Three-phase induction motor
When three-phase supply connected insulated coils set into slots in
the inner surface the stator stationary part induction motor as
.c.
Supply
Field
Load
Speed
Armature
FIGURE 10.c.
series motor connections and characteristics.15
Series motor connections and characteristics.c. machine construction. d.
Reversal rotation may achieved reversing the connections either
the field armature windings but not both. This characteristic means
that the machine will run both a.14
Showing d. motors
If three-phase supply connected three separate windings equally
distributed around the stationary part stator electrical machine, an
alternating current circulates the coils and establishes magnetic flux.c.
The magnetic field established the three-phase currents travels around
the stator, establishing rotating magnetic flux, creating magnetic forces
on the rotor which turns the shaft the motor. For this reason the motor
is only suitable for direct coupling load, except very small motors,
such vacuum cleaners and hand drills, and ideally suited for applica-
tions where the machine must start load, such electric trains, cranes
and hoists.
Three-phase a.Baisc Electrical Installation Work
208
Pole
pieces
Field
winding
Field
supply
Armature
(laminated)
Carbon
brushes
Conductors
in slots
Commutator
N
N S
S
Steel
yoke
FIGURE 10. and is, therefore, sometimes
referred ‘universal’ motor
