Generator Expert: James Timperley – Combined Cycle Journal

Generator Expert: James Timperley

About James Timperley

Mr. Timperley received his BSEE from Oklahoma State in 1968 and joined American Electric Power that year, as a substation engineer, working on switchyard design ranging from 13 kV to 765 kV. This was followed by helping establish an electrical engineering laboratory, where he designed test equipment and developed test procedures. He then served as the primary AEP rotating electric machinery engineer for over 25 years. He was responsible for inspecting, failure analysis, setting operation limits and establishing maintenance procedures for a fleet of over 200 AEP generators. These ranged from small air cooled, 80 year old hydro generators, to newest 1100 MW nuclear and 1300 MW coal fired, steam turbine generators. He also provided training and technical guidance to the AEP repair shop of 30 winders that worked on these generators. Stator winding maintenance and replacement were based on test results and inspection history. All generator stator rewinds were upgraded with improved ventilation and or enhanced stator winding designs. These same activities included the hundreds of large motors and numerous synchronous condensers within AEP.

Jim retired from AEP and joined Doble Engineering in 2007. He was the lead in development and application of Electro Magnetic Interference (EMI) testing. This new on-line testing technology was provided to more than 100 international sites. Including generators driven by coal, oil, wood, nuclear and gas fired steam turbines, hydroelectric, internal combustion engines, as well as petrochemical sites, refineries, plastics and chemical locations and off-shore platforms. EMI was expanded to be an in-service condition assessment tool for brushless exciters, isolated phase and non-segregated bus. Testing oil filled and dry type power and instrument transformers was developed as well as testing power cables, including Paper Insulated Lead Covered systems. Jim retired from Doble Engineering in 2019. J E Timperley Consulting LLC was then established to continue service to the industry.

He has published and presented over 80 technical papers in the areas of applied research, diagnostic testing, inspecting, maintaining, repairing and specifying rotating machinery for IEEE, Doble, ASME, CIGRE, EPRI, E/EIC, TGUG and the American Power Conference. Subjects also included operating, maintaining, and testing of critical power system assets, managing isolated phase bus, root cause failure analysis, evaluation of advanced insulation materials, and applying EMI Diagnostics. He is recognized as an accomplished speaker to many types of industrial, business, technical and management level audiences.

Mr. Timperley is an IEEE Life Fellow, the peer elected 0.1% assembly of IEEE members. He was presented the 2006 Dakin Award by the IEEE Dielectric & Insulation Society for the development of EMI Diagnostics. He has been a member of several IEEE standards groups, has completed numerous safety programs and security verifications for unescorted access to nuclear and petrochemical facilities. He has completed, OSHA 10 training and Basic Offshore Safety Induction & Emergency Training (BOSIET) for working on off-shore facilities. He was a registered professional engineer in Ohio for 40 years. Mr. Timperley’s passport and TWIC card are current.

General comments and observations

Mr. Timperley has focused on remote support of clients through J E Timperley LLC, to analyze equipment failures, through the extensive use of photographs, test data and the guided inspections of on-site personnel. This includes motors, generators, bus, power cables and instrumentation transformers.

Improvements in equipment service life and improved operation are often possible with review of detailed operation information and the existing design. Enhancements are often possible through the use of modern materials and improvements in cooling.

Generator Areas of Special Skill

  • Stator windings
  • Stator core and frame
  • Excitation systems
  • Failure root cause
  • Inspection
  • Testing
  • Maintenance/Repairs
  • Mis-operation
  • Other – Generator system EMSA data analysis


  • Onsite
  • Remote Assistance
  • Remote support preferred, onsite support if necessary




640 MURNAN Road
GALLOWAY, OH 43119-8702
United States

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