Step-up Transformer Picture Electricity is usually generated at voltages ranging from 13,000 to 24,000 volts. Some electric utilities have all of their generators operating at the same voltage while other utilities do not. This is not a problem since the voltage is often increased significantly -- using a step-up transformer -- before it's sent into the transmission system which is usually between 69 and 765 kV -- kilovolts or thousands of volts. Higher voltages are the most economical way to ship large quantities of power over long distances, where it is then stepped back down to distribution levels.