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Power Quality & Protection PowerPoint Outline
Objectives



I.
Identify and describe the various types of external power problems.
Differentiate between catastrophic and degradation types of damage.
Identify and describe various protective measures against power problems.
External Power Problems
A. Some common external power problems: line noise, spikes, surges, brownouts,
blackouts
,
.
B. All of these (except the blackouts ) go unnoticed by the computer.
C. These common power problems can lead to reliability problems with the
computer.
D. When plugged directly into a wall outlet, over time these can result in
major damage to a computer.
Type of Power
Description
Problem
 Consists of small variations in the voltage of the power line.
 Plug your PC into its own circuit.
Line Noise
 Sharing an extension cord with an appliance will cause major
problems. This causes your power supply to burn out and any
line noise passes through to the motherboard or
Disk drive .
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 A power spike or over-voltage happens when disturbances like
distant lightening strikes, or other anomalies in the electrical
Power surges
supply grid, create a voltage spike that travels down the line
and to your wall plugs.
 The surge lasts for only a few thousandths of a second, but can
cause the voltage to increase to 1.000 volts or higher.
 High voltage spikes degrade the power supply. Multiple surges
over time can destroy it.
 Also known as under-voltage, is the opposite of a power surge
and happens when a sudden dip occurs in the power line
Brownouts
voltage.
 It doesn’t normally last too long. Usually the power level
drops below normal levels for a time and then returns to
normal.
 They are extremely common during periods of heavy load on
the electrical system (hot afternoons/cold mornings).
 The reduced voltage level causes many devices to run
Slower than normal or malfunction in other ways.
 Occur when the power fails completely.
 Problems caused are usually more frustrating than
Blackouts
damaging.
 NOTE: The fluctuation of power surrounding a blackout
can, however, harm your system.
 If you are in the middle of something that is not saved, or
defragging a hard drive when a blackout occurs you will have
problems.
 More often the damage occurs when the power
returns suddenly, usually in the form of a huge spike.
IT: Computer Maintenance: Power Quality and Protection Plan
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 This spike delivers a million volts or more if it were to hit a
home or office directly.
Lightning
 A strike even in your vicinity can result in a very high voltage
spike.
strikes
 A lightning strike has been known to completely
destroy or melt down everything plugged in: computers,
copiers, fax machines, telephones, and more.
II. Protecting Against Power Problems
A. Two types of damage can be done to the PC by electrical forces:
1. Catastrophic: When the device is
single
destroyed
all at once in a
event.
2. Degradation: When a device is damaged
period
over a
of instances and begins to fail
intermittent
or has
problems.
III. Surge Suppressor
A. Most users plug their computers into a power strip or surge
suppressor
.
B. The primary component of a surge suppressor is a metal Oxide Varistor (MOV).
C. The MOV protects the computer by taking the hit from voltage spikes.
D. The problem with MOV is that one big spike, or an accumulation
of small surges over time can knock it out.
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E. Some surge suppressors have a light to indicate that the MOV is still all right.
F. A surge suppressor reduces power problems by absorbing spikes
and surges and by smoothing out line noise (called line
conditioning)
G. Not all surge suppressors include line conditioning.
H. Consider two main features when choosing a surge suppressor:
I.
Clamping voltage: The voltage at which the suppressor begins to protect the
computer.
J. Clamping speed: The time lapse before the protection begins, or how much time
elapses between detection and protection.
K. Energy absorption: Surge suppressors are rated in Joules, which measures
their capability to absorb energy
L. The higher the rating, the better the protection:
M. 200 Joules is basic protection – 400 Joules is good protection – 600
Joules is superior protection
N. Line conditioning: Line conditioning capability is measured in
decibels.
O. The more decibels of noise reduction, the better the line conditioning.
P. Protection indicators: An LED indicates you are protected
Q. If the LED is out, get a new suppressor
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R. Levels of protection: Surge suppressors have three levels of protection that
indicate the maximum number of watts the suppressor allows to pass through
to anything plugged into it. The standard ratings are: 500 (Good) –
400 (Better) – 330 (Best)
S. Line conditioners filter the power stream to eliminate
line noise.
T. Because they are usually expensive, few PC users use a true line conditioner.
U. They prefer to purchase this capability in other devices, such as a surge suppressor.
.
V. In the event of an electrical storm or lightening strike, power can surge up the
telephone lines as well as the power lines.
W. When installing a surge protector, be sure it has phone line protection.
IV. UPS
A. An uninterruptible power supply (UPS) provides a
constant power stream to the computer.
B. Under normal conditions, it’s a surge protector that can also handle
brownout conditions.
C. When the power drops below a certain level or is disrupted
completely, the UPS kicks in and provides power for a certain number of
minutes, or even hours in some cases.
IT: Computer Maintenance: Power Quality and Protection Plan
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D. All UPS units have two sets of circuits: the AC circuit - is a surge
suppressor.
E. The other side is the battery and DC to AC Conversion.
F. The batteries store a DC charge that must be converted to AC (because that’s
what the PC expects).
G. Two types of UPS units are available: Standby UPS: Operates normally from its
AC side.
H. When the power drops , it switches over to its battery backup side.
I.
In-line UPS: Operates normally from its DC or battery backup side.
J. The AC side is only used in the event of a problem with the battery powered circuits.
K. UPS units are often confused with a standby power supply (SPS), or battery
backup, which only supplies power when none is available and has no power
Conditioning abilities.
L. Never plug a laser printer or monitor into a conventional PC UPS. These
devices are not critical to the operation of the PC and draw tremendous
amounts of power at startup.
IT: Computer Maintenance: Power Quality and Protection Plan
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