Basic distribution designs

In designing a distribution system, engineers and planners will choose from three basic designs:

• radial system — This system provides a single power source for a group of distribution customers. It is the cheapest system to build, but it also has the lowest reliability, because a power failure or short circuit can interrupt power along the entire line. This design is widely used in sparsely populated areas.
  
  
• loop system — This system loops through the entire service area, with switches located in strategic locations. The loop is usually connected to an alternative power source. By placing switches in strategic locations, the distribution utility can supply customers, as needed, from either power source. This system design provides more reliable service, with only short interruptions for switching.
  
  
• network system — This system is a more complicated, interconnected loop system that can supply customers from two or more different power suppliers. This design is the most reliable, and the most expensive. It is often used in heavily populated urban areas.