Shaft Failure Analysis in Soft-Starter Fed Electrical Submersible Pump Systems

Electric submersible pumps (ESPs) are widely used for high volumetric oil and gas recovery from downhole wells. ESPs in oil fields can be equipped with multiple ac motors in tandem. To assist a motor start-up, a solid-state soft-starter can be deployed in such ESP wells. ESP shafts have a long axial length, and thus experience significant dynamic torsion when started from reduced voltage soft-starters. Premature shaft breakdowns had occurred in...