unplanned generator repairs resulting from …...agtservices, inc. generating timely repair...

AGTServices, Inc.Generating timely repair solutions

Unplanned Generator Repairs

Resulting from Increasing Start/Stop

Duties

Jamie Clark – AGT Services


Case Study Unit Details

• GE 324 Steam Turbine

Generator

– 290T303

– Mfg ~1995

– COD ~1996

• Rating Info

– 287 MVA

– 18 kV

– 9,206 Amps

– 72 Slots

– Coal Fired, Base

Load

– 3,600 RPM

– 550 V, 1469 Amps

(Field)

– 30 PSIG H2 pressure


2000 – YTD June 2016

Starts & Discounts

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 YTD 2016

24 23

60

2917

39

126

65

35

117106

87101 106

80

104

40- -

-

-

-

-

-

84

49

93

183

149139

191

184

177

32

Starts Discounts


Operational and Maintenance History

➢ 2001 – Field Retaining rings removed to address slot migration and

gas path blockage

➢ 2003 – Two belly bands installed to address generator stator

looseness

➢ 2007 – Field rewind performed due to shorted turns

➢ 2011 – Two original belly bands removed and replaced with 5 belly

bands by AGT, including partial rewedge.

➢ 2015 – Stator Voltage mismatch on sychronization

➢ 2016 – End winding treatments, short term repair of bottom bar

damage, bushing box viscasil and RTV dams, hardware

replacements where indicated, field retaining rings removed, field

and RR ammortisseurs modified, wedges removed and re-staked,

bore plate seal replaced


2016 Test/Inspect Findings and

Recommendations

Moving Field Wedges (poorly staked)


Migrating Slot Ammorts


Loose Axial Stop Blocks (CE worst)


Main Lead Indications (not

present in 2011 inspection)


Connection Ring Insulation

Cracked

Loose Trapezoidal Blocking


G11 Blocks Used in Bar-to-Bar


Bottom Bar Insulation Damage


Recommendations• Remove and Modify Field Ammorts

– Address loose blocking when RR’s removed.

• Replace bore plate seal

• Recondition HVB Box, Hardware, RTV, terminal plate

sealing, etc..

• Replace loose trapezoidal blocks

• 100% install of tangential EW blocks

• Short term repair of bottom bar damage– Plan for future full stator rewind


Full Length Slot Ammorts and

Patented RR Ammort Mods


TE Cap-to-Cap Block/Tie, EW

Red Eyed



• GE 7FH2 Gas Turbine

Generator

– 337X717

– Mfg ~1999

– COD ~2000

• Rating Info

– 214 MVA

– 18 kV

– 6,880 Amps

– 60 Slots

– 2x1 Combined Cycle

in Maine

– 3,600 RPM

– 300 V, 1516 Amps

(Field)



2000 – YTD June 2016

Starts


2000 – YTD June 2016

Starts & Discounts

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 YTD 2016

24 23

60

2917

39

126

65

35

117106

87101 106

80

104

40- -

-

-

-

-

-

84

49

93

183

149139

191

184

177

32

Starts Discounts


Operational and Maintenance History

• 2000 – COD

• 2007 – First major inspection. Complete series connection

block/tie on TE and CE. Recommended connection ring block/tie,

but owner deferred.

• 2012 – MAGIC inspection revealed ammortisseur migration.

• 2015 – Personnel noted increase in noise level. Acoustic analysis

confirmed “keybar rattle” with likely belly band tightening req’d

2016 Scope Included:

• Field shipped offsite for field rewind and ammort migration repair

• Standard Test/Inspect

• Belly Band Tightening (to arrest keybar rattle issue)


Significant Connection Ring Tie

Greasing – ‘07


Movement Between Binding

Band and Bar End Arm – ‘07


Series Loop Block and Tie – ‘07


As Left – ‘07


Bar-Bar Tie Greasing TE/CE – ‘16


More Connection Ring Grease – ‘16


Corona Activity at Phase Breaks – ‘16


Core Iron Oxide – ‘16


Wedge Map – ’07 vs ’16 as Found


RecommendationsPlanned

• Tighten belly bands

Unplanned

• Full Stator Rewedge

• Reblock and Retie Connection Rings

• Redeye bar/bar ties

• Tighten core

Future Recommendations

• 100% Endwinding stiffening treatment


New Connection Ring Block/Tie – ‘16


Application of Redeye Bar/Bar– ‘16


Belly Band Tightening – ‘16


Finished – ‘16



• GE 7FH2 Gas Turbine

Generator

– 338X512

– Mfg ~2001

– COD ~2003

• Rating Info

– 205 MVA

– 18 kV

– 6,575 Amps

– 60 Slots

– Multi-block, 2x1

Combined Cycle in

Arizona

– 3,600 RPM

– 350 V, 1771 Amps

(Field)



Planned Scope

2017 “Minor”:

• Upper endshields removed

• Field installed


– Including test the H2 seals on terminal studs


Significant Connection Ring Tie

Greasing – ‘07


Loose Bar Ties at Phase Breaks


More Severe Greasing


Global Greasing at Endwedges


Terminal Stud Seals Held!!!



