Power plants are located far from communities, requiring long transmission lines to transmit power to homes. Transmission losses are reduced by transmitting power at high voltage and low current, which necessitates the use of step-up transformers at power plants and step-down transformers before distributing power to homes.

1.  Power plants
are usually far
from
communities,
thus long lines
are needed to
transmit power
into homes

2.  The resistance of
such lines are
enormous to
start with
because of their
length
L
R
A

3.  Transmission
losses are
less if power
is conducted
at low
current
Ploss  I
2
R

4.  In order to transmit at low
current, power must be drawn
from substations at high
voltage
Ps  IV

5.  For safe
consumption,
however, the
voltage must be
brought down
before being
distributed into
homes

6.  Thus, the necessity for step-up and
step-down transformers