Bench Testing: Rotor

Visually inspect rotor for stripped threads or damage at pulley end. Check for scored bearing surfaces, scuff marks on the pole fingers, or dirty or contaminated slip rings. Check resistance across rotor slip rings. If there is not 2-6 ohms resistance, replace rotor. Check resistance between individual slip rings and rotor shaft. Reading should be infinite. If resistance exists, rotor or slip ring is grounded. Replace rotor.