5.92. Electrical Grid http://www.ck12.org
FIGURE 5.197
Power Plants
Electricity originates in power plants. They have electric generators that produce electricity by electromagnetic
induction. In this process, a changing magnetic field is used to generate electric current. The generators convert
kinetic energy to electrical energy. The kinetic energy may come from flowing water, burning fuel, wind, or some
other energy source.
Transmission Lines
Transmission lines on big towers—like those in the opening photo above—carry high-voltage electric current from
power plants to electric substations. Smaller towers and individual power poles carry lower-voltage current from
electric substations to homes and businesses.
Electric Substations
Electric substations have several functions. Many substations distribute electricity from a few high-voltage lines
to several lower-voltage lines. They have electric transformers, which use electromagnetic induction to change the
voltage of the current. Some transformers increase the voltage; others decrease the voltage. In theFigure5.198,
you can see how both types of transformers are used in an electrical grid.
FIGURE 5.198
- A step-up transformer increases the voltage of the current as it leaves the power plant. After the voltage has
been increased, less current travels through the high-voltage power lines. This reduces the amount of power
that is lost due to resistance of the power lines.