Abstract: A method for repairing a stator core of a generator is presented. The stator core includes laminations grouped into packs. A ventilation spacer is disposed between adjacent packs. Laminations are separated from each other by insulation layers. The ventilation spacer is removed between adjacent packs having a damaged insulation layer between the laminations to locally loosen the laminations in the adjacent packs which allows the damaged insulation layer between the laminations to be repaired. A new ventilation spacer is reinstalled between the adjacent packs where the ventilation spacer being removed to retighten the laminations in the adjacent packs after completion of the repair. The new ventilation spacer is adhesively secured between the adjacent packs.

Abstract: A false tooth assembly for a generator stator core is presented. The false tooth assembly has a tapered shape including multiple tapered false tooth pieces. The multiple tapered false tooth pieces are installed into a damaged area in a tooth of a lamination of the stator core such that a wide end of the false tooth assembly is disposed into a wide opening of the damaged area and a narrow end of the false tooth assembly is flushed with a narrow opening of the damaged area at a tip of the tooth. The tapered shape of the false tooth assembly enables the false tooth assembly to fill the entire damaged area and to lock the false tooth assembly into the damaged area. The false tooth assembly can be used to repair stator core in any region of the stator core including step iron region without being dislodged during generator operation.

Abstract: An assembly and a method for preventing an axial migration of a spring in a generator rotor are presented. The assembly includes a step pin radially disposed through an amortisseur and inserted into a spring of the generator rotor. The step pin is arranged axially apart from an adjacent radial vent passage and radially extends through the spring into a slot clearance between the spring and a creepage. The amortisseur includes a counter bore to retain a pin head and a pin shoulder. The spring includes a pin hole for a pin body extending therethrough. Diameters of the counter bore and the pin hole are smaller than diameters of amortisseur radial vent aperture and spring radial vent aperture. The step pin prevents an axial migration of the spring in rotor slots.

Abstract: A method of determining the risk of a stator failure is provided. The stator includes multiple stator coil windings. Each of the windings includes multiple conductive metal strands. The number of strand failures is determined from an image captured by a radiography. A risk analysis is assessed from the determined number of strand failures.

Abstract: A method for restoring a separation between laminations of a stator core of a generator is presented. The laminations are separated from each other by an insulation layer disposed between the laminations. Wicking resin is applied to an area where the laminations are in contact with each other. Etching using an etching solution is applied to the area where the laminations are in contact with each other until a separation between the laminations is restored. The wicking resin seals the insulation layer to prevent the etching solution from penetrating into the insulation layer and causing a detrimental effect on the insulation layer.

Abstract: A false tooth assembly for a generator stator core is presented. The false tooth assembly has a tapered shape including multiple tapered false tooth pieces. The multiple tapered false tooth pieces are installed into a damaged area in a tooth of a lamination of the stator core such that a wide end of the false tooth assembly is disposed into a wide opening of the damaged area and a narrow end of the false tooth assembly is flushed with a narrow opening of the damaged area at a tip of the tooth. The tapered shape of the false tooth assembly enables the false tooth assembly to fill the entire damaged area and to lock the false tooth assembly into the damaged area. The false tooth assembly can be used to repair stator core in any region of the stator core including step iron region without being dislodged during generator operation.

Abstract: A method for repairing a stator core of a generator is presented. The stator core includes laminations grouped into packs. A ventilation spacer is disposed between adjacent packs. Laminations are separated from each other by insulation layers. The ventilation spacer is removed between adjacent packs having a damaged insulation layer between the laminations to locally loosen the laminations in the adjacent packs which allows the damaged insulation layer between the laminations to be repaired. A new ventilation spacer is reinstalled between the adjacent packs where the ventilation spacer being removed to retighten the laminations in the adjacent packs after completion of the repair. The new ventilation spacer is adhesively secured between the adjacent packs.

Abstract: An assembly and a method for preventing an axial migration of a spring in a generator rotor are presented. The assembly includes a step pin radially disposed through an amortisseur and inserted into a spring of the generator rotor. The step pin is arranged axially apart from an adjacent radial vent passage and radially extends through the spring into a slot clearance between the spring and a creepage. The amortisseur includes a counter bore to retain a pin head and a pin shoulder. The spring includes a pin hole for a pin body extending therethrough. Diameters of the counter bore and the pin hole are smaller than diameters of amortisseur radial vent aperture and spring radial vent aperture. The step pin prevents an axial migration of the spring in rotor slots.

Abstract: A method of determining the risk of a stator failure is provided. The stator includes multiple stator coil windings. Each of the windings includes multiple conductive metal strands. The number of strand failures is determined from an image captured by a radiography. A risk analysis is assessed from the determined number of strand failures.

Abstract: A radial lead seal assembly of a generator and a method for sealing a radial chamber from an axial chamber of a generator using a radial lead seal assembly are presented. The radial lead seal assembly includes sealing elements disposed around a radial lead to seal an annular space between the radial lead and the radial chamber and thereby seal the axial chamber fluidically from the radial chamber. Conical springs are disposed annularly around the radial lead between the sealing elements and a junction between the radial lead and the axial lead. The radial lead seal assembly includes a nut for exerting a compressive load on the radial lead seal assembly in a radially inward direction such that the conical springs are only partially compressed.

