Short to ground- 1 or more of the phases are no longer insulated from ground (spindle)
Short leg to leg- 2 of the 3 phases are no longer insulated from each other
Broken wire- The wire of 1 or more phases has broken
Single phase- Not all 3 phases are functioning causing loss of power
Causes of failures:
Overload: Exceeding the stators recommended power rating causes heat which causes the windings insulation to break down.
Contamination: If conductive contamination (water based coolant) is allowed to contact the stator windings short circuits can occur.
Overheating: due to lack of cooling
Incorrect voltage to hertz ratios
Recommended repair procedure: When a stator fails our incoming QC inspection we recommend that it be rewound. The stator windings are removed and replaced with new windings with new insulation. The price for this service varies with stator size.