IV INTERNATIONAL TRANSFORMER SEMINAR –JORPA 2017

Trends and New Technologies

The Panorama Changes Quickly…

... DONDE LA INNOVACION Y COLABORACION SON LA CLAVE.

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Agenda

THE GLOBAL ENERGY CHALLENGE

FUNCTIONS OF TRANSFORMER OILS

INHIBITED VERSUS UNINHIBITED

SHELL GTL

Q&A

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Functions of Transformers Oil

HIGHER VOLTAGES

OPERATION UNDER

OVERLOAD

HIGHER OPERATING

TEMPERATURES

LONGER TRANSFORMER OPERATING LIFELESS

REDUNDANCY

HIGHER POWER TO WEIGHT &

VOLUME RATIOS

Changes to Transformer Technology and Operation

PLACE INCREASING DEMANDS ON TRANSFORMER OILS (HIGHER STRESS) 6

CARRY INFORMATION

▪ Detect impurities viameasurement ofinterfacial tension

▪ Detect heat orelectrical issues usingDGA – Duval

ELECTRICAL INSULATION

▪ High BreakdownVoltage (DBV)

▪ High impulseBreakdown Voltage

▪ Low conductivity

PROTECTION

▪ Prevention of coppercorrosion

▪ Maintaining lowacidity to protectpaper insulation

DISSIPATE HEAT

▪ High heatconductivity

▪ Low viscosity in thecold

AGEING RESISTANCE: FUNCTION HAVE TO BE KEPT OVER OIL LIFE TIME OXIDATION STABILITY IS KEY FOR THIS 7

Transformer oil requirements

Inhibited versus Uninhibited

What is the difference between an uninhibited

and an inhibited oil?A paper published in 1948 informs the differences!

THERE ARE NO TRANSFORMER OILS

WITHOUT INHIBITOR!

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▪ Mineral-based oils are mainly produced by traditionalrefining of crude oil.

▪ This process relies on the quality and composition of thecrude oil.

▪ Different crude oils from different parts of the worldhave different compositions.

▪ The crude oils contain different levels of impurities suchas sulphur, oxygen or nitrogen.

EXAMPLE OF A TYPICAL PARAFFINIC OIL

EXAMPLE OF A TYPICAL NAPHTHENIC OIL

CP = 67%; CN = 32%; CA = 1% CP = 47%; CN = 49%; CA = 4%

THESE VARIATIONS CAN AFFECT THE QUALITY AND CONSISTENCY OF THETRANSFORMER OILS PRODUCED FROM THEM

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Mineral-based oils

Base oil composition of a typical hydrocarbon insulating oil

PARAFFINIC MOLECULESlinear, regular, can have wide molecular distribution, impurities

Variable performance, high pour point

NAPHTHENIC MOLECULESirregular, rings, can have wide molecular distribution, impurities

Variable performance, low pour point

GTL BASED OILSprimarily iso-paraffinic, narrow molecular distribution, no impurities

Stable performance, good additive response, good fluidity at low temperatures

▪ No simple/direct correlation between base oil composition and transformer oil performance

▪ Global standards such as IEC 60296 typically therefore require/define performance limits such as oxidation testing, rather than composition limits

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Base oil for transformer oils

Vacuum Gas Oil

Distillate, Naphthenic

Base Oil for Uninhibited

Transformer Oil

Base Oil for Inhibited

Transformer Oil

ACCEPTABLE OXIDATIONS STABILITY

IEC 61125C –164 HRS

BUT:

▪Aromatic content causes sludge

▪Sulphur could cause Copper Corrosion

▪Both working as natural antioxidants

NOT ACCEPTABLE OXIDATIONS STABILITY

BUT:

▪Good additive response allows to pass IEC 61125C – 500 hrs when AO is added

▪Low aromatic content

▪Low sulphur content can be achieved

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Inhibited versus uninhibited

TRANFORMER OIL

DEFINITION ADVANTAGE DISAVANTAGE

INHIBITED

Transformer oil with addition of a synthetic inhibitor (~0.2%m) to slow down the process of oxidative degradation

▪ More consistent

▪ More predictable

▪ More measurable

▪ Greater purity

▪ More oxidation resistant

▪ Longer oil life

▪ Prone to oxidation if synthetic inhibitor is not added

UNINHIBITED (NATURALLY INHIBITED)

Transformer oil with natural sulphur based inhibitor that can act as mild inhibitors for oxidation

▪ Less prone to oxidation

▪ Less consistent

▪ Less predictable

▪ Less measurable

▪ More impurity

▪ Less oxidation resistant

▪ Shorter oil life

“Our laboratory and field testing of transformer oils show that inhibited oils offer enhanced performance compared with uninhibited oils.”Ivanka Hoehlein, Manager, Material Testing Laboratory, Siemens 13

Oil

Life

IEC

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25

C (

ho

urs

) 500STANDARD INHIBITED

“I”HIGH INHIBITED

“HI”

332STANDARD TRACE-INHIBITED

“T”HIGH TRACE-INHIBITED

“HT”

164STANDARD UNINHIBITED

“U”HIGH UNINHIBITED

“HU”

Ageing Resistance▪ TAN: 1.2 mgKOH/g ▪ Sludge: 0.8%▪ DDF@90C: 0.500

▪ TAN: 0.3 mgKOH/g▪ Sludge: 0.05%▪ DDF@90C: 0.050

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Inhibited versus uninhibited

Current IEC 60296 Specification (2012)

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Inhibited versus uninhibited

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The difference is clear to see: uninhibited oils clearly age more quickly

Degradation

Start Test

10 Days

Inhibited Grades NO Degradation

UNINHIBITED OIL D INHIBITED OIL INHIBITED GTL OIL

Testing derived from IEC 62535, 3 vials, 100°C (dark), air atmosphere, visual check, test duration up to 14 days

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Today the challenges on the oil mean that in many applications an uninhibited oil is not suitable

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Inhibited versus uninhibited

USA China

Europe

Asia

ONLY INHIBITED TRANSFORMER OILS

MIXTURE (INHIBITED AND UNINHIBITED TRANSFORMER OILS)

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SHELL GTL

Bintulu Gas to Liquids Plant, Malaysia

▪ 1922 – German scientists, Franz Fischerand Hans Tropsch, discover the synthesisstep core to the GTL process.

