Download Power Supplies - E-Portfolio: Robert Power

CP1610:
Introduction to Computer
Components
Computer Power Supplies
Purpose of a Power Supply
Connect PC to wall outlet.
 Distribute the right amount of power to all
parts.
 Transformer.
 Rectifier.

What is a Transformer?
PC power supplies ‘transform’ electrical
voltage from the building’s power supply.
 Reduces voltage from 120V or 240V
down to 12V, 5V, or 3V (as needed by the
PC).
 Distributes the right voltage to each PC
part.

What is a Rectifier?
Wall outlets provide Alternating Current
(AC).
 Computer needs Direct Current (DC).
 Power supply converts electricity from AC
to DC.

Power Regulation
Computers need stable, well-regulated
power supplies.
 Fluctuations or interruptions can:

 Damage
parts;
 Cause loss of data;
 Create electromagnetic interference (EMI);
Protecting Power Supplies

SPS
 Stand-by
Power
Supply

UPS
 Uninterruptable
Power Supply
SPS vs. UPS

SPS
 Stand-by

Power
Supply;
 Acts like a backup
battery in case of
power failure;
UPS
 Uninterruptable
Power
Supply;
 Computer is constantly
powered by the
battery;
 Also regulates voltage;
 Reduces EMI;
Electricity Basics

Three fundamental properties:
 Potential
difference across the circuit
(Voltage)
 Current, or flow of electricity (Ampere or Amp)
 Resistance on the circuit (Ohm)
Ohm’s Law

Formula to calculate
voltage, current, or
resistance.
V
=IxR

Symbols:
V
= Voltage
 I = Current
 R = Resistance
Calculating with Ohm’s Law

Voltage:
V

Current:
I

=IxR
=V/R
Resistance:
R
=V/I

Symbols:
V
= Voltage
 I = Current
 R = Resistance
Electrical Power
Measured in Watts (W)
 Multiply Voltage by Current

W
=VxI
Alternating vs. Direct Current
AC cycles back and forth.
 DC travels in only one direction.
 AC is more economical on a large scale.
 Computers require DC to operate.

Short Circuits
Occur when electricity crosses paths or
circuits.
 Can be dangerous.
 Can damage equipment.
 Prevented by using fuses.

Electrical Safety

Before you open the case:
 Turn
off the computer;
 Unplug the computer;

After you open the case:
 Use
a static strap and rubber mat;
 Never use magnetized tools;
 Don’t touch parts with a graphite pencil;
 Don’t stack parts on top of each other;
 Don’t touch parts with your hands or fingers!
Working with Monitors;
DON’T!
 Monitors use very high voltage.
 Retain a charge, even when turned off.
 The high voltage can KILL!
 Let a qualified technician do the work.
 Do not throw monitors in the garbage.

Overheating
Computers overheat above 180oF.
 Use fans to cool:

 Power
supply;
 CPU;
 Interior
of case;
Never leave your case open.
 You can also use liquid cooling.

Power Management




Conserve electricity
Protect environment
Save money
Can control power to:
 Main
system;
 Monitor;
 Hard drives;
 Printers;
 Other components;
Power Management Settings

Doze Time
 Reduces

Standby Time
 Reduces

92% of power consumption;
Suspend Time
 Reduces

80% of power consumption;
99% of power consumption;
Hard Drive Standby Time
 Shuts
down the hard drive;
Energy Star Ratings
Devices that comply with environmental
protection standards.
 Can apply to:

 Computers;
 Monitors
 Printers;
 Fax
Machines;
 Other Devices;