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EPRI PILC Cable Condition EPRI PILC Cable Condition Assessment Assessment

Project SummaryProject Summary

30 April 2003

Presented by

Vern BuchholzPowertech Labs

To ICC Educational Program

EPRI Project Manager

Rob Keefe

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Project ObjectivesProject Objectives

• Examine five field, diagnostic techniques for PILC cable insulation.

• Compare the results of the field techniques to lab measurements

• Evaluate five diagnostic methods for lead sheath.

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Project TasksProject Tasks• Collect lengths of PILC cable

• “Field” Testing:• Insulation diagnostics on terminated cables• Lead sheath diagnostic tests• Tests in Substation on 2.5 km long cable.

• Lab Testing:• Conduct chemical lab tests on insulation samples• Conduct AC Breakdown tests• Conduct water ingress test• Conduct accelerated aging test on lead.

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Cables TestedCables Tested

BC Hydro19565 kV, 3-Ph, JacketG

Reliant Energy ?12 kV, 1-Ph, Cambric TappedK

BC Hydro195915 kV, 3-Ph, U/JJ

BC Hydro198615 kV, 3-Ph, JacketI

BC Hydro19555 kV, 3-Ph, U/JH

San Antonio Pub Srv196114 kV, 3-Ph, U/JF

Northern States Pwr>40 yrs5 kV, 3-Ph, U/JE

Reliant Energy 193812 kV, 1-Ph, U/JD

Utility Age TypeCable

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Cables Tested (Cables Tested (con’tcon’t))

United Illuminating198615 kV, 3-Ph, JacketS

Toronto Hydro193113.8 kV, 1-Ph, U/JO

PSE&G196926 kV, 3-Ph, JacketR

BC Hydro197315 kV, 3-Ph, JacketQ

BC Hydro197315 kV, 3-Ph, JacketP

BC Hydro1993 15 kV, 3-Ph, JacketN

Reliant Energy 195212 kV, 1-Ph, U/JM

Reliant Energy 195612 kV, 1-Ph, U/JL

Utility Age TypeCable

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Cable Cross SectionsCable Cross Sections

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Diagnostic Tests for Insulation Evaluation on Terminated Cables

• Isothermal Relaxation Currents (IRC)• Return Voltage Method (RVM)• LIpATEST • Dielectric Spectroscopy • Harmonic Method

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Isothermal Relaxation Currents (IRC)Model KDA-1 from SebaKMTSold in North America by HDW Electronics

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Isothermal Relaxation Currents (IRC)

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Return Voltage Method (RVM)

• Automated measurement:

• Charge @ 1kV dc for 30 minutes• Quick discharge for 2-5 seconds• Measure & record return voltage for 30 min. (typ.)• Discharge for 30 min.• Charge @ 2 kV dc for 30 minutes• Quick discharge for 2-5 seconds• Measure & record return voltage for 30 min. (typ.)

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Return Voltage Method (RVM)Model CD 31 made by SebaKMTSold in North America by HDW Electronics

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Return Voltage Method (RVM)Return Voltage Method (RVM)

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LIpATESTLeakage Current pico amp TESTLIpATEST service provided by Powertech Labs

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LIpATEST Results Normalized to Cable Capacitance

0

20

40

60

80

100

120

0 1 2 3 4 5 6

Maximum Test Field (kV/mm)

Cur

rent

/Cab

le C

ap (n

A/n

F)

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Dielectric SpectroscopyModel IDA 200 from ProgrammaSold by General Electric

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Dielectric SpectroscopyDielectric SpectroscopyTan Delta on 2 cables

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.001 0.01 0.1 1 10 100 1000Frequency (Hz)

Tan

d

IA NABC

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Harmonic MethodHarmonic Method

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Lead sheath diagnostic tests

• Rebound Hardness Tests • Dye Penetrant Examination• Eddy Current Examination• In-Situ Metallography (Replica)• Chemical Analysis of small samples

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Rebound HarnessRebound Harness

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Rebound HarnessRebound Harness

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Rebound HarnessRebound Harness

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Fluorescent Dye ExaminationFluorescent Dye Examination

Cracks on the Wrinkled Area of the Lead Sheath

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Eddy Current Dye ExaminationEddy Current Dye Examination

Established NDT method usually applied to metal structuresEstablished NDT method usually applied to metal structures

Surface of the lead sheathImpedance-phase Diagram

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InIn--situ situ MetallogaphicMetallogaphic Examination Examination

“Replica” of the surface structure taken on acetate film

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InIn--situ situ MetallogaphicMetallogaphic Examination Examination

Micrograph of the lead directly Micrograph of the “Replica”

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Chemical Tests on paper and oil samples

• Karl-Fischer Moisture Measurement• Fourier Transform Infra-Red (FTIR) • Fluorescence Measurements under UV

Light• Dielectric Thermal Analysis (DTA)

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AC break down testsAC break down tests

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AC break down test AC break down test procedureprocedure

•All cables in ACBD test were 9 m long terminated with stress tubes•Tested one phase at a time with other phases grounded•Test started at two times normal operating voltage and held for 6 hours•Voltage increased in steps equal to normal operating voltage•At each step voltage held for 6 hours•After each failure cable examined to determine were cable failed

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Water Ingress Test Water Ingress Test

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Water Ingress Test ProcedureWater Ingress Test Procedure

Cable P ( 1973) placed in tank under 1 m of tape water3 phase connected in series for current cycling330 A on for 8 hrs, off for 16 hrs8 kv always on12.5 cm slit cut in lead sheath for 1.5 monthsSlit enlarged to 1 cm by 12.5 cm holeMeasure LIpATEST and RVM at intervalsMonitor current and voltage for harmonic measurement

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Water Ingress test failure siteWater Ingress test failure site

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REPORTREPORT

Available on EPRI.com

“Assessment of Paper-Insulated Lead-Covered Cable Condition: Electrical, Chemical, and Metallurgical Condition” 1001724 - 2/25/2003