13_KRUEGER_Cond Assess HV Bushings.pdf

Advanced Diagnostic Tests on High Voltage Bushings Dr. Michael Krger, OMICRON Austria

Cigre A2.37 Transformer Failure Statistics Failure Locations of Substation Transformers >100kV

Source: No. 261 - April 2012 ELECTRA

PAGE 2

Insulation Systems of High Voltage Bushings

RBP Resin Bonded Paper

RIP Resin Impregnated Paper

OIP Oil Impregnated Paper

PAGE 10

RBP RIP OIP

1913 to 1974 since 1950 since 1960

Recommended measures

Time schedule

Visual check leakage and mechanical damage

In case of maintenance work

Measurement of capacitance and dielectric dissipation factor

- after installation as reference for later measurements (fingerprint) - 10 years after commissioning

- dependend on results after each 5 years (uncritical values) or shorter

Insulation Systems of High Voltage Bushings

Source: B. Heil (HSP Troisdorf, Germany), Diagnose und Bewertung von Durchfhrungen, OMICRON AWT Germany 2010

PAGE 11

Capacitive Bushings (1)

Emax= high

A

Emax= smaller

A

without capacitive

layers

with capacitive

layers Earthing Cap

PAGE 17


PAGE 18

Aluminium foils with equal areas

Aluminium foil Paper

Aluminium foil Conductor


PAGE 19

Current at the Measurement Tap

50 = = 10 100 1.2 = / = 200

Bushing Measuring Tap

PAGE 25

Measuring Taps

MICAFIL

ABB

PAGE 26

Measuring Taps

HSP

PAGE 27

Measuring Taps

GE

PAGE 28

Arcing at the Measurement Tap

PAGE 29

Source: Norbert Koch Diagnoseverfahren an Hochspannungsdurchfhrungen aus Herstellersicht, Diagnoseverfahren an Schaltanlagen und Transformatoren, HdT Essen 2013

Partly Burned Measurement Tap of a 245kV-RIP Busing

PAGE 30 Source: Hubert Goebel GmbH

Partly Burned Measurement Tap of a 400kV-OIP Busing


Diagnostic Methods

PAGE 32

Type of FaultMoisture AgeingContact problems and high impedance faults between layersShorted grading layersLeakagePartial discharges Diagnostic Technique

OIP 5 1 5 5 5 5RBP 5 1 5 5 5 5RIP 5 1 5 5 5 5OIP 4 5 4 3 4 5RBP 4 5 4 3 4 5RIP 4 5 4 3 4 5OIP 5 4* 1 3 4 4RBP 5 4* 1 3 4 4RIP 5 4* 1 3 4 4OIP 3 5 3 1** 2 2RBP 3 5 3 1** 2 2RIP 3 5 3 1** 2 2OIP 3 5 1 1 1 1RBP 3 5 1 1 1 1RIP 3 5 1 1 1 1OIP 1 5 3 1 5 4RBP 1 5 3 1 5 4RIP 1 5 3 1 5 4

Dissolved gas analysis 1 5 1 1 4 5Moisture in oil 5 5 4 5 3 1DF/PF 4 5 4 3 2 2Conductivity of oil (IEC 61620) 4 5 4 3 2 2Particles in oil 5 5 5 5 2 5Analysis of Furanic components 5 5 5 5 1 5Test for corrosive Sulfur 5 5 5 5 2 51=very good, 2=good 3=fair 4=poor 5=not applicable*big leakages can be detected with hot collar test **DF/PF from 2-12kV

OIP

Gen

eral

Ele

ctric

al B

asic

Dielectric Responsewith FDS / PDC

Partial discharge measurementEle

ctric

al

Adv

ance

dO

il

Capacitance

DF/PF

Visual Inspection

Thermography

Infrared Thermography

PAGE 33

Source: ABB Brochure Bushing diagnostics and conditioning, 2750 515-142 en

C-Tan Progression of a Bushing

Source: RWE

PAGE 34

Source: Volker Seitz: Vorbeugende Instandhaltung an Leistungstransformatoren, OMICRON Anwendertagung 2003, Friedrichshafen

Bushing Fault

Source: RWE

PAGE 35

Source: Volker Seitz: Vorbeugende Instandhaltung an Leistungstransformatoren, OMICRON Anwendertagung 2003, Friedrichshafen