▪ 1945 – Fischer-Tropsch (F-T) was used inGermany during the Second World War.

▪ 1973 – Shell took the F-T process thatconverts gas to liquids and furtherdeveloped it at the Amsterdam laboratory.

▪ 1983 – Shell built a pilot plant inAmsterdam for larger scale tests to makeGTL products.

▪ 1993 – Shell opened the world’s firstcommercial GTL plant at Bintulu, Malaysia.

▪ 2006 – Pearl GTL project (Shell and QatarPetroleum) was approved by TheGovernment of the State of Qatar.

▪ 2012 – Full-scale production at Pearl GTLcommenced, with 140,000 barrels per dayof high quality GTL products.

GTL BACKGROUND

Shell GTL base oil global reach, global consistency

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CRUDE OIL VARIES GREATLY AND IS DIFFICULT TO EXTRACT AND TO CLEAN:

▪ SULPHUR CONTENT CAN BE UP TO AND ABOVE >>1%

▪ MANY TRADITIONAL SOURCES OF NAPHTHENIC CRUDE ARE DEPLETING

NATURAL GAS:A BASE STOCK THAT IS ABUNDANT, CLEAN AND CONSISTENT

NATURAL GAS FOR GTL COMPRISES METHANE –THE SIMPLEST HYDROCARBON

North America

South America

Europe Eurasia

Middle East

Africa Asia Pacific

Conventional Gas Resources

Unconventional Gas Resources

GAS RESOURCES ARE PLENTIFUL, GROWING AND GEOGRAPHICALLY DIVERSE

Summary of the GTL process

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LIFETIMETHE LIFETIME OF A TRANSFORMER IS GOVERNED BY THE LIFE OF THE OIL AND OF THE INSULATING PAPER

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Neutralization Number

INSULATING PAPER DEGRADATION PROCESS

RejectCau tionSa tisfacto ry

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

Ne

utr

ali

za

tio

n V

alu

e,

mg

KO

H/

g

Tim e

TA

N (

mg

KO

H/

g)

21 day s = ~5 00 h

0 5 10 15 20 25 30 35

Tim e (days)0

0.1

0.2

Uninhibited NaphthenicOil

Inhibited GTL Oil

RESISTANCE TO DEGRADATION

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Resistance to degradationInhibited GTL versus conventional uninhibited

▪ INHIBITED OILS SHOW PREDICTABLE & BEST RESISTANCE TO DEGRADATION.▪ MONITORING ANTIOXIDANT CONCENTRATION GIVES INDICATION OF OIL CONDITION BEFORE SIGNIFICANT QUANTITIES OF ACIDS ARE DEVELOPED (AND POTENTIALLY ATTACK THE PAPER).

TAN

(m

gKO

H/g

)21 days = ~500 h

0 5 10 15 20 25 30 35

Time (days)0

0.1

0.2

Uninhibited Naphthenic Oil

Inhibited GTL Oil

IEC 61125C = THE INDUCTION PERIOD IS REACHED WHEN THE VOLATILE ACIDITY

SIGNIFICANTLY EXCEEDS 0.1 mg KOH/g

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Benefits of using Shell transformer oils with GTL base oil

LIGHT BOX TEST SHOWS THAT THERE ARE CHEMICAL STRUCTURES IN NAPTHENIC OILS WHITCH COULD EASILY REACT

Transformer oil is usually not exposed to light

Inhibited GTL

After 768 hrs

Uninhibited Naphthenic

After 168 hrs

Inhibited Naphthenic

After 168 hrs

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1

COOLINGMAIN FUNCTIONS OF THE OIL IN A TRANSFORMER IS TO TRANSFER HEAT FROM THE CORE TO THE EXTERNAL RADIATORS

Uninhibited Naphthenic Oil

Uninhibited Naphthenic Oil

Inhibited Naphthenic Oil

Inhibited GTL Oil

Viscosity (fluidity)

UNINHIBITED

NAPHTHENIC OIL

INHIBITED

NAPHTHENIC OIL

INHIBITED GTL OIL

THERMAL PROPERTIES

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Bintulu Gas to Liquids Plant, Malaysia

▪ Colourless▪ Odourless▪ Readily biodegradable ▪ Enhanced oxidation control▪ Improved performance at low and high

temperature▪ Improved thermal characteristics (thermal

conductivity and specific heat)▪ Increased VI▪ Low volatility▪ Low density▪ Improved chemical combination with additives▪ Sulfur free - lower corrosion potential

GTLPRODUCTS

Conventional Diesel (left) and

Shell GTL Fuel (right)

Colour comparison between GTL (left) and Diesel (right)

Benefits of using Shell transformer oils with GTL base oil

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Copyright of Shell Global Solutions US Inc.

31Junio 2017Copyright of Shell International