1. Electric Power Distribution, Generators and Motors
Benchmark Companies Inc
PO Box
Aurora CO 80047

2. Electric Power Distribution,

3. New ideas for today
Magnetic induction
Lenz’s law
Transformers and power transmission
Motors and Generators

4. Observations about Power Distribution
Household power is AC (alternating current)
Power comes in voltages like 120V & 240V

5. Observations about Power Distribution
Power is transmitted at “high voltage” like 500KV

6. Observations about Power Distribution
Power transformers are visible everywhere

7. Observations about Power Distribution
Power substations are visible on occasion

9. Power Consumption in wires
Reminder:
power consumption = current x voltage drop IxV
voltage drop = resistance x current IxR
power consumption = resistance x current I2xR
Impact of the calculation:
Wires waste power as heat
Doubling current quadruples wasted power

10. 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.

11. DC AC
Edison
Tesla
Westinghouse

12. DC vs AC a visual approach
DC can supply power . So can AC
For transmission AC is superior
DC= “direct current”
AC=“alternating current”

13. AC = alternating current
Let’s explore why……
DC= “direct current”
AC=“alternating current”
Rotation Amplitude Amplitude/Time

14. AC = alternating current
As a conductor is rotated within a magnetic field alternating current is produced in that conductor
Rotation within a
magnetic field
Amplitude
Current
Amplitude vs. time 0o
90o
180o
270o
360o
90o 0o
180o
Positive
Amplitude P N
Negative
Amplitude
360o
270o
Time

15. 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.

16. Click for Bar Magnet
And Pick-up coil
example

17. Electromagnetic Induction
Changing magnetic field produces an electric field

18. Electromagnetic Induction
Current in a conductor produces a magnetic field

19. Electromagnetic Induction
An Induced magnetic field opposes the original magnetic field change (Lenz’s law)

20. Lenz’s Law

21. Electromagnet
Transformer
Example

22. 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
Demonstration: AC Electromagnet and Wire Loop with Lamp.

23. Transformer on fire

24. 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!

25. 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

26. 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

27. 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

28. Click me

29. Electric Generator Rotating magnet makes changing magnetic field
induces AC current in the loop
Converts mechanical power into electrical power

30. 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 generator run backwards !

31. End of Presentation