Bench Tests: Rotor

Fig 1: Bench Testing Rotor for Grounds and Opens

Check rotor for grounds using an ohmmeter set at the x1000 scale. See Fig 1 . Connect ohmmeter leads to rotor shaft and, in turn, to each slip ring. Resistance should be very high (infinity). If resistance is not infinity, replace rotor assembly.
Test rotor for an open using an ohmmeter set to the x1 scale. Connect ohmmeter leads to each slip ring See Fig 1 . Resistance reading should be 2.4-3.5 ohms. If resistance is not as specified, replace rotor assembly.