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Doerenburg introduced the differentiation between electricaland thermal failure mode and introduced ratios for fault gaseswith similar solubility.
Halstead developed the theoretical thermodynamic theory. The ratiosare temperature dependent. With increasing the hotspot the amountof gases increases in the order: methane-ethane-ethylene.
The evaluation scheme of the modern Gas-in-Oil Analysis isdeveloped by Rogers, Mueller, Schliesing, Soldner (MSS).
Development of In-Line Monitoring
1970
1973
1975
1995
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Change/Ageing
Different phenomena in oil take place like:
dielectric
thermal
dynamic
chemical
! Gas-in-Oil Analysis (DGA = Dissolved Gas Analysis)
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! Type
! Complexity
! Seriousness
The measurement of dissolved gasesallow the knowledge on
of event
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! Perfectly cleaned & Dried
! Free from dust & moisture
! Airtight
! Glass or Metal cans, syringes
Sampling Container
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! Protect sample from direct light
! Avoid moisture & dust contamination
! Use the sampling containers exclusivelyfor transformer oil sampling
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1 Handwheel2 Sealing cap3 Safety chain4 Polyamid gasket5 Nut6 Drain valve7 Hose and screw connector8 Sampling bottle9 Overflow vessel
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Required information concerning oil sample(example)Requested analysis: 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: FTNR (Manufacturing No.):
Customer: WNR (Order No.):
Location: Sample No.:
Year of manufacture: Date sample taken.:
Type: Type of oil
Power: Quantity of oil:
Rating: Oil temperature in the sample taken:
Sample taken from: Oil sample valve Oil drainage device OthersA 22/31/40 DIN 42 551
Tank: Top Middle Bottom
conservator Transformer OLTC Bushing
OLTC OLTC tank
Bushing
Others:
Reason for sample taking:
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
Lab information: special features:
Consecutive no.:Date sample received:Date sample analysed:Type of sample container:
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DGA. Headspace at Ambient Temperature
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Gaschromatographic Analysis
CarrierGas
Detector
Detectorgas
Sampleinjection
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! 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
Failures which can be identified by DGA
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! Incipient Failures
! Long lasting temperatures < 150 °C
Failures which can not be identified by DGA
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Patterns
Partial DischargesElectrical Discharges Thermal Problem
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MSS Scheme
22130Local overheating and partial discharge22111Local overheating and discharge22/3101Local overheating over 1000 ºC22100Local overheating from 300 ºC to 1000 ºC21000Local overheating up to 300 ºC0n.i.031Partial discharge with low energy0n.i.031Partial discharge with high energy12/3122Discharge of low energy12/3112Discharge of high energy00000Normal ageing of insultans
Number sequencesDiagnosis23132! 10.0031223.0 to < 10.0121111.0 to < 3.0110010.3 to < 1.010000<0.3
[CO2][CO]
[C2H4][C3H6]
[C2H4][C2H6]
[H2][CH4]
[C2H2][C2H6]
Ratio numbersRatio ranges
n.i. = not indicative
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In case of quotient information it must be clear, that quotientsare only representative, if following values of the fault gases(in ppm) are exceeded:
C2H2 ! 1
H2 ! 15
" [CXHY] x=1;2;3 ! 50
CO ! 80
CO2 ! 200
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MSS-Code 00120
N2
O2
CO2
COC3H6
C3H8
C2H2
C2H4
C2H6
CH4
H2
61662Nitrogen18222Oxygen1903Carbon dioxide
253Carbon monoxide4824Propylene
401Propane57Acetylene
8323Ethylene2013Ethane8008Methane1967Hydrogen
ppmFault gas
DGAExample – thermal Problem
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N2
O2
CO2
COC3H6
C3H8
C2H2
C2H4
C2H6
CH4
H2
58084Nitrogen11805Oxygen6158Carbon dioxide1047Carbon monoxide1012Propylene
83Propane25Acetylene
1726Ethylene295Ethane
1041Methane537Hydrogen
ppmFault gas
MSS-Code 00120 Manufacturing year 1970360 MVACarbon deposits on PLTC Contacts
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N2
O2
CO2
COC3H6
C3H8
C2H2
C2H4
C2H6
CH4
H2
44120Nitrogen6743Oxygen2431Carbon dioxide1196Carbon monoxide1320Propylene
58Propane8236Acetylene2813Ethylene
