Annual DGA Review. MEA Electric Operations Roundtable May 13-15, 2015 Springfield, IL

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1 Annual DGA Review MEA Electric Operations Roundtable May 13-15, 2015 Springfield, IL

2 BGS GSU Moloney 161/19kV GSU, 200MVA Manufactured in 1967 Retrofilled with Natural Ester Fluid, FR3, on 3/27/2004 Gases Monitored Through Semi-Annual Samples Sent to Lab Serveron TM8 On-Line Gas Monitor Installed in October /20/2015 2

3 BGS GSU Minimal Gassing in Transformer per DGA Samples 5/20/2015 3

4 BGS GSU On Line Monitor Took Samples Every 4 Hours No Methane, Ethylene or Acetylene Identified in 2 Years Hydrogen at Less than 5ppm Would be Periodically Recorded Ethane Was Typically Less than 15ppm 5/20/2015 4

5 BGS GSU During a Plant Maintenance Outage, the DETC Position Changed from Tap 3 to 4 After Plant Started Up, Began Seeing Gassing in On-Line Monitor Results There was a Correlation Between Gassing and Load Inspection Revealed that the DETC was Operating Between Taps 3 and 4 5/20/2015 5

6 BGS GSU Monitored Gas Increases Using On Line Monitor for Several Days Methane is generated at Temperatures of C, Ethylene at 300 C C and Acetylene at greater than 700 C 5/20/2015 6

7 BGS GSU Took Oil Sample and Sent to Lab to Confirm Data 5/20/2015 7

8 BGS GSU Performed Various Electrical Tests to Determine Condition of Transformer: Power Factor, Exciting Current, Sweep Frequency Response, TTR and Winding Resistance SFRA, Power Factor, TTR and Winding Resistance indicated Winding Movement/Deformation and Overheated Insulation 5/20/2015 8

9 BGS GSU Visual Inspection Showed DETC Gears were Gummed Up due to Old Oil. Smaller Gear was Rusted Away No Solid Connection Between Copper Contacts in DETC Caused Extreme Temperatures and Arcing of the Contacts and the Leads Would Have Eventually Resulted in Transformer Failure 5/20/2015 9

10 BGS GSU 5/20/

11 BGS GSU Flywheel with Old Grease 5/20/

12 BGS GSU Rusted Gear 5/20/

13 BGS GSU DETC Uneven Contact Wear Marks B Phase (Bottom), C Phase (Top) 5/20/

14 BGS GSU Burnt Paper Covering on Center Phase Coil 5/20/

15 BGS GSU Deformation of LV B Phase--Buckling 5/20/

16 Anamosa Plant LTC 34.5/12.5kV, 5/7 MVA Rewound by SW Electric in 1985 LTC is TLS Model, Sealed Unit Reversed Ethylene-to-Acetylene Ratio Opened in 2012, no Problems with Contacts Noted New Oil Installed and Transformer Returned to Service 5/20/

17 Anamosa Plant LTC Significant Increase in Gases Between July 2013 and November 2014 Samples 5/20/

18 Anamosa Plant LTC 5/20/

19 Anamosa Plant LTC Burning on A Phase Collector Ring 5/20/

20 Anamosa Plant LTC Burnt Lead on Opposite Side of Board Only held by a couple of strands of wire Stud Through A Phase Board 5/20/

21 Anamosa Plant LTC 5/20/

22 Anamosa Plant LTC Stud burned about halfway through A phase board 5/20/

23 Anamosa Plant LTC Stud on B Phase Board 5/20/

24 LTC Statistical Analysis Performed a Statistical Analysis of Individual Gases by LTC Model Hydrogen, Methane, Ethane, Ethylene and Acetylene Created Three Different Comparisons Data from all historical samples One Sample for each LTC One Sample for each LTC, but Eliminated Individual Gas if it was Greater than 5000ppm 5/20/

25 LTC Statistical Analysis 5/20/

26 LTC Statistical Analysis 5/20/

27 LTC Statistical Analysis 5/20/

28 LTC Statistical Analysis 5/20/

29 Genencor LTC 69/12.5kV, 16/24 MVA Transformer LTC is a McGraw Edison 550B Manufactured in 1990 Infrared Showed LTC 11 C Warmer Than Main Tank Oil Sample Had Very Strong Odor LTC Had Only Gone Through Neutral Once in 14 Years 5/20/

30 Genencor LTC No Heating Reported in 2013 LTC Compared to Main Tank as Reference Main Tank Temperature = 31C LTC Temperature = 42C 5/20/

31 Genencor LTC Ethylene to Acetylene Ratio Reversed in October 2013 There was a Significant Increase in Gases in /20/

32 Genencor LTC Coking was Found on C Phase Reversing Switch Many of the Arcing Contacts Showed Wear/Erosion Found Warped Barrier Board Installed a Complete Rebuilt LTC Moved DETC to Ensure LTC Goes Through Neutral in the Future 5/20/

33 Genencor LTC 5/20/

34 Genencor LTC 5/20/

35 Genencor LTC 5/20/

36 Genencor LTC DGA Taken Shortly After Transformer was Returned to Service 5/20/

37 Alden LTC 34.5/4.16kV, 2.5/3.5 MVA GE Transformer LTC is an LRT72 Gas Levels Fairly Typical for this Model LTC, except Hydrogen - Disproportionately High Compared to Other Gases Particle Levels Increased Significantly Moisture/Acid Number - Always Elevated 5/20/

38 Alden LTC Acetylene Level Should Always Be Highest in Arcing Style Tap Changer 5/20/

39 Alden LTC Smallest Particles Increased by a Factor of 10 Between 2012 and 2013 Samples Other Particle Sizes Increased by Over 100 Times 5/20/

40 Alden LTC Acid Number is Extremely High Our Lab Recommends as the Upper Limit for Acid Number in Service Aged Oil, Regardless of Type of Equipment 5/20/

41 Alden LTC 5/20/

42 Alden LTC 5/20/

43 Alden LTC 5/20/

44 Alden LTC 5/20/

45 Alden LTC 5/20/

46 Alden LTC 5/20/

47 Alden LTC 5/20/