Method of repairing a hydrogenerator

A method of repairing a hydroelectric generator structure, without removing a generator rotor, with an apparatus connected to a hydroelectric turbine structure, said hydroelectric generator structure comprising a forebay and dam, a penstock, a turbine shaft, a generator rotor assembly coupled to an upper portion of said turbine shaft, a turbine blade assembly coupled to a lower portion of said turbine shaft, a turbine chamber having a cylindrical configuration and formed by a vertically disposed turbine liner wall adjacent distal ends of said turbine blades, and a tailwater and afterbay, said method comprising:

• said forebay comprising a body of water at the top held by said dam at the top of the structure containing said turbine;
• said penstock comprising a pipe structure which carries the water from said forebay to said turbine;
• said tailwater comprising the area where the water is emptied after proceeding through said penstock and said turbine;
• said afterbay comprising the body of water where said tailwater travels;
• said generator rotor assembly comprising a spider attached to said turbine shaft;
• said spider comprising a welded steel structure having spider arms, and said spider arms having vertical posts to support a rim;
• said rim comprising a number of poles that provide energizing during generation of electricity;
• said rotor deteriorating during years of use and producing a lack of support for said rim due to operational forces;
• said operational forces comprising low cycle forces that occur at least with the start and stop of the generator or from transient operating conditions;
• said transient operating conditions comprising at least one of radial expansion of said rim from rotation of said rim, stopping and cooling of the rim upon at least one of said generator shut down, overspeed condition, out-of-phase synchronizations, short circuits, and transient torque spikes;
• damaging said rim and said rotor structure resulting from at least one of fretting and galling due to lack of support of said rim;
• said fretting comprising corrosion damage to contact surfaces under load due to operation of said generator;
• said galling comprising wear caused by adhesion and friction in which a transfer of material between metallic materials occurs during horizontal motion transverse to said rim;
• searching for and discovering damage to said rim and said rotor structure through at least one of testing via ultrasonic testing or penetrant testing;
• said discovery comprising testing by ultrasonic means using a transducer that vibrates at an ultrasonic frequency, and said vibrations creating echo signals that indicate the presence of a defect, testing by penetrant means using a penetrant on a non-porous material, said penetrant reveling any defects;
• rotating said turbine blades and said turbine shaft to facilitate repair of pitting and general deterioration of surfaces of said rim;
• said repair prolonging the life of said surfaces and structure of said rim by a minimum of five years;
• supporting mounting of said rim and energizing means to said spider and said spider arms;
• said supporting comprising attaching thrust plates to the top of said rim to provide support for said rim from above, so that said rim is held up from said thrust plates;
• said thrust plates comprising machined plates attached to the top of said rim, adjacent to said spider arms, using a number of bolts and screws;
• said bolts comprising at least commercial Grade 5 bolts;
• threading of said bolts into the top plate of said rim;
• allowing for tightening said bolts of said thrust plate to said rim as said thrust plate wears over time;