Generator Rotor Dovetail Crack Inspection

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Cost Effective Options Based On Sound Engineering Evaluation

Dovetail groove cracking may be caused by fretting, negative sequence heating events, or extensive start/stop cycles. Crack propagation can be mitigated by a dovetail groove inspection, wedge replacement and dovetail groove machining. REGENCO’s solution to this problem features:

Generator Rotor Inspection

• Rings removed using induction heating

• Rings NDE inspected after removal

• Wedges removed, inspected and catalogued

Dovetail Groove Mag Particle Inspection

• Winding remains in-place and protected during inspection

• Inspection by Level II or III Certified Inspectors

Metallurgical Evaluation

• Metallurgical Engineers evaluate indications and recommend corrective actions necessary

Engineering Evaluation and Recommendations

• Metallurgical findings combined with engineering evaluation of electrical and mechanical situation

• A range of options to address any problems is provided

• Complete final report provided

Corrective Action Options

• Dovetail crack machining

• Manufacture replacement aluminum wedges, using in-house CNC machining centers

• Correct other typical problems such as main lead cracking, copper dusting, and journal machining

• High-speed balance with electrical tests to verify performance

Shop Inspection and Repair versus On-Site

• Experienced Inspectors, Engineers, and Craftspeople

• Engineers in-house and available
  

• Proper setup, procedures, and cleanliness
  

• Large machine tools and tooling for any contingency
  

• Fast turn-around, due to inspection method and immediate availability of necessary tools and personnel

Proven Experience

• REGENCO routinely inspects dovetail grooves on every rotor we have rewound