Electrical Engineering Basics Around the Home Part II

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Electrical EngineeringBasics Around the
HomePart II
UEET 101

• Presented by
• Donald S. Zinger

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ReviewElectricity Everywhere

• Entertainment
• Communication
• Industry
• Lights
• Anything dealing with electron flow
• Electrical engineers involved in all

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Electrical Engineering Major Areas

• Signal and Systems
• Communications
• Controls
• Digital
• Computers
• Logic Systems
• Power
• Generation and distribution
• Power conversion

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Quantifying Electricity

• Current
• Flow of positive electrical charge
• Measured in Amperes
• Voltage
• Pressure that causes current to flow
• Measured in volts
• Impedance
• Circuit opposition to current flow
• Resistance in many circuits
• Measured in ohms (W)

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Basic Electrical Quantity Relationships
I current V voltage Z impedance (resistance
for dc) P power W energy (work)
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Example Calculations

• Find P for various voltages
• Z 2 W

V P
2.5
2.0
1.5
1.0
0.5
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Design Process

• Find a consumer need
• Determine technical specifications
• Develop system and components
• Evaluate design
• Repeat as necessary

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Tools of Electrical Engineer

• Calculator
• Analysis and design
• Computer
• Analysis and design software
• Simulation software
• System (e.g. Simulink)
• Circuit (e.g. PSPICE)

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Example of PSPICE

• Simple circuit
• Battery and resistor
• Highly complicated circuits possible

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Other Tools Laboratory Equipment

• Testing and evaluation
• Meters
• Measure average RMS values
• Oscilloscopes
• Measure time varying values
• Others
• Signal generators
• Spectrum analyzers
• Etc.

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ExampleElectric Glove

• Developing an electrically heated glove
• Uses resistive heat
• Nominal heat 1 W
• Not to exceed 2 W
• Should last 2 hours (90 of nominal power).

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Challenge Choose Resistance and Battery

• Light weight
• Meets original specifications

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Batteries in Series

• Voltages add
• Total energy increases

Pictorial
Schematic
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Batteries in Parallel

• Current capability adds
• Total energy increases
• Current sharing problems

Pictorial
Schematic
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Battery Choices
From http//www.duracell.com/oem/Pdf/others/alkal
ine.pdf
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Class Problem

• Divide into groups (4 to 5 people)
• Decide on a set of batteries and a resistance
• A number of designs will be randomly chosen and
  simulated
• All designs meeting spec will be compared for
  weight
• Lowest weight to meet specs will be winner

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Discharge Curves
From http//www.duracell.com/oem/primary/alkaline
/alkaline_manganese_data.asp
D Cell
C Cell
AAA Cell
AA Cell
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What was done

• Found a consumer need
• Desire for warm hands
• Determined technical specifications
• Previously defined
• Developed system and components
• Found battery and resistance
• Evaluate design
• Simulated
• Eliminated unsuitable designs

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Should Repeat Cycle

• Where specifications proper?
• 1 W enough?
• 2 Hrs long enough?
• Would design work as expected?
• Simulation model
• Need to build to actually check?
• Other factors
• Glove materials
• Reliability
• Reproducibility

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Math, Science, and Engineering Skills Needed

• Emphasized in course work
• Basis of all steps of design
• Engineers should have a solid grasp of
  fundamentals

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Technology Changes

• Technology always changing
• Computer processing power
• Other areas as well
• Need to keep active

Graph from http//www.awe.co.uk/main_site/scienti
fic_and_technical/publications/discovery/pdf/disco
very_july_2001/computers.pdf
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Engineers Not Alone

• Work in teams with others
• Electrical
• Industrial
• Mechanical
• Work with others
• Marketing
• Manufacturing
• Look at big picture
• Societal implications
• Ethical Considerations

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Summary

• Electrical engineers involved in many designs
• Design requires many interconnected steps
• Based on fundamentals
• Constantly improving
• Keep the big picture
• Team work
• Society as a whole