UPS and their types?
ANSWER
The
Uninterrupted Power Supply (UPS) is a device necessary for uninterrupted
functioning of the computer. It gives power to a computer when there is a
blackout, checks the voltage that the computer needs and protects it from
harmful effects.
UPS has 2
sources of power: The Primary and Secondary. When there is power, the computer
gets power from the primary, but when there is not it gets power from battery.
A switch in the UPS does the switching- from secondary to the primary, vice
versa. The inverter in the UPS converts DC power from the battery to AC power
which the computer uses. These are types of UPS:
Offline UPS:The primary power supply is the
mains. Voltage is given to surge suppressor and battery through separate units.
If there is any power failure it uses battery power and the inverter changes the
power to AC.
Line Interactive UPS: Here one unit is used to provide
direct power and charge battery. The unit is made into an inverter. So the main
power comes from the battery.
Online UPS:It has two power sources and a
switch. Primary power supplies the from the mains. The most expensive and the
best.
What is laser printer?
ANSWER
Laser
printer is a page printer which can receive page of information one at a time
and print the data using electrostatic charges, toner and laser light. It has
many significant features like letter quality, high speed, high resolution, no
noise and a very high quality printing using paper type material called toner.
Its
component consists of:
Transfer corona assembly: This is used to provide the paper
with positive charge when it moves through the electrostatic drum. Then the
tonner being negatively charged will stick to the paper.
DC power supply: Produces +5V, -5V and +24V DC for
the motors and other chips integrated in the board.
High voltage power supply: Converts the AC supply into high
voltage which charges the transfer and wire corona.
Paper Transport System: A mechanism that moves the paper
from input tray to output tray.
Laser Scanning Assembly: Receives data in form of tiny dots,
puts the dots together and prints them out.
Formatter board: This is a circuit board that
contains the printer controller for the controlling of the printer.
Toner cartridge: This is a cartridge that contains
the toner used to print data on the paper.
What is SMPS?
ANSWER
Switch
Mode Power Supply (SMPS) is a power unit used in a computer to produce Direct
Current (DC) output. At the heart of the converter in SMPS is the high
frequency inverter section, where the input supply is chopped at very high
frequencies (20 to 200kHz using present technologies) and then filtered and
smoothed to produce DC outputs. The circuit configuration which determines how
the power is transferred is called the “the topology” of the S.M.P.S., and it
is a very important part of the design process. The topology consists of an
arrangement of transformer, inductors, capacitors and power semiconductors as
well.
Power
supplies are classified as :(1) Linear power supply and Switch Mode Power
Supply.
The linear
power supply dissipates more power during conversion, and so the large heat
sink is required to cool the system. The amount of power wasted in dissipation
is dependent on input voltage and load fluctuations. So, because of the excess
heat generated, they are viewed as inefficient and are no suitable for
computers.
The Switch
mode Power Supply has a transistor switch and a closed feedback loop to
generate output. These features make the output stable irrespective of the
input nature. It has transformer which works at boosting up voltage and
stepping it down at a required level. The AC input of the power supply is
converted to DC usingprimary rectifiers. Then it is sent to the filter to remove undesired signals.
It also has afilterwhich allows a particular range of
frequencies to pass and remove spikes.
Output DC
voltages are:
+12V:This is used to drive the disk drive
motors
-12V:This voltage works on the
motherboard to provide power to the serial ports.
+5V:Provides the motherboard +5V power
supply. The CPU’s built recently operates with little voltage.
-5V:It provides the motherboard with a
-5V backward compatibility. RAM and ISA slots works with this voltage.
+3.3V:With the advancement in technology,
+5V was replaced with +3.3V to reduce power consumption and enhance the speed
of operation. It is also used by the CPU to add system memory, AGP cards and
other circuits.
+5V Pwr OK: This is also known as the power god signal. It is used to indicate
that the power in the motherboard is sufficient enough to carry other
components of the computer after a stabilized output is obtained by the
motherboard.
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