20_krueger_pd measurements on it.pdf

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Partial Discharge Measurements on Instrument Transformers Dr. Michael Krüger (c) OMICRON

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Page 1: 20_KRUEGER_PD measurements on IT.pdf

Partial Discharge Measurements on Instrument Transformers

Dr. Michael Krüger (c) OMICRON

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Faults on Instrument Transformers

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Faults on Instrument Transformers

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Faults on Instrument Transformers

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Faults on Instrument Transformers

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Measurement Method Application Indicated by FRT*

Oil Diagnosis(Water Content, Breakdown Voltage , DGA ...)

Routine TestPeriodical Testse.g. every 7 years

FRT

Tan-Delta / PFInsulation Diagnosis, Ageing, Moisture

Karl-Fischer Titration, DGA FRT

Dielectric Response Insulation Diagnosis, Ageing, Moisture

Karl-Fischer Titration, DGA FRT

Partial Discharge Measurement

Insulation Diagnosis, Partial Discharges

DGA T

Ratio VT Accuracy After Outage, Oil Values FRTRatio CT Accuracy Wrong Current Readings FRTExcitation Current VT Core Faults, Shorted Turns After Outage, Oil Values FTExcitation Current CT Knee Point Voltage Malfunction of the Protection FRT*F=Fingerprint, R=Routine, T=Troubleshooting

Electrical Measurement Methods for Instrument Transformers

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PD Circuit according to IEC60270

(IEC 60270)

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PD Testing on Instrument Transformers

Example Ur = 10kV

1 min

28kV 7kV

< 20pC

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Design of a MV Epoxy Type Voltage Transformer

Source: RITZ Technical Dictionary Instrument Transformers

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Faults on MV Epoxy Type Instrument Transformers

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Exploded 6.6kV Voltage Transformer

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HV Transformer with Coupling Capacitor, Quadripole and PD Instrument

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Generation of the 150Hz Test Voltage with CPC100 + TR7

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Good CT with PD < 10pC at 12kV

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Conspicuous Voltage Transformer PD > 500pC at 8kV

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Hazardous PD on a Voltage Transformer TE = 2nC at 2.5kV!

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High Hydrogene on a 123kV VT-CT

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PD Measurements on GIS Voltage Transformers

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GIS Voltage Transformer

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Technical Assessment

Test Voltage: 1.2 x Um / √3 = 1.2 x 242 / √3 = 170 kV

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Technical Assessment

Calculation of the test current Voltage Transformer DataPrimary voltage UPrim 242 [kV]

Sekundary voltage USec 0,11 [kV]

Maximum operation voltage Um 245 [kV]Operation voltage U 230 [kV]

Calculation of the Capacitances Capacitance of the busbar -B3 CGIS 600 [pF]

Capacitance of the voltage transformer CTP 300 [pF]

Capacitance of the HV SF6 - outdoor bushing CTrav 400 [pF]

Cpacitance of the coupling capacitor 300 kV CCondo 300 [pF]

Total capacitance Ctot 1600 [pF]

Test DataTest voltage 1.2 * Um / V3 170 [kV]Test frequency f 60 [Hz]

Calculation of the Test CurrentPrimary current (245kV) IPrim 0,103 [A]

Secondary current (110V) ISec 226 [A]Needed test power = 75V * 226A S 17 [kVA]

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Test Setup

> 01.31.13034 Omicron - Diag.-Woche - TE 220 kV Spgswandler

GIS Gas volume B4

GIS SF6 / outdoor

bushing

GIS Gas volume B3

Coupling capacitor 333pF / 300kV

Quadripole

PD instrument

MPD600

CPC100

CP TR8

CP CR6

CP CR6 CP CR6

CP CR6

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110V Measurement Circuit

> 01.31.13034 Omicron - Diag.-Woche - TE 220 kV Spgswandler

ω

ω

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Resonance:

I = 226A

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Setup - 110V Side

CPC100 (Source)

Matching transformer and compensation reactors

Secondary terminals PAGE 24

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Setup 242kV Side Coupling Caoacitor 333pF 300kV with Quadripole and MDD600

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PD Calibration with 100pC

PD Calibrator

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PD Level < 6pC at 170kV

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[email protected] Questions and Remarks?