1. Jake Perez
Student ID 1514624
ELMT 1391.2001 – Special Topics in ElectroMechanical Technology
Senior Essay – “From Wind to 120VAC in Austin, TX – The Process”
Electricity has been around for hundreds of years. Through out
the years we have discovered many ways to harness electricity.
There is coal, solar, nuclear, geothermal, steam, gas, oil, and
finally wind. This essay will be about how Austin harnesses the
wind to generate electricity for every day use.
Before any power can be generated, the wind turbine must first
detect a few things. The speed, direction and consistency of the
wind must be at the right conditions for the turbine to turn on.
This is done by using an anemometer. An Anemometer is a device used
for measuring wind speed. The Anemometer is hooked up to a computer
with a fiber optic cable inside the nacelle which then tells it
the direction its blowing from and how consistent it is. Along with
other important information. Once all requirements are met the
turbine starts winding up.
After it winds up, the nacelle rotates to the wind with the help
of yaw motors located directly below structure. Once the turbine
is facing the wind, the blades will then pitch to a 45 degree angle

2. so it can begin to harness the wind. These blades are similar to
airplane wings. Air passes on both sides of the blade, because of
the shape of the blade. It causes air pressure to become uneven.
The pressure is higher on one side and lower on the other. The uneven
pressure causes the blades to spin around the hub of the turbine.
The blades are connected to a rotor which is connected to a
low-speed shaft inside the hub. Which will take us to the next
paragraph.
The low-speed shaft spins at about 30-60 rotations per-minute.
(RPM) The shaft is connected to a gear box which increases the
rotation speeds to 1,000-1800 rpm. The gear box is one of the
heaviest part of the turbine and also the a very expensive piece
of equipment to replace. From the gear box you have the High-speed
shaft that is connected to the generator.
The most common generator in a wind turbine is a Induction
Generator. Induction generators produce electrical AC power when
their shaft is rotated faster than the synchronous frequency of
the equivalent induction motor. Induction generators are
mechanically and electrically simpler than other generators types.
Induction generators require an external supply to produce a
rotating magnetic flux. The external supply can be supplied from
either the electrical grid or from the generator itself once it

3. starts producing power. You can also use a capacitor bank to start
the generator as well. Once generated the power travels down tower.
The voltages the generator creates can vary from 600 V to 4000 V.
Each operating wind turbine has a three-phase pad mounted
transformer at the base of each wind turbine. The Three-phase pad
mounted transformers job is to increase the voltage the generator
makes. This voltage can but up to 400,00 volts. From the pad mounted
transformer it is sent to a switch station that is connected to
all the wind turbines on that particular farm. From the transformer
it is sent to a transmission substation where the power will be
distributed on the grid.
Once power is on the grid it is sent across the state by high
voltage transmission lines. These transmission lines are made of
copper or aluminum because they have a low resistance to
electricity. Higher resistance means the wire will get warmer.
Because the wires heat up some of the energy is lost in transit.
There are 450,00 miles of high-voltage power lines and 160,00 miles
of over head transmission lines in the United States connecting
electrical power plants to homes and businesses.
From the high voltage transmission lines power is then sent to
a step down transmission substation. A step down transmission

4. substation are located at switching points on the electrical grid.
They connect different parts of the grid and is a source for
distribution lines. A step down substation can change the
transmission voltage to a sub transmission voltage. This is usually
69 kV. The sub transmission voltage lines can then serve as a source
to distribution substations.
There are two types of distribution substations. One is above
ground and the other is underground. It is called a underground
distribution substation. Its job is to change the transmission or
sub transmission voltage to a lower voltage so it can be used at
a consumer level. Distribution voltages vary from 34,500Y/19,920
volts to 4,160Y/2400 volts. Underground distribution substations
do the same job but have a few more parts. An underground system
may consist of conduits, duct runs, manholes, high-voltage
underground cables, transformer vault, riser and transformers.
Conduits are hollow tubes running from manhole to manhole in an
distribution system. They contain one or more ducts. These ducts
can be made of plastic, fiberglass, fiber, tile, concrete or steel.
PVC and fiberglass are most commonly used though. Duct runs are
hollow tubes running from man hole to manhole inside a conduit in
an underground system. They vary from 2 to 6 inches in diameter.
High-voltage underground cables are then ran though the ducts.