Definitions of Dielectric Losses

Dielectric losses are caused by Conductive losses

Polarization losses

Partial discharges

0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

2.50E-03

0 50 100 150 200 250 300 350 400

Parallel

Parallel

Parallel circuit Serial circuit

RP CP RS

CS totR

SSC

R

UU

CRUU

=

==

cos:PF

tan:DF

||||cos:PF

1||||tan:DF

tot

RP

PPCP

RP

II

CRII

=

==

0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

2.50E-03

0 50 100 150 200 250 300 350 400

Serial

Serial

0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

2.50E-03

0 50 100 150 200 250 300 350 400

SerialParallelSum

PAGE 38

Standards

Type RIP OIP RBP Main insulation Resin

impregnated paper

Oil impregnated paper

Resin bonded paper

DF / tan delta (20C, IEC60137)

< 0.7 % < 0.7 % < 1.5 %

PF cos phi (20C, IEEE C57.19.01)

< 0.85 % < 0.5 % < 2 %

Typical new values 0.3-0.4 % 0.2-0.4 % 0.5-0.6 %

PD (IEC60137) at Um 1.5 Um /3 1.05 Um /3

< 10 pC < 5 pC < 5 pC

< 10 pC < 5 pC < 5 pC

< 300 pC

PAGE 39

Cigre WG A2.34 Brochure 445 Guide for Transformer Maintenance

www.e-cigre.org

PAGE 43

Frequency

Not free of cavities Partial Discharges possible also at rated voltage

Higher dielectric losses can feed to thermal instability

RPB has cavities and cracks in the paper which are normally filled with the surrounding oil

Increase of capacitance

After a longer storage period this oil is running out. The PD level is increasing and the capacitance is getting smaller

RBP - Bushings

PAGE 44

RBP Bushings Cracks in the Insulation

PAGE 45

Micafil Bushings RBP Superresocel RBP Drysomic OIP and RIP Tan = f(T)

PAGE 49

Source: Karl Frey, Micafil

Measurement on 220kV RBP Bushings (1971)

PAGE 52

TanDelta 15-400Hz

PAGE 53

RBP Bushing Oil-Filled Cracks Oil Ingress by Capillare Effect

PAGE 54

RBP Bushing 123kV (1963)

PF (f) A, B, C

0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2% 0.

0Hz

50.0

Hz

100.

0Hz

150.

0Hz

200.

0Hz

250.

0Hz

300.

0Hz

350.

0Hz

400.

0Hz

450.

0Hz

A

Influence of Moisture

PAGE 55

Micafil UTXF 24 (Drysomic) RBP Bushings

A,B,N humid after wrong storage

C dried

PAGE 56

Micafil UTXF 24 RBP Bushings A,B,N never used, wrongly stored, C dried

Messung bei 20C DF (f) A, B, C, N

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

0.0H

z

50.0

Hz

100.

0Hz

150.

0Hz

200.

0Hz

250.

0Hz

300.

0Hz

350.

0Hz

400.

0Hz

450.

0Hz

ABCN

dried

humid

PAGE 57

RBP Bushing 123kV

?

PAGE 60

RBP Bushing 123kV

PF (V) A, B, C

0.5%

0.6%

0.7%

0.8%

0.9%

1.0%

1.1% 0.

0V

2000

.0V

4000

.0V

6000

.0V

8000

.0V

1000

0.0V

1200

0.0V

1400

0.0V

A B C

PAGE 61

RBP Bushing 123kV

PF (f) A, B, C

0.0%

0.5%

1.0%

1.5%

2.0%

2.5% 0.

0Hz

50.0

Hz

100.

0Hz

150.

0Hz

200.

0Hz

250.

0Hz

300.

0Hz

350.

0Hz

400.

0Hz

450.

0Hz

A B C

PAGE 62

RBP Bushing 123kV

Bushing has to be exchanged defective contact on the measuring tap or

defective connection between the innermost layer and the HV conductor or

partial breakdown between layers

PAGE 63

Measurement Tap O.K.

PAGE 64

Innermost Layer was not Properly Connected to the HV Conductor.

PAGE 65

123kV RBP Bushing

PAGE 66

Dissipation Factor Measurement

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

8.0%0.

0Hz

50.0

Hz

100.

0Hz

150.

0Hz

200.

0Hz

250.

0Hz

300.

0Hz

350.

0Hz

400.

0Hz

450.

0Hz

DF (f) A, B, C

A

B

C

PAGE 67

Measurement of the Removed Bushing

PAGE 68

Measurement of the Removed Bushing

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

14.0%

16.0%0.

0Hz

50.0

Hz

100.

0Hz

150.

0Hz

200.

0Hz

250.

0Hz

300.

0Hz

350.

0Hz

400.

0Hz

450.

