Worn Gears
Electrical Fault
Surface Fatigue
Abrasive Wear
▪ Soft foot
▪ Uneven air gap
▪ Cracked or broken rotor bars
▪ Eccentric rotors can be either
o 2X line frequency
(120 Hz)
o # of rotor bars X Turning
Speed▪ Caused by abrasive particles in lubricant
making contact with both sliding/impacting
surfaces