Page 45 - Electromechanical Devices and Components Illustrated Sourcebook

Chapter 1 Basic Electricity 7

+ Reversible
- Rotation

+ −
DC Motor

Reverse Polarity
(Reverse)

Straight Polarity
Battery Knife Switch (Forward)
Reversing Switch
(Double Pole, Double Throw)
Figure 1-14 Reversing Circuit

Connecting Rod
Crank Shaft

Plunger Rod
Upper Wire

+
AC Output
Battery (DC)
−
Lower Wire

Polarity Reversing Switch
Figure 1-15 Synthesizing Alternating Current

+
Positive Wave Form
zero volts. The data points located above or below the line
represent volts, with points above the line—positive volts,
Zero volts and points below the line—negative volts. In the United
States, AC power is delivered at 60 cycles per second,
1
which means that a full AC cycle is / of a second. The
60
illustration shows that for the first half of the cycle the polar-
− Negative ity is positive and for the second half of the cycle the polar-
ity is negative.
Alternating current power has many useful attributes that
One Full Cycle (1/60 sec)
will be discussed further in the following chapters of the
Figure 1-16 Alternating Current Cycle book.