A
transformer has at least two coils of insulated copper wire wrapped together.
When alternating current (AC) energizes the primary coil, electricity is transferred
to the secondary coil. The voltage can be increased or reduced, depending on
how many windings are in each coil.
This step-up transformer multiplies the 14,000 volt output of the generator by ten, increasing it to 140,000 volts. The voltage is stepped up because higher voltages lose less power along long-distance transmission lines.
When electricity passes through transformer coils, some energy is converted to heat. Heat above 200° F can damage the coils, causing the transformer to burn out. To keep the transformers cool, oil circulates around the coils. The hot oil passes through radiators and fans blow air through through them to get rid of the excess heat.