Download Electromagnetic Induction

Electricity Transmission:
Power Plant
Regardless of the
fuel used, power
plants use this fuel
to spin a turbine
which in turn assists
in producing
electricity


Step-Up
Transformer
As electricity leaves the
power plant, it will likely go
through a step-up
transformer. Stepping up
the AC voltage is often
necessary, as some
energy will likely be lost in
the transmission of
electricity through the grid
Transmission Lines
Transmission lines are used to
distribute electricity to locations
that may be far away. While
travelling, some of the electrical
energy may lose voltage, in the
form of thermal energy loss.
Transformers are used to boost
the energy lost. These lines
eventually reach a substation in
your area
Step-Down
Transformer
Stepping voltage down is
more economic for
distribution to customers.
Voltage is reduced here
so that it can move
through distribution lines.
The voltage is
significantly less than in
transmission lines, but is
still very dangerous.
Distribution
Lines
Distribution lines carry
electricity form a
substation to a home or
business. These lines
can either be overhead
or underground (more
expensive). Power
outages often occur
between this point and
your home.
Step-Down
Transformer
Just before the electricity
enters your home,
voltage must be reduced
once more. These
transformers are much
smaller in size and can
be located on power line
poles or on the ground,
as large boxed objects.
Residence
Electricity goes
through your home
and goes through a
meter which reads
roughly how much
electricity your
household is using.
Meter is generally
read monthly.
As power is transmitted through transmission lines a significant amount of power is lost due to
thermal energy losses as large currents pass through the wires.
The formula for Power is P=VI but if we substituted V=IR in for the voltage we get P= I2R.

To calculate the power loss on the transmission lines, the equation P= I 2R is used. The resistance
of the line is known and the current is adjusted to decrease the power loss. The equation P=VI is
used to calculate the power transmitted.

A transformer is used to step up the voltage (which decreases the current). This decreases the
power loss (P= I2R) but still keeps the same amount of power being transmitted (P=VI).

So we use high voltages to transmit our power and have the low current for minimal power loss.
Question: Why is voltage stepped up on transmission lines from power plants?
To answer this question compare the power lost in transmission for a 1000W line at 100V to the same
power on a line at 1000V. In both cases, the resistance of the line is 1.0 Ω.
First calculate the current for each scenario. Then calculate the power loss for each scenario.
Your work: Review questions for Unit Test