End-ring wear in deep well submersible motor pumps

Wear of end-ring is an up to date unreported and uninvestigated failure which very frequently takes place in deep well submersible motor pumps. The present paper first analyses the particularities of these induction motors, specially their unusual rotor manufacturing process. Failure mechanism related to the end-ring wear is described, showing several examples of damaged rotors in a motor repair shop. Then, the difficulties of its diagnosis through conventional rotor asymmetry indicators are described, caused by the subtlety of this fault, and the very easy appearance of false negatives. The end-ring wear detection through a multicomponent approach is researched, showing, through simulation, laboratory results and the diagnosis of a field motor, that new levels of fault alarm need to be defined. To perform this last step, for the first time in the technical literature, an induction motor (working in a deep well), has been continuously monitored (four measurements per day) during nearly a year.