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9 Power Problems
Problems with Power
Power Factor Inc.
The Problems with Power
1. Flickering Lights
2. Errors in Data Transmissions between Nodes
3. Unexplained Component Lockup
4. Premature Component Failure
5. Hard Drive Crashes
6. Corruption or Loss of Data in CMOS and Other
7. System Devices Behave Erratically when too
many are turned on
8. Frequently Aborted Modern Transfer
9. Wavering Monitor Screens
10. Disc Drive Write Errors
are sensitive to their power environment. Anyone who has ever had a
computer toasted by a lightning strike or who has lost a
morningís work to a sudden blackout knows that all too well. But even
with the increased awareness of the need to protect computers from
power problems, many people still believe their vulnerability is
limited to the occasional storm or utility outage. There are two
unfortunate realities of the electronic age; the utility companies
simply cannot provide the clean, consistent power demand by sensitive
electronics, and you are responsible for the health and safe operation
of your equipment.
In fact, studies suggest that the
electrical environment in which most computers operate is a far
"dirtier" place than we once realized. Final data from massive
five-year survey of power quality in North America conducted by
National Power Laboratory indicate that the average computer site is
subject to 289 disruptive or destructive power disturbances per year.
Moreover, the most noticeable types of problems-blackouts and
lightning strikes-account for less than 12% of these events. Most are
under- and over-voltage conditions and electromagnetic
interference-disruptions that are nearly impossible to detect with the
naked eye. A more recent study by IBM has showed that a typical
computer is subject to more than 120 power problems per month. The
effect of the power problems range from the subtle-Keyboard lockups,
hardware degradation-to the dramatic data loss or burnt motherboards.
So how do you know if electrical glitches
are disrupting or damaging your computer, short of investing a fortune in
power monitoring equipment? Here are ten tell-tale signs of power
trouble. While no single symptom is conclusive evidence of flaky power
if your computer suffers two or three symptoms regularly, you should
probably look into an Uninterruptible Power System (UPS) or some other
power protection device.
Symptom One: Flickering Lights
Like blackouts and lightning strikes,
this is one sign that most people recognize as being power related.
And flickering lights usually are a sign that your facility is
experiencing split second outages or voltage sags. Unfortunately,
there is often a tendency to dismiss these flickers as
inconsequential: after all they are over with literally in the blink
of an eye.
|But a computer
functions in a world where milliseconds count. While it may take an
outage of hundreds of milliseconds is sufficient to crash a network.
If your workstation is in the same office as the file server, you may
notice a tendency for the server to lock up after the light flicker.
If your workstation is remote, however, you may never make the
Workstations or non-critical may be fine with level 3 UPS. It is recommended for servers and other critical equipment to use a
level 9 UPS and a minimum of level 5 UPS.
Need help with your selection?
Symptom Two: Errors in Data Transmission Between Nodes
While this is one of the most common
problems LANs face, few network technicians recognize that power
problems may be the cause. Actually, two different kinds of power
aberrations can interfere with internode communications: ground loops
can occur and electromagnetic interference (EMI).
can occur between any two devices linked by a data cable, especially
if the devices are a considerable distance apart. When a significant
voltage difference develops between the two devices, the difference
develops between the two devices, the difference develops will
"equalize" as an impulsive traveling on the cable. The result can be a
scrambling of the data carried on the cable; if the voltage potential
is large enough, it can even damage I/O cards.
EMI consists of electrical impulses
generated by noisy devices such as radio transmitters, fluorescent
lights, and even computer power supplies. These impulses travel
through the air, and a data cable can pick them up in the same way
that an antenna picks up broadcast signals. These conducted EMI
impulses create noise on the data cable, interfering with
communication between workstations, servers, and other peripherals.
Where possible, keep voltage differential from
developing by plugging all devices into a single grounding point, such
as a Level 5 or Level 9 UPS. Use data line surge
suppressors to prevent impulses from reaching the computer. Run longer
data cables through shielded, grounded metallic conduit to prevent EMI
from reaching the cable. Keep cable runs away from noise
generators-especially fluorescent lights.
Need help with your selection?
Unexplained System Lockup
Another common sign of power problems is
the tendency of servers or workstations to freeze. While many factors
can cause this sort of lockup, random system crashes are often a sign
of low voltage sags or subcycle power failures have sapped your logic
circuits of the voltage they need to operate properly. NPL and Bell
Labs power quality data show that voltage sags are the most common
type of power problem.
operate on very low voltages-typically just 5 volts DC. Manufacturersí
tolerances for logic voltage are fairly tight; when voltage drops
below 4.75 volts, RAM errors start to increase. If low-voltage
sags or subcycle outages starve the computerís power supply, it may be
unable to maintain logic voltage, and the system crashes.
Ironically, certain Level 3 UPS's can also cause this kind of logic voltage drop. While these
devices may advertise a fast transfer
time in the event of a power outage, they are often unable to provide
full power for one or two cycles after the transfer. In laboratory
tests, computer logic voltage has been measured to drop as low as 3.5
volts when powered by some inexpensive
Level 3 protection.
Use a Level 9 UPS which have no transfer time
when powering your computer to battery or use a quality level 5 UPS
that will allow and compensate for sags with a buck-boost internal
Need help with your selection?