• Standard Testing – 2-3 shifts

Unplanned

• Complete disassembly, field removal

• Bump test and reblock/retie endwindings

• Wedge map performed, 100% rewedge required


• None


Wedge Tightness Results with

Field Out – 100% Rewedge Req’d

EXCITER END TURBINE END

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

1 4 3 2 3 3 3 4 4 4 2 3 4 4 2 4 4 4 3 4 3 3 3 3 3 3 3 4 3

2 3 4 4 4 4 4 4 3 4 3 3 4 3 3 3 4 3 2 4 4 3 3 4 4 3 3 4 4

3 4 4 4 3 4 4 4 4 4 3 3 3 2 3 4 3 3 2 3 3 2 3 2 3 3 3 3 4

4 4 4 3 4 4 3 4 3 4 2 3 3 3 3 3 4 3 3 3 3 2 3 3 3 3 3 3 4

5 3 4 4 4 4 4 4 3 3 3 3 3 3 3 4 2 3 2 4 4 3 3 3 4 4 3 3 3

6 3 4 4 3 4 4 4 4 4 3 4 4 4 2 3 3 2 3 3 2 3 4 2 3 2 3 4 4

7 3 4 4 3 4 1 1 1 3 3 4 3 4 2 3 3 2 2 2 2 2 3 4 1 3 3 2 3

8 2 4 4 4 4 4 4 2 3 4 2 3 3 3 4 2 2 1 2 2 3 3 3 3 3 3 3 3

9 3 3 3 4 3 2 3 3 4 4 2 2 2 2 2 2 3 1 3 3 4 3 4 3 3 3 3 4

10 3 2 3 3 4 3 3 3 3 2 2 4 3 3 3 3 2 3 3 2 3 3 3 2 3 3 3 3

11 4 3 3 3 3 3 3 4 4 4 3 4 4 4 4 2 3 3 2 2 3 3 4 4 4 3 2 3

12 4 3 3 3 3 4 2 4 4 4 4 3 4 3 3 1 2 3 2 3 2 3 2 2 3 2 2 4

13 4 3 3 3 2 2 4 4 3 4 4 3 4 3 2 2 1 2 3 3 2 2 3 2 1 2 3 4

14 4 4 3 4 4 3 2 3 2 3 4 4 4 4 2 2 1 2 2 1 2 3 3 3 2 2 3 3

15 4 3 3 4 2 3 4 2 1 2 2 3 3 3 4 3 1 3 2 3 3 2 3 3 1 3 4 4

16 4 4 3 3 3 3 3 3 3 3 2 3 2 2 2 3 1 3 2 4 3 2 3 2 2 4 3 4

17 4 4 4 4 2 4 4 3 2 3 2 3 2 4 2 4 2 3 4 3 3 2 4 3 2 3 2 3

18 3 4 4 4 3 3 3 4 3 3 3 2 3 3 3 4 3 4 4 3 4 4 4 3 2 3 4 2

19 3 4 4 4 3 3 3 4 4 3 4 3 4 3 3 3 3 4 4 3 4 2 3 3 3 3 3 3

20 3 4 4 4 4 4 3 4 4 4 3 2 2 3 4 2 2 3 4 3 4 3 4 4 3 3 3 3

21 4 4 4 4 4 4 4 4 4 4 4 3 3 4 3 3 3 3 3 4 2 4 4 3 3 4 3 3

22 4 4 4 4 4 3 4 2 4 4 3 3 3 3 3 3 3 3 3 3 1 3 3 3 3 3 4 3

23 4 4 3 3 4 4 3 3 4 3 4 3 4 3 3 3 4 3 3 3 3 4 3 3 3 3 3 3

24 3 4 3 4 3 4 4 2 4 2 3 2 3 2 3 2 4 3 3 3 3 4 4 3 2 3 4 4

25 3 3 3 2 2 3 2 4 4 4 3 2 4 2 4 4 4 3 4 4 3 4 3 3 3 2 4 3

26 3 3 2 3 4 4 3 2 3 3 2 2 3 3 2 2 3 3 4 4 3 3 3 4 3 3 4 3

27 4 4 3 3 3 3 3 2 2 3 3 3 4 3 3 4 3 2 2 2 2 4 3 3 3 3 4 3

28 3 3 3 3 3 2 1 3 2 2 3 3 4 3 3 4 3 3 1 3 3 3 3 2 4 4 4 3

29 3 4 2 4 2 2 2 2 3 3 4 3 3 2 4 3 2 3 3 3 3 2 3 4 3 3 3 4

30 3 2 3 2 3 3 2 2 3 2 3 4 3 2 3 3 2 3 2 3 3 2 2 3 3 4 4 3

31 4 3 3 3 3 3 3 2 3 2 4 1 4 3 2 4 2 3 3 4 2 3 2 2 3 4 4 3

32 4 4 2 2 3 3 4 2 1 2 2 1 3 4 2 2 2 3 2 3 3 2 3 3 3 4 4 4

33 4 4 2 4 2 2 3 2 2 3 2 3 2 2 2 2 3 3 2 2 3 3 3 2 2 4 3 3

34 4 4 1 2 2 2 2 3 3 2 2 2 3 3 3 3 3 3 3 4 2 3 3 3 3 3 4 4

35 3 4 3 2 1 1 3 3 2 2 3 4 3 3 4 2 3 3 2 3 3 3 2 2 3 4 4 4

