02a-DGA Diagnosis 2014- Part 1

Criteria for the Interpretation of Data for y nTransformers a Dissolved Gases-In-Oil From p m e e n i ng

E e l ob

©D

C g n ri

o

Doble Laboratory Seminar

©2014 Doble Engineering Company. All Rights Reserved

1 ©2014 Doble Engineering Company. All Rights Reserved

Why Measure Gases in Oil

• Excellent indicators of incipient fault condition Most important diagnostic in the industry ny a p • Materials involved om C g n i r nee • Severity of the conditionng- iabnormal amounts E e l b o D • Detect of wide © variety of conditions • Complex - not easily simplified for analysis in all cases ©2014 Doble Engineering Company. All Rights Reserved

2

Energy Required to Break Bonds and Form Gases Various gasses are created during oil decomposition depending on the type of fault H H 338 Hydrogen y kJ/mole Low n a C H omp Temperature 338 kJ/mole Methane 4C About 120 C

High Temperature About 700 C

g n i r ee

in g n Ethane E e l ob D H © Ethylene

H

Acetylene

H

607 kJ/mole

C

C

C

C


H H H

720 kJ/mole 960 kJ/mole 3

Standard Gas Chromatogram

©

le b o D

e n i g En

C g n eri

ny a p om


4

Minimum Detection Limits (MDL) MDL Method A (ppm)

Gas Hydrogen

5

Carbon Monoxide

25

Hydrocarbons

1

©

le b o D

MDL Method B (ppm)

MDL Method C (ppm)

ny a p o0.6m

C g n 2 ri 0.09 e e in 1 0.04-0.06 20

MDL Method IEC 60567 (ppm)

Eng

2 10

0.2 –1

ASTM D 3612 Method A - Vacuum extraction/GC Analysis Method B - Stripper Column/GC Analysis Method C - Headspace/GC Analysis ©2014 Doble Engineering Company. All Rights Reserved

5

Repeatability - Moderate Concentration Hydrogen 338 341 344 349 343 340 331 342 355 343

Acetylene Ethylene Ethane 70 92 95 69 91 94 69 92 95 69 93 95 g n i r 69 93 95 e e n i g 69 92En 95 e l 91 b 68 94 o D 68© 92 95 69 93 95 68 92 94

Methane Carbon monoxide 134 209 132 205 y n a 135 212 p m 212 Co 135 134 208 133 205 131 203 134 210 137 215 134 210


6

Gas-in-Oil Standard: Headspace Spiked Amount Ave. of 3 runs

H2

Methane

CO

Ethane

CO2

Ethylene

Acetylene

150.0

56.4

94.0

37.6

313.0*

37.6

37.6

152.7

57.1

96.6

37.8

324.3

37.5

34.6

ny a p om

C g n *CO – includes about 50rippm in blank e e n i ng E le b o ©D 2


7

Historical Information

• Nameplate information including age • Has the Total Combustible Gas risen suddenly? ny a p • Is the unit heavily loaded or overloaded? om C g n i r etest - trend? e n • Previous dissolved gas-in-oil i ng E le b o • Did a bushing or the transformer fail at some point? ©D • If the unit has been repaired, was the oil filtered or degassed? ©2014 Doble Engineering Company. All Rights Reserved

8

Oil Preservation Systems

©

le b o D

e n i g En

C g n eri

ny a p om


9

Oil Preservation Systems

©

le b o D

e n i g En

C g n eri

ny a p om


10

Partition Coefficients Gas

Ostwald Coefficient

Oxygen Nitrogen Carbon Dioxide Carbon Monoxide Hydrogen e l b o Methane D © Ethane Ethylene Acetylene

in g n E

g n i r ee

0.138 0.0745ny a p m Co0.900 0.102 0.0429 0.337 1.99 1.35 0.938


11

Gas Partitioning Gas-in-Oil ppm (vol/vol)