5. Underground cables can be constructed in many different ways, but
are usually shield cables. They are made with either a
conductor-strand shielding, insulation, metallic insulation
shielding and a sheath. These types of cables are use mostly in
circuits operating at 2400 volts or higher. Some of the
high-voltage cables are ran though a transformer vault. This is
a structure or room underground in which power transformers,
network protectors, voltage regulators, circuit breakers, and
meters are stored.
Once the high power cable has left the transformer vault, it
is ran up a utility pole to a riser. A riser is a set of devices
that connects an overhead line to a underground line. A riser has
a conduit from the ground up the utility pole where potheads are
used. Potheads are a type of insulator with a bell or pot-like shape
used to connect underground electrical cables to overhead lines.
They serve to separate the bunched up conductors from one another
in the cable, to a much wider separation in the overhead line. It
also protects the cable end from weather related damage. These
cables are then ran from utility pole to utility pole and connected
by a hot line connector, till it has either reached a neighborhood
or a business. It is then wired to a distribution transformer or
service transformer. This last piece of equipment provides the

6. final voltage transformation in the electric power distribution
system. It steps down the voltage in the distribution lines to the
level used by the consumer. Distribution transformers have ratings
less than 200 kVA. From the distribution transformer, a service
wire is then connected to the house. This is called a service drop.
The service drop is then wired a meter box outside of the
residential home.
What does a meter box or electricity meter do? The most common
type of electricity meter is the electromechanical induction
watt-hour meter. Electric companies use electric meters to measure
electric energy being delivered. If energy saving during certain
periods is needed, some of the meters may measure demand, the
maximum use of power in some interval. "Time of day" metering allows
electric rates to be changed during the day, to record usage during
peak high-cost periods and off-peak, lower-costs, periods.
After it is wired to the meter box, a NMD90 cable is then wired
to the a service box that houses the main switch. The main switch
is a mechanism allowing a residential house power to be cut off.
Power is then ran from the main switch to a distribution panel with
a 240-volt feeder cable. This device is forming the junction of
the public electricity grid and the electric circuits of the house.
The distribution panel is a pretty important part of the power

7. process. From this panel the houses ground wire is wired to a ground
connection in the event of a short circuit. 2 types of current come
of the the distribution panel. There is a 120-volt circuit and a
240-volt circuit. The 120-volt is composed of one live wire, one
neutral wire and one ground wire. This wire allows electricity to
reach small appliances or a light. The 240-volt uses two live wires,
one neutral wire and one ground wire. This allows electricity to
reach devices requiring a lot of power. Example would be like a
stove or a washer and dryer. Both of these wires are hooked to a
single and double circuit breaker. A few other key pieces to a
distribution panel are the plastic insulator, the neutral wire,
hot bus bar, ground/neutral bus bar terminal and the ground fault
circuit interrupter. The plastic insulator is made up of
noncondutive material which prevents the hot bus bars from coming
in contact with the back of the panel. A neutral wire has no
electric charge and it allows the current to return to the
distribution panel and the grid. The hot bus bar is a conductive
part of the panel into which the breakers for each circuit are
plugged into. The ground fault circuit interrupter is a device
that reduces the risk of electric shock in a humid place in the
event of an accidental leak of current to the ground. Finally the
ground/neutral bus bar receives the current from the neutral

8. grounded wires of the various circuits and conducts them to the
neutral service wire and the ground connection.
From the distribution panel the 120-volt and 240-volt wires are
then ran through out the house with Romex cables to its proper
destination. Romex is the trade name for a type of electrical
conductor with non-metallic sheathing. It is commonly used as
residential branch wiring. Romex will be the most common type of
cable you will use in wiring residential houses. Romex is used for
most light and outlet circuits in the home. It will be labeled with
"12-2" or "12-3". The first number indicates the gauge of wire.
The second number indicates the number of conductors. After the
wires have been ran to the proper destination, you can then wire
them into wall outlets. When wiring a wall outlet the neutral wire
should connect to the white or metal screw. The hot wire should
connect to the brass colored screw. The green screw is for the
ground wire. There is a tab between each of the screws of similar
color. This allows you to put the top and bottom receptacles on
separate circuits or to put one receptacle on a switch. This tab
can be removed with some if needed. Normally you would leave the
tab in place so that both outlets are powered once you have
connected to either of the screws. After that you will have 120VAC
ready to be used at the outlet.

9. As you can see the process in which we harness electricity from
the wind, all the way till it comes out of the electrical socket
is complicated and has many steps it has to take. In conclusion,
I hope this has cleared up and helped with learning the process
in which we get our power from wind turbines.
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