Turbogenerator Capabilities

NEC Engineers have led the industry in addressing a number of design-related issues that have emerged in the newest generation of large air-cooled generators.


  • Stator winding manufacture
  • Testing, inspections and life assessments
  • Stator rewinds
  • Core restacks and repairs, Partial or Complete
  • Parallel ring modifications
  • Main-Neutral Interchanges
  • Stator winding end turn support modifications
  • Rewedges, wedge tightening
  • Through bolt retightening and hardware replacements; through bolt replacements
  • Field testing of large generators for confirmation of performance parameters
  • Full redesign of generator stator core and on-site or in-shop restacking
  • Analysis of stator frame structure and measures for eliminating deficiencies

High-Speed, Cylindrical Rotors

  • Rotor winding manufacture
  • Testing, inspections and life assessments
  • Collector Ring Machining
  • Fan Repairs/Replacement
  • Radial lead stud replacement
  • Slot Wedge replacement
  • Supply or repair magnetic or non-magnetic retaining rings
  • Rotor tooth top cracking repair
  • Calculations to determine the proper shrink fits of rotor components
  • Calculations involving stress, flexure, fatigue, and fracture mechanics
  • Static electrical testing of generator rotors
  • Evaluation and determination of fatigue life; redesigns
  • Retaining Ring Modifications, Short or Long Types
  • Leak Testing & Modification of Rotor Radial Lead Assemblies
  • Field Crossover Replacements
  • Improvements to Enhance Vibration Stability
  • Design and implementation of the direct end turn cooling systems
  • Electrical Testing
  • Replacement of end turn blocking
  • Replacement, repair, re-insulation of individual turns of coils.
  • Removal, cleaning and re-insulation of existing copper winding.
  • Manufacturing new coils using OFHC silver-bearing copper.
  • New slot liners and insulating materials
  • Main leads, studs and stud seals
  • Replacement retaining rigs, slot wedges, fans
  • Collector ring repair or replacement
  • Redesign to eliminate problems
  • Complete rewind of rotor
  • Dynamic balancing of rotor at rated speed plus momentary 10% overspeed
  • Manufacturing of complete new rotor
  • Vibration analysis of high-speed flexible generator rotors at all dynamic mode shapes, two and three bearing machines
  • Dimensional checking of generator rotor components and calculations to determine proper interference fits