Transcript Practical Electricity - The Pennsylvania Renewable Energy

Practical Electricity, part 2
Ev I R P
OHMS LAW
hFE
current gain
chassis
Diodes in action
Turn Sig
chassis
chassis
chassis
TURN
SIGNAL
BRAKE
Agenda
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Voltage
Current
Resistance
Power, Volt Amps
Symbology
Single Phase
Three Phase
Circuits
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Electric Circuits Consist of Three Parts :
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–
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1. Power Source – Battery, Solar Cell,
2. Conductors - Connecting Wires
3. Load - Device such as, Motors, Lights, Heating
etc.
1. Power
Source
3. Load
2. Conductors
Simplified Circuit
“VOLTAGE TYPES”
Squirrel Power
STATIC
CHEMICAL
SOLAR
Voltage
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Voltage (EMF Electromotive Force)
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Volts (E or V) = Measurement of electrical force or pressure.
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Similar to pressure.
Expressed as Electromotive Force (E) or (emf) in Ohm’s Law.
Common Units:
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Microvolt (uV) = 1/1,000,000 Volt
Millivolt (mV) = 1/1000 Volt
Volt = 1
Kilovolt (kV) = 1000 Volts
“Difference of Potential”
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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”.
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Similar to liquid flow there must be a difference in
pressure or “differential pressure” or there will be no
flow.
Analogy to Liquid Level
“Difference of Potential”
Difference
of
Potential
Level
Liquid
Pressure
Valve
“Difference of Potential”
Power
Source
Difference
of
Potential
Load
Tank A
Switch
Tank B
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.
“CURRENT”
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Electric Current =
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The flow of electrons through conductive
materials when electricity is being converted to
useful work.
Two Electric Current Types
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Direct Current (DC)
Alternating Current (AC)
“CURRENT”
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Measurement of Amperage (Current Flow)
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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.
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Expressed as Intensity (I) in Ohm’s Law
Common Units:
= 1 Amp
Milliamp (mA) = 1/1000 Amp
ma
Microamp (uA) = 1/1,000,000 Amp
.001A
1
.000001A
1µa
“RESISTANCE”
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Resistance (Opposition to Current Flow)
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Ohm (W) = Measurement of resistance in an electrical circuit.
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Similar to restriction of liquid or gas flow.
Expressed as Resistance (R) in Ohm’s 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.
*Circular Mils = the standard unit of measurement of a round wire crosssectional area
The area in circular mils of a round conductor is obtained by squaring the
diameter, measured in mils.
The OHM
CURRENT
RATING
WIRE SIZE
(known as
‘gauge’)
WIRE
DIAMETER
(expressed in
circular mils*)
30 Amps
20 Amps
15 Amps
10 AWG
12 AWG
14 AWG
10383
6530
4110
10 Amps
8 Amps
16 AWG
18 AWG
2580
1620
Ohms Per Foot
“IMPEDANCE, DC ”
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IMPEDANCE – Algebraic sum of all the
Resistance in the circuit.
For DC = Z is the same as the total
resistance of the circuit ( Rt )
Z
“VOLTAGE DROP”
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Resistance and Voltage Drop
100 Psig
98.36 Psig
Pressure Drop
1000 ft.
1” Pipe - 100 Psig water pressure - 1 GPM flow
100 Volts
98.38 Volts
Voltage Drop
1000 ft.
12 Gage Wire - 100 Volts - 1 Amp Current flow
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.
“POWER” “WATT”
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Electrical Power (Horsepower)
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Watt (W) = 1 Watt = 1 Volt times 1 Amp of current
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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
Review Discussion
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Voltage is a measurement of:
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Amperage is a measurement of
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resistance to current flow (similar to restriction)
Wattage is a measurement of
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current flow (similar to flow)
Ohm is a measurement of
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electrical force (similar to pressure)
power used to perform work (horsepower)~
Voltage Drop is the result of
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the corresponding result of opposition to current flow.
2 More Electrical Terms
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Inductance (Coil, transformer)
Capacitance (Capacitor)
Factors present in an AC circuit because the
current is operating at 60 HZ, frequency
dependant.
XL= 2π f L
1
XC= 2π f C
AC Current Relationships
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Current thru Resistor is in phase
Current thru Inductor will lag 90
Current thru Capacitor will lead by 90
Magnitude of current thru RLC
will dependent on Impedance
which is a vector sum
POWER FACTOR CORRECTION
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Capacitor Banks
Resistive vs Inductive
ELI
ICE
MAN
Voltage leads Current in a inductive circuit
Current leads voltage in a capacitive circuit
Electrical Theory
Basic Formulas - Ohm’s Law
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Law 1 -If the voltage remains constant the
current is inversely proportional to the resistance
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Law 2 - If the current remains constant the emf
voltage across a device varies directly with the
resistance
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Law 3 - If the resistance remains constant the
current varies directly with the applied voltage
V = EMF in Volts
I = Intensity in Amps
R = Resistance in Ohms
IR
V
Symbols
Electrical Theory
Basic Formulas - Calculating Power
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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=IxV
P = Power in Watts
I = Intensity in Amps
V = EMF in Volts
IV
P
Electrical Theory
Summary of
Basic
Formulas
Calculate Voltage Using Ohms Law
Calculate Resistance Using Ohms Law
Calculate Current Using Ohms Law
Handout
Calculate Resistance (Handout)
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Resistors in series
Resistors in parallel
Resistors in combination
Calculate Current
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Current is same in series (Rt)
Current in parallel adds (Rt)
Calculate Power
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Power Adds in parallel
Voltage Drop
Wires, Connected, Crossing
Symbology
Wires, Not Connected, Crossing
LADDER LOGIC
ELECTRIC DRYER
BUILDINGS
BLUEPRINT
Solar Cell Battery Regulator
Solar Cell Battery Regulator
AC Single Phase
3 Coils in Generator
Cycles are 120 degrees apart
ABC
AC 3 Phase
A
B
C
A
Advantages of 3 PH AC
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3 or 4 Wires Depending on Load
Wire is Expensive, but will be smaller
3 PH - WYE Connected Load
Power in Delta & Y Connected Systems
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Power = √3 * E * I * pf
DELTA
Y
WYE
WYE Neutral Current Occurs ONLY when Phase
current is unbalanced
Battery Configurations