A surge protector [AKA surge suppressor] is an electrical plug-in
device designed to distribute safe electrical voltages to other
electrical or electronic devices. Surge protectors resemble power strips
in appearance; however, they are more sophisticated and deliver a
constant, continuous power supply.
In addition to connecting multiple devices to a single power source,
surge protectors provide protection from frequent problems that plague
conventional utility power. The most common of these problems are surges
(temporary increase of voltage) and brownouts (temporary decrease of
voltage). These disturbances slowly degrade many power supply units and
cause premature equipment failure. The rising demand on our nation’s
power grids is causing more brownouts than ever before (Gamble; Power
Protect Your Computer).
The Inside of a Surge Protector
Toroidal Choke Coil: The toroidal choke coil is an electromagnet
wrapped in wire. It filters out line noise as the hot wire passes
Metal Oxide Varistors (MOV’s): An MOV has three parts: a piece of
metal oxide material in the middle and two semiconductors joined to the
hot and ground wire. As a protective connecting unit it shifts unsafe
voltage levels to the ground wire.
Neutral Wire: The neutral wire is common in modern wiring practices
for safety. It is used in conjunction with the hot wire and the ground
Hot Wire: The hot wire holds the passing current which contains
Fuse: A fuse is a resistor used to protect the wiring from getting
too hot. Fuses “blow or burn out”, thereby preventing the electrical
current from traveling further.
Ground Wire: The ground wire protects users from getting an
electrical shock. It receives excess voltage from the MOVs. Most surge
protectors contain a parallel circuit design whereby the extra voltage
is fed away from the standard path to another circuit. Another design is
a series circuit where the electrical current is slowed; moreover it
detects high voltage, stores the electricity, and releases it gradually
The majority of the electrical currents diversion is done through the
metal oxide varistor or MOV. The MOV acts as a pressure-sensitive valve:
based on the level of voltage, the electrons in the semiconductors
behave differently either creating lower or higher resistance. When the
voltage is correct, an MOV doesn’t do anything (Harris).
Specifications and Quality Considerations
Energy Absorption: Surge processors are measured in joules (the
amount of energy they can absorb). The higher the number, the better the
protection: 200 joules provides basic protection, 400 is good and 600 or
high is superior protection.
UL1449: Standard rated by Underwriters Laboratories as the minimum
protection standards for surge protectors. It rates suppressors by the
amount of voltage passage they allow.
Protection Indicator: LED indicator as to metal-oxide varistors
functioning. MOVs do not last forever – one lightening strike can fry
Line Conditioning: Most surge protectors contain this feature. It
filters out line noise using a toroidal choke coil to “condition” the
Power Switch: There are manual on/off power switches as well as
circuit switches. Circuit switches are useful for keeping some
components running while others are shut off.
Circuit Breaker or Fuse: A fuse is a resistor that can conduct
current below a certain level. If the current is higher than acceptable,
heat burns the fuse and cuts off the circuit. Breakers are more
economical than fuses as they do not have to be replaced.
Protection Guarantee: Read the terms and conditions carefully! It is
important to understand your consumer rights in the event of damage to
devices your surge protector neglects to protect (Kozierok).
According to data published on Hewlett Packard’s website, recent
statistics reveal 63 percent of all electronics casualties are the
result of a power related problem. Most affected are devices using
computer chips and high-speed microprocessors. Unprotected computers can
suffer hardware degradation and extensive damage when exposed to power
surges (Power Protect Your Computer).
The cost of a surge protector varies greatly depending on user needs.
Basic models sell for as low as $10 but one should be cautious as to the
capabilities these units offer.
NOTE: It is important to connect all peripheral equipment to the
surge protector for complete protection. This includes phone jacks,
modems, cables, and any other external devices that will receive
All visuals have been removed from this article to comply with the
publishing rules for this site.
Gamble, T. “Storm Season” www.bestbuy.com 15 Sep. 2004 http://www.bestbuy.com/site/olspage.jsp?id=pcmcat31600050019&type=category
Harris, T. “How Surge Protectors Work” www.computer.howstuffworks.com
15 Sep. 2004 http://computer.howstuffworks.com/surge-protector2.htm
Kozierok, C.M. “External Power Problems” www.pcguide.com 15 Sep.
Power Protect Your Computer, www.hp.com 15 Sep. 2004
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