Section 5. Troubleshooting Model 8210/8250 Maintenance Manual
AC Electric Motors
5-14 Publication: 1146945/001, Revised: 25 Sep 2018
AC Electric Motors
AC Motor Type
The traction motor is a brushless, 3-phase,
variable speed AC motor.
The AC motor has a rotor (in place of the DC
armature) and a stator (in place of the DC field).
There is no electrical connection to the rotor;
current is induced in the rotor. The stator has
three windings staggered 120° apart, and three
external connections labeled U, V, and W. See
Figure 5-4 and Figure 5-5.
Figure 5-4. AC Traction Motor circuit - Phase A
MOTOR_AC3PHASEA.tif
Figure 5-5. AC Traction Motor circuit - Phase B
MOTOR_AC3PHASEB.tif
Open Winding
If the AC motor fails with an open winding, the
motor moves erratically, as if
hunting/searching, and there is a ticking
sound. Rotation is much slower than normal.
Using a clamping ammeter, measure current in
each of the motor power cables. The open phase
reads significantly lower than the other two
phases.
Shorted Winding
If the AC motor fails with a shorted winding, the
motor speed fluctuates up and down, as if
hunting/searching, and there is a high-pitched
sound.
Using a clamping ammeter, measure current in
each of the motor power cables. The shorted
phase reads significantly higher than the other
two phases.
Property of American Airlines
To Next Page
Loading...