Abstract: An electric motor such as an AC induction electric motor includes a rotor having a rotor core and a rotor shaft. The rotor shaft defines an axially extending bore which has an electrical grounding ring positioned therein. The electrical grounding ring has an inertia insensitive configuration and forms a relatively low resistance electrical circuit segment between the rotor shaft and an electric motor housing to ground the electric motor rotor. The electric motor includes an oil lubricated bearing for the rotor shaft, and a sealing member such as a lip seal is positioned within the axially extending bore to inhibit lubricating oil intrusion therein. A non-rotating stub shaft may be mounted in the housing and extends into the axially extending bore to fluidly seal with the sealing member and electrically connect with the electrical grounding ring, which is fixed to rotate with the rotor shaft.

Abstract: An electric motor such as an AC induction electric motor includes a rotor having a rotor core and a rotor shaft. The rotor shaft defines an axially extending bore which has an electrical grounding ring positioned therein. The electrical grounding ring has an inertia insensitive configuration and forms a relatively low resistance electrical circuit segment between the rotor shaft and an electric motor housing to ground the electric motor rotor. The electric motor includes an oil lubricated bearing for the rotor shaft, and a sealing member such as a lip seal is positioned within the axially extending bore to inhibit lubricating oil intrusion therein. A non-rotating stub shaft may be mounted in the housing and extends into the axially extending bore to fluidly seal with the sealing member and electrically connect with the electrical grounding ring, which is fixed to rotate with the rotor shaft.