1. Involve to Solve
Slide No. 1 Copyrights © 2005 TNB Research
WHAT IS YOUR
TRANSFORMER OIL
TELLING YOU ?
GOMATHY SETHURAMAN
TRANFORMER OIL
TESTING LABORATORY
16th June 2006

2. Involve to Solve
Slide No. 2 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
PRESENTATION OUTLINE
* INTRODUCTION
> TRANSFORMER OIL
> WHAT ARE THE INGREDIENTS ?
> TYPE OF TRANSFORMER OIL
> JOB SCOPE OF THE TRANSFORMER OIL
> TESTING TRANSFORMER OIL
* WHAT IS YOUR TRANSFORMER OIL TELLING YOU?
* CSI OF TRANSFORMER OIL
> CASE STUDY A
> CASE STUDY B
> CASE STUDY C
* CONCLUSION

3. Involve to Solve
Slide No. 3 Copyrights © 2005 TNB Research
TRANSFORMER OIL
CnH2n+2
• Composition of Mineral Transformer Oil
• Mixture of hydrocarbon compounds
» Naphthenic – 5, 6 or 7 carbon bonded in ring form
» Paraffin – carbon in straight chain
» Aromatic – 6 carbon bonded in ring form
» Heterocyclic – contains nitrogen, sulphur and oxygen
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?

4. Involve to Solve
Slide No. 4 Copyrights © 2005 TNB Research
WHAT ARE THE INGREDIENTS ?
Naphthenic ( Cn)
•Have good low temperature
properties
•More soluble and volatile than
paraffinic
Paraffinic (Cp)
•Have poor low temperature
properties
•Less soluble and volatile than
naphthenic
Aromatic (Ca)
•Are highly soluble
Hetero Atoms
• x = NH, S, O
•Co – exist in the oil
x
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?

5. Involve to Solve
Slide No. 5 Copyrights © 2005 TNB Research
TRANFORMER OIL CLASSIFICATION
Typical paraffinic oil Typical naphthenic oil
Classification of Transformer Oil
Paraffinic compound
42 – 50 % Naphthenic Oil
50 – 56 % Intermediate Oil
56 – 65 % Paraffinic Oil
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?

6. Involve to Solve
Slide No. 6 Copyrights © 2005 TNB Research
JOB SCOPE OF THE TRANSFORMER OIL?
ELECTRICAL INSULATION
 High breakdown voltage
 High electrical resistivity
 Low dissipation factor
 Low moisture
COOLING AGENT
 Low viscosity
 Low pour point
 High flash point
PROTECTING THE SOLID
INSULATION
 High resistance to
oxidation
 High chemical stability
 Low gassing tendency
MESSENGER
 Gassing tendency
 Ability to absorb
produced gasses
under electric
stress
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?

7. Involve to Solve
Slide No. 7 Copyrights © 2005 TNB Research
PHYSICAL TEST
1. Kinematics Viscosity
2. Flash Point
3. Pour Point
4. Density
5. Interfacial Tension
6. Appearance
7. Color
TESTING THE TRANSFORMER OIL?
CHEMICAL TEST
1. Dissolved Gas Analysis
2. Neutralization Value
3. Water Content
4. Carbon Composition
5. Oxidation Stability
6. Polychlorinated Biphenyl
7. Furanic Compound
8. Metals-In-Oil
9. Inhibitor Content
10. Corrosive Sulphur
11. Copper Corrosion
12. Sludge and Sediment
ELECTRICAL TEST
1. Dielectric
Breakdown Voltage
2. Dielectric
Dissipation Factor
3. Resistivity
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?

8. Involve to Solve
Slide No. 8 Copyrights © 2005 TNB Research
Accredited Tests
1. Dissolved Gas Analysis
2. Neutralization Value
3. Water Content
4. Dielectric Voltage Breakdown
5. Color
WHAT DOES ACCREDITATION MEAN?
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
Accreditation :
Is a process of evaluation
1. An institution to determine whether the institution meets the
standards set-up by the accrediting body.
2. The institution meets the standard
3. Granting recognition for meeting the standard requirements
4. Recognizes that the institution is competent to carry out
specific tasks.

