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UNIT V

Electrical Power Control Systems

In this unit, electrical power control systems are studied. The funda-
mentals of electrical power control are discussed in Chapter 15. This chap-
ter examines several of the fundamental types of equipment that are used
for electrical power control. This equipment includes electromechanical
contactors, relays and switches.
Chapter 16 examines the mechanical and electronic power control sys-
tems that are used with electrical machinery, and the motor control systems
that are used extensively in day-to-day industrial, commercial, and resi-
dential applications. In addition, programmable logic controllers (PLCs) are
introduced, since they now lay a significant role in machine control.
Chapter 17 discusses electronic control devices such as silicon con-
trolled rectifiers (SCRs), triacs and diacs.
Figure V shows the electrical power systems model used in this book,
and the major topics of Unit V—Electrical Power Control Systems.

UNIT OBJECTIVES

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

1. Describe the function of standards organizations, such as NEMA,
   ANSI, and IEEE, in electrical power control.


2. Define important terms used with electrical power control sys-
   tems.


3. Recognize and sketch symbols used for electrical power control
   systems.


4. Describe the following types of switches used for electrical power
   control:
   Toggle Switch
   Rocker Switch
   Pushbutton Switch
   Rotary Switch