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Power Services | Jebel Ali Service Center

Generator Component Final Repair Report

Job Number 40741506Component FieldShop Name Jebel Ali Service Center

Customer STEG Bir M ChergaSite Name Bir M Cherga

Serial Number 336x111Assembly # 135E9415

Prepared By Marcelo Conson JrDate Received December 5, 2017

Reveiwed By: Biju SimonApproved By: Suresh Tudimella

Customer: STEG Bir M Cherga Job #: 40741506 of 55

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Component Identification Inspection Scope Repair Results and Comments Additional Attachments

Table of Contents



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1. Component Identification

Table 1: Component Identification Details

2. Inspection ScopeThe 9A3 generator rotor was received at Jebel Ali Service Center for full field rewind andhigh-speed balancing

Make GEUnit Number 1A

Frame 9Ax

3. Repair Results and Comments Generator Rotor Receipt• The 9A3 Generator Rotor from BIR Mcherga arrived in Jebel Ali GE Service Centre, on05 December 2017 for rewind and HSB. Rotor was packed in a wooden box with steel base. Rotor was supported on journalsand on rotor body. General Visual Inspection The following general conditions were noted: • Rotor was wrapped with tarpaulin and polythene sheets added on the retaining ringsand journals. Upon unloading and removal of the packing the following general conditions werenoted: • The retaining rings were in assembled condition. • The journals were cover by nomex insulation. • Fan blades not received. Component Specific Visual Inspection Turbine End (TE) Coupling: • Light contamination, scouring on coupling rear face and bolt holes. • Deep scratches from outer rear face. • The balancing plane groove has no weights found. • Jacking marks from outer face.




Out–board Seal Area - TE: • Light dust, oil and carbon contamination. Bearing Journal TE: • Multiple scouring marks. • Light dust, oil and carbon contamination. • Rubbed marks. In–board Seal Area TE: • Light dust, oil and carbon contamination. • Light impact marks on outer rear edge corner. Shaft forging balancing plane - TE: • Shaft groove with 11 weights, punch locked. • Light oil contamination. Retaining Ring/Center ring- TE: • Light oil and dust contamination. • No mechanical damage was found. Snap Ring - TE: • No damage was found. End winding - TE: • Light dust and carbon contamination. • Heavy oil contamination. Rotor Body: • Multiple wedges were found migrated and gaps were seen between wedges. • Black paints peel off observed. • Significant overheating indications towards TE side • Misaligned creepage block ventilation holes observed from wedges ventilation holes. • Three each magnetic wedge per slots. End Winding CE: • Light dust and carbon contamination. • Heavy oil contamination. • Flexible copper from stud, one leave found cut from first turns. Retaining Ring/Center ring - CE: • Light oil and dust contamination. • No mechanical damage was found.




Snap Ring - CE: • No damage was found. Shaft forging balancing plane - CE: • Shaft groove with 6 weights, punch locked. Inboard Seal Area - CE: • Rubbing signs and brass deposit observed. • Oil and carbon contamination. Bearing Journal - CE: • Multiple light scouring and scratched marks observed. • Dust and oil contamination. Out–board Seal - EE: • Oil and carbon contamination. Exciter Armature: • No damage was found on winding. • Clearances observed between slot core and coil. • Light uneven surface. • Light oil contamination. Rectifiers: 12 diodes 12 heat sinks 12 fuses 2 capacitors 1 ground fault detector. List of Components received with Rotor (assembled). Set of field winding Set of wedges Set of Retaining and centering rings Set off exciter armature. Set of rectifiers D-Lead terminal was covered. Attachment: Field Electrical test (Electrical Test showed unhealthy winding) Incoming Run-out




Following are the major deviations noted after disassembly of complete parts fromgenerator rotor:- Retaining Rings and sap rings Retaining Rings, Insulation and Amortissuer • Excessive oil, dust and carbon contamination. Pool of oil was found inside retainingring after disassembly. • Heavy dust and carbon observed from amortissuer. • RR silver plating shredded off on shrunk area of retaining rings. • End winding insulation aged, degraded and burned. Snap rings • Excessive oil, carbon and dust contamination. • Impact marks on snap ring. End winding • Excessive oil, dust and carbon contamination. • Discoloration and indications of overheating on coils were observed • Below coil turns were found open from brazed joint. Turn 1 and 2 from Coil 5, Pole 0 (turn 1 starting from bottom) Turn 5, coil 1, Pole 180. Slot contents Slot wedges • Excessive oil, dust and carbon contamination. • Aged and degraded top creepage block. • Tip broken, aged and degraded slot armor. Sub slot cover • Excessive carbon, dust and oil contamination. • Aged and degraded sub slot covers Body end • Heavy dust and carbon contamination. • Light rust observed on shrink fit areas and silver contamination from retaining ring. Stud bolts • Aged degraded and broken ghoose neck connection. • Flexible copper leaves 2 each were found broken from pole 180. • Flexible copper leaves 1 each were found broken from pole O.