36 3 3 3 3 2 4 3 3 2 3 3 2 4 2 2 2 3 2 2 2 3 3 2 3 3 4 4 4

37 2 2 3 2 2 3 4 4 3 3 3 2 2 2 2 3 2 2 3 3 4 2 3 4 3 4 3 4

38 4 4 3 3 4 4 2 3 3 3 2 3 1 2 2 3 2 2 2 2 3 2 3 3 3 4 4 3

39 4 3 4 1 2 3 3 3 4 3 2 3 1 2 2 1 2 2 2 2 3 2 3 2 3 3 3 3

40 4 3 2 2 3 3 3 3 3 3 3 3 2 2 3 3 3 3 3 3 3 2 3 3 4 3 3 3

41 3 4 2 3 2 2 4 3 3 3 2 2 2 3 4 3 3 2 3 2 3 3 3 4 4 3 3 3

42 3 4 4 4 3 3 2 2 2 3 2 3 2 3 4 3 2 2 2 2 2 3 3 3 2 3 2 3

43 3 3 2 3 3 2 4 4 3 3 3 3 3 3 3 3 3 2 3 3 1 3 3 3 3 3 3 3

44 2 3 4 3 3 3 4 3 3 3 3 3 2 2 2 2 2 2 2 2 2 3 2 2 3 3 2 3

45 3 2 2 2 3 3 3 3 3 4 4 4 3 3 3 3 3 3 2 2 2 2 2 2 2 3 3 4

46 3 4 3 2 3 3 2 3 3 3 3 3 3 2 3 3 3 3 2 3 2 1 3 2 3 3 3 4

47 3 4 4 4 3 3 4 2 3 4 2 2 3 2 3 2 2 2 3 2 2 3 3 1 2 3 4 3

48 3 3 3 3 2 4 1 3 3 2 3 4 2 2 2 2 3 2 2 2 3 3 2 2 3 3 4 3

49 2 3 3 3 4 4 2 3 4 4 3 3 3 2 3 3 3 3 3 3 1 3 3 2 3 3 3 4

50 3 4 2 4 4 3 2 2 4 3 3 3 3 3 4 3 4 2 2 3 3 2 3 3 3 3 3 4

51 4 4 3 4 3 4 2 3 3 3 3 4 4 4 3 4 4 3 3 3 2 2 3 3 3 3 3 4

52 4 4 4 4 3 4 3 3 3 2 2 4 4 3 3 3 4 3 2 3 3 3 3 2 3 3 3 4

53 3 2 2 4 3 3 3 3 3 3 3 4 3 3 3 3 3 3 4 3 3 3 3 3 4 3 3 4

54 3 4 3 3 3 3 4 4 3 4 3 2 4 3 4 4 4 4 4 4 4 3 3 3 4 2 3 3

55 4 4 3 3 2 3 4 3 2 2 3 3 3 3 4 4 3 3 3 3 3 3 2 2 3 3 3 3

56 3 4 4 4 2 4 4 3 3 3 4 3 3 2 3 3 3 3 4 4 3 3 3 2 3 3 4 3

57 4 4 4 3 3 4 2 4 4 4 4 2 3 3 3 3 4 4 4 4 4 4 4 4 4 3 4 4

58 2 4 2 4 4 4 4 4 4 3 3 3 3 3 3 3 2 2 3 3 4 3 4 4 4 3 3 3

59 3 3 3 3 4 4 2 3 4 2 4 4 3 3 3 3 4 4 3 4 4 4 3 4 4 3 3 4

60 2 4 3 3 3 4 4 4 3 2 3 4 4 4 4 2 2 3 3 3 3 4 4 3 4 4 4 4

SLOTS

WEDGES

DISTRIBUTION

1-TIGHT 2- 1/3 LOOSE 3- 2/3 LOOSE 4- LOOSE 5- MOVES TOTAL

33 358 830 459 0 1680

2% 21% 49% 27% 0% 100%


TE Series Loop Cap Block/Ties

Removed


TE 100% Block and Tie (WET!!)


100% Block and Retie CE (WET!)


100% Rewedge Complete


100% Rewedge Complete (add

Flux Probe!)


2x1 7F Block Major

• 2x GE 7FH2 Turbine 1x

324 Generators

– Typical Ratings

– 4 Blocks at this site

• Operating Info

– 338X422, 23 &290Txxx

-


Planned Scope

Fall ’17 – 3 Unit Majors

• Upper endshields removed

• Field removed


– Including test the H2 seals on terminal studs



• Standard Testing – 2-3 shifts per unit

Unplanned

• Core Tightening – 3 Units

• Belly Band Tightening – 3 Units

• Wedge map performed, 100% rewedge required all three

• Core Iron repair – 1 Unit (Included adjacent bar removal)

• Field Rewind – 1 Unit

• Endwinding tightening and repairs – 3 Units


• Complete Rewedge on 324 STG (no time, budget left)


