Stray currents in electric pumping systems, especially in systems that include Variable Speed Drives (VSDs) for pumps and fans, can have detrimental effects on motor bearings, leading to premature failure. Understanding the sources of these currents and implementing effective mitigation strategies is crucial for engineers, facility managers and project managers responsible for the maintenance and commissioning of motor-driven equipment. 

Understanding Stray Currents and Their Impact

STRAY CURRENTS DEFINED 

• Stray currents are unintended electrical currents that deviate from their intended path, often resulting in unwanted electrical discharges through motor bearings. 

• These currents can be caused by various factors such as winding faults, unbalanced power supplies, electrostatic effects, and magnetic field asymmetries. 

EFFECTS ON MOTOR BEARINGS 

• When stray currents flow through the motor bearings, they can lead to electrical erosion of the rolling elements,...