As was shown in Chapter 2, there are numerous types of loading,
torque-measuring, and speed-measuring devices used in the testing
of electric motors. These devices are not necessarily directly
applicable to the testing of small electric motors. Chapter 3 shows
that the selection of a loading device to be used as a dynamometer
depends upon the operating characteristics desired. A dynamometer
having the desired operating characteristics of either constant speed
or constant torque requires the application ofgenerator,
a vacuum-tube-controlled power supply, and tachometric feedback. The
size and type of generator, vacuum tubes, and tachometer depends upon
the magnitude of torque required, the magnitude of rotational losses of
the generator, the current demand of the generator, and the speed range
to be covered.