Gas

Estimated ppm gas-in-gas space**

Estimated % gas-in-gas space

ny a p om

Oxygen 28,400 206,000 20.6 Nitrogen 59,000 792,000 79.2 Carbon Dioxide 1,000 1,110 0.11 Carbon Monoxide* 100 980 0.10 Hydrogen* 100 2,330 0.23 Methane* 100 297 0.03 Ethane* 100 50 0.01 Ethylene* 100 74 0.01 Acetylene* 100 107 0.01 *Combustible gases **Estimated value under equilibrium conditions at 25C and 1 atm

©

le b o D

e n i g En

C g n eri


12

Solubility of Gases in Oil • Hydrogen, Nitrogen, CO, and Oxygen increase with >temperature • CO2, Acetylene, Ethane, Ethylene decrease with >temperature y n a p m o C g • Methane essentially unchanged with change in temperature n i r e e n i g n E • All increase proportionally le with Pressure b o ©D – doubling pressure doubles gas concentration in oil, in atmospheres

• All modestly increase with decreasing oil density ©2014 Doble Engineering Company. All Rights Reserved

13

Solubility of Gases in Oil

ny a p om C g n i • Hydrogen, Carbon Monoxide,e(Methane to lesser degree) r e in g n – proportionally higherleinEclosed conservator than gas blanketed unit ob D ©atmosphere in open conservator – slowly lost to – If leak in nitrogen blanketed unit, these gases decrease the most out of the combustible gases ©2014 Doble Engineering Company. All Rights Reserved

14

Homogeneity of Gases in Oil

• Rate of generation

• Access of fault area to flow

ny a p m o C • Rate of mechanical mixing mostinimportant g r e e n i ng influencing factor • Presence of a gas lblanket E e b o D © • Diffusion – Extremely slow


15

Gas Bubbles • Super-saturation of the oil with gas

ny a p om C g insulation n • Thermal decomposition of the cellulosic i r e e n i ng E le b o ©D • Vaporization of adsorbed moisture in the cellulose (primary issue) ©2014 Doble Engineering Company. All Rights Reserved

16

Oxygen and Nitrogen

• Oxygen – increase-leak – decrease-overheating

C g n eri

e n – consumed in chemical reactions i g n

• Nitrogen

E e l ob

ny a p om

©D

– pressure and operating temperature dependent in gas blanketed systems ©2014 Doble Engineering Company. All Rights Reserved

17

Combustible Gases and Carbon Oxides

• Norms - What is a normal rate of gassing • Total combustible gas - Guidelines • • • •

ny a p Key gases - Identification of type of Cproblem om g n i r e problem e n Ratios -Identification ofntype of i g E le b o Trends - What’s © D new Fingerprints - Typical gassing behavior for certain families of transformers ©2014 Doble Engineering Company. All Rights Reserved

18

Dissolved Gas Acceptable Limits Various Sources Hydrogen

CO

Methane

Ethane

Ethylene

DOBLE

100

250

100

60

100

*IEEE

100 101-700 701-1800 >1800

350 351-570 571-1400 >1400

120 121-400 401-1000 >1000

65 66-100 101-150 >150

ng C

IEC 60599 Typical Range

50-150

ri e e ngin

E e l 400-600ob 30-130 ©D

20-90

50 51-100 101-200 >200

Acetylene

5 ny a p 1 m o

60-280

2-9 10-35 >35 2-20

(No OLTC) 60-280 (Communicating OLTC)

CO2

TCG

--

610

2500 2500-4000 4001-10000 >10000

720 721-1920 1921-4630 >4630

3,800-14,000

Would consider 1 ppm or more or acetylene as abnormal for further evaluation Values based on statistical norms or consensus values ©2014 Doble Engineering Company. All Rights Reserved

19

Total Combustible Gas Limits (ppm) TCG 0-500

LOW LEVEL OF GASSING

501-1500 1501-2500 >2500

©

ny a p MODERATE DECOMPOSITION om - ESTABLISH C g TREND n i r e e n i HIGHELEVEL ng OF DECOMPOSITION - ESTABLISH le TREND b o D VERY HIGH LEVEL OF DECOMPOSITION - IDENTIFY CAUSE


