Feb 16, 1998
Surge suppression: the first line of power defence. (Technology Information)
Electrical power is a driving force behind today's economy. As such, electricity is used to
power engines, to light millions of homes, offices and buildings, and to power computers
and computer networks.
Unfortunately, the electrical genie is not something that is always neatly bottled or
controlled. As a result, power disturbances such as electrical outages and brownouts have
become commonplace. So have transient voltages and power surges. These latter
problems, however, can be dealt with effectively by good-quality surge suppression
products.
A surge suppressor is simply a power diverter, directing harmful power disturbances
safely through a bypass path of least resistance to ground. This protects your sensitive
computer components. A high quality surge suppressor is vital to protect your computer.
Thirty-five per cent of power problems are generated off-site, by events such as lightning,
utility grid switching, line slapping, mis-wiring, etc. Sixty-five per cent of all electrical
surges or transient voltage activity is generated within the home or business.
Power supply problems are generally caused by motors and other electrical devices being
turned on and off. Sources can be elevators, air conditioners, vending machines, copiers,
large computers, even lighting equipment.
Every workplace with electrical devices is subject to both internal and external transient
voltages. These transients may not be apparent in all cases, but the effects can be
degenerative, and over time failure will occur.
A leading source of concern over power surges is current microprocessor technology. A
few years ago, computer chips had only 2,000 transistors in about 3/8" square. Today's
Pentium-type chips have over 10,000,000!
As a result, space between components has become so compressed that damaging arcing
will occur above 5 to 10 volts. Damage can also result from lightning even miles away.
The situation isn't likely to improve, either: more sensitive chips that work at higher and
higher frequencies are always under development.
Clock speeds, or operating frequencies, have increased and reached the frequency range
of high-voltage transients. The slower processors used in the past were unaffected by
these transients, but today's high-speed microprocessors may actually interpret a transient
as a command sequence!
The susceptibility of a computer network to power problems also increases with the
growth of the network itself. In addition, the architecture of the LAN also influences the
network's vulnerability to problems. A LAN running on a backbone is more susceptible to
power disruptions than a cluster-oriented one.
Poorly protected power can scramble data, prematurely wear out components, or even
destroy expensive chips. The symptoms of damage include: unknown data errors, I/O
retries, irregular performance, lost files, high maintenance rates, intermittent, unreliable
system operation, mysterious bugs and unexplained hardware problems.
It is important to remember that a failed chip may cost up to a thousand dollars to
replace, and that the associated downtime may end up costing even more than that.
Fixing a computer can cost days or even weeks of your valuable time.
Not all surge suppression products currently on the market are alike. Here are some
product features to look for when choosing a surge suppressor.
A volt clamp rating of 400 volts means that spikes will rise to 400 volt levels before they
are contained. If this is from the bottom of the sine wave, the uncontained spike may
actually rise to nearly 570 volts!
This means that your equipment will be damaged every time the photocopier fires off a
copy; or when transients jolt from air conditioners, elevators or large switching motors,
etc.
Choose a surge suppressor with a volt clamp rating of 330 volts: the best rating offered by
Underwriters Laboratories Inc. (UL).
Look for sine wave tracking, a high-tech capability that clamps spikes tightly against the
sine wave. This prevents spikes from rising too high. High-rising spikes are killers.
Many devices have a 5 nanosecond response time. Some are even slower than that. This
is too slow to be effective. A response time of less than 1 nanosecond (a billionth of a
second) is much more acceptable, and it's available in products now on the market.
Joule rating is a measure of how much damage energy suppressors can handle. The
higher the better. Many device manufacturers don't even mention joule rating at all, or
else they only offer products that are in the 50 to 200 joule range.
Such a low rating means that the surge suppression device is not made to handle serious
power disturbances like lightning. Look for a range from 360 up to 740 joules.
If you are attached by a modem to the outside world -- on the Internet, for example -- you
need telephone line protection. Telephone lines are basically antenna systems that direct
powerful surges right into the heart of your computer -- and to anyone attached to it --
even if the lightning activity occurs many miles away from your computer system.
Electro-Magnetic Interference (EMI) and Radio Frequency Interference (RFI) are
disruptions on the smooth AC power line sine wave, and can be caused by lightning,
generators, radio transmitters or even household appliances. A surge suppressor that
offers noise attenuation protects against this hazard.
A thermal fuse is a safety device that is activated in the event that there is an extended
overvoltage (these can and do happen). It will automatically take the device off the power
line, eliminating the possibility of a burned protector or damaged equipment. Thermal
fuses add to the cost of surge suppression, and so they are seldom found in low-cost
products.
Finally, too many surge suppressors offer no warranty at all. Make sure the product you
select is covered by a solid, lifetime warranty.
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COPYRIGHT 1998 Plesman Publications
in association with The Gale Group and LookSmart. COPYRIGHT 2000 Gale Group
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