Best Practices in Transformer MaintenanceNWPPA, Anchorage, AK October 2009Wayne BishopWayne Bishop Business Development Manager

Today’s PresentationToday’s Presentation• Introduction to OMICRON• Meeting the Challenges in our Industry• Condition Assessment of Transformers• Condition Assessment of Transformers• New Technologies for Testing (Peter

F )Fong)– Current Transformer Testing– Dielectric Response Analysis

© OMICRON January 13, 2008 Page 2

OMICRONOMICRON• World Leader in the design and

f t f t t i t t fmanufacture of test instruments for power system apparatus

• Test Instruments in 130 countries• Team of 400 employees worldwidep y

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OMICRON worldwide– A truly international team with a worldwide

network

Houston / USA Shanghai / China

KoreaBoston/ USA

Stafford / Great Britain

Hong Kong

New Delhi / India

Madrid / Spain

Cergy / France

Berlin / GermanyMelbourne / Australia

Bahrain

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Klaus / Austria Erlangen / Germany

BUprim - Hardware– The Innovations in Primary

Testing!

MPD600 (PD) DIRANA (DFR)

CPC 100 Multifunctional CP CU1Primary Test Set CP CU1Coupling UnitCP GB1

Grounding Box

CPC 100 + CP TD1Power Factor Testing

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CT Analyzer FRAnalyzer (SFRA)

BUsec - Hardware

CMC 256plus CMC 356

CMC 156CMS 156

CMS 252CMS 252CMB IO-7

CMA 156

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Challenges Facing our Industry

With deregulation of the energy markets, the life span of electrical assets becomes critical. p

• All assets including all transformers have to be in service as long as possible.service as long as possible.

• For transformers this can mean continuous operation over the life span of the asset at full loadoperation over the life span of the asset at full load or even more since redundant transformer assets are not available.

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Situation for Most of IndustryS tuat o o ost o dust y

A large percentage of transformers are in service for more than 25 years – with the health of the transformers

t ft knot often known.

About 35% - 40% of all transformer faults are caused by ybreakdowns in the aged insulation.

• TemperatureTemperature• Moisture

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Situation Today

Many of the transformers in Germany have an age of 25-30 years

70

80

90

100

70

80

90

100

ers

30

40

50

60

70

30

40

50

60

70

f tra

nsfo

rme

0

10

20

30

0

10

20

30

1-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 46-50 51-55

No.

of

Problem: faults happen more often with increasing age

Betriebsalter der Transformatoren in JahrenAge of transformers / years

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increasing age

Healthy 90 year oldHealthy 90 year old

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Healthy?• Blood Tests

Urinal sis• Urinalysis• Temperature and Blood Pressure• Ultrasound • MRIMRI• Family Health History

Life Style Environment Stress• Life Style, Environment, Stress

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I thi H lth T f ?Is this a Healthy Transformer?

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Si il M th d lSimilar Methodology

Healthy Person ? Healthy Transformer ?Healthy Person ?• Blood Tests, Urinalysis,

Temperature

Healthy Transformer ?• DGA, Power Factor, %

Moisture Insulationp• Family History • Transformer Design

HistoryL d P fil L ti f• Stress, Environment,

Workplace, Lifestyle• Load Profile, Location of

Transformer

• Type of Care • Maintenance Program (TBM, CBM, RCM)

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Transformer DiagnosticsReview Patients History• Family History ofy y

– High Blood Pressure and Heart Disease– High Cholesterol, Cancer Risks, etc.

Review History of Transformer• Maintenance History• Operational History• Service Advisories• Factory TestsFactory Tests• Site Inspections• Routine Tests

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Generator Transformer 27/400kV

HV Bushing

Measuring Tap LV BushingMeasuring Tap LV Bushing

High Voltage Winding

Tapped Winding

L V l Wi di

Tap Selector

Diverter Switch

C

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Low Voltage WindingCore

Failure Mode Properties

Di l t i St• Dielectric Stress

• Thermal Degradation• Thermal Degradation

• Mechanical Stress• Mechanical Stress

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Maintenance Philosophies

• Time Based Maintenance (TBM)P f R ti P t ti M i tPerform Routine Preventative Maintenance

• Reliability Centered Maintenance (RCM)Focus Resources on Bad Actors

• Condition Based Maintenance (CBM)Condition Based Maintenance (CBM)Require Indication while In-service

• The Maintenance SpectrumRun to Failure Diagnostic Overkill

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Transformer Tests• DGA/Oil Screen/Furans• Power Factor and Capacitance• Power Factor and Capacitance• Excitation Current

Turns Ratio (TTR)• Turns Ratio (TTR)• SFRA• Leakage Reactance• DC Winding Resistance• Dielectric Frequency Response• IR

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Dielectric Thermal Mechanical

DGA DGA SFRA

Oil Screen Oil Screen Leakage Reactance

PF/Cap Thermal Imaging Capacitance

Excitation Current DC Winding Excitation CurrentExcitation Current DC Winding Resistance

Excitation Current

TTR DC Winding Resistance

Partial Discharge

Dielectric Frequency

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Response

Electrical Measurement Methods I

Measurement Method Application Indicated by Kind of

Test*on-/off-

line

Winding resistance (static)

Contact problems,broken or loose connections,broken conductors

High internal temperatures, e.g. indicated by DGA results or Buchholz Relay

FRT off

Wi di i t Contact problems at theWinding resistance (dynamic)

Contact problems at the diverter switch, broken transition resistors

DGA, Buchholz Relay FRT off

Leakage reactance (stray reactance)

Winding deformation High through-fault currents FRT offreactance)Frequency Response of the Stray Losses (FRSL)

Broken parallel strands High internal temperatures, e.g. indicated by DGA results

FT off

No-load impedance Core problems, shorted turns High internal temperatures, e g indicated by DGA results

FT offe.g. indicated by DGA results

Magnetising current Core problems, shorted turns High internal temperatures, e.g. indicated by DGA results

FT off

F=Fingerprint, R=Routine, T=Troubleshooting, S=Special

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Electrical Measurement Methods IIKindMeasurement

Method Application Indicated byKind

of Test*

on-/off-line

Turns ratio After Buchholz Relay Buchholz Relay has T off

Frequency Response Analysis (FRA)

Winding deformation, winding displacement, core faults, faulty screen or core

High through-fault currents, transportation

F(R)T off

screen or core

Insulation resistance Insulation problems Breakdowns, Buchholz Relay

FRT off

Capacitance and Main insulation: ageing, pDielectric Dissipation Factor

g g,moisture - Bushings: ageing, partial

DGA FRT on/off

Dielectric Response M t (FDS

Main insulation: ageing, i t B hi

high water content in il / hi h di l t i FRT ffMeasurement (FDS

and PDC)moisture - Bushings: ageing, partial

oil / high dielectric losses

FRT off

Partial Discharge Insulation problems DGA T on/off F=Fingerprint, R=Routine, T=Troubleshooting, S=Special

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g p g p