243Ethane1758Methane4973Hydrogen
ppmFault gas
Gas-in-Oil AnalysisTurn-to-Turn Fa
MSS-Code 21121
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CO2
COC2H2
C2H4
C2H6
CH4
H2
995Carbon dioxide450Carbon monoxide
4Acetylene2187Ethylene
703Ethane2481Methane1060Hydrogen
ppmFault gas
DGAThermal Problem with Partial Discharges
MSS-Code 00101 Manufacturing year 1991234 MVA, 330 kVDefective welding joint
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N2
O2
CO2
COC3H6
C3H8
C2H2
C2H4
C2H6
CH4
H2
23700Nitrogen5180Oxygen
222Carbon dioxide67Carbon monoxide
< 1Propylene< 1Propane< 1Acetylene< 1Ethylene< 1Ethane
1Methane488Hydrogen
ppmFault gas
DGACatalytical Effects
MSS-Code ?3??0 Manufacturing year 1977Closed type Color 0,5 / Acidity 0,01
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N2
O2
CO2
COC3H6
C3H8
C2H2
C2H4
C2H6
CH4
H2
52000Nitrogen24600Oxygen
1920Carbon dioxide143Carbon monoxide50Propylene
5Propane288Acetylene81Ethylene
5Ethane25Methane
128HydrogenppmFault gas
DGAUntight OLTC
MSS-Code 22122
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Ratios
Absolute Values
Gas increase
rates
Trend
DGADiagnostic Importance in Service
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IEC 60599 (VDE 0370-7)
60"
280
CommunicatingOLTC
2"20
No OLTC
2800"
14000
400"
600
20"90
60"
280
30"
130
50"
150All transformers
CO2COC2H6C2H4CH4H2C2H2
Absolute Values
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a) Eliminates the effect of the oil volume
b) Eliminates some effects of sampling
c) Especially interesting is the ratio formation for faultgases which exhibit similar solubilities, but theirdevelopment is temperature dependent –e. g. the thermodynamic considerations of Halstead.
Ratios
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Thermodynamcal considerations of Halstead
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272,90,250,400,330,360,01Alltransformers
CO2COC2H6C2H4CH4H2C2H2
Gas Increase Rates –information on seriousness of failure
! 90% gas increase source: Cigre TF11 in ppm/dayGas increase rates are temperature and volume dependent
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0
100
200
300
400
500
600
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
ppm
CO
2
0
10
20
30
40
50
60
70
80
90
100
ppm
H2,
CO
,CH
4, C
2H
4, C
2H
6, to
p oi
l (°C
)
Carbon Dioxide
Hydrogen
Methane
Carbon Monoxide
Ethane
Ethylene
top oil temp °C
Development of the Fault Gases After Two Months of On-Line Monitoring
Trend Analysis
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0
5
10
15
20
25
30
35
40
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 (
°C)
0
1
2
3
4
5
6
Rat
io C
2H4/C
2H6,
CH
4/H
2
Top oil Temperature (°C)
C2H4/C2H6
CH4/H2
0
5
10
15
20
25
30
35
40
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 (
°C)
0
1
2
3
4
5
6
Rat
io C
2H4/C
2H6,
CH
4/H
2
Top oil Temperature (°C)
C2H4/C2H6
CH4/H2
! Trendanalysis is important not only with absolute values,but also with the ratios.
Trend Analysis
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# 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 monitoringsystems and Off-Line analyses. The brochure is on the way.Evaluated are:" Precision" Longterm stability" RepeatabilityIn case of" Routine concentrations, d.h. 5 * Detection Limit" Low Concentrations, d. h. 2-5*Detection Limit
On-Line Monitoring
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# Necessary in case a problem has been identified
# Often, however, difficult to maintain
# Interfaces can lead to problems
# Able to deliver important informationin a short time
# Does not automatically lead to higher reliability
Recommendation of Cigre A2.27for On-LineMonitoring
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! Temperature
! Current, Voltage
! OLTC
! Oil level
! Gas-in-Öl Analysis
! Humidity in oil
! Bushings
! Acoustic Signals
! Magnetic Circuit
! Coolers
What can be measured on-line:
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More Data does not mean automaticallymore Information
Data Explosion1) (Total Exabytes)
1) Exa = 1016 = 10 Mil of Billions
2002 2003 2004 2005 2006 2007
200
0
50
100
150
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Transformer Failure Rate
Failure atComissioning
Constant failure rate
Failure becauseof aging
$ Failure rate
Aging / years %
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# Further development of the On-Line analysiswith decision criteria
# Gas-in-oil analysis in OLTC
# Gas-in-oil analysis in alternative insulation fluidsand high temperature insulating materials
Future Developments