ABSTRACT
The physical structure of most power systems consists of generation facilities feeding bulk power into
a high-voltage bulk transmission network, that in turn serves any number of distribution substations.
A typical distribution substation will serve from one to as many as ten feeder circuits. A typical
feeder circuit may serve numerous loads of all types. A light to medium industrial customer may
take service from the distribution feeder circuit primary, while a large industrial load complex
may take service directly from the bulk transmission system. All other customers, including residen-
tial and commercial, are typically served from the secondary of distribution transformers that are in
turn connected to a distribution feeder circuit. Figure 20.1 illustrates a representative portion of a
typical configuration.
