Figure 7-63.--Three-phase, four-pole, series-delta winding.
5. No unusual noise or vibration
Parallel-Delta Winding
Testing Direction of Rotation
The machine used in the other examples, connected
for three-phase, four-pole, parallel-delta operation is
Once the unit has been installed and aligned, it
shown in figure 7-64. The phase windings contain the
should be tested for proper direction of rotation. This
same pole-phase group numbers, and the polarities of
should be done prior to coupling the motor to the driven
the pole-phase groups are the same as in the previous
load if possible. Running some types of equipment in
cases.
the wrong direction may cause a hazard to personnel or
damage the equipment.
POST WINDING TESTS
Once any danger tags have been properly removed
the equipment is ready to be "bumped" or momentarily
Once repairs have been completed and the unit has
energized to test for rotation. Ships force should be on
been assembled, it is necessary to conduct tests to ensure
hand to verify the rotation of the equipment is proper.
that all work has been satisfactorily completed. These
tests include the following:
If the direction of rotation is proper, the unit maybe
coupled and further tests conducted. If the direction of
1. Roper direction of rotation
rotation is incorrect, the direction should be reversed by
2. Proper speed
one of the following methods.
3. Normal bearing and stator temperature rise
REVERSING DIRECTION OF ROTATION OF
DC MOTORS.-- The two methods for reversing a dc
4. Balanced phase currents
7-43
