electric power distribution, generators and motors
DESCRIPTION
Electric Power Distribution, Generators and Motors. Benchmark Companies Inc PO Box 473768 Aurora CO 80047. Electric Power Distribution,. New ideas for today Magnetic induction Lenz’s law Transformers and power transmission Motors and Generators. Observations about Power Distribution. - PowerPoint PPT PresentationTRANSCRIPT
Electric Power Distribution, Generators and Motors
Benchmark Companies Inc
PO Box 473768
Aurora CO 80047
Electric Power Distribution,
New ideas for todayNew ideas for today
•Magnetic induction•Lenz’s law•Transformers and power transmission•Motors and Generators
Observations about Power Distribution
Household power is AC (alternating current)Power comes in voltages like 120V & 240V
Observations about Power Distribution
Power is transmitted at “high voltage” like 500KV
Observations about Power Distribution
Power transformers are visible everywhere
Observations about Power Distribution
Power substations are visible on occasion
Power Consumption in wires
Reminder:power consumption = current x voltage drop IxVvoltage drop = resistance x current IxRpower consumption = resistance x current2 I2xR
Impact of the calculation:Wires waste power as heatDoubling current quadruples wasted power
Power Consumption in wires
Example:Resistance of 1 mile of power line is 10 Ohms. Determine the voltage drop across the power line if 200
Amps is transmitted at 240 Volts to power one typical house.
The Power consumed across 1 mile is I2xR = 200A2x10 = 400KW is needed before we can begin to deliver power to a typical house.
DC AC
Edison TeslaWestinghouse
DC vs AC a visual approachDC vs AC a visual approach
DC can supply power . So can ACFor transmission AC is superior
DC= “direct current” AC=“alternating current”
AC = alternating currentAC = alternating current
Let’s explore why……
AC=“alternating current”
Rotation Amplitude Amplitude/Time
DC= “direct current”
AC = alternating currentAC = alternating current
As a conductor is rotated within a magnetic field alternating current is produced in that conductor
Rotation within a magnetic field
AmplitudeCurrent
Amplitude vs. time
Positive Amplitude
Negative Amplitude
Time
N P
0o 90o 180o 270o 360o
0o
90o
180o
270o
360o
Power Transmission For efficient power transmission:
Use low-resistance wires (thick, short copper)
Use low current and high voltage drop
Can accomplish this with AC (alternating current) power transmission.
Click for Bar Magnet And Pick-up coil
example
Electromagnetic InductionChanging magnetic field produces an electric field
Electromagnetic InductionCurrent in a conductor produces a magnetic field
Electromagnetic InductionAn Induced magnetic field opposes the original magnetic field change (Lenz’s law)
Lenz’s LawLenz’s Law
Electromagnet Transformer
Example
Transformer Alternating current in one circuit induces an alternating
current in a second circuit Transfers power between the two circuits Doesn’t transfer charge between the two circuits
Transformer on fire
Transformers
Power arriving in the primary circuit must equal power leaving the secondary circuit
Power = current x voltage A transformer can change the voltage and
current while keeping the power unchanged!
Step Down Transformer Fewer turns in secondary circuit so charge is
pushed a shorter distance Smaller voltage rise A larger current at low voltage flows in the
secondary circuit
Step Up Transformer More turns in secondary circuit so charge is pushed a
longer distance Larger voltage rise A smaller current at high voltage flows in
the secondary circuit
Observations about Electric Generators and Motors
A generator provides electric power A generator requires a mechanical power A motor provides mechanical power A motor requires electric power
Alternator
Click me
Electric GeneratorRotating magnet makes changing magnetic field induces AC current in the loop
Converts mechanical power into electrical power
Electric Motor Input AC power AC current makes changing magnetic field causes magnet to turn
Converts electrical power into mechanical power
A motor is a A motor is a generator run generator run backwards !backwards !
End of Presentation