Transcript Why Electrical Engineering I?

Why Take Electrical Engineering?
Like computer literacy, electrical literacy is very
important to engineering and everyday life
• So many things are powered or
controlled by electricity
• It is used to communicate by
video, wireless, phone or data
• So many physical phenomena are
measured using transducers (devices that convert
between a physical phenomena and an electrical
voltage, current or resistance that is easily
measured and recorded for analysis)
Some Transducers
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Light bulbs, buzzers, alerting devices
Speed indicators
Strain gauges
pH sensors
Temperature or light sensors
Flow sensors
Electric motors
Sound or movement sensors
Problem Solving
EE 188 also develops
problem-solving and
thinking skills – circuit
problems must be
solved using reasoning
and thought, not just by
plugging into formulas
Energy Crisis
• People are using up cheap, nonrenewable
energy sources such as oil and coal
• Use of oil and coal produces excess carbon
dioxide and global climate change
• 70% of oil is imported
– Dependent on global pricing variations
– Impacts our security
Renewable Alternatives
• Nuclear energy
– Atmospherically clean
– Dangerous
– Nuclear waste problems
• Wind energy
– Clean but unsightly
– Not dependable – needs storage capability
– Not abundant where needed most
Renewable Alternatives
• Solar
– More expensive
– Not dependable – needs storage capability
• Geothermal and Hydroelectric
– Environmentally sensitive
– Limited resources
Transportation Alternatives
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Plug-in electric gasoline hybrids
Biofueled vehicles
Natural gas-powered vehicles
Hydrogen-powered vehicles
Fuel cell-powered vehicles
Plug-In Electric Hybrids
• Potential Barriers?
Where Does Electricity Come From?
• We buy it from power plants
• We can generate it ourselves
– Diesel or gasoline generators
– Generated in our car
– Generated by home solar or wind power
• We can get it from batteries
• Sometimes we get it when we don’t want it
– Lightning
– Static
What is the main fuel used to
generate electricity in the US?
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Natural Gas
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Oil
Put a one by the fuel
most used,
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Hydroelectric
a 2 by the next most
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Nuclear
used, etc.
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Coal
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Wind, Solar, Biomass and Geothermal
Fuels Used to Generate Electricity
• #1 Coal is used to generate 49% of the
electricity in the U.S.
Fuels Used to Generate Electricity
• #2 Natural gas is used to generate 20% of
the electricity in the U.S.
http://www.powertechnology.com/projects/bethlehem/index.h
tml#bethlehem2
Fuels Used to Generate Electricity
• #3 Nuclear is used to generate 19.4% of the
electricity in the U.S.
http://www.srpnet.com/about/stations/palover
de.aspx
Fuels Used to Generate Electricity
• #4 Hydroelectric is used to generate 7% of
the electricity in the U.S.
http://www.desertusa.com/gc/gcd/du_glencan
damtour.html
Fuels Used to Generate Electricity
#5 Other Renewables account for 2.4%
•Wind
•Solar
•Biomass
•Geothermal
Wind Power
Solar Photovoltaics
http://www.aps.com/
my_community/Solar
/Solar_22.html
Solar Parabolic Trough
A trough can focus the sun at 30 to 100 times its normal intensity
to heat liquid in the receiver pipe to over 400 degrees Celsius.
Solar Dish and Engine
A solar dish concentrates the sun at a factor of 2000 achieving
temperatures of 750 C to run an engine which turns a generator.
Fuels Used to Generate Electricity
• #6 Petroleum is used to generate 1.6% of
the electricity in the U.S.
http://www.powertechnology.com/projects/riyadh/index.html#
riyadh1
Fuel Usage Pie Chart (2006)
Energy Usage
Electricity Cost Chart (2006)
How does Electricity Get to Us?
• Wires connect the power plants to the users
via the power grid.
• Long distances are covered by wires
carrying hundreds of thousands of volts
– Same power delivered by half the current and
twice the voltage
– Saves money on wire (typically 40mm in
diameter)
– Saves money on losses due to resistance in the
wire
Power Grid
Industrial Power
• Industrial plants use
three phase power
(480v) to run most
large machinery
• They run small
machines, lights,
computers on single
phase power
(120/240v)
Residential and Commercial
• Residential and commercial customers use
single phase power – 120 volts for most
uses or 240 volts for high power appliances
• Transformers are used to
reduce the high voltages
on the power lines to the
lower voltages needed
AC and DC Power
• Most power generated is Alternating Current
(AC) power where the current and voltage
varies sinusoidally with time
• Direct Current (DC) power doesn’t vary with
time
• Most consumer products use both AC and DC
• http://www.pbs.org/wgbh/amex/edison/sfeatu
re/acdc.html
DC Power
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DC power is used to power electronics
DC power is easier to store (batteries)
DC power is used in mobile applications
DC power is useful when off the power grid
Inverters convert DC to AC
AC Power
• AC power is easier to distribute
– Higher voltage and smaller current yields same
power distributed
– Transformers make it easy to change voltage
levels so smaller wire can used
• AC is used for most machinery, lights and
appliances
• Power supplies convert AC to DC
Study of Circuits at NAU
• EE 188 – DC circuits and AC circuits when
at steady state
• EE 280 – Transients, frequency response &
both digital and analog electronic circuits
• EE 380 – Linear and nonlinear electronic
circuits, device models and simulation
• EE 480 – Advanced Electronics
• EE 482 – Intro. to VLSI electronics design