Fundamentals of Electricity



Delivery System Overview

Transmission Lines Picture As electrical energy is generated, it is transformed and transported instantaneously through a network of wires, substations, and transformers to the consumer. Electricity is generated at a comparatively low voltage at most generating stations. In order to transport this energy great distances, the voltage has to be increased, or stepped up; to values as high as 765,000 volts. This is accomplished through the use of large transformers located near the generating station, and provides an efficient and economical method of transmission. Transmission line voltages can range from 69,000 volts to 765,000 volts.

Substation PictureThe first dividing point for the delivery of power is the transmission substation. These large substations are located near cities, small towns, or large industrial locations. At transmission substations power is divided into secondary transmission lines, then carried to strategic points within each major use area.

These secondary transmission lines run to distribution substations where transmission voltage is reduced to distribution system levels. The distribution lines connect to service transformers located near homes or businesses, where the voltage is further reduced.

From the generating station to the final destination, the energy from generated electricity undergoes numerous changes in voltage and direction. Each change requires expert design and handling to provide the consumer with the least expensive, most reliable energy they can buy. This section examines each aspect of delivering this energy to the consumer.