203

UNIT III

Electrical Power Distribution Systems

Once electrical power has been produced, it must be distributed to
the location where it is used. Unit III deals with electrical power distribu-
tion systems. The fundamentals of distribution systems are discussed in
Chapter 8. This chapter provides an overview of distribution systems,
transformer operation, and conductor characteristics. Chapter 9 examines
specialized power distribution equipment such as protective devices, high-
voltage equipment, and switch gear. Then, Chapter 10, Single-Phase and
Three-Phase Distribution Systems, discusses the types of distribution sys-
tems used today. Ground-fault interrupters are also discussed extensively
in this chapter, since their use is becoming widespread in electrical power
distribution systems.
Figure III shows the electrical power systems model used in this book
and the major topics of Unit III, Electrical Power Distribution Systems.

Figure III. Electrical power systems model

Power Distribution Fundamentals (Chapter 8)
Power Distribution Equipment (Chapter 9)
Single-phase and Three-phase Distribution Equipment (Chapter 10)

UNIT OBJECTIVES

Upon completion of this unit, you should be able to:

1. List several purposes of transformers.


2. Describe the construction of a transformer.


3. Explain transformer action.