The speed almost
constant. Connection carbon brushes can then be
made external resistance improve starting. Its applications are for constant speed machines such fans
and pumps. supply produces pulsating magnetic field, not the
rotating magnetic field produced three-phase supply.
The cage induction motor has small starting torque and should used
with light loads started with the load disconnected.
Alternatively the load may connected after the motor has been run up
to full speed.c. All a.c.18
Various speed–torque characteristics for induction motor.
Single-phase a.c. motors
A single-phase a. motors
. The windings may
be connected star delta and the end connections brought out slip
rings mounted the shaft.Baisc Electrical Installation Work
210
Arrangement conductor bars cage rotor Skewed rotor conductors
Shorting ring
FIGURE 10.
Torque
Speed
(a)
(c)
(b)
Load
torque
line
FIGURE 10. Reversal rotation achieved reversing any two the
stator winding connections.17
Construction cage rotor.
The wound rotor consists laminated cylinder silicon steel with cop-
per coils embedded slots around the circumference
