POWER
AND YOUR PC
The electrical power coming into your home or business is provided,
normally, by the local power company. Depending on where in the world
you are, that could be 110-120 volts or 220 volts Alternating Current
(AC). Also, depending on where you are in the world, the quality of
that power can vary wildly.
The factors that affect the quality of the power delivered to your home
or office can include:
Age and condition of transmission lines (the big ones and the local
distribution lines) in your area
Age and condition of substations, transformers and switching equipment
in your area
Power load on the distribution system in your area
Distance to the nearest substation
Age and condition of electrical closet (and its parts), grounding, and
wiring in your home or business
Design of the wiring circuits in your home or business (e.g., too much
load on one circuit)
Fire, flood, earthquakes, tidal waves, weather (tornadoes, hurricanes,
typhoons, rain, sleet, snow, wind)
With all these factors, it is almost a miracle that most of us have
any power at all. In any case, the factors affect the quality of the
power. This involves the cleanliness of the power (how smooth the wave
form in the AC), as well as the voltage level. You can see this in your
own power outlets by putting a good multimeter to use. Know what you
are doing before trying this. 110 or 240 volts is nothing to play with.
The 240 voltage rating is normally found in large institutional
buildings where three-phase power is the usual supply. It is rarely in
the home outside the dedicated service for stoves and clothes dryers.
I'm going to use US voltages as my examples. Those of you in Europe and
other areas, YMMV.
A multimeter set across one of the hot lines and the ground on one
of my home outlets might read 112 volts AC. If I leave the meter on
those lines for a while, I will probably see fluctuations in the
voltage level from 108 to 120 volts. Power below the 108 voltage level
can give me brown-out conditions, making my lights dim and some other
appliances flicker. Voltages much above 120 can damage some appliances,
depending on their ratings (listed on the power labels).
The power supply on your computer takes the AC input power and
transforms it to 12, 5, 3, or 1.5 volts (= or -; Positive or Negative;
on or off). The lable will indicate the input power ranges (AC) it can
handle, the input amperages, and the output voltage (DC) and amperages
(normally in milliamps). The quality of the input power, variations in
the voltage and spikes in voltage can damage the parts in the power
supply. Variations in the power supply are produced by the load demand
in your area, a transformer that is getting old, a couple cracked
insulators on the neighborhood distribution line, and other factors.
Spikes occur when a switch kicks over to shift load at an area
substation (especially if it is an old-style switch). You get a very
brief drop, then a large spike or surge in power that quickly drops
back to normal levels. The spikes can blow capacitors or other parts in
your power supply or just flood through the PS and over amp your
motherboard. Of course, when this happens, it is time to get a new
MoBo. This is the unexciting kind of spike or surge. The other kind,
much more exciting, is from lightning.
Surge protectors, the good ones, are designed to provide a certain
amount of power filtering on each leg (both power legs and the neutral
leg) of the supply. High quality resistors and other electrical parts
are placed on each leg and provide the spike clamping and voltage
regulation. Most of the surge protectors, even the best ones, are just
that--surge protectors. They perform admirably at that task, but they
normally go no further. Many have guarantees that provide a cash value
in the event that they fail and your system is destroyed. I've seen
surge protectors that took lightning hits and were piles of melted
slag. But the computer they protected was still running just fine
(connected to another surge protector, of course). My own old XT system
took a lightning-induced hit that was absorbed by the surge protector.
But the modem was fried because the lightning strike had jumped to the
phone lines. This was in the old days before phone line or network
cable protections were added to surge protectors.
What surge protectors don't do is provide any battery backup for
clean shutdowns, brownout protection or full power conditioning. Most
of the battery backup devices you can buy now (uninterruptible power
supply or UPS) provide all this. The value of a battey backup is
obvious, of course. When the power goes out, it gives you a couple
minutes to bring your system down cleanly so the damage is minimized.
Brownouts won't flicker or reboot your system arbitrarily.
The greatest value of full power conditioning in these units is not
only the surge/spike protection, but the managed flow of power. Power
on your system when connected to one of these units and the power is
managed as the system comes to life. No fluctuations or over-voltages
as the system powers up. On power down, similar behavior. Nice and
easy. Nice and clean. The overall effect is lower stress on the
electrical parts, circuits and hard drive(s) and longer life and fewer
breakdowns for the entire system.
So, the answer to the question, "Do I need a surge protector?" is a
definite Yes. Get a good one. It will last a long time. If you need
more, get a UPS. There are many sizes and types to fit your needs.
Original Tutorial by rapier57
for TheTAZZone-TAZForum
Originally posted on May 18th, 2006 here
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