Colloqium 1

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Slide No. 1 Copyrights © 2005 TNB Research

WHAT IS YOUR

TRANSFORMER OIL

TELLING YOU ?

GOMATHY SETHURAMAN

TRANFORMER OIL

TESTING LABORATORY

16th June 2006

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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

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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


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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


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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


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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


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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


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Accredited Tests

1. Dissolved Gas Analysis

2. Neutralization Value

3. Water Content

4. Dielectric Voltage Breakdown

5. Color

WHAT DOES ACCREDITATION MEAN?


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.

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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

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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


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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


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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



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Visible sludge and moisture

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Sludge Contaminant

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Overheating

burn mark

Rusk mark due

to moisture

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Overheating

burn mark

Overheating

marks

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CSI OF TRANSFORMER OIL : CASE B


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)


(Tan Delta) 0.0081 0.03 (max)

REMARK EVALUATION

GOOD

•High concentration of moisture →

Low BDV value

NORMAL

LOW

HIGH

NORMAL

NORMAL

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Transformer Oil

Hydrogen 8 300

Oxygen 46228 -

Nitrogen 80877 -

Methane 4 30



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



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Visible sludge and moisture

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Contaminant Overheating

burn mark

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Overheating burn mark

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CSI OF TRANSFORMER OIL : CASE C


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)


(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

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Transformer Oil

Hydrogen 12.5 300

Oxygen 42564 -

Nitrogen 75302 -

Methane 4 30



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



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Visible sludge

and moisture Contamination

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Overheating / burn mark on the cellulose / paper insulation

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Contaminant Overheating

burn mark

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• Transformer oil in an instrument is subjected to

HEAT

OXYGEN OXIDATION

WATER DEGRADATION

ELECTRICAL

COTAMINANTS


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.

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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

Documents

Colloqium 1