Premature Component Failure
When an I/O card, mother-board, power
supply, or other vital component suddenly fails for no apparent
reason, the failure is often blamed on manufacturing defect. In
reality, the quality control and burn programs of most reputable
manufacturers make built-in defects a rarity. The real cause is more
likely to be latent chip damage caused by a high voltage spike, line
noise or harmonic distortion.
other spikes, line noise and harmonic distortion do not always cause immediate component failure. Often,
the delicate conductive traces in a microchip can simply be weakened
by high voltage or heat dissipation, only to fail weeks or months later, when the event
the event that hastened the chipís demise has faded from memory.
Unless such component failures are frequent, the network technician
may never suspect the true cause of the damage.
You say youíve protected you server with
a surge protector, and you are still getting component failure? Surge
protectors may protect against spikes, but does nothing for line noise
and harmonic distortion. It is
possible that the surge device itself has become the victim of
repeated lightning strikes-especially if it is one of the cheap
hardware-store variety. Or spikes could be seeking into your system
via other routes, such as data cables or modem connectors.
Be sure that all network devices are
protected by high-quality, multi-stage surge suppressors, which carry
a UL 1449 rating. Many level 3,5,and 9 protection carry this rating.
Contact Us to find the
appropriate solution for your application. See to it
that data cables and modern lines are also protected by
Hard Drive Crashes
While this nightmare is less frequent
than it used to be hard drives still crash, and power problems can be
Suddenly power loss can be especially
dangerous to hard drives; if power fails during a read/write
operation, the heads can drop precipitously onto the disc, damaging
the delicate magnetic medium and creating bad sectors. If this damage
occurs in the wrong place, disk boot failures may result.
Use a quality UPS system Level 3, 5 or 9, to provide
enough backup power to allow you to do an orderly shutdown of the
system. Need help with your selection?
Corruption or Loss of Data in CMOS and Other EPROM Chips
Many computer users have experienced the
horror of turning on their computer and finding itís suffering from
amnesia; it no longer remembers how many drives it has, what kind of
monitor itís supporting, or how much memory is on its mother-board.
Again, bad power may be the culprit.
arrival of 386,486 and Pentium systems, vital system configuration
data is stored in ROM. High-voltage impulses can scramble the data on
these chips, forcing the user to do a system setup from scratch. CMOS
chips can also fall prey to electronic discharge(ESD)-that nasty,
high-voltage shock you sometimes get when you touch a metal object on
a dry day. ESD discharges can be several thousand volts in amplitude,
enough to cause you pain and to wipe a ROM chip clean.
Protect Equipment with
high-quality surge suppressors. Use various devices on the
market (grounding wrist straps, touch-pads, anti-static sprays, etc.)
to reduce the risk of ESD near your computer. Need help with your
selection? Contact Us.
System Devices Behave Erratically When Too Many are Turned On
If your network begins to behave
strangely as more and more workstations are powered up, your problem
could be harmonics, which show up on oscilloscopes as current or
voltage distortions. Ironically, computers themselves are one of the
biggest sources of harmonics, because their power supplies draw
current in big, isolated gulps instead of nice smooth sine waves. If
many of your network devices are powered from the same circuit, the
harmonic content of that circuit can build as the devices are turned
on. The result: the more workstations operating, the flakier they
Install a FERRUPS UPS or power conditioners, which feature a ferroresonant transformer. This special type of transformer is
extremely effective at filtering harmonics from the input line. A
ferroresonant-based device will also keep harmonics generated by the
workstation from affecting other computers on the same circuit. A
level 9 UPS will also provide protection against harmonics. Need
help with your selection?
Frequently Aborted Modem Transfers
Power problems can cause modem
uploads/downloads to abort or cause a high rate of block messages. The
situation can arise when high-frequency spikes or impulses traveling
on the power line couple into phone lines, which are almost never
protected by any kind of shielding. These signals are then interpreted
by the receiving modem as bad blocks.
Surge suppressors and many UPS systems are now available that include phone-line
jacks. These devices can stop many of the impulses that travel on any
phone-lines. You simply plug the modem line into one jack, and run
another line from the second jack to the wall connection. Give one of
these devices a try if aborted modem transfers are recurrent problem.
Be certain the device you select is designed with a single grounding
point for both the electrical and modem or data line connections. Need
help with your selection?
Wavering Monitor Screens
If your display flickers, wavers, or
dances, it could be a sign of larger power problems that may be
affecting your entire network. Voltage sags can make monitor displays
shrink. A wavering display could also be a sign of strong
electromagnetic fields neat the monitor. Either f theses situations
and do more than just disrupt your screen; they can cause RAM errors,
scramble data, and contribute to component failure.
Use a level 5, level 9 UPS or FERRUPS , which feature
voltage regulation, to keep input power at a proper level. Keep EMI
generator (especially electrical motors) well away from network
peripherals. Need help with your selection?
Disk Drive Write Errors
Because your hard and floppy drives are
really the only moving parts in your network, they are especially
vulnerable to power aberrations. Weíve already looked at two reasons:
damage caused by sudden loss, and RAM errors attributable to low logic
One additional way bad power affect disk
drives is to interfere with the rotation speed of the disks
themselves. Proper drive access depends on the correct rotation rate;
undervoltages can cause the drive to try to read or write data in the
wrong sector. Lost or garbled data, or actual drive failure, can
Protect equipment with voltage-regulating devices, such as a level 5
or 9 UPS. Need help with your selection?
Is poor power quality causing all of your
network woes? Probably not. Any device as complex as a computer is
vulnerable to failure from many sources, and networking many deices
together only compounds this vulnerability.
But donít be too quick to discount the
threat of bad power. A National Power Laboratory survey of 1,200
computer systems, showed that the number of service calls dropped an
average of 82% after the installation of a UPS.
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