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Use of Composite Coresfor High Temperature-Low Sag (HTLS)

Conductors (T-33)

PSERC Tele-SeminarSeptember 4, 2007

Ravi Gorur & Barzin Mobasher: Principal Investigators at Arizona State UniversityR. Olsen: Principal Investigator at Washington State UniversityM. Dyer & J. Hunt: Industry Advisors, Salt River ProjectJ. Gutierrez: Industry Advisor, Arizona Public Service

Disclaimer• The information contained in this presentation was prepared by ASU

as an account of work sponsored certain utilities and PSERC. Neither PSERC, any cosponsor, ASU:(a) makes any warranty or representation whatsoever, express or implied, (i) with respect to the use of any information, apparatus, method, process, or similar item disclosed in this presentation,including merchantability and fitness for a particular purpose, or (ii) that such use does not infringe on or interfere with privately owned rights, including any party’s intellectual property, or (iii) that this presentation is suitable to any particular user’s circumstance: or

• (b) Assumes responsibility for any damages or other liability whatsoever (including any consequential damages) resulting from your selection or use of this presentation or any information, apparatus, method, process, or similar item disclosed in this package

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Motivation

• Increase power delivery on existing ROW without violating sag criterion

• Different methods presently in use– ACSS (aluminum conductor steel supported)– AAAC (aluminum alloy conductor)– ACIR (aluminum conductor invar reinforced)– Gap type conductor

• Composite cores for conductors is fairly recent

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Composite cores evaluated

Metal matrix composite Carbon composite

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What we intend to achieve

• Develop laboratory techniques for fingerprinting and screening core materials

• Understand failure modes and mechanisms of composite core materials

• Develop thermal models for evaluating core temperature

Practical Benefits• Better technical specifications• Data to assist in dynamic rating

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Research Questions• Two “very different” types of HTLS conductors using

composite cores presently available. How do they compare?

• Supposed to operate at 180-240 oC (> 2 times presently used values). How does this affect performance (mainly mechanical)?

• Conductors are expected to last many decades, how can be predict useful life? What about failure mechanisms?

• Performance is strongly related to formulation and processing (manufacturer’s domain). What measures can users employ to validate manufacturers’ claims

• Mixed experience with composite (polymeric) materials for insulators, can we avoid doing the same mistakes?

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Microscopic DetailsMetal matrix composite Carbon composite

Submicron size Al2O3 fibers in aluminum metal matrix

glass fibers + carbon fibers in epoxy resin matrix

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Preliminary observations• Visible physical changes in different

batches of carbon composite provided

1 2 3

1: 2004, 2: 2005, 3: 2006 ; 4: sample 3 tested at 180 oC for 500h

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8

-20

0

20

40

60

80

100

120

650 1150 1650 2150 2650 3150 3650

Wave numbers

%Tr

ansm

ittan

ceInfra-Red Spectroscopy Finger Prints of composite housing materials used in insulators

Numerous formulations available presently, big differences in electrical and mechanical stability

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Thermal stability of Carbon Composite core

• Fiberglass section • Carbon fiber section Initial Weight: 32 mg

-6

-5

-4

-3

-2

-1

0

10 200 400 600 800 1000 1200

Temperarure (C)

Mas

s Lo

ss (m

g)

140 C, start of degradation

Degradation starts at 140oC

Initial Weight: 28.75 mg

-30

-25

-20

-15

-10

-5

0

50 200 400 600 800 1000 1200

Temperature (C)

Mas

s Lo

ss (m

g)

150 C, Start of degradation

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Thermal Stability of metal matrix core

-5

-4

-3

-2

-1

0

1

0 100 200 300 400 500 600

Temperature (C)

Mas

s Lo

ss (m

g)

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Virgin and heat treated Metal matrix composite

Virgin 210 oC, 120 hours

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Change due to thermal stress (carbon composite)

• Virgin • 120 hours at 200 oC

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Tensile Strength Testing

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Tensile Failure mode of metal matrix after high temperature treatment

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Cracking in resin of carbon composite after 240oC, 120 hours

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Exposure of core to elementsGun shot damage (Arizona)Bird caging

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Chemical Stability of Carbon composite core under tension

High purity water 1 N nitric acid

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Ongoing Research

• Explore different methods of fingerprintingSpectroscopic: Infrared, Energy Dispersive X-ray,

Optical microscopyAssess fiber volume and distributionElectrical: partial discharge, tan δ (fiberglass)Mechanical: Failure under tension, bending and

fatigue loadsAre their differences before and after laboratory

aging?

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Ongoing Research

Accelerated aging tests:elevated temperatures (150, 200, 250 oC) for

500 hoursCombined mechanical (bending) and Chemical

exposure (water, nitric acid) testsCharacterize samples

Spectroscopic analysisMechanical (tensile) tests

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Ongoing research

• Core is expected to be hotter than the conductor• Can the core temperature exceed the glass

transition temperature (transition from elastic to plastic phase)?

• IEEE 738 used for ACSR, new materials and construction methods have yield heat transfer properties. How does this affect ampacity

• We will use Finite elements packages available at ASU

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Finite element modeling for conductor temperature distribution

1

X

Y

Z

MAR 26 200615:05:30

ELEMENTS1

MN MXX

Y

Z

325.14

334.473343.806

353.139362.472

371.805381.138

390.471399.804

409.137

MAR 26 200615:06:26

NODAL SOLUTION

STEP=1SUB =7TIME=115TEMP (AVG)RSYS=0SMN =325.14SMX =409.137

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Collaboration with Advisors

• Brief monthly progress reports (email)• In-person meeting with local advisors

(APS, SRP)• Conference call (quarterly) with BCTC• Discussions during IAB meetings

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Month 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Task 1 Task 2 Task 3 Task 4 Task 5

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