9. Involve to Solve
Slide No. 9 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL ?
Failure Investigation Project
1. CSI OF TRANSFORMER OIL : CASE A
2. CSI OF TRANSFORMER OIL : CASE B
3. CSI OF TRANSFORMER OIL : CASE C
Executive Summary :
A number of failed instruments were brought to TNB Research
to be analyzed for the cause of failure.
The failed instruments were subjected to
• Electrical tests at the High Voltage Laboratory
• Oil test at the Transformer Oil Testing Laboratory
• Material and Visual test at the Advance Material Laboratory

10. Involve to Solve
Slide No. 10 Copyrights © 2005 TNB Research
TEST DETAILS
List of Test
1) Colour (ASTM 1500)
2) Density (ASTM D 4052)
3) Dielectric Breakdown (IEC 156)
4) Dissolved Gas Analysis (IEC 567)
5) Moisture Content (IEC 814)
6) Neutralization Value (IEC 296)
7) Dissipation Factor (IEC 247)
8) Interfacial Tension (ASTM D 971 – 99a)
9) Kinematic Viscosity 40 °C (ASTM D 445)
10) Carbon type (ASTM 2140)
NOTE :
1) Three samples were taken from each failed unit.
2) All three samples were tested individually based on the International Testing Method
3) Test were conducted under the transformer oil testing guidelines / settings
4) Interpretation of test results are based on IEC 60422 and IEC 60599
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?

11. Involve to Solve
Slide No. 11 Copyrights © 2005 TNB Research
PROPERTY
TEST
Average
(3 Samples)
LIMIT (IEC 422)
Transformer Oil
1 Colour L 1.5 1.0 – 2.5
2 Density 0.8881 0.895 (max)
3
Dielectric
Breakdown
21.7 30kV (min)
4
Moisture
Content
112 30 (max)
5
Neutralization
Value
0.14 0.3 (max)
6
Dissipation
Factor
(Tan Delta)
0.0069 0.03 (max)
7
Interfacial
Tension
15 24 (min)
8 Kinematic
Viscosity 19.3 <11
9 Carbon Type Cp > Cn Cn > Cp
REMARK EVALUATION
GOOD •Oil does not meet
the required limits
of IEC 422
•High
concentration
moisture → Low
BDV value
•Low IFT value →
Presence of
contamination
•High Viscosity →
Poor heat insulation
NORMAL
LOW
HIGH
NORMAL
NORMAL
LOW
HIGH
Cp > Cn
CSI OF TRANSFORMER OIL : CASE A
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?

12. Involve to Solve
Slide No. 12 Copyrights © 2005 TNB Research
DISSOLVED
GAS ANALYSIS
AVERAGE
LIMIT (IEC 60599)
Transformer Oil
Hydrogen 260 300
Oxygen 7173 -
Nitrogen 46243 -
Methane 69 30
Carbon Monoxide 65 300
Carbon Dioxide 3796 900
Ethylene 30 10
Ethane 318 50
Acetylene 2 2
REMARK EVALUATION
NORMAL • High
concentration
Ethane
Methane
Ethylene
→ Overheating
Carbon dioxide
→ Cellulose /
Paper Insulation
Degradation
-
-
High
NORMAL
High
High
High
NORMAL
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE A

13. Involve to Solve
Slide No. 13 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE A
Visible sludge and moisture

14. Involve to Solve
Slide No. 14 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE A
SludgeContaminant

15. Involve to Solve
Slide No. 15 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE A
Overheating
burn mark
Rusk mark due
to moisture

16. Involve to Solve
Slide No. 16 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE A
Overheating
burn mark
Overheating
marks

17. Involve to Solve
Slide No. 17 Copyrights © 2005 TNB Research
CSI OF TRANSFORMER OIL : CASE B
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
TEST Average
LIMIT (IEC 422)
Transformer Oil
1 Colour L 1.5 1.0 – 2.5
2 Density (g/cm3
) 0.8722 0.895 (max)
3
Dielectric
Breakdown (kV)
9 30kV (min)
4
A
Dissolved Moisture
Content (ppm)
54
30 (max)
B
Emulsified Moisture
Content (ppm)
393
5
Neutralization
Value( mgKOH/g)
0.03 0.3 (max)
6
Dissipation Factor
(Tan Delta)
0.0081 0.03 (max)
REMARK EVALUATION
GOOD
•High
concentration of
moisture →
Low BDV value
NORMAL
LOW
HIGH
NORMAL
NORMAL