20

Key Gases - Arcing

Combustibles, %

100 80

60 40 20 0

© CO

le b o D Hydrogen

e n i g En

Methane

C g n eri

Ethane

ny a p om

Ethylene


Acetylene

21

Key Gases - Overheating, Oil

Combustibles, %

100 80

60 40

20 0

© CO

le b o D

e n i g En

Hydrogen

Methane

C g n eri

Ethane

ny a p om

Ethylene


Acetylene

22

Key Gases - Partial Discharge

Combustibles, %

100 80

60 40

20 0

© CO

le b o D

e n i g En

Hydrogen

Methane

C g n eri

Ethane

ny a p om

Ethylene


Acetylene

23

Key Gases - Overheating, Paper Carbon dioxide, non-combustible gas also important

Combustibles, %

100 80 60 40 20 0

©

le b o D CO

e n i g En

Hydrogen

C g n eri

Methane

Ethane

ny a p om

Ethylene


Acetylene

24

Key Gases - Composite

Combustibles, %

100 80 60

40 20 0

©

le b o D

CO

Hydrogen

e n i g En Methane

C g n eri

Ethane

Ethylene

ny a p om

Arcing Heating Oil PD Heating Paper

Acetylene


25

Transformers With Incipient Faults GAS Hydrogen Oxygen Nitrogen Methane Carbon Monoxide Ethane Carbon Dioxide Ethylene Acetylene *TGC **TCG

1 - Arcing

©

0 1,100 79,000 9 33 7 510 8 9 80,676 57

le b o D

e n i g En

2 - PD 1,700 3,000 110,000 43 440 6 8,400 2 0 123,591 2,191

C g n eri

ny a p om

3 - Thermal 540 2,300 87,000 1,300 420 160 2,000 810 2 94,532 3,232

*TOTAL GAS CONTENT **TOTAL COMBUSTIBLE GAS ©2014 Doble Engineering Company. All Rights Reserved

26

Transformers Exhibiting Overheating Of Oil GAS Hydrogen Methane Carbon Monoxide Ethane Carbon Dioxide Ethylene Acetylene

1

le b o Total combustible gas ©D

540 1,300 420 160 2,000 810 2

e n i g En 3,232

TRANSFORMERS 2 3 1 69 400 2,300 6,800 180 0

C g n eri

16 390 240 480 4,400 33 0

110 110 140 39 1,500 8 0

1,059

407

ny a p om

2,950

4

Decreasing temperature ©2014 Doble Engineering Company. All Rights Reserved

27

Ratio Methods • Advantages – quantitative – independent of oil volume – can be computer programmed

• Disadvantages

e n i g En

C g n eri

ny a p om

– don’t always yield b anleanalysis o D – not always © correct – dependence of preservation system

• Solid insulation handled separately ©2014 Doble Engineering Company. All Rights Reserved

28

Roger’s Ratio-Fault Diagnosis Case

Acetylene Ethylene

Methane Hydrogen

Ethylene Ethane

Fault

0

<0.1

>0.1,<1.0

<1.0

Normal

1

<0.1

<0.1

<1.0

2

0.1-3.0

0.1-1.0

3

<0.1

4

<0.1

5

©

le b o D

<0.1

m o C ng >3.0

eeri

in g n E

Low energy y n pa PD

>0.1<1.0

1.0-3.0

>1.0

1.0-3.0

>1.0

>3.0

Arcing

Low temp thermal Thermal <700C Thermal >700C

Apply when normal levels exceeded ©2014 Doble Engineering Company. All Rights Reserved

29

IEC 60599 Ratio-Fault Diagnosis Acetylene Ethylene

Methane Hydrogen

Ethylene Ethane

Fault

NS

<0.1

<0.2

PD

>1

0.1-0.5

>1

0.6-2.5

0.1-1

>2

NS

>1 (NS)

