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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:
,
,
,
,
.
B. All of these (except the
) go unnoticed by the computer.
C. These common power problems can lead to
problems
with the computer.
D. When plugged directly into a wall outlet, over time these can result in
damage to a computer.
Type of Power
Description
Problem
 Consists of small variations in the
of the
power line.
Line Noise
 Plug your PC into its
circuit.
 Sharing an extension cord with an
will cause
major problems. This causes your power supply to burn out and
any line noise passes through to the
or
.
IT: Computer Maintenance: Power Quality and Protection Plan
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 A power spike or over-voltage happens when disturbances like
distant
Power surges
, or other
anomalies in the electrical supply grid, create a voltage spike
that
down the line and to your wall plugs.
 The surge lasts for only a few
of a second,
but can cause the voltage to increase to
volts or
higher.
 High voltage spikes
the power supply. Multiple
surges over time can
it.
 Also known as
, is the opposite
of a power surge and happens when a sudden
Brownouts
occurs
in the power line voltage.
 It doesn’t normally last too long. Usually the power level
below normal levels for a time and then
to normal.
 They are extremely common during periods of heavy
on the electrical system (
afternoons/
mornings).
 The reduced voltage level causes many devices to run
than normal or
 Occur when the power
in other ways.
completely.
 Problems caused are usually more frustrating than
Blackouts
.
 NOTE: The
of power surrounding a
blackout can, however,
your system.
 If you are in the middle of something that is not
, or
a hard drive when a blackout occurs you
will have problems.
 More often the damage
when the power
suddenly, usually in the form of a huge spike.
IT: Computer Maintenance: Power Quality and Protection Plan
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 This spike delivers
volts or more if it were to hit a
home or office directly.
Lightning
 A strike even in your
can result in a very high
voltage spike.
strikes
 A lightning strike has been known to completely
or
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
all at once in a
event.
2. Degradation: When a device is
over a
of instances and begins to
or has
problems.
III. Surge Suppressor
A. Most users plug their computers into a power strip or surge
.
B. The primary component of a surge suppressor is a
(MOV).
C. The MOV protects the computer by
D. The problem with MOV is that one big
the hit from voltage spikes.
or an
of small surges over time can knock it out.
IT: Computer Maintenance: Power Quality and Protection Plan
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E. Some surge suppressors have a
to indicate that the MOV is still all
right.
F. A surge suppressor reduces power problems by
and surges and by smoothing out
spikes
(called line
conditioning)
G. Not all surge suppressors include line
.
H. Consider two main features when choosing a surge suppressor:
I.
voltage: The voltage at which the suppressor begins to protect
the computer.
J. Clamping speed: The time
before the protection begins, or how much
time elapses between detection and protection.
K. Energy absorption: Surge suppressors are rated in
measures their capability to
, which
energy
L. The higher the rating, the
the protection:
M.
Joules is good protection –
Joules is basic protection –
Joules is superior protection
N. Line conditioning: Line conditioning capability is measured in
.
O. The more decibels of noise reduction, the
the line conditioning.
P. Protection indicators: An LED indicates you are
Q. If the LED is out, get a
suppressor
IT: Computer Maintenance: Power Quality and Protection Plan
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R. Levels of protection: Surge suppressors have three levels of protection that
indicate the maximum number of
the suppressor allows to pass
through to anything plugged into it. The standard ratings are:
(Better) –
(Good) –
(Best)
S. Line
filter the power stream to
line noise.
T. Because they are usually
, few PC users use a
line
conditioner.
U. They prefer to purchase this capability in other devices, such as a
.
V. In the event of an electrical
the
or
strike, power can surge up
lines as well as the power lines.
W. When installing a surge protector, be sure it has
line protection.
IV. UPS
A. An
power supply (UPS) provides a
power stream to the computer.
B. Under normal conditions, it’s a surge protector that can also handle
conditions.
C. When the power
below a certain level or is
completely, the UPS kicks in and provides
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:
circuit - is a surge
.
E. The other side is the
F. The batteries store a
and DC to AC
.
charge that must be converted to
(because
that’s what the PC expects).
G. Two types of UPS units are available:
from its
side.
H. When the power
I.
UPS: Operates normally
, it switches over to its
In-line UPS: Operates normally from its
J. The AC side is only used in the event of a
backup side.
or battery backup side.
with the
-
powered circuits.
K. UPS units are often
with a standby power supply (SPS), or battery
backup, which only supplies power when
is available and has no power
abilities.
L. Never plug a laser printer or monitor into a conventional PC
devices are not critical to the operation of the PC and
. These
tremendous
amounts of power at startup.
IT: Computer Maintenance: Power Quality and Protection Plan
Copyright © Texas Education Agency, 2011. All rights reserved.
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