Categorizing Faults via DGA GE Grid Solutions M&D
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Categorizing Faults via DGA
GE Grid SolutionsM&D
Doctors extract information about our health from our blood. Technicians extract information
about the health of our transformers from the oil via DGA. Substations are more challenging for
this sampling process than a doctor’s office .
First, What Is Transformer Dissolved Gas Analysis?
Sample Test Doc Diagnosis
Transformer Dissolved Gas Analysis, The Process & Logic
Sample Test Tech Diagnosis
We prefer a clean sample with no issues detected, just as a blood test in a doctor’s office.
Duvall’s Triangle
Transformer Construction
CoolingSystem
Core
Tap changer
CoilsTank
Oil
Control Cabinet
Bushings
What Are The Relevant Gases?
“Hot Metal Gases”
“Paper & Oil Gases”
6
CC
HHHH
CC
HHHH
CC
HHHH
CC
HHHH
CC
HHHH
HH
H
HCC
H
H
H
HH
H
HC
HH
H
H
CC
HHHH
H
H
HC
C
HH
HH
Oil degradation – Typical oil Molecule
Knowing Industry Standards & Their Intended Use
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;Dissolved key gas concentration limits - IEEE C57.104
H2 CH4 C2H2 C2H4 C2H6 CO CO2 TDCG
Condition 1 100 120 1 50 65 350 2500 720
Condition 2 101 - 700 121 - 400 2 - 9 51 - 100 66 - 100 351 - 570 2,500 - 4,000 721 - 1,920
Condition 3 701 - 1,800 401 - 1,000 10 - 35 101 - 200 101 - 150 571 - 1,400 4,001 - 10,000 1,921 - 4,630
Condition 4 >1,800 >1,000 >35 >200 >150 >1,400 >10,000 >4,630
Condition 1TDCG below this level indicates satisfactory operation. Any individual combustible gas exceeding specified
levels should prompt additional investigation.
Condition 2
TDCG within this range indicates greater than normal combustible gas level. Any individual combustible gas
exceeding specified levels should prompt additional investigation. Action should be taken to establish a
trend. Fault (s) may be present.
Condition 3
TDCG within this range indicates a high level of decomposition. Any individual combustible gas exceeding
specified levels should prompt additional investigation. Immediate action should be taken to establish a
trend. Fault (s) are probably present.
Condition 4TDCG within this range indicates excessive decomposition. Continued operation could result in failure of
the transformer.
Understanding Duval’s Triangle, Fault Codes.
IEEE C57.104 Key Gases Evaluation
Partial Discharge in Oil
Overheated Oil
Arcing in Oil
Overheated Cellulose
0%
10%
20%
30%
40%
50%
60%
70%CO
H2
CH4
C2H6
C2H4
C2H2
0%
20%
40%
60%
80%
100%CO
H2
CH4
C2H6
C2H4
C2H2
0%
20%
40%
60%
80%
100%CO
H2
CH4
C2H6
C2H4
C2H2
0%
10%
20%
30%
40%
50%
60%CO
H2
CH4
C2H6
C2H4
C2H2
Ratios for key gases—Doernenburg
Ratio 1 (R1)
CH4/H2
Ratio 2 (R2)
C2H2/C2H4
Ratio 3 (R3)
C2H2/CH4
Ratio 4 (R4)
C2H6/C2H2
Oil Gas
space
Oil Gas
space
Oil Gas
space
Oil Gas
space
1. Thermal decomposition >1.0 >0.1 <0.75 <1.0 <0.3 <0.1 >0.4 >0.2
2. Partial discharge
(low-intensity PD) <0.1 <0.01 Not significant <0.3 <0.1 >0.4 >0.2
3. Arcing (high-intensity PD) >0.1 to <1.0 >0.01 to <0.1 >0.75 >1.0 >0.3 >0.1 <0.4 <0.2
Suggested fault diagnosis
Ratios for key gases—Doernenburg
Rogers Ratios For Key Gases
CaseR2
C2H2/C2H4
R1
CH4/H2
R5
C2H4/C2H6Suggested fault diagnosis
0 <0.1 >0.1 to <1.0 <1.0 Unit normal
1 <0.1 <0.1 <1.0 Low-energy density arcing—Pda
2 0.1 to 3.0 0.1 to 1.0 >3.0 Arcing—High-energy discharge
3 <0.1 >0.1 to <1.0 1.0 to 3.0 Low temperature thermal
4 <0.1 >1.0 1.0 to 3.0 Thermal <700 °C
5 <0.1 >1.0 >3.0 Thermal >700 °C
a There will be a tendency for the ratios R2 and R5 to increase to a ratio above 3 as the discharge develops in intensity.
Rogers ratios for key gases
Transformer Operating Temperatures
20 – 80 C?
• First signs of gassing begins around 100 C with CO2 & CO.
• First signs of hot metal gases begins around 150 C.
Diagnosing Transformer Main Tank Faults
0%
10%
20%
30%
40%
H2 CH4 C2H6 C2H4 C2H2
Where’s The Problem?
