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

©2014 Doble Engineering Company. All Rights Reserved

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

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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

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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

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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

©2014 Doble Engineering Company. All Rights Reserved

9

Oil Preservation Systems

©

le b o D

e n i g En

C g n eri

ny a p om

©2014 Doble Engineering Company. All Rights Reserved

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

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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

©2014 Doble Engineering Company. All Rights Reserved

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

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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

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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

©2014 Doble Engineering Company. All Rights Reserved

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

©2014 Doble Engineering Company. All Rights Reserved

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

©2014 Doble Engineering Company. All Rights Reserved

Acetylene

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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

©2014 Doble Engineering Company. All Rights Reserved

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

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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, 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).

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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

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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

©2014 Doble Engineering Company. All Rights Reserved

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 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 =>0.51.0 o C g =>2.05.0 n i r ee