Patent ID: 8823226

Claim:
A sealed electric generator comprising: a rotor with field windings, a stator, a shaft connected to the rotor, the shaft having an axis of rotation, an exciter, and a casing housing the stator and the rotor; wherein the shaft comprises a duct and a lead arranged in the duct to extend longitudinally along the axis of rotation parallel to the shaft, the lead configured and arranged to carry electric power from the exciter to the rotor field windings, said duct comprising a sealing unit configured and arranged to prevent gas inside the casing from reaching the exciter; wherein said sealing unit comprises a first seal and a second seal defining a chamber between the first and second seals, such that gas that leaks past either of the first and second seals enters the chamber; and wherein the first and second seals are annular and arranged in contact with and surrounding the lead that extends longitudinally along the axis of rotation, parallel to the shaft.