0Hz

DF (f)

C1

PAGE 69

Aktivteil

PAGE 70

OIP Bushings

Paper of the OIP bushings ages particularly at high temperatures

Through aging the dielectric losses will increase -> this increases the power factor

Temperature dependent aging decomposes the Paper and produces additional water -> this accellerates the aging

PAGE 73

OIP Bushing Fault


OIP Bushing


OIP Bushing Breakdown at the Sharp Edge of the Foil


OIP Bushing


33kV OIP Bushings

New bushings

Removed bushings

C-Tan-Delta Meas.

PAGE 95

Tan Delta (T) at 50Hz (OIP DF)

0.10

1.00

10.00

20 30 40 50 60 70 80 90C

[%]0.1-0.3% Water in paper

0.4-0.6% Water in paper

1% Water in paper

Source: ABB, Bushing diagnostics and conditioning

PAGE 96

Tan Delta (f) at 30C (33kV OIP DF)

Tan Delta (f) A, B, C

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.80 50 100

150

200

250

300

350

400

450Hz

%

ABCA RemovedB RemovedC Removed

PAGE 97

123kV OIP Bushings TanDelta = f(U)

PF (V) A, B, C

0.4%

0.5% 0.6% 0.7%

0.8% 0.9% 1.0%

1.1% 1.2% 1.3%

0.0V

2000

.0V

4000

.0V

6000

.0V

8000

.0V

1000

0.0V

1200

0.0V

1400

0.0V

A B C

PAGE 98

123kV OIP Bushings TanDelta = f(f)

PAGE 99

123kV OIP DF Corroded Measuring Tap

PAGE 100

Ageing of RIP Bushings

Partial breakdowns between capacitive layers are rather seldom

Decrease of the power factor with increasing test voltage can be an indicator for partial breakdowns

Also defective connections of the measurement layer to the test tap or of the innermost layer to the high voltage conductor may be the reason for a decrease of the power factor with increasing test voltage

Increase of the capacitance after a partial breakdown between two layers:

Cnew = Cold x n / (n-1) n= number of layers approx. 4-7 kV per layer

PAGE 101

RIP Bushings

PAGE 113

RIP Bushing

PAGE 114

Partial Breakdown on a RIP Bushing

Source: B. Heil, Diagnose und Bewertung von Durchfhrungen, OMICRON AWT Germany 2010

PAGE 115

220kV RIP Bushing, Stored Outside

PAGE 119

220kV RIP Bushing, Stored Outside

0.25 %

0.35 %

0.45 %

0.55 %

0.65 %

0.75 %

0.85 %

0.0 Hz 100.0 Hz 200.0 Hz 300.0 Hz 400.0 Hz 500.0 Hz

Tan

Del

ta

after removing from TR 3 months after removing6 months afetr removing

Minimum

Minimum

Minimum

PAGE 120

Influence of Humidity for 123kV Bushings with Silicone Coated Composite Insulators Mounted Horizontally

DF (f)

0.2%

0.3%

0.4%

0.5%

0.6%

0.7%

0.8%

0.9%

1.0%

0.0Hz 50.0Hz 100.0Hz 150.0Hz 200.0Hz 250.0Hz 300.0Hz 350.0Hz 400.0Hz 450.0Hz

T31 2U2(f)T31 2V2(f)T31 2W2(f)T32 2U2(f)T32 2V2(f)T32 2W2(f)T33 2U2(f)T33 2V2(f)T33 2W2(f)



DF (f)

0.2%

0.3%

0.4%

0.5%

0.6%

0.7%

0.8%

0.9%

1.0%

0.0Hz 50.0Hz 100.0Hz 150.0Hz 200.0Hz 250.0Hz 300.0Hz 350.0Hz 400.0Hz 450.0Hz

ABC

DF (f) A, B, C

0.0%

0.1%

0.2%

0.3%

0.4%

0.5%

0.6%

0.0H

z

50.0

Hz

100.

0Hz

150.

0Hz

200.

0Hz

250.

0Hz

300.

0Hz

350.

0Hz

400.

0Hz

450.

0Hz

ABC

Bushings with moss and outer humidity

Bushings cleaned, measured at dry weather

Measurement with Guard Leakage current is bypassing the meter

Meas. tap

Guard

Capacitive layer

Meas. layer

Leakage current

Measurement With High Humidity With and Without Guard

Measurement With High Humidity With and Without Guard

without Guard

with Guard

RIP Bushings without Epoxy Tube

before cleaning after cleaning PAGE 128

RIP Bushing without Epoxy Tube Inner Moisture

PAGE 129

PresenterPresentation NotesHier der Hinweis, dass es auch satte = niederohmige Teildurchschlge gibt.

