from the air inlets in the end bells. Vertically
field and the stator's revolving magnetic field.
mounted motors usually have a dripproof cover
Figure 9-3 shows the parts of a typical polyphase
over the top to prevent moisture from entering
(3-phase) induction motor.
the housing.
Many other components of the 3-phase motor
are used for cooling, support, balancing, and
Single-phase motors
protection of the motor. Ball bearings support the
rotor and provide for low friction loss. Balancing
Single-phase motors operate on a single-phase
disks are used to balance the rotor. Rotor fans
power supply. These motors are used extensively
are normally provided to cool the motor with air
Figure 9-3.--Typical 3-phase induction motor.
9-4