Abstract: A retrofit method for modifying a radial lead seal assembly of a generator and a radial lead seal assembly of a generator are presented. The radial lead seal assembly seals a radial chamber from an axial chamber. The radial lead seal assembly includes sealing elements disposed around a radial lead to seal an annular space between the radial lead and the radial chamber, a coil spring disposed around the radial lead between the sealing elements and a junction between the radial lead and the axial lead, and a nut. The retrofit method includes removing one or more of the sealing elements to define a radial space between the remainder of the sealing elements and the coil spring. Conical springs are inserted in the radial space and only partially compressed under a radially inward compressive load exerted on the radial lead seal assembly via the nut.

Abstract: A retrofit method for modifying a radial lead seal assembly of a generator and a radial lead seal assembly of a generator are presented. The radial lead seal assembly seals a radial chamber from an axial chamber. The radial lead seal assembly includes sealing elements disposed around a radial lead to seal an annular space between the radial lead and the radial chamber, a coil spring disposed around the radial lead between the sealing elements and a junction between the radial lead and the axial lead, and a nut. The retrofit method includes removing one or more of the sealing elements to define a radial space between the remainder of the sealing elements and the coil spring. Conical springs are inserted in the radial space and only partially compressed under a radially inward compressive load exerted on the radial lead seal assembly via the nut.

Abstract: A radial lead seal assembly of a generator and a method for sealing a radial chamber from an axial chamber of a generator using a radial lead seal assembly are presented. The radial lead seal assembly includes sealing elements disposed around a radial lead to seal an annular space between the radial lead and the radial chamber and thereby seal the axial chamber fluidically from the radial chamber. Conical springs are disposed annularly around the radial lead between the sealing elements and a junction between the radial lead and the axial lead. The radial lead seal assembly includes a nut for exerting a compressive load on the radial lead seal assembly in a radially inward direction such that the conical springs are only partially compressed.

Abstract: A winding for a rotor for use in an electrical generator utilized in the power generation industry. The winding includes a plurality of axial sections and a plurality of transversely oriented end arc sections. An integrated leg section extends from each end arc section to form an associated corner section at an intersection of each leg section and associated end arc section. Each leg section is affixed to an associated axial section at a joint that is spaced apart from an associated corner section such that the joint is not subjected to stress concentration which occurs at the associated corner section.

Abstract: A winding for a rotor for use in an electrical generator utilized in the power generation industry. The winding includes a plurality of axial sections and a plurality of transversely oriented end arc sections. An integrated leg section extends from each end arc section to form an associated corner section at an intersection of each leg section and associated end arc section. Each leg section is affixed to an associated axial section at a joint that is spaced apart from an associated corner section such that the joint is not subjected to stress concentration which occurs at the associated corner section.

Abstract: An improved generator rotor (30) and a method of repairing an existing generator rotor (12) are disclosed. Methods consistent with the present invention provide techniques for repairing existing stress-damaged rotors (12) to remove stress-induced cracks (29), without requiring new retaining rings (16), to significantly extend the useful life of a generator without the cost and complexity of conventional repair techniques. Improved generator rotors (30) consistent with the present invention provide a tooth-top design that is more resistant to stress-induced cracking than conventional designs, resulting in new generators with longer useful lives.

Abstract: An improved generator rotor (30) and a method of repairing an existing generator rotor (12) are disclosed. Methods consistent with the present invention provide techniques for repairing existing stress-damaged rotors (12) to remove stress-induced cracks (29), without requiring new retaining rings (16), to significantly extend the useful life of a generator without the cost and complexity of conventional repair techniques. Improved generator rotors (30) consistent with the present invention provide a tooth-top design that is more resistant to stress-induced cracking than conventional designs, resulting in new generators with longer useful lives.

Abstract: An improved generator rotor (30) and a method of repairing an existing generator rotor (12) are disclosed. Methods consistent with the present invention provide techniques for repairing existing stress-damaged rotors (12) to remove stress-induced cracks (29), without requiring new retaining rings (16), to significantly extend the useful life of a generator without the cost and complexity of conventional repair techniques. Improved generator rotors (30) consistent with the present invention provide a tooth-top design that is more resistant to stress-induced cracking than conventional designs, resulting in new generators with longer useful lives.

Abstract: A dynamoelectric machine 20 includes a rotor assembly 24 and a main lead insulating assembly 26. The rotor assembly 24 includes a shaft 28 having a main lead receiving recess 32 in its outer surface, a rotor 30 mounted to the shaft 28, and a stator 22 surrounding the rotor 30. The main lead insulating assembly 26 lines the main lead receiving recess 32 and includes at least one insulating bottom block 34 axially secured to the shaft 28 and at least one insulating sidewall block 40 secured to the at least one insulating bottom block 34 with at least one interlocking joint 42. A main lead 35 is received in the main lead insulating assembly 26.

Abstract: A dynamoelectric machine 20 includes a rotor assembly 24 and a main lead insulating assembly 26. The rotor assembly 24 includes a shaft 28 having a main lead receiving recess 32 in its outer surface, a rotor 30 mounted to the shaft 28, and a stator 22 surrounding the rotor 30. The main lead insulating assembly 26 lines the main lead receiving recess 32 and includes at least one insulating bottom block 34 axially secured to the shaft 28 and at least one insulating sidewall block 40 secured to the at least one insulating bottom block 34 with at least one interlocking joint 42. A main lead 35 is received in the main lead insulating assembly 26.