Practical Electricity, part 2

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Practical Electricity, part 2

• Ev I R POHMS LAW

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Skin effect?
hFEcurrent gain
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Diodes in action
chassis
Turn Sig
chassis
chassis
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Agenda

• Voltage
• Current
• Resistance
• Power, Volt Amps
• Symbology
• Single Phase
• Three Phase

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Circuits

• Electric Circuits Consist of Three Parts
• 1. Power Source Battery, Solar Cell,
• 2. Conductors - Connecting Wires
• 3. Load - Device such as, Motors, Lights, Heating
  etc.

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VOLTAGE TYPES
CHEMICAL
SOLAR
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Voltage

• Voltage (EMF Electromotive Force)
• Volts (E or V) Measurement of electrical force
  or pressure.
• Similar to pressure.
• Expressed as Electromotive Force (E) or (emf) in
  Ohms Law.
• Common Units
• Microvolt (uV) 1/1,000,000 Volt
• Millivolt (mV) 1/1000 Volt
• Volt 1
• Kilovolt (kV) 1000 Volts

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Difference of Potential

• Difference of Potential
• Is the force that causes free electrons to move
  through a conductor as an electric current is
  referred to as difference of potential or often
  shortened to potential.
• Similar to liquid flow there must be a difference
  in pressure or differential pressure or there
  will be no flow.

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Difference of Potential
Analogy to Liquid Level
Difference of Potential
Level
Liquid Pressure
Valve
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Difference of Potential
When a difference in potential exists between two
charged bodies that are connected by a conductor,
electrons will flow until the two charges are
equalized.
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CURRENT

• Electric Current
• The flow of electrons through conductive
  materials when electricity is being converted to
  useful work.
• Two Electric Current Types
• Direct Current (DC)
• Alternating Current (AC)

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CURRENT

• Measurement of Amperage (Current Flow)
• Amperes or Amps (A) The measurement of
  current flow through a conductor (wire).
• Number of (electrons) that pass through a given
  point, in a second.
• Expressed as Intensity (I) in Ohms Law
• Common Units
• 1 Amp
• Milliamp (mA) 1/1000 Amp .001A
  1 ma
• Microamp (uA) 1/1,000,000 Amp .000001A
  1µa

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RESISTANCE

• Resistance (Opposition to Current Flow)
• Ohm (W) Measurement of resistance in an
  electrical circuit.
• Similar to restriction of liquid or gas flow.
• Expressed as Resistance (R) in Ohms Law.
• Common Units
• Ohms (W) 1 Ohm
• Kilohms (k W) 1000 Ohms
• Megohms (meg W) 1,000,000 Ohms
• Every load on an electrical circuit creates
  resistance.
• Resistance to the current load creates heat.

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The OHM
Circular Mils the standard unit of
measurement of a round wire cross-sectional area
The area in circular mils of a round conductor is
obtained by squaring the diameter, measured in
mils.
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Ohms Per Foot
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IMPEDANCE, DC
Z

• IMPEDANCE Algebraic sum of all the Resistance
  in the circuit.
• For DC Z is the same as the total resistance of
  the circuit ( Rt )

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VOLTAGE DROP

• Resistance and Voltage Drop

100 Volts
98.38 Volts
1000 ft.
12 Gage Wire - 100 Volts - 1 Amp Current flow
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Power

• In Back to the Future, Doc Emit Brown declares
  that it takes 1.21 gigawatts to travel through
  time.
• The gigawatt is a unit of power, not energy. Now,
  a gigawatthour is a unit of energy.

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POWER WATT

• Electrical Power (Horsepower)
• Watt (W) 1 Watt 1 Volt times 1 Amp of current
• Expressed as (P) in power calculation formulas.
• 746 Watts 1 Horsepower.
• 1 HP ¾ KiloWatt

Common Units 1 Microwatt 1/1,000,000 Watt 1
Milliwatt 1/1000 Watt 1 Kilowatt 1000 Watts 1
Megawatt 1,000,000 Watts 1 GigaWatt 1 Billion
Million Watts Kilowatt Hour Kilowatts used in 1
hour
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Review Discussion

• Voltage is a measurement of
• electrical force (similar to pressure)
• Amperage is a measurement of
• current flow (similar to flow)
• Ohm is a measurement of
• resistance to current flow (similar to
  restriction)
• Wattage is a measurement of
• power used to perform work (horsepower)
• Voltage Drop is the result of
• the corresponding result of opposition to current
  flow.

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2 More Electrical Terms

• Inductance (Coil, transformer)
• Capacitance (Capacitor)
• Factors present in an AC circuit because the
  current is operating at 60 HZ, frequency
  dependant.

1 XC 2p f C
XL 2p f L
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AC Current Relationships

• Current thru Resistor is in phase
• Current thru Inductor will lag 90
• Current thru Capacitor will lead by 90
• Magnitude of current thru RLCwill dependent on
  Impedance which is a vector sum
• POWER FACTOR CORRECTION
• Capacitor Banks

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Resistive vs Inductive
ELI ICE MAN Voltage leads Current in a
inductive circuit Current leads voltage in
a capacitive circuit
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Electrical Theory

• Basic Formulas - Ohms Law
• Law 1 -If the voltage remains constant the
  current is inversely proportional to the
  resistance
• Law 2 - If the current remains constant the emf
  voltage across a device varies directly with the
  resistance
• Law 3 - If the resistance remains constant the
  current varies directly with the applied voltage

I
R
V EMF in Volts I Intensity in Amps R
Resistance in Ohms
V
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Symbols
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Electrical Theory

• Basic Formulas - Calculating Power
• The basic formulas used for calculating power as
  it is related to volts of emf, Amps of current.
  and resistance are contained in the following
  summary pie graph.

P I x V
P Power in Watts I Intensity in Amps V EMF
in Volts
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Electrical Theory

• Summary of Basic Formulas

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Calculate Voltage Using Ohms Law
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Calculate Resistance Using Ohms Law
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Calculate Current Using Ohms Law
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Handout
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Calculate Resistance (Handout)

• Resistors in series
• Resistors in parallel
• Resistors in combination

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Calculate Current

• Current is same in series (Rt)
• Current in parallel adds (Rt)

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Calculate Power

• Power Adds in parallel

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Voltage Drop
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Symbology

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LADDER LOGIC
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ELECTRIC DRYER
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BUILDINGSBLUEPRINT
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Solar Cell Battery Regulator
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Solar Cell Battery Regulator
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AC Single Phase
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AC 3 Phase
3 Coils in GeneratorCycles are 120 degrees
apart A B C
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Advantages of 3 PH AC

• 3 or 4 Wires Depending on Load
• Wire is Expensive, but will be smaller

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3 PH - WYE Connected Load
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Power in Delta Y Connected Systems

• Power v3 E I pf
• DELTA Y
  WYE
• WYE Neutral Current Occurs ONLY when Phase
  current is unbalanced

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Battery Configurations
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• http//www.freesunpower.com/system_sizing.php

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