DGA - Method in the Past and for the Future
Page 2 May 2012
1970 1973 Doerenburg introduced the differentiation between electrical and thermal failure mode and introduced ratios for fault gases with similar solubility. Halstead developed the theoretical thermodynamic theory. The ratios are temperature dependent. With increasing the hotspot the amount of gases increases in the order: methane-ethane-ethylene. 1975 The evaluation scheme of the modern Gas-in-Oil Analysis is developed by Rogers, Mueller, Schliesing, Soldner (MSS). 1995 Development of In-Line Monitoring Page 3 May 2012
Different phenomena in oil take place like: dielectric thermal dynamic Change/Ageing chemical! Gas-in-Oil Analysis (DGA = Dissolved Gas Analysis) Page 4 May 2012
The measurement of dissolved gases allow the knowledge on! Type! Complexity! Seriousness of event Page 5 May 2012
Sampling Page 6 May 2012
Sampling Container! Perfectly cleaned & Dried! Free from dust & moisture! Airtight! Glass or Metal cans, syringes Page 7 May 2012
! Protect sample from direct light! Avoid moisture & dust contamination! Use the sampling containers exclusively for transformer oil sampling Page 8 May 2012
1 Handwheel 2 Sealing cap 3 Safety chain 4 Polyamid gasket 5 Nut 6 Drain valve 7 Hose and screw connector 8 Sampling bottle 9 Overflow vessel Page 9 May 2012
Page 10 May 2012
Requested analysis: Required information concerning oil sample(example) Colour ISO 2049 Appearance IEC 60422 Neutralisation value IEC 62021-1 Breakdown voltage IEC 60156 Water content IEC 60814 Loss factor at 50 Hz IEC 60247 Interfacial tension ISO 6295 PCB-content EN 12766-2 Furananalysis (DGA) IEC 61198 Gas-in-oil-analysis IEC 60567 Please fill in the following data: Manufacturer: Customer: Location: Year of manufacture: Type: Power: Rating: FTNR (Manufacturing No.): WNR (Order No.): Sample No.: Date sample taken.: Type of oil Quantity of oil: Oil temperature in the sample taken: Sample taken from: Oil sample valve Oil drainage device Others A 22/31/40 DIN 42 551 Tank: Top Middle Bottom conservator Transformer OLTC Bushing OLTC Bushing Others: Reason for sample taking: OLTC tank Date of operation fault: Date of repair : Date of oil treatment/reclaiming Routine checkup: Further informations and previous history: Sample taker: Date Name in block letters Company/ Department Phone Page 11 May 2012 Lab information: Consecutive no.: Date sample received: Date sample analysed: Type of sample container: special features:
Extraction of Gases from the Oil Page 12 May 2012
DGA. Toepler Pump Page 13 May 2012
DGA. Partial Degassing Page 14 May 2012
DGA. Headspace at Ambient Temperature Page 15 May 2012
DGA. Headspace at 70 C Page 16 May 2012
Gaschromatographic Analysis Page 17 May 2012
Gaschromatographic Analysis Sample injection Detector Carrier Gas Detector gas Page 18 May 2012
Failures which can be identified by DGA! Partial discharges! Electrical discharges! Charcoal coating of contacts! Accelerated cellulosic degradation! Local overheating! Untightness of OLTC tank! Catalytic reactions of materials! Additional information from BHR gas Page 19 May 2012
Failures which can not be identified by DGA! Incipient Failures! Long lasting temperatures < 150 C Page 20 May 2012
