2018 RMEL FIBERGLASS CROSSARM PROGRAM AT XCEL …...– Xcel Energy is working on a galloping...

Presented by David Flaten

2018 RMEL

F IBERGLASS CROSSARMPROGRAM AT XCEL ENERGY

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JUPITER STORM

• The storm severely damaged trees and power lines in the Texas Panhandle

• As much as 1 ½” of ice. Initially had strong winds

• Damage To Over 7,500 Structures– 1,350 power poles replaced– 2,300 cross-arms replaced– 6,000 insulators replaced– Over 9 miles of conductor

• A 73 mile portion of a 34.5kV line serving the communities of Higgins,Follett, Lipscomb, and Darrouzett was lost

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STRUCTURE DAMAGE

• Infrastructure Age –– Some assets new as two months old – Some are over 50 years old – Asset renewal can reduce but not eliminate failures from icing events

• Damage on both Grade C and Grade B construction – Cross arm Failure

• Ice loading in some areas added 500+ pounds per phase based off icing profiles

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FIBERGLASS CROSSARM DAMAGE

• Failures– Typical fiberglass crossarm damage from Jupiter Storm

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FIBERGLASS ARM FAILURES

• Arm pins failures– Had very heavy loads– Had high wind– Had lines that galloped

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FIBERGLASS ARM TESTING

• Attachment to pole– Fiberglass arm to metal pole bracket does not hold it immobile

• Holes will enlarge• Inserts might not be of much help

– Xcel Energy is working on a galloping certification test

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FIBERGLASS ARM TESTING

• Lead head Insulator Arm Pin– Insulator pin failed. Roughly 1,400 lb force, some crossarm damage

after the pin failed. – Nut was tightened very tight. (If it was loose would probably tear.)

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FIBERGLASS ARM TESTING

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FIBERGLASS ARM TESTING

• 35kV Porcelain Post– Don’t overtighten, can crack surface– 707 lb ultimate load with 2 ¼” x 2 ¼” flat washer– 4” x 4” washer – 1,204 lb test strength – 70% improvement

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FIBERGLASS ARM TESTING35KV POLYMER POST

• Light Series– 450 lb, - 2 ¼” washer– 4” x 4” bottom only – 452 lb, insulator side fails– 4” x 4” top and bottom – 698 lb, 54% increase in strength

• Stronger Series - 82% stronger arm model, • Wall thickness - .200→.270 H, .180→.240 V (Different composition)• 495 lb - 2 ¼” washer

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FIBERGLASS ARM TESTING

• Angle Pin – 35kV Polymer Post– Use ¾” bolt, 4” x 4” washer – Load 1,119 lb– Testing is ongoing for product improvements

• Blocking inside for better crush and failure resistance?

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WOOD CROSSARM TESTING

• Wood Arm– Wood has higher compressive strength– Tangent, 822 lb

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FIBERGLASS CROSSARMSPECIFICATION

Testing Requirements• Standard Tests

– Vertical – Horizontal– Transverse

• Test Positions– 2-point– 4-point

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FIBERGLASS CROSSARMSPECIFICATION

Testing Requirements• Dynamic Load Test

– Simulated galloping conditions• 5-30 revolutions per minute• Load to 50% of ultimate

strