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Encotech Seminars
Generator Maintenance Seminar Presented by
Clyde V. Maughan, P.E.
Mr. Maughan is a licensed professional engineer with degrees in Electrical Engineering and Mechanical Engineering. For 36 years with General Electric, Mr. Maughan served as both an engineer and manager in the generator and turbine departments in the areas of engineering design, service, development, manufacturing production and quality control product services in the field and factory, and project manager of five product service replacement of three leading OEM's.
He is presently a professional consultant on generators rated 2 MW to 1400 MW manufactured by various major companies. His consulting services have included the technical training of generator service specialists, writing of maintenance and repair procedures, failure investigations and analyses, design and manufacturing consultation, and insurance claims resolution.Mr. Maughan has prepared or revised numerous training and repair documents, slides, and video. He has authored an EPRI document on generator maintenance and initiated the present IEEE Working Group on generator partial discharge analysis, participated in three IEEE Working Groups, and is also an inductee of OEM Academy of Generator Maintenance Specialists.
SEMINAR OUTLINE
I. General Considerations
Design, manufacturing, operation/maintenance, and business trends
II. Design Technical Considerations
Challenges & duties, stator winding failure mechanisms, vibration control, winding voltage grating, partial discharge, field failure mechanisms, centrifugal forces, insulation deterioration, thermal duties, differential forces, thermal sensitivity, core failure mechanisms, lamination insulation, vibration, compressive loading, frame failure mechanisms, vibration & resonances, cracking and fractures
III. Generator Operation
Normal duties, cycling, start-stops, contamination, current unbalance, abnormal duties, sudden short circuits, overload, overspeed, overtemperature, lubrication loss, negative sequence currents, overfluxing
IV. Failure Modes
Stator winding vibration, grounds, leaks, migration, stator core damage, frame vibration, cracking, field com ponent fractures, insulation failures, migrations
V. Monitoring
Capabilities, limitations, retrofit options, mechanical equip., vibration: rotor, windings, electrical equip., partial discharge, stator & field grounds, turn shorts, flux probes, thermal equip., condition monitors, RTD's/TC's
VI. Visual Inspection
Training/experience/equip./tools/ robots, evidences of concern, time intervals, stator inspection procedures, slot bar vibration, end winding vibration, corona: slot end windings, core & frame inspection, vibration, foreign object damage, looseness, contamination, lamination insulation, over-flux failure, field inspection procedures, winding insulation/ conductors, retaining rings, wedges & forging
VII. Design Technical Considerations
Over-potential, personnel/equip. cautions, merits, risks, AC vs. DC vs. 0.1Hz, over-potential test procedures, hipot, controlled voltage, power factor& tip-up, partial discharge, radio frequency/ ultrasonic, special field considerations, gen. field & stator tests, stator wedge tightness, end winding modal analysis, NDE of mech. components, conductor resistances, bearing insulation, gas cooled bars, stator core, low & high power flux tests, tightness, through bolts, flux shunts, liquid cooled stator windings, personnel and equip., water flow verification, removal, vacuum & pressure decay, tracer gases, wet-bar capacitance, results interpretation
VIII. Component Maintenance
Maint. programs, predictive maint., condition based maint., parts replacement/storage, cleaning & painting, armature winding repairs, rewedging, tightening end windings, corona damage repair, winding water leak correction, bar replacement, full stator rewind, stator core, mech. damage, looseness, restacking, field repairs, removal & handling, retaining rings, fans & compressors, rewedging, cracks & burning, couplings & journals, partial rewinds, full rewinds