4 Prevost Oil Analysis
Transcript of 4 Prevost Oil Analysis
-
8/12/2019 4 Prevost Oil Analysis
1/42
31 October 2013
Oil Analysis An Important Tool for Transformer Diagnosis
Conference on Electrical Power Equipment Diagnostics
Bali, Indonesia
Thomas Prevost
-
8/12/2019 4 Prevost Oil Analysis
2/42
Oil Analysis
Study and test the oil to determine
the condition of overall insulation
system
1. Dissolved Gas Analysis DGA
2. Oil Quality
3. Furans
Page 2 OMICRON
-
8/12/2019 4 Prevost Oil Analysis
3/42
-
8/12/2019 4 Prevost Oil Analysis
4/42
Source of Gas Byproducts of Faults
Oil
Hydrogen
Hydrocarbons
Cellulose
Carbon Oxides
Water
Page 4 OMICRON
-
8/12/2019 4 Prevost Oil Analysis
5/42
-
8/12/2019 4 Prevost Oil Analysis
6/42
OMICRON
Page 6
Degradation of cellulose
O
H
O
HO
H
OH
OH
O
H H
CH2O
CH2OH
H
O
HH
O
OH
H
Heating
Heating
C O O C O
O
H H
Carbon Monoxide Carbon Dioxide
Water
Section of
Cellulose
Molecule
-
8/12/2019 4 Prevost Oil Analysis
7/42
DGA Analysis
1. Fault Gas Levels
2. Rate of Gas Generation (Trend)
3. Ratio of Gas Levels
Page 7 OMICRON
-
8/12/2019 4 Prevost Oil Analysis
8/42
OMICRON
Page 8
Gases reported:
Fault Gases
Methane CH4 Ethane C2H6
Ethylene C2H4Acetylene C2H2
Carbon Monoxide CO
Carbon Dioxide CO2
Atmospheric Gases
Nitrogen N2
Oxygen O2
-
8/12/2019 4 Prevost Oil Analysis
9/42
OMICRON
Page 9
Thermal Faults:
Normal Operating Temperature:
Carbon Monoxide CO
Carbon Dioxide CO2
150 C 500 C:
150-250 C : Relatively large quantities of low molecular
weight hydrocarbons
Hydrogen H2 Methane CH4
250-350 C : Increasing hydrogen relative to methane
Ethane C2H6
350-500 C : Still increasing hydrogen and ethylene
Ethylene C2H4
Sources of Fault Gases in Transformers
-
8/12/2019 4 Prevost Oil Analysis
10/42
OMICRON
Page 10
Electrical Faults:
Partial Discharges:
Oil: HydrogenCellulose: Hydrogen, Carbon Monoxide
Arcing:
Oil: Acetylene, Hydrogen
Sources of Fault Gases in Transformers
-
8/12/2019 4 Prevost Oil Analysis
11/42
OMICRON
Page 11
Gas Generation(Not to Scale)
Approximate Oil Decomposition
Temperature above 150oC
IEEE and IEC Codes to Interpret Incipient Faults in Transformers, Using Gas in Oil Analysis,
by R.R. Rogers C.E.G.B, Transmission Division, Guilford, England. Circa 1978.
Partial Discharge (Not TemperatureDependent)
Range of Normal OperationHot Spots
(Of increasingtemperature)
Arcing Conditions
65o
150
o
200o
300o
800o
700o
500o
350o
250o
Hydrogen (H2)
Methane
(CH4)
Ethane (C2H6)
Ethylene (C2H
4)
Acetylene (C2H2)
CH4>H2
C2H6>CH4
C2H4>C2H6
C2H2>10% of C2H4
Trace
Combustible Gas Generation vs.
Approximate Oil Decomposition Temperature
-
8/12/2019 4 Prevost Oil Analysis
12/42
DGA Diagnostic Methodology
1. Determine if DGA results are Normal1. Single sample compare results to C57.104-2008 Table 1
2. If greater than condition 1 then retest sample within two months1. Verifies results from first test
2. Establishes gas generation rate
3. Greater than one sample
1. Calculate gas generation rate2. Compare rate to values in C57.104-2008 Table 3
1. Sampling interval
2. Action
2. If DGA results are abnormal then follow various methodologies todetermine fault type and possible cause.1. Key gas
2. Gas ratios
Page 12 OMICRON
-
8/12/2019 4 Prevost Oil Analysis
13/42
OMICRON
Page 13
Dissolved Key Gas Concentration Limits (L/L
(ppm))
StatusH2
HydrogenCH4
MethaneC2H2
AcetyleneC2H4
EthyleneC2H6
Ethane
CO
CarbonMonoxide
CO2
CarbonDioxide TDCGb
Condition 1 100 120 1 50 65 350 2500 720
Condition 2 101-700 121-400 2-9 51-100 66-100 351-570 2500-4000 721-1920
Condition 3 701-1800 401-1000 10-35 101-200 101-150 571-1400 4001-10000
1921-4630
Condition 4 >1800 >1000 >35 >200 >150 >1400 >10000 >4630
IEEE C57.104-2008 Table 1
-
8/12/2019 4 Prevost Oil Analysis
14/42
OMICRON
Page 14
TDCG
Levels(L/L)
TDCG Rate
(L/L/day)
Sampling Intervals and Operating Procedures for Gas
Generation Rates
SamplingInterval Operating Procedures
Condition 4 >4630 >30 Daily Consider removal from service.