The oil side of RBP and RIP bushings doesn't need a housing

Cellulose near to the surface can absorb water, if bushings are not stored properly

Incoming water, also from the ambient air reduces the dielectric strength this causes an increase of the dielectric dissipation factor

Moisture in RBP and RIP Bushings

PAGE 130

Water in RBP and RIP Bushings

RIP wet RIP dry

Drying of RBP and RIP bushings

is limited

PAGE 131

PresenterPresentation NotesFeuchtigkeit ist nicht in allen Fllen durch erhhten Verlustfaktor erkennbar.

Die Verlustfaktormessung ist eine integrale Methode, welche das gesamte Volumen und das Streufeld erfasst.

Feuchtigkeit durchdringt selten mehr als 1% des Harzvolumens.

Bei einem Anstieg des Verlustfaktors um beispielsweise 10% ist die Oberflche erheblich strker elektrisch geschwchtals das innere Dielektrikum.

Die hheren Verlustfaktoren sind nicht nur bei hheren Temperaturen besser erkennbar.

Es sind die Betriebstemperaturen. Hier beschleunigen sie auch die Alterung.

Measurement of the Dielectric Response with FDS und PDC

PAGE 132

PDC FDS

Combination of PDC und FDS reduces measurement time

Combined FDS-PDC Measurement on a RIP Bushing

PAGE 133

RBP RIP

OIP

FDS Results on RIP, RBP and OIP Bushings

PAGE 134

25C

60C

FDS/PDC on a RIP Bushing at Different Temperatures

50Hz tan

PAGE 135

Source: G. Kopp, Measurement of the dielectric response on HV bushings

dry surface

wet surface

FDS/PDC with Dry and Wet Surface

50Hz tan equal

PAGE 136

Source: G. Kopp, Measurement of the dielectric response on HV bushings

[email protected]

Questions and Remarks?

Advanced Diagnostic Tests on High Voltage BushingsDr. Michael Krger, OMICRON AustriaCigre A2.37 Transformer Failure StatisticsFailure Locations of Substation Transformers >100kVInsulation Systems of High Voltage BushingsInsulation Systems of High Voltage BushingsCapacitive Bushings (1)Capacitive Bushings (2)Capacitive Bushings (3)Bushing Measuring TapMeasuring TapsMeasuring TapsMeasuring TapsArcing at the Measurement TapSlide Number 30Slide Number 31Diagnostic MethodsInfrared ThermographyC-Tan Progression of a BushingBushing FaultDefinitions of Dielectric LossesStandardsSlide Number 43Slide Number 44Slide Number 45Slide Number 49Measurement on 220kV RBP Bushings (1971) TanDelta 15-400HzRBP Bushing Oil-Filled Cracks Oil Ingress by Capillare EffectRBP Bushing 123kV (1963)Micafil UTXF 24 (Drysomic) RBP BushingsMicafil UTXF 24 RBP Bushings A,B,N never used, wrongly stored, C driedRBP Bushing 123kVRBP Bushing 123kVRBP Bushing 123kVRBP Bushing 123kVMeasurement Tap O.K.Innermost Layer was not Properly Connected to the HV Conductor.Slide Number 66Slide Number 67Slide Number 68Slide Number 69Slide Number 70Slide Number 73Slide Number 80Slide Number 81Slide Number 82Slide Number 90Slide Number 91Slide Number 9433kV OIP BushingsTan Delta (T) at 50Hz (OIP DF)Tan Delta (f) at 30C (33kV OIP DF)123kV OIP Bushings TanDelta = f(U)123kV OIP Bushings TanDelta = f(f) 123kV OIP DF Corroded Measuring TapSlide Number 101RIP BushingsRIP BushingPartial Breakdown on a RIP Bushing220kV RIP Bushing, Stored Outside220kV RIP Bushing, Stored OutsideInfluence of Humidity for 123kV Bushings with Silicone Coated Composite Insulators Mounted HorizontallyInfluence of Humidity for 123kV Bushings with Silicone Coated Composite Insulators Mounted HorizontallyInfluence of Humidity for 123kV Bushings with Silicone Coated Composite Insulators Mounted HorizontallyMeasurement with GuardLeakage current is bypassing the meterMeasurement With High Humidity With and Without GuardMeasurement With High Humidity With and Without GuardSlide Number 128Slide Number 129Slide Number 130Slide Number 131Slide Number 132Slide Number 133Slide Number 134Slide Number 135Slide Number 136Slide Number 169

13_KRUEGER_Cond Assess HV Bushings.pdf

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