Stator Visual Inspection - Frame 6 Users...
Transcript of Stator Visual Inspection - Frame 6 Users...
AGTServices, Inc.Generating timely repair solutions
2019 Frame 6 User’s
Conference
2 GE Frame 6/6A3 “Minor” Outages,
Turned to Majors with Field Rewinds
Presented By:
Jamie Clark – AGTServices
www.agtservices.com
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Agenda Summary
• Unit Details
• Unit Inspection History
• Unit “B” Minor – Fall ‘18
• Unit “A” Minor – Spring ‘19
• Findings/Root Cause
• Field Rewind
• Additional Stator Work
• Unit “C” Plans – Fall ‘19
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Unit Inspection HistoryYear Unit A Unit B Unit C STG Findings
2001 Minor Major Minor B EW greasing, wedge greasing. C
partial rewedge, EW greasing
2002 Major Major B End Wedge Rewedge, STG Full
Rewedge
2003 Forced Forced A Repair/Replace 2 bottom bars, B
water ingress, no issues.
2007 Minor Noted more turn insulation migration
2008 Minor
2009 Minor Mag Particles, Rub Ring wear
2011 Minor Minor EW Greasing
2012 Minor EW Repairs w/ field in
2013 Minor Bus bar heating, Minor Grease
2015 Major Stator cleaned, field insulation
migration
2018 Minor Turned Major, Field RW, Rewedge
2019 Minor Turned Major, Field RW, Rewedge
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Minor Inspection Scope (Both B-A)
• Outer end covers removed
• GAC in place
• Field installed
• Borescope aided visual inspection
• Standard Stator Electrical Testing
• Standard Field Electrical Testing
• Standard, limited disassembly, brushless exciter tests
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Unit “B” Summary Findings
Global, aluminum
metallic particle
contamination
from rub ring
wear.
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Unit “B” Summary Findings
Rub Ring
Inner Oil
Deflectors
Contamination Ingress:
• Aluminum Particles
caused by rubbing of the
Inner Oil Seals or Inner
Ring.
Possible Contributors:
• Field Vibration
• Tilt Pad Bearing Wear.
• Alignment ??
Rub Ring
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Unit “B” Summary Findings
• GE – 6A3 - S/N: 336X402
• Significant Amount of End Turn Insulation Migration
End Turn Insulation
FIELD WINDING:
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Unit “B” Summary Recommendations
Generator Field – To Remove Metallic Particles from Winding:• Remove field from stator.
• Perform a complete rewind with a new Class F Insulation.
• Perform a HSB with Running Electrical Tests.
Duration: Rewind – 21 Days / With HSB – 28 Days
Brushless Exciter: • Remove Diodes and Fuses.
• Clean.
• Replace All Fuses with New. Test & replace any bad Diodes.
• Replace Insulators and Hardware with new.
• Replace missing hardware from GFD.
• (Owner to supply Parts).
Stator – To Remove Oil Contamination & Assess Wedge System:• Clean Windings.
• Perform a Complete Wedge Tightness Survey – Perform Rewedge, if necessary.
• Ultimately, a full stator rewedge was required.
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Unit “B” Rewind
Global, and GROSS, turn
insulation migration
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Unit “B” Rewind
Significant End Winding
Elongation/Distortion
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Unit “B” Rewind
Numerous End Creepage
Blocks Broken
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Unit “B” Rewind
Top Coil To Coil Connectors
Undersized, Top Turn
Distortion From Soft Copper
FACTORY DEFECTS
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Unit “B” Rewind
Numerous Slot Armors
Damaged/Compromised, and
numerous turn insulation
migration or cracking
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Unit “A” Summary Findings
No Rub Ring
Aluminum
Contamination,
but GLOBAL and
GROSS turn
insulation
migration
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Unit “A” Summary Findings
Second Verse, Same as the
First…but Worse!
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Unit “A” Rewind
End Creepage Blocks Broken
– Same as Unit “B”
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Unit “A” Rewind
Main Lead Leaf Broken and
Spun Up. Numerous slot
armors nearly worn through
near slot exit.
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Unit “A” Rewind
Slot Armor Patch
FACTORY FIX
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Unit “A” Rewind
Numerous Areas of Turn
Insulation Breaks and Pulling
Away
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Unit “A” Rewind
Turn Insulation Severe
Enough to Expose Copper
Turns
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Unit “B” vs “A” Differences and
Similarities
Condition Unit “B” Unit “A”
Aluminum Contamination Yes No – but present in ‘03
Loose Distance Blocks Yes Yes
Turn Insulation Migration Yes Yes
Creepage Block Breaks Yes Yes
Top Turn Distortion/Soft Cu Yes No
Turn Insulation Crack/Splits Yes Yes
Main Lead Cracks No Yes
Coil Crossover Undersize Yes Yes
Slot Armor Damage Yes Yes (worn)
Also “Patched”
End Turn Distortion Yes No
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GE 6A3 Generator Field
Rewind
AGTServices, Inc.Generating timely repair solutions
GE 6A3 Generator Field
Rewind
AGTServices, Inc.Generating timely repair solutions
GE 6A3 Generator Field
Rewind
AGTServices, Inc.Generating timely repair solutions
GE 6A3 Generator Field
Rewind
AGTServices, Inc.Generating timely repair solutions
GE 6A3 Generator Field
Rewind
AGTServices, Inc.Generating timely repair solutions
GE 6A3 Generator Field
Rewind
AGTServices, Inc.Generating timely repair solutions
GE 6A3 Generator Field
Rewind
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GE 6A3 Rewind Complete
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GE 6A3 Rewind Complete….
But What About the
Stator(s)???
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Stator Endwindings
Unit B Unit A
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Stator Connection Rings
Unit B Unit A
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Stator Connection Rings
Unit B Unit A
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Stator Axial Support Hardware
Unit B Unit A
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Stator Wedge System
Unit B Unit A
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Stator Wedge System
Only 21% are tight
Unit B
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Stator Wedge System
80% are tight, so marginal. Due to
desired duration until next major,
rewedge recommended and approved
Unit A
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Summary
Stator Area Unit B Unit A Comments
Endwinding Greasing Greasing Global cleaning,
partial block/retye
Stator Core No Issues No Issues
Wedge System 79% loose 20% loose Rewedge req’d
Buss/Lead Connections Minor retape Replace
some leads
Electrical Testing Passed Passed
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Stator Repairs and Rewege
(similar for both)
AGTServices, Inc.Generating timely repair solutions
Stator Repairs and Rewege
AGTServices, Inc.Generating timely repair solutions
Stator Repairs and Rewege
AGTServices, Inc.Generating timely repair solutions
Stator Repairs and Rewege
AGTServices, Inc.Generating timely repair solutions
Stator Repairs and Rewege
AGTServices, Inc.Generating timely repair solutions
AGTServices, Inc.Generating timely repair solutions
Conclusions/Summary
• Most 6A3’s at/beyond 30 year service life
• Oil is the enemy!
• Unit “C” at this site is in the same boat – Fall’19 Plans
• Many “minor” inspections turning into MAJORS
• Get your units baselined NOW, and fix it as a SYSTEM
• Cycling Duty is negatively impacting BOTH field and
stators
• Stator rewinds are next – 8-12 week winding cycle!
• Add 24-28 days to wind it!!