<0.1 <0.2

©

le b o >1 D >1

ny a p om

D1 - Low energy

C D2 - High energy g n eri

e<1 n i g En

1-4 >4

T1 <300C T2 >300C <700C Thermal >700C

NS = not significant regardless of value ©2014 Doble Engineering Company. All Rights Reserved

30

Overheating of Oil GAS Hydrogen Methane Carbon Monoxide Ethane Carbon Dioxide Ethylene Acetylene

1

Total combustible gas

y pan

4

540 1,300 420 160 2,000 810 2

1 69 400 2,300 6,800 180 0

16 390 240 480 4,400 33 0

110 110 140 39 1,500 8 0

3,232

2,950

1,059

407

om C ng

ri e e ngin

E e l ob

©D

TRANSFORMERS 2 3


31

Overheating of Oil

• Roger’s Ratio evaluation – Case 1: Core and tank circulating currents, overheated joints any

– Case 2: Overheating 150-200°Cring

e e n i ng – Case 3: Overheating 150-200°C E le b o © Doverheating <150°C – Case 4: Slight

p m Co


32

Ratio Methods Do Not Always Work GAS

CASE 3

Hydrogen Methane Carbon Monoxide Ethane Carbon Dioxide Ethylene Acetylene

©

le b o D

Total combustible gas

650 81 380 170 g n i r 2,000 e e n i Eng 51 270

CASE 7 76 6,000 36any p 27,000 Com 4,400 120,000 1,700

1,602


154,812

33

Problems Detected

• Case 3 - Electrical problem caused by poor shield contact. ny a p • Case 7 - Core problem - metal particles, omcarbon found, C g n i r e erosion by electric currentinfound e ng E le b o ©D


34

Important Ratios • Acetylene/Ethylene – <10% thermal problems

y

n electrical fault – a – > 10 but <20% thermal problems often developing into p m o C beginning of discharge activity ng – >20% arcing

ri e e ngin

E e l ob monoxide • Carbon dioxide/Carbon D ©

– <3:1 indicative of high temperature localized overheating of paper

– >10:1 general heating of the winding ©2014 Doble Engineering Company. All Rights Reserved

35

Important Ratios • Ethylene/Ethane – >4:1 indicative of heating of bare metal

y

n a – <4:1 indicative of heating of paper-wrapped conductor p m

o C g n that paper is involved even when – Not always correct, provides indication i r e carbon oxides are low ngine E e l ob paper overheated to increase carbon oxides – Sometimes notDenough © in large oil volume above normal – Sometimes paper burned away at some point and little further deterioration in paper ©2014 Doble Engineering Company. All Rights Reserved

36

Classical Duval Triangle for Transformers Filled with Mineral Oil

©

le b o D

e n i g En

PD = Corona Partial Discharges D1 = Discharges of low energy D2 = Discharges of high energy T1 = Thermal faults, T < 300 °C T2 = Thermal fauts, 300 °C < T < 700 °C T3 = Thermal faults, T > 700 °C DT = Mixtures of electrical, thermal faults

C g n eri

ny a p om

Provided by Michel Duval of IREQ ©2014 Doble Engineering Company. All Rights Reserved

37

The Use of Triangular Coordinates Example:

y If CH4 = C2H4 = C2H2 pa=n100 ppm, om C ng

©

le b o D

ri The triangular coordinates to use are: e e n i Eng %CH4 = % C2H4 = % C2H2 = 100/ 300 = 33.3%, and correspond to only one point in the Triangle.

Free triangular paper and software to calculate triangular coordinates, and to display the DGA point in the Triangle, are available from [email protected], for all versions of the Triangle presented here ©2014 Doble Engineering Company. All Rights Reserved

38

The Duval Triangle 2 for LTCs of Oil-Type Fault zones:

©

le b o D

N = Normal operation T3 = Thermal faults y T > 700°C n a p T2 = Thermal faults 300°C < T < 700°C m o C g = Fault T3/T2 in progress X3 n i r e X3 = Abnormal arcing D2 e n i Eng D1 = Abnormal arcing D1 : Normal operation; : Severe coking; : Light coking; : “Heating”; : Strong arcing D2; : Arcing D1


39

The Duval Triangle for Low Temperature Faults in Mineral Oil (H2, CH4 and C2H6) Fault zones:

n i r e ine

ng E le

ob D ©

PD = Corona Partial Discharges S = Stray gassing of oil nTy< 250°C a O = Overheating, p m o C C =gCarbonization of paper T > 300°C Stray gassing can easily be distinguished from the other low temperature faults. : Corona partial discharges; : Stray gassing at 120°C; ■ Stray gassing at 200°C; : Hot spots with carbonization of paper; : Overheating (T < 250°C).


