designed to accept voltages as high as 6,000 volts and
divert any voltages above 200 to ground. They can
accommodate normal surges; but surges, such as a
direct lightning strike, blow right through them. These
devices can lose their effectiveness with successive
surges.
NOTE
APPROVED LINE CONDITIONERS
AND SURGE PROTECTORS ARE
LIMITED FOR USE ABOARD SHIPS;
CHECK NAVY SAFETY REQUIRE-
MENTS FOR USE ABOARD SHIPS.
Backup Power
Backup power devices provide protection to a
computer in the event of a complete power loss of the
primary power. They provide the time needed for an
orderly shutdown or continued operations.
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