transformer oils - production, performance and in-service

TRANSFORM Partner

Johan Grövik

Nynas AB

Transformer oils - Production, performance and in-service behaviour

06.06.2013 Johan Grövik, Nynas AB

Nynas

Johan Grövik

M.Sc Chemical Engineering

M.Sc Business Administration

Market Manager Electrical Industry

e-mail: [email protected]

Nynas AB founded 1928

Swedish based company

Approximately 850 employees

Turnover 2 billion EURO

28 Sales channels

More than 18 TRO depots

Market leader of transformer

oils with market share of 25 %

Oil demand in the world 2012 versus transformer oil

Manufacturing of a transformer oil

Failure statistics

Selection of insulating oil

Maintenance of an insulating oil

Summary

06.06.2013 Johan Grövik, Nynas AB

Outline

Johan Grövik, Nynas AB

Naphthenic crude supply

Proven

Naphthenic

crude

reserves for

the next 70

years

TOTAL= 4442 million Mt BASE OIL= 36 million Mt TRO = 1,2 Million Mt

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Basic: -Chemical composition of crude oil

Mineral insulating oil is made from crude oil by different refining processes.

The constituents are hydrocarbons combined in various structures and sizes.

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Trends in the world of refining

Technical trend

- Development of base oils with high VI

Focus on lubrications

- Market >36 Mt

Key driver for engine oils

- To minimize friction

- Fuel efficiency

TRO oils do not have

that technology driver!

It require a low VI oil

for best performance

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Provide good cooling

Act as an electrical insulator

Have an excellent cold start property

Material compatibility

Last the lifetime of transformer

Act as an information carrier


What are the requirements of an insulating oil?

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Production of insulation oil

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A modern hydrotreatment refinery

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Distillation

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Hydro-treating processes

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Degree of refining

Before HT (%)

CA (IR) 25CN 30CP 45Sulphur 2

IP346 10

After HT (%)

T NS SCA (IR) 15 10 5CN 42 50 50CP 43 40 45Sulphur 0.03 <0.01 0.01

IP346 2.0 1 <1

Before

hydrotreatment

CA 25%

CN 30

CP 45

Sulphur 2

IP346 10

After

hydrotreatment

A B C

CA 15 10 5

CN 42 50 50

CP 43 40 45

Sulphur 0.03 0.01 0.01

IP346 2 1 <1

Carbon type distribution determined with IR analysis

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Failure statistics

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Failure rates of substation transformers

Ref; April 2012 Electra Failure rate for step up transformers

= 0,46 %

Failures /

population

info.

69-100

kV

100-200

kV

200-300

kV

300-500

kV

>700

kV

ALL

Failures 145 206 136 95 7 589

Transformer

- years

15077 46152 42635 29437 219 135491

Failure rate 0,96% 0,46% 0,32 0,32% 3,20% 0,43%

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Failure rate conclusion

Preliminary results; (data collection still in progress)

I. Study based on 150 000 unit years

II. Totally 685 failures

III. Data from 48 utilities

Average failure rate = 0,44%

Main fault locations (*=GSU transformer)

45-49* % of failures related to windings

26-11* % of failures related to tap changers

9*-17 % of failures related to bushings

7-19* % of failures related to lead exits

Old study from 1983

(failures occurring 1968-1978)

Concluded a failure rate

benchmark of

2%

Ref; April 2012 Electra

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Generic failure model; 2 – perspective methodology

Grid design

Operations

Protection equipment

Transformer quality

Analysis => information

Maintenance actions

Damage from incidents

Maintenance

Failure

Strength

Stress encountered

Incidents

Time

Stress / Strength

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What is the lifetime of a transformer dependent on?

Design / Manufacturing / Material

Maintenance Operations

e.g. load

Operating conditions

Ambient temperature

Design and materials

Manufacturing and installation

Follow up and maintenance

Electricity quality/protection

equipment

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Selection of insulating oil

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Product Data Sheets

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Values and benefits - life cycle perspective

Less maintenance over time

Slow degradation

of oil and paper

Longer transformer life

Low viscosity

oils

Lower operating

temperatures

Good oxidation

stability

Low acid values

and low sludge

production

High solvency Keep sludge

dissolved in oil

Better circulation

properties

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Values and benefits – daily operations

Transformer can be energized

in low temperatures

Very strong and stable

insulation system enable

compact design and high

voltages

Diagnostic tool to prevent

failures and avoid outages

Low pour point

Excellent insulator

Can withstand

very high

electrical stress

Information

carrier

Record & store

fault gases

Allow to detect

electrical &

thermal faults

Good flow

properties at very

low temperatures

Excellent

compatibility with

cellulose

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Selection of transformer oil

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Maintenance

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Antioxidant molecule and specification limits

IEC 60296 Edition 4. 2012

Uninhibited Not detectable

Trace Max 0,08

Inhibited Max 0,40

ASTM D 3487

Type I Max 0,08

Type II Max 0,30

DBPC

Di-tert-butyl-para-cresol

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Acidity level and inhibitor content

0

0,1

0,2

0,3

0,4 1

24

47

70

93

116

13

9

16

2

18

5

20

8

23

1

25

4

27

7

30

0

32

3

34

6

36

9

Inhibitor (%)

No of samples (increased inhibitor content to the right)

Acidity (mg KOH/g)

- 400 oil immersed power transformers

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Maintenance strategy

What?

How?

Who?

Why?

Historical data

Analysis

Diagnostic

Information

Decisions

Maintenance New investment Upgrade etc. Risk level

Oil status DGA status

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Summary; Standards for insulating oils

Fluids for

electrotechnical

applications

Unused mineral

insulating oils for

transformers and

switchgear

IEC 60296

Mineral insulating

oils in electrical

equipment

Supervision and

maintenance

guidance

IEC 60422

Test & Measuring

methods

IEC 60296

Before filling into

a transformer

IEC 60422

After filling

into a transformer

Insulating liquids

Determination of

breakdown

voltage at power

frequency – test

method

IEC 60156

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Summary

Transformer oil quality

Excellent insulator

Low Viscosity & VI

Superior long term stability

Operations

Cooling

- As low temperature as possible

Oxygen

- Protection systems

Loading

- Do not over load

Maintenance

Antioxidant levels

- Monitor and top up

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Nynas Group Head Office

P.O. Box 10700

SE-121 29 Stockholm

Sweden

My contact details;

Johan Grövik

[email protected]

Phone: + 46 70 658 68 35

Transformer oils - Production, performance and in-service behaviour

[email protected]

06.06.2013

mailto:[email protected]

transformer oils - production, performance and in-service

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