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FEATURES
• Protect against surges, damage caused
by induced lightning, electrostatic dis-
charges, noise, and ground loops.
• Surge protectors are available for
various network types.
• Protectors are also available for various
communication lines.
• We even carry surge protectors for
special equipment, such as CATV,
keyboards, and more!
1/16/2007
724-746-5500
#11141
OVERVIEW
Here's why you need a surge protector:
In an ideal world, the flow of electrical current in your com-
puter systems would be equal at all times. No outside power
disturbances would disrupt the balance of power in your
electronic devices.
In the real world, however, several forms of power disturb-
ances can wreak havoc on your electrical devices. These power
disturbances come in the forms of induced transients (which
include lightning, electrostatic discharge [ESD], and noise),
ground-loop currents, and surges.
Although only a lightning arrestor can protect against direct
lightning hits, a surge protector can guard your equipment
against damage caused by induced lightning. To understand the
need for this protection, consider the enormous magnitude of
energy that a lightning strike generates. As this large current
flows through conductors, the expanding magnetic field causes
induced current to flow in nearby conductors that could then
carry damaging impulses to computers.
A surge protector can also guard against the second
type of induced transient, electrostatic discharge (ESD). What
we commonly think of as static is that zap we get when we
grab something metallic after walking across a carpet during
the winter. This static is actually called triboelectricity, from
the Greek word tribo, which means rubbing. When two unlike
materials rub together, the electrons from one and the electrons
from the other produce a negative charge (or electrostatic
discharge), causing a potential difference between the two
surfaces. The excess electrons look for a discharge path, which
they find in any good conductor. The excess energy can damage
your equipment.
A third type of induced transient, noise, can also damage
your equipment. Noise is a signal appearing in a circuit other
than the desired signal. It can result from lightning or ESD, but
more commonly results from other events happening in the
blackbox.com
environment. Low-magnitude noise does not bother a PC,
but high-magnitude noise or impulses can interfere with data
processing or damage internal components. Noise as it
appears on power lines comes in two varieties: normal-mode
and common-mode noise. Turning large loads off or on, or
shunting utility power-factor correcting capacitors across the
line, creates normal-mode noise. Lightning, tripping and
reclosing utility breakers, poor grounding techniques, ground
faults, radio transmitters, time clocks, and machine tools can
cause common-mode noise.
Another hazardous form of power disturbance is called
a ground loop. A ground loop is formed when a potential
difference exists between any two places that are, by
definition, at ground potential. A ground loop may form
in a circuit when the circuit contains two or more different
ground connections. This circuit may also be formed between
boards inside a PC or in a local area network. Whenever there
is some impedance existing between two points, voltage can
appear across these points and current can flow. Ground
loops can also develop because of a circuit wire's length.
The final type of power disturbance which the protectors
guard against is, quite obviously, surges. A surge is a short-
term voltage increase that exceeds established upper limits
for less than 2.5 seconds. Each type of electrical interface
contained in your data communications equipment has an
acceptable operating voltage range. Voltages above the
range of the particular device's interface can damage the
device in two ways. First, a massive voltage (called a spike)
can immediately damage your equipment. Second, multiple
smaller out-of-range voltages can gradually damage your
equipment over time.
Our surge protectors provide an immediate path to
ground, so power disturbances go straight to ground
instead of to your equipment.
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