• Copper discoloration observed. Bore copper • Light dust and rust contamination on the bore copper insulation. • Pieces of insulation packing added from outer end. • Indications of overheating and discoloration observed on bore copper insulation. The following refurbishment /repair activities are were performed on belowcomponents: • Polishing and smoothening on retaining rings/center rings and perform NDTexamination. • Silver coated in retaining rings shrink seat area. • Cleaning, visual inspection, Magnetic Particle Inspection, and painting of rotor forging. • Refurbishment of slot wedges and perform Dye Penetrant inspection. • New Gooseneck Main Terminals installation with special brazing material. • Revalidation of slot amortisseur. • Coils were cleaned by grit blasting. • Unbrazed all butt brazing of all coils. • Existing silfos brazed from butt joints were thoroughly removed. • Modified butt joint to lap joint by machining C coils and brazed using special brazingmaterial. • Annealed all coils and polish, prior inserting into slots. • Cleaned exciter winding assembly and diode assembly. The following tests and inspections were performed during the course of the rotorrefurbishment: - Electrical Tests – Incoming • Winding Ohmic resistance – not acceptable • Insulation resistance – not acceptable • Impedance – not acceptable • Pole to pole - not acceptable • RSO test – not acceptable Dye-penetrant test • Wedges - acceptable • Retaining rings - acceptable • Journal – acceptable




Rotor Forging • Magnetic particle inspection – acceptable Electrical Test after bake/before RR install • Insulation resistance - acceptable • Winding Ohmic resistance - acceptable • Impedance - acceptable • RSO test - acceptable • Pole to pole comparison - acceptable • Voltage drop test - acceptable Electrical Tests – Before retaining rings assembly • Insulation resistance - acceptable • Winding Ohmic resistance – acceptable • Impedance - acceptable • RSO test – acceptable • Pole to pole compilation – acceptable. • High Voltage test – acceptable Electrical Tests – After retaining rings assembly • Insulation resistance - acceptable • Winding Ohmic resistance – acceptable • Impedance - acceptable • RSO test – acceptable • Pole to pole compilation – acceptable. • High Voltage test – acceptable Electrical Tests – During Balancing • Insulation resistance - acceptable • Flux waveform test - acceptable Mechanical balancing report • Shaft vibrations – acceptable • Bearing vibrations - acceptable • Weight mapping - acceptable • Over speed test - acceptableFinal Electrical Tests • Insulation resistance – acceptable




• Winding Ohmic resistance - acceptance • RSO test – acceptable • High Voltage test – acceptable Run out measurement • Incoming – Acceptable • After balancing - acceptable Conclusions: - All the rotor key components were refurbished / replaced and used for reassembly afterapplicable NDT and electrical tests as stated below: • Rotor body, slot closing wedges, retaining rings, centering rings were reused afterrefurbishment by cleaning and NDT. • New bore copper and new main terminal studs were assembled then high potentialtested. • Revalidation of all slots amortissuer. • Assembled all modified copper turns coils with new top, bottom connectors and poleto pole jumpers. • All the insulation parts like, slot armor, turns insulation and sub slot covers werereplaced with GE supplied new insulation kit. • Installed existing slot amortissuer and wedges. • Replaced all end space blocking with new. • New retaining ring insulation and new end winding amortissuer used for the assemblyof rings.• Performed final run-out. • Performed high speed balancing to operating speed and dynamic electrical test. • Final electrical testing of rotor stand still condition. • Packing and shipment. Enclosures Incoming test. • Insulation resistance • Winding resistance • Impedance • Pole to pole • RSO




Nondestructive Test. • Slot wedges • Retaining Ring • Journal • Rotor forging Test after bake • Insulation resistance • Winding Ohmic resistance • Impedance • RSO test • Pole to pole comparison Test Before Retaining Rings assembly • Insulation resistance • Winding Ohmic resistance • Impedance • RSO test • Pole to pole comparison • High Voltage test Test After Retaining Rings assembly • Insulation resistance • Winding Ohmic resistance • Impedance • RSO test • Pole to pole comparison • High Voltage test Electrical Tests – During Balancing • Insulation resistance • Flux waveform test Mechanical balancing report • Shaft vibrations• Bearing vibration • Over speed test•• Weight mapping




Shipping Electrical Test • Insulation resistance • Winding Ohmic resistance • RSO test • High Voltage test




4. Additional Attachments




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Receipt Pictures

Box moved from support frame




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Disassembly pictures Retaining Rings, Insulation and Amortissuer

End winding insulation deteriorated

End winding

Coil 1 pole O, 5 each turns open brazed joint End winding coil 1 pole O turns open

Coil 5 pole 180, one turn open, brazed joint

Heated Discoloration

Carbon and heated Discoloration




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Slot wedges

Creepage block

Armor.

Sub slot cover




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Body end

Stud bolts

Bore copper

Two leaves broken

One leaves broken




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Incoming pictures

Turbine End (TE) Coupling:

Out–board Seal Area - TE:




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Bearing Journal TE:

In–board Seal Area TE:

Shaft forging balancing plane - EE:




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Retaining Ring/Center ring- TE:

End winding - TE:

Rotor Body:




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End Winding CE:

Retaining Ring/Center ring - CE:

Inboard Seal Area - CE:

Cut strand




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Shaft forging balancing plane - CE:

Bearing Journal - CE:

Out–board Seal - EE:




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Exciter Armature:

Rectifiers:




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INSPECTION RECORD

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Grit blast wedges

Refurbished wedges and snap rings

Slot Amortissuer




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RR contact areas silver coated




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Painted rotor forging

Clean / blasted coils




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C-coil unbrazing

Annealed copper coils




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Copper turns ready for rewind

New bore copper

Materials / Parts




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Rewinding coil # with new main terminal studs




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Blocking assembly




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Installing New Retaining rings insulation and new amortissuer




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RR assembly

HSB




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Packing / Shipping




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