Large Utility 7FH2 Fleet

• GE 7FH2 Turbine

Generators

– 211-234MVA

– 23 units

• Operating Info

– Baseloaded

– 30,000-90,000 EOH

– 2.5-9.5% Start Factor

– 272 Avg Starts

• 94 LSL

• 804 USL

– 11 - 2x1 Combined

Cycle

– 12 - 1x Simple Cycle

– Peakers

– 12,279-54,885 EOH

– 48.1-64.8% Start Factor

– 1835 Avg Starts!!!

• 769 LSL

• 2707 USL



Baseload Combined Cycle Peaking Simple Cycle



Baseload Combined Cycle Peaking Simple Cycle

- Excellent Wedge Tightness Results

- Acceptable EL CID Results

- Pass Knife Check/Building Bolt

Torque

- Only Minor Greasing in Endwinding

- Overall Good Machine Health

- 3 Forced Outages Due to J-Straps

- J-strap Cracks ID’d in 2 inspections

- Slot Liner Delamination Discovered

- Pole/Pole and Coil/Coil Crossover

Deficiencies ID during J-strap repairs

- 2 Units required 2nd rewind due to

poor initial rewinds

- 5 Units required core tightenin

- Keybar Rattle Due to Loose Belly

Bands

- 100% Rewedges Required on All

- Connection Ring Dusting/Movement

- 4 Units Required Endwinding/Series

Connection Block and Retie



• Siemens TLRI Gas

Turbine Generator

– Mfg ~1997

– COD ~1998-99

• Rating Info

– 208 MVA

– 16 kV

– 7,500 Amps

– 48 Slots

– 2x1 Combined Cycle

– 3,600 RPM

– 326 V, 1023 Amps

(Field)

– TEWAC Air Cooled


2014 Inspections Showed no

EW Vibration!

2017 Phase to Phase Failure

due to EW Vibration!!!

- Full VPI Stator Rewind Req’d

- Sister unit had 11 series

connections with high

resistance

- Sister unit also rewound!!


Conclusions• Get your unit’s BASELINE Condition now. And fix it right the first

time (even if it means taking a MAJOR to do it)

• Then consider robotic inspections in lieu of field removal

• Significant changes (ie – increases) in operating duty warrant

shorter outage intervals

– Baseloaded or seldom run units may enjoy longer intervals

• Compared to prior outages, recent findings confirm that the most

involved repairs were due to cycling.

– EW loosening and insulation damage can result

– Core loosening, belly band loosening

– Monitor field main lead, Pole/Pole and Coil/Coil jumpers

– Ammort migration will block off cooling

• Some units (OEM, model, etc.) suffer common problems – Know

What They Are!!

unplanned generator repairs resulting from …...agtservices, inc. generating timely repair...

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