MM0704, Lesson 3
Series Motor. AC series motors have the same characteristics as DC series motors. They have a stationary field and a
commutated armature winding and both windings are in series. The series motor is a variable speed motor with low
speeds for heavy loads and high speeds for light loads. These motors are noted for their light weight in relation to the
power delivered. They are well suited for portable devices such as power tools.
Synchronous Motors. The speed
of a synchronous
motor is controlled
by the frequency
AC power source
which drives it. It is synchronized or in time with this frequency. In order that its speed may be left constant, a
synchronous motor is regulated to a high degree of accuracy. These motors are used for timing devices such as meters
that record the time which equipment has been used.