Interpretation Schemes Page 21 May 2012
Duvals Triangle Page 22 May 2012
Patterns Electrical Discharges Thermal Problem Partial Discharges Page 23 May 2012
MSS Scheme Ratio ranges Ratio numbers [C 2 H 2 ] [H 2 ] [C 2 H 4 ] [C 2 H 4 ] [C 2 H 6 ] [CH 4 ] [C 2 H 6 ] [C 3 H 6 ] <0.3 0 0 0 0 0.3 to < 1.0 1 0 0 1 1.0 to < 3.0 1 1 1 2 3.0 to < 10.0 2 2 1 3! 10.0 2 3 1 3 Diagnosis Number sequences Normal ageing of insultans 0 0 0 0 Discharge of high energy 2 1 1 2/3 Discharge of low energy 2 2 1 2/3 Partial discharge with high energy 1 3 0 n.i. Partial discharge with low energy 1 3 0 n.i. Local overheating up to 300 ºC 0 0 0 1 Local overheating from 300 ºC to 1000 ºC 0 0 1 2 Local overheating over 1000 ºC 1 0 1 2/3 Local overheating and discharge 1 1 1 2 Local overheating and partial discharge 0 3 1 2 n.i. = not indicative Page 24 May 2012 [CO 2 ] [CO] 1 1 1 0 2 0 1 1 0 0 2 2 2 2 2
IEC Scheme Page 25 May 2012
In case of quotient information it must be clear, that quotients are only representative, if following values of the fault gases (in ppm) are exceeded: C 2 H 2! 1 H 2! 15 " [CXHY] x=1;2;3! 50 CO! 80 CO 2! 200 Page 26 May 2012
DGA Example thermal Problem MSS-Code 00120 Fault gas Hydrogen Methane Ethane Ethylene Acetylene Propane Propylene Carbon monoxide Carbon dioxide Oxygen Nitrogen H 2 CH 4 C 2 H 6 C 2 H 4 C 2 H 2 C 3 H 8 C 3 H 6 CO CO 2 O 2 N 2 ppm 1967 8008 2013 8323 57 401 4824 253 1903 18222 61662 Page 27 May 2012
MSS-Code 00120 Manufacturing year 1970 Fault gas ppm 360 MVA Carbon deposits on PLTC Contacts Hydrogen 537 Methane Ethane Ethylene Acetylene Propane Propylene Carbon monoxide Carbon dioxide Oxygen Nitrogen H 2 CH 4 C 2 H 6 C 2 H 4 C 2 H 2 C 3 H 8 C 3 H 6 CO CO 2 O 2 N 2 1041 295 1726 25 83 1012 1047 6158 11805 58084 Page 28 May 2012
Gas-in-Oil Analysis Turn-to-Turn Fa MSS-Code 21121 Fault gas Hydrogen Methane Ethane Ethylene Acetylene Propane Propylene Carbon monoxide Carbon dioxide Oxygen Nitrogen H 2 CH 4 C 2 H 6 C 2 H 4 C 2 H 2 C 3 H 8 C 3 H 6 CO CO 2 O 2 N 2 ppm 4973 1758 243 2813 8236 58 1320 1196 2431 6743 44120 Page 29 May 2012
DGA Thermal Problem with Partial Discharges MSS-Code 00101 Manufacturing year 1991 Fault gas ppm 234 MVA, 330 kv Defective welding joint Hydrogen 1060 Methane Ethane Ethylene Acetylene Carbon monoxide Carbon dioxide H 2 CH 4 C 2 H 6 C 2 H 4 C 2 H 2 CO CO 2 2481 703 2187 4 450 995 Page 30 May 2012
DGA Catalytical Effects MSS-Code?3??0 Manufacturing year 1977 Fault gas ppm Closed type Color 0,5 / Acidity 0,01 Hydrogen 488 Methane Ethane Ethylene Acetylene Propane Propylene Carbon monoxide Carbon dioxide Oxygen Nitrogen H 2 CH 4 C 2 H 6 C 2 H 4 C 2 H 2 C 3 H 8 C 3 H 6 CO CO 2 O 2 N 2 1 < 1 < 1 < 1 < 1 < 1 67 222 5180 23700 Page 31 May 2012
DGA Untight OLTC MSS-Code 22122 Fault gas Hydrogen Methane Ethane Ethylene Acetylene Propane Propylene Carbon monoxide Carbon dioxide Oxygen Nitrogen H 2 CH 4 C 2 H 6 C 2 H 4 C 2 H 2 C 3 H 8 C 3 H 6 CO CO 2 O 2 N 2 ppm 128 25 5 81 288 5 50 143 1920 24600 52000 Page 32 May 2012
DGA Diagnostic Importance in Service Ratios Gas increase rates Absolute Values Trend Page 33 May 2012