18. Involve to Solve
Slide No. 18 Copyrights © 2005 TNB Research
DISSOLVED
GAS ANALYSIS
AVERAGE
LIMIT (IEC 60599)
Transformer Oil
Hydrogen 8 300
Oxygen 46228 -
Nitrogen 80877 -
Methane 4 30
Carbon Monoxide 20 300
Carbon Dioxide 949 900
Ethylene 3 10
Ethane 20 50
Acetylene ND 2
REMARK
EVALUATION
Normal
• High
concentration
Carbon dioxide
→ Overheating
→ Cellulose /
Paper Insulation
Degradation
-
-
Normal
Normal
High
Normal
Normal
Normal
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE B

19. Involve to Solve
Slide No. 19 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE B
Visible sludge and moisture

20. Involve to Solve
Slide No. 20 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE B
ContaminantOverheating
burn mark

21. Involve to Solve
Slide No. 21 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE B
Overheating burn mark

22. Involve to Solve
Slide No. 22 Copyrights © 2005 TNB Research
CSI OF TRANSFORMER OIL : CASE C
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
TEST Average
LIMIT (IEC 422)
Transformer Oil
1 Colour L 1.5 1.0 – 2.5
2 Density (g/cm3
) 0.8739 0.895 (max)
3
Dielectric
Breakdown (kV)
9 30kV (min)
4
A
Dissolved Moisture
Content (ppm)
61
30 (max)
B
Emulsified Moisture
Content (ppm)
613
5
Neutralization
Value( mgKOH/g)
0.035 0.3 (max)
6
Dissipation Factor
(Tan Delta)
0.0075 0.03 (max)
REMARK EVALUATION
GOOD
•High
concentration
moisture → Low
BDV value
•Two types of
moisture
→ Dissolved
→ Emulsified
NORMAL
LOW
HIGH
NORMAL
NORMAL

23. Involve to Solve
Slide No. 23 Copyrights © 2005 TNB Research
DISSOLVED
GAS ANALYSIS
AVERAGE
LIMIT (IEC 60599)
Transformer Oil
Hydrogen 12.5 300
Oxygen 42564 -
Nitrogen 75302 -
Methane 4 30
Carbon Monoxide 27 300
Carbon Dioxide 1136 900
Ethylene 4 10
Ethane 27 50
Acetylene ND 2
REMARK EVALUATION
Normal
• High
concentration
Carbon dioxide
→ Overheating
→ Cellulose /
Paper Insulation
Degradation
-
-
Normal
Normal
High
Normal
Normal
Normal
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE C

24. Involve to Solve
Slide No. 24 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE C
Visible sludge
and moisture
Contamination

25. Involve to Solve
Slide No. 25 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE C
Overheating / burn mark on the cellulose / paper insulation

26. Involve to Solve
Slide No. 26 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CSI OF TRANSFORMER OIL : CASE C
Contaminant Overheating
burn mark

27. Involve to Solve
Slide No. 27 Copyrights © 2005 TNB Research
• Transformer oil in an instrument is subjected to
HEAT
OXYGEN OXIDATION
WATER DEGRADATION
ELECTRICAL
COTAMINANTS
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CONCLUSION
• The reliability of a transformer oil depends on the basic character of the oil
The BETTER the OIL → The BETTER PERFORMANCE
• BEST PRATICE
•Monitoring the performance of the transformer oil
•Deciding the type of test to be done.

28. Involve to Solve
Slide No. 28 Copyrights © 2005 TNB Research
WHAT IS YOUR TRANSFORMER OIL TELLING YOU ?
CONCLUSION
WHY ONE SHOULD MONITOR THE TRANSFORMER OIL ?
• CHEAP AND FAST
•Testing the oil is cheaper than replacing a transformer
• EFFECTIVE and RELIABLE
•Test results can pin-point the fault (if ANY)
• MONITORING THE PERFORMANCE OF THE OIL
• Trending the rate of degradation of the oil