This 250 HP, 1,800 RPM AC electric motor failed as a result of inefficient cooling due to corn product buildup. The excessive thermal conditions resulted in insulation degradation and a grounded winding. Our observations of the damage included:
- The windings were burnt
- The lubrication in both bearings was degraded thermally
- The grease was darkened in color and had oil separation causing dryout
- The drive end bearing housing and shaft were found to be out of tolerance
To return the motor to working order, Bodine sleeved the housing, and fabricated and installed a new shaft. Bearing isolators were installed, the stator was rewound, the bearings were replaced and the rotor assembly was balanced before reassembling the motor.