40

The Duval Triangle for Low Temperature Faults in Mineral Oil (CH4, C2H6 and C2H4)

©

le b o D

Fault zones: PD = Corona Partial Discharges S = Stray gassing of oil O = Overheating,aTn 300°C o C gHigh temperature faults T > 700°C n T3 = i r e e n i Stray gassing can easily be distinguished Eng from the other low temperature faults. : Corona partial discharges; : Stray gassing at 120°C; ■ Stray gassing at 200°C; : Hot spots with carbonization of paper; : Overheating (T < 250°C); : faults T3 > 700°C


41

Trend Analysis + Doble Database

• Key gases

• Total combustible gas • Rate of gas generation

• Fingerprints le b o ©D

e n i g En

C g n eri

ny a p om


42

Conversion - Absolute Value to PPM

ny 6 a p m (GAS IN FTg C)o(7.48)(10 )  n i r e e n i g (GALLONS OF OIL) n E le b o ©D 3

PPM

Feet3 = 0.028 Meter3 ©2014 Doble Engineering Company. All Rights Reserved

43

Gassing Rates • Arcing - active gassing needs to be monitored closely and investigated to identify source • Usually more than two data points required and needs to be over a y n a p significant amount of time m o C g n i r • Thermal and PD e e –

in g n <1 ppm per day - normal, depending on loading, previous behavior, time E e l interval ob D ©

– 1-3 ppm- indications of developing problem – 3 + ppm increasing serious problem – 100 ppm - immediate removal from Service


44

Transformer Fingerprints GAS (PPM) Hydrogen Methane Carbon Monoxide Ethane Carbon Dioxide Ethylene Acetylene

Initial 3 years later Initial 3 years later 350 260 110 210 44 61 11 ny 13 a p 670 650 520 630 m o 26 25ng C 3 4 i r e 3000 1900 5000 3900 e n i g 9En 5 8 10 e ---obl --

©D


45

Transformer Fingerprints GAS (PPM) Initial 2 years later Initial 2 years later Hydrogen 20 12 0 0 y Methane 55 16 60 pan29 Carbon Monoxide 2 9 0om 0 C g Ethane 25 83erin 61 46 e Carbon Dioxide 1900 ngin 1500 650 250 E Ethylene 500 620 200 150 le b o Acetylene TRACE 0 0 D 1

©


46

Water And Other Materials

• Water – Electrolysis of free water + core steel + heat = hydrogen + y n a p oxygen om

C g n ri hydrogen – wet cellulose under PD yields more e e in g n E e l • Silicone compounds, ob organic polymers D ©

– under severe thermal and electrical discharge (arcing)

– hydrogen and CO ©2014 Doble Engineering Company. All Rights Reserved

47

Carbon Oxide Gases and Ratios

• Cellulose Insulation • Shell form > CO2 than core form - due to mass ny a p • Accidental CO2 om C g n i r • CO2/CO : 3 -14 (Vitols)nginee E e l ob • CO2/CO Avg. 7:1 D © • Approach 1 high temperature faults • High CO2 with low CO-lack of cooling/general overheating ©2014 Doble Engineering Company. All Rights Reserved

48

IEEE Trial Use Guide • No acetylene acceptable • 3 classes based on gassing rate in ppm/hr. • Condition I - No problem

ny a p om

C g n ri duplicate sample and e • Condition II - Possible Problem, take e in g n E of data, advise customer investigate cause by review e l ob D • Condition III © - Certain problem, manufacturer and customer conference • HC = methane + ethane + ethylene ©2014 Doble Engineering Company. All Rights Reserved