0%
10%
20%
30%
40%
H2 CH4 C2H6 C2H4 C2H2
Nitrogen Sealed #2 – 30 MVANitrogen Sealed #1 – 36 MVA
0
20
40
60
80
100
120
Pre Event
Post Event
0
1
2
3
4
5
6
7
Pre Event
Post Event
CO2/CORatio
CO2/CORatio
Where’s The Problem? Continued
Primary Lead – Repairable #2Winding Failure #1
Transformer Replaced Transformer Repaired
CO2/CO Ratio Experiment
0
10
20
30
40
50
60
70
80
90
test1 test2 test3 test4 test5 test6 tes 7 test8 test9 test10
oil flash
paper
CO2/CO RATIO
Where’s The Problem?
0
2
4
6
8
10
12
14
16
1 2 3 4 5 6 7 8 9
CO2/CO
CO2/CO
Linear (CO2/CO)
DATE H2 O2 N2 CH4 CO CO2 C2H6 C2H4 C2H2 TDCG CO2/CO
11/4/2009 235 12,771 68,988 686 277 2,879 228 1,523 52 3001 10.3935
1/8/2010 268 14,477 81,770 986 369 4,063 323 2,196 54 4,238 11.01084
2/23/2010 282 13,893 76,571 821 312 4,506 329 2,239 47 4,030 14.44231
3/22/2010 272 13,034 71,225 834 284 3,200 302 1,892 33 3,617 11.26761
5/6/2010 226 11,639 68,938 974 350 4,000 325 2,054 39 3,968 11.42857
8/13/2010 134 11,897 59,148 1,138 298 3,451 337 2,358 14 4,279 11.58054
1/12/2011 329 8,613 72,536 1,663 577 5,183 447 3,215 14 6,245 8.982669
1/25/2011 256 9,233 67,438 1,151 491 4,979 421 2,443 16 4,778 10.14053
0
500
1,000
1,500
2,000
2,500
3,000
3,500
1 2 3 4 5 6 7 8 9
C2H4
C2H4
Linear (C2H4 )
2% Decline Overall
38% IncreaseOverall
DETC Coked
Descending CO2/CO Ratios -75 MVA, N2 Blanketed
DATE H2 O2 CH4 CO CO2 C2H6 C2H2 C2H4 CO2/CO
30-Jul-12 ND 9715 1 64 453 ND ND ND 7
6-Jul-11 ND 1180 1 22 485 2 ND 1 22
25-Jan-10 ND 5893 1 17 439 2 ND 2 26
9-Mar-09 ND 1738 TRACE 4 475 1 ND TRACE 118
26-Mar-08 ND 2829 1 25 851 2 ND 3 34
15-Feb-07 ND 1667 TRACE 22 816 1 ND 3 37
0
20
40
60
80
100
120
140
2007 2008 2009 2010 2011 2012
CO2/CO
CO2/CO
Linear (CO2/CO)
81% Drop in5 Years
M
15 MVA, 100 kV – Manufactured 1999 –Pre-Fault
Date H2 O2 CO2 CO CH4 C2H6 C2H4 C2H2 CO2/CO
2011 <2 845 579 8 5 6 2 <1 72.3
2012
<2 831 524 5 2 4 1 <1 104.8
2013 <2 509 226 3 1 <1 <1 <1 75.3
2014 <2 1092 178 6 1 <1 <1 <1 29.6
2015 <2 500 124 10 2 1 <1 <1 12.4
0
20
40
60
80
100
120
140
1 2 3 4 5 6
CO2/CO
CO2/CO
Linear (CO2/CO)
83% Drop
M
0
10
20
30
40
50
60
70
80
2011 2015
CO2/CO Ratio
2011
2015
1999, 15 MVA, 100 kV, Complete Picture
Date H2 O2 CO2 CO CH4 C2H6 C2H4 C2H2 CO2/CO
2011 <2 845 579 8 5 6 2 <1 72.3
2012 <2 831 524 5 2 4 1 <1 104.8
2013 <2 509 226 3 1 <1 <1 <1 75.3
2014 <2 1092 178 6 1 <1 <1 <1 29.6
2015 <2 500 124 10 2 1 <1 <1 12.4
2016 post fault
212 802 1188 414 210 72 372 422 2.8
0
20
40
60
80
100
120
140
1 2 3 4 5 6
CO2/CO
CO2/CO
Linear (CO2/CO)
96% Drop 2011 - 2016
0
10
20
30
40
50
60
70
80
2011 2016
CO2/CO Ratio
2011
2016
10 MVA Mobile Transformer
Test Date Hydrogen Methane Ethane Ethylene Acetylene CO2 CO CO2/CO Nitrogen Oxygen
9/5/2002 2 0 0 0 0 1820 221 8.235294 68476 9186
8/19/2004 4 o 0 0 0 1875 249 7.53012 80061 7268
6/16/2005 2 1 0 0 0 1951 231 8.445887 79140 7284
8/14/2006 6 3 0 0 0 3450 322 10.71429 82900 7507
8/7/2008 2119 736 44 666 1405 2530 239 10.58577 67189 7881
9/18/2008 2096 937 48 954 1888 3475 298 11.66107 85360 11046
0
500
1000
1500
2000
2500
1 2 3 4 5
H2
CH4
C2H6
C2H4
C2H2
1
2
3
4
5
0
2
4
6
8
10
12
14
1 2 3 4 5 6
CO2/CO
CO2/CO
Linear (CO2/CO)
DETC Failed
29% IncreaseOverall
115-4kV, MVA Rating 18/24/33.6
Test Date Hydrogen Methane Ethane Ethylene Acetylene CO2 CO CO2/CO Nitrogen Oxygen
2/19/2013 2 12 14 17 0 2118 61 34.72 77642 242
8/1/2013 2 7 12 13 0 1776 53 33.51 84976 1819
7/31/2014 2 5 11 5 0 660 24 27.50 78121 207
9/21/2015 3 5 10 2 0 355 64 5.55 69550 159
11/29/2016 344 204 35 494 570 400 72 5.56 0 7881
0.00
10.00
20.00
30.00
40.00
50.00
1 2 3 4 5
CO2/CO
CO2/CO
Linear(CO2/CO)
0
100
200
300
400
500
600
1 2 3 4 5
1
2
3
4
5
0
10
20
30
40
2011 2016
CO2/CO Ratio
2011
2016
84% Drop2013 - 2015
Analyzing Events via CO2/CO
0
50
100
150
200
250
20
08
20
09
20
10
20
11
20
13
CO
CO
1700
1800
1900
2000
2100
2200
20
08
20
09
20
10
20
11
20
13
CO2
CO2
0
20
40
60
80
100
120
20
08
20
09
20
10
20
11
20
13
C2H6
C2H6
0
20
40
60
80
100
120
2011 2013
CO2/CO Ratio
2011
2013
Failed the following year, 2014
1850 ppm
200 ppm
2136 ppm
21 ppm
Finding The Problem
-20
0
20
40
60
80
100
120
1999 2005 2013
36 MVA Nitrogen Blanket
CO2:CO
Linear (CO2:CO)
• C2H2>5
• C2H4>550
• C2H6>70
• CH4>293
• CO2<2500
• CO<50
• Gassing began in 2001
Finding The Problem, Continued
• Long history of gassing including acetylene and high levels of ethylene.
• Due to high combustible gas levels and the increasing CO2:CO ratio, problem was narrowed down to overheating occurring on either the DETC or primary/secondary leads.
• Primary lead was found bare against a corona shield. It was re-taped and in subsequent DGA tests there has been no production of combustible gas.
Do I Have Healthy Paper? Are There Indicators Within DGA?
Date H2 CH4 C2H6 C2H4 C2H2 CO2 CO O2 CO2/CO
June-12 ND 2 1 1 ND 282 14 1507 20
Nov-13 ND 3 4 ND ND 566 15 10390 38
Sept-14 ND 3 ND ND ND 466 11 8712 42
July-15 1 3 2 ND ND 313 5 9141 63
20
3842
63
0
10
20
30
40
50
60
70
2012 2013 2014 2015
CO2/CO RATIO
CO2/CO RATIO
M
Acetylene Is Problematic, But Is It Fatal?
Not always:• Is it present due to activity in the winding insulation, or is it bare metal?
• The problem could be easy to get to and simple to repair.
• Transformers have been discarded when the problem was a simple fix, but that was unknown at the time.
• It can mean the difference between a few thousand dollar$ in repairs, versus a few million dollar$ in potential replacement costs.
Effects Of Thumping Faults With A Power Transformer
Sampled right after main tank fault. Notice the arcing signature in the main tank.
Effects Of Thumping Faults With A Power Transformer, Continued
0%
10%
20%
30%
40%
50%
60%
H2 CH4 C2H6 C2H4 C2H2
H2
CH4
C2H6
C2H4
C2H2
kkkkkkkkkkkkkkkkkkkk
Main Tank ArcingEffects of Thumping Faults w/Power Transformer
0%
10%
20%
30%
40%
50%
60%
H2 CH4 C2H6 C2H4 C2H2
H2
CH4
C2H6
C2H4
C2H2
% Gas Generation Chart - Arcing in OilReference: IEEE Std C57.104-2008
0
50
100
150
200
Pre-Fault Ratio
Post Fault Ratio
CO2/CO Ratio
Summary/Conclusion
• All internal faults are not fatal.
• Know your fleet. It will be beneficial in solving the diagnostic puzzles as they present themselves.
• All faults are not as easily identified. Don’t give up, as there is an answer. Allow software to help with the data analysis and direct you to the critical assets and information, which are now available.
• Trending the fluctuations of gas concentration, rate of change and ratios is very important for understanding your transformers’ vital signs.
• Know when to reach out for additional support, if needed.
• We are all in this together.
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