Advise manufacturer10-30 Daily
30 Weekly Exercise extreme caution.
Analyze for individual gases.
Plan outage.
Advise manufacturer.
10-30 Weekly
30 Monthly Exercise caution.
Analyze for individual gases.
Determine load dependence.10-30 Monthly
30 Monthly Exercise caution.
Analyze for individual gases.
Determine load dependence.
10-30 Quarterly Continue normal operation.
-
8/12/2019 4 Prevost Oil Analysis
15/4215
Factors influencing the interpretation of results:
Type of faults:
-PD: partial discharges of the corona-type.
-D1: discharges of low energy.
-D2: discharges of high energy.
-T1: thermal fault (T < 300C).
-T2: thermal fault (300 C < T < 700C).
-T3: thermal fault (T > 700C).
-DT: mixtures of discharges and thermal faults.
-S: stray gassing of oil (T < 200 C), catalytic reactions (notrelated to faults).
-
8/12/2019 4 Prevost Oil Analysis
16/4216
Typical faults in the equipment:
-PD: corona partial discharges in voids or gas bubbles(poor drying, impregnation).
-D1: partial discharges of the sparking type, tracking in
paper, small arcing, arc breaking in LTC oil.
-D2: short circuits with power follow-through, flashovers,
tripping, gas alarms; extensive damage, metal fusion.
-
8/12/2019 4 Prevost Oil Analysis
17/4217
Typical faults in the equipment:
-T3: large circulating currents, shorts in laminations,carbon particles in oil.
-T2: circulating currents, defective contacts,
carbonization of paper.
-T1: overloading, insufficient cooling.
-S: stray gassing , catalytic reactions on wet metal
surfaces.
-
8/12/2019 4 Prevost Oil Analysis
18/4218
Mixtures of faults
-mixtures of faults sometimes occur rather than pure faults and may be more difficult to identify with certainty.
-for instance, mixtures of faults D1 and T3 may appear
as faults D2 in terms of gas formation.
-
8/12/2019 4 Prevost Oil Analysis
19/4219
Energy/ temperature required to produce gases:
-Low energy/temperature: H2, CH4, C2H6, CO, CO2.
-High temperature: C2H4.
-Very high temperature/energy: C2H2.
-In practice, always mixtures of gases are formed.
-
8/12/2019 4 Prevost Oil Analysis
20/4220
Fault identification methods
-Key gas
-Rogers
-Duval Triangle
-CO and CO2(paper involvement in faults)
-O2/N2 (hot spots, membrane leaks)
-C2H2/H2(OLTC leaks)
-
8/12/2019 4 Prevost Oil Analysis
21/42
OMICRON
Page 21
Oil
Cellulose
Hydrogen
Carbon Monoxide, Carbon Dioxide
Partial Discharge
Oil Low Temperature Hydrogen, Methane, Ethane
High Temperature Hydrogen, Ethylene, Methane, Ethane
Cellulose Low Temperature Carbon Dioxide
High Temperature Carbon Monoxide, Carbon Dioxide
Pyrolysis
(Acetylene is most significant)
Hydrogen, Acetylene, Methane, Ethane, Ethane, Ethylene
Arcing
IEEE C57.104-2008 Key Fault Gases
-
8/12/2019 4 Prevost Oil Analysis
22/42
Possible Faults
-
8/12/2019 4 Prevost Oil Analysis
23/42
Possible Reasons
-
8/12/2019 4 Prevost Oil Analysis
24/42
Rogers Ratio
-
8/12/2019 4 Prevost Oil Analysis
25/42
DGA Diagnosis (Duval)
-
8/12/2019 4 Prevost Oil Analysis
26/42
OMICRON
Page 26
Oil Quality Tests
Tests the condition of the insulating fluid.
Use results for maintenance action No action
Recondition
Reclaim
Replace Use the results to access the condition of the
Insulation System
Dielectric Strength
Power Factor
Moisture Acid
Furans
-
8/12/2019 4 Prevost Oil Analysis
27/42
OMICRON
Page 27
Oil Quality Tests
Several standards are referenced for oil quality testsand result interpretation:
IEC 60422 Mineral Insulating Oil in Electrical Equipment
Supervision and Maintenance Guide
IEEE Guides
C57.106-2006 Guide for Acceptance and Maintenance of
Insulating Oil in Equipment
C57.152 IEEE Guide for Diagnostic Field Testing of FluidFilled Power Transformers, Regulators, and Reactors
-
8/12/2019 4 Prevost Oil Analysis
28/42
Dielectric, Physical and
Chemical Analysis
Dielectric measurementsBreak down voltage ASTM D 877
Break down voltage ASTM D 1816 IEC 60156Power factor ASTM D 924 IEC 60247 Physical propertiesInterfacial tension ASTM D 971 EN 14210
Particle Count ASTM D 6786 IEC 60970Sludge ASTM D 1698
Water content ASTM D 1533 IEC 60814Visual ASTM D 1500 ISO 2049
Specific gravity ASTM D 1298 ISO 3675Color (lab) ASTM D 1500 ISO 2049Color (field) ASTM D 1524Chemical propertiesPolychlorinated biphenyl ASTM D 4059 IEC 61619Acidity ASTM D 974 IEC 62021
Dissolved gas ASTM D 3612 IEC 60599
-
8/12/2019 4 Prevost Oil Analysis
29/42
OMICRON
Page 29
IEEE Oil Classifications
Class I This group contains oils that are in satisfactory
condition for continued use.
Class II This group contains oils that do not meet the
dielectric strength and/or water content requirement of Table 5 andshould be reconditioned by filter pressing or vacuum dehydration.
Class III This group contains oils in poor condition that should
be reclaimed using Fullers earth or an equivelent method. Oils that
do not meet the interfacial tension (IFT), dissipation factor, and
neutralization number limits provided in table 5 should be reclaimed.
-
8/12/2019 4 Prevost Oil Analysis
30/42
OMICRON
Page 30
IEEE C57.106-2006 Suggested Limits
If limits for:
IFT
Dissipation Factor
Acidity
are exceeded theoil should be
reclaimed
otherwise the oil
can be
reconditioned if the
limits areexceeded.
-
8/12/2019 4 Prevost Oil Analysis
31/42
OMICRON
Page 31
Moisture Content
Karl Fisher Titration
Requires approximately 10 mL of oil.
Results are in ppm (mg/kg)
-
8/12/2019 4 Prevost Oil Analysis
32/42
OMICRON
Page 32
Interfacial Tension (IFT)
Measures the strength of the interface between the oil
under test and water.
Indicator of the presence of polar contaminents.
-
8/12/2019 4 Prevost Oil Analysis
33/42
OMICRON
Page 33
Dielectric Strength
-
8/12/2019 4 Prevost Oil Analysis
34/42
OMICRON
Page 34
Aging process : Cellulose depolymerization
CH2OH
O
OH
OH
O
CH2OH
OH
OH
O
O
CH2OH
OH
OH
O
CH2OH
O
OH
OH
OH
CH2OH
OH
OH
O
O
CH2OH
OH
OH
O
OH
-
8/12/2019 4 Prevost Oil Analysis
35/42
-
8/12/2019 4 Prevost Oil Analysis
36/42
OMICRON
Page 36
Degree of Polymerization
Measurement of intrinsic viscosity after dissolving the cellulose
in a specific solvent.
Gives an average measurement of the number of glucose units
per molecular chain.
DP of Insulation Components prior to processing ~1200
DP of Insulation Components following processing ~1000
DP level considered as over-processed ~800
DP level considered end of life ~200
-
8/12/2019 4 Prevost Oil Analysis
37/42
-
8/12/2019 4 Prevost Oil Analysis
38/42
OMICRON
Page 38
HOH
CO HOH
HOH
CH2OH
OH
O
O H
H
H H OC
OH
H
OCHO
H
H
H
WATER
WATER
WATER
FURAN
CARBON
MONOXIDE
Degradation of Cellulose
-
8/12/2019 4 Prevost Oil Analysis
39/42
OMICRON
Page 39
Most labs determine the concentration of five furanic compounds:
1. 2-furaldehyde (2FAL)
2. 5-methyl-2-furaldehyde (5M2F)
3. 5-hydroxylmethyl-2-furaldehyde (5H2F)
4. 2-acetyl furan (2ACF)5. 2-furfuryl alcohol (2FOL)
Note: 2FAL is stable for years while all other furanic compounds are less
stable. They tend to form and then degrade to 2FAL over a time period of
months.
Furans
-
8/12/2019 4 Prevost Oil Analysis
40/42
OMICRON
Page 40
2- Furfural vs. DP Correlation Plots
Correlation of DP with 2-FAL
-
8/12/2019 4 Prevost Oil Analysis
41/42
OMICRON
Page 41
Summary & Conclusions
DGA is a valuable tool to detect transformer problems
Sample can be taken while transformer is in service
Can trend fault gases
Industry Acceptance
Oil Quality Testing can detect transformer problems as well as
indicate maintenance actions
Oil can be reconditioned or reclaimed
Inceases life of insulation system
Remove moisture, acids, particles etc.
The remaining life of the insulation can be estimated with Furan
analysis
-
8/12/2019 4 Prevost Oil Analysis
42/42
Questions