49

IEEE Trial Use Guide Gas Component Hydrogen

Condition I

Condition II

y n a p =>0.5<1.0 m =>1.0 o C g =>2.0<5.0 =>5.0 n i r ee

<0.8

Hydrocarbon

<0.5

CO CO2

<2.0 <20.0

©

le b o D

Condition III

in g n E

=>0.8<1.5

=>1.5

=>20.0<40.0

=>40.0

Gassing rates given in ppm/hour


50

DGA for Factory Heat Runs

©

le b o D

e n i g En

C g n eri

ny a p om

New transformer tested in factory ©2014 Doble Engineering Company. All Rights Reserved

51

DGA on 345 kV Auto Transformer Tests at Transformer Factory Hydrogen

Methane

Carbon Monoxide

Ethane

Utility Limits

13.8

2.3

34.5

2.3

Before Tests

1

0

5

After OA (TV)

4

0

After OA (HV)

5

After FA (HV)

12

After TV (FA) After all Tests

Description

Carbon

Acetylene

ny a 2.3 p om

Comb Gas

0

N/A

0

0

6

0

56

0

0

14

9

0

39

0

0

14

1

8

0

36

1

0

22

23

4

18

0

61

4

0

48

23

4

20

0

83

4

0

52

©

e 0l b o D

e 11in g En

Dioxide 138

C22 g n eri 0

Ethylene


52

Using IEEE Proposed Limits After All Tests Gases Hydrogen HC CO

Conc. (ppm)

Condition

Problem

0.92

Condition II

Possiblempa o >0.8, <1.5 Problem C g

ny

n i r e e I No problem Condition 0.34 n i g n E e l b o Condition I No problem 0.63 ©D

CO2 CO2/CO

2.54

Condition I

IEEE Limits

No problem

OK ©2014 Doble Engineering Company. All Rights Reserved

<0.5 <2.0

<20.0 >4, <10 53

Using IEEE Proposed Limits After FA (HV) Gases Hydrogen HC CO CO2

Rate (ppm/hr.)

Condition

IEEE Problem Limits y n a p om ppm/hr.

C Possible g n Condition IIeri 1.7 e Problem n i g n E e l Condition I No problem b 0.29 o ©D 0 0

Condition I Condition I

No problem No problem


>0.8, <1.5 <0.5 <2.0 <20.0 54

Using IEEE Proposed Limits After FA (TV) Gases

Rate (ppm/hr.)

1.83

Hydrogen HC CO CO2

©

le b 1.0 o D

Condition

IEEE Problem nLimits y a p om ppm/hr.

C g Certain n ri Condition III e e Problem n i g En Certain Condition III

problem

>1.5 >1.0

1.7

Condition I

No problem

<2.0

4.2

Condition I

No problem

<20.0


55

Problem

e n i g En

C g n eri

ny a p om

le a CT open during testing causing b Mistakenly left o D © current transformer to fail and CT terminal board under oil to flash over. This apparently caused the increased gas levels ©2014 Doble Engineering Company. All Rights Reserved

56

DGA on 345 kV Auto Transformer Re-test at transformer factory Description

Hydrogen Oxygen Nitrogen Methane Carbon

Utility Limits Before 2nd Heat Run After OA (TV) After OA (HV) After FA (HV) After FA (TV)

Ethane Carbon EthyleneAcetylene Comb Monoxide Dioxide Gas

ny a p 13.8 N/A N/A 2.3 34.5 2.3 m 138 2.3 o C g 0 n i 2 4015 27263 0 10 51 0 r e e in 12 g n 2 6961 24224 0 0 41 0 E e l b o 4 5626 9 0 40 0 © D 18934 0

0

N/A

0

12

0

14

0

13

3

7258

24675

2

17

0

56

0

0

21

2

8361

28775

2

20

0

81

0

0

24


57

02a-DGA Diagnosis 2014- Part 1

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