Absolute Values IEC 60599 (VDE 0370-7) C 2 H 2 H 2 CH 4 C 2 H 4 C 2 H 6 CO CO 2 All transformers 50 " 150 30 " 130 60 " 280 20 " 90 400 " 600 2800 " 14000 No OLTC 2 " 20 Communicating OLTC 60 " 280 Page 34 May 2012
Ratios a) Eliminates the effect of the oil volume b) Eliminates some effects of sampling c) Especially interesting is the ratio formation for fault gases which exhibit similar solubilities, but their development is temperature dependent e. g. the thermodynamic considerations of Halstead. Page 35 May 2012
Thermodynamcal considerations of Halstead Page 36 May 2012
Gas Increase Rates information on seriousness of failure C 2 H 2 H 2 CH 4 C 2 H 4 C 2 H 6 CO CO 2 All transformers 0,01 0,36 0,33 0,40 0,25 2,9 27! 90% gas increase source: Cigre TF11 in ppm/day Gas increase rates are temperature and volume dependent Page 37 May 2012
Trend Analysis Development of the Fault Gases After Two Months of On-Line Monitoring 600 100 90 ppm CO 2 500 400 300 200 100 80 70 60 50 40 30 20 ppm H 2, CO,CH 4, C2H 4, C 2 H6, top oil ( C) Carbon Dioxide Hydrogen Methane Carbon Monoxide Ethane Ethylene top oil temp C 10 0 0 1.7.08 11.7.08 21.7.08 31.7.08 10.8.08 20.8.08 30.8.08 9.9.08 Sampling date Page 38 May 2012
Trend Analysis 40 6 35 5 30 top oil ( C) 25 20 15 4 3 2 Ratio C 2 H 4 /C 2 H 6, CH 4 /H 2 Top C2H CH 40 6 10 35 5 5 1 top oil ( C) 30 25 20 15 0 0 4 1.7.08 11.7.08 21.7.08 31.7.08 10.8.08 20.8.08 30.8.08 9.9.08 Sampling date Top oil Temperature ( C) Ratio C 2 H 4 /C 2 H 6, CH 4 /H 2 3 C2H4/C2H6 CH4/H2 2 1 5! Trendanalysis is important not only with absolute values, Page 39 May 2012 10 but also with the ratios. 0 0 1.7.08 11.7.08 21.7.08 31.7.08 10.8.08 20.8.08 30.8.08 9.9.08 Sampling date
On-Line Monitoring # Early failure recognition # Diagnosis is only possible with the sofisticated types where IEC ratios can be built Cigre TF 15 DGA did a comparison between On-Line monitoring systems and Off-Line analyses. The brochure is on the way. Evaluated are: " Precision " Longterm stability " Repeatability In case of " Routine concentrations, d.h. 5 * Detection Limit " Low Concentrations, d. h. 2-5*Detection Limit Page 40 May 2012
Recommendation of Cigre A2.27 for On-LineMonitoring # Necessary in case a problem has been identified # Often, however, difficult to maintain # Interfaces can lead to problems # Able to deliver important information in a short time # Does not automatically lead to higher reliability Page 41 May 2012
What can be measured on-line:! Temperature! Current, Voltage! OLTC! Oil level! Gas-in-Öl Analysis! Humidity in oil! Bushings! Acoustic Signals! Magnetic Circuit! Coolers Page 42 May 2012
More Data does not mean automatically more Information Data Explosion 1) (Total Exabytes) 200 150 100 50 0 2002 2003 2004 2005 2006 2007 1) Exa = 1016 = 10 Mil of Billions Page 43 May 2012
Transformer Failure Rate $ Failure rate Failure at Comissioning Failure because of aging Constant failure rate Aging / years % Page 44 May 2012
Future Developments # Further development of the On-Line analysis with decision criteria # Gas-in-oil analysis in OLTC # Gas-in-oil analysis in alternative insulation fluids and high temperature insulating materials Page 45 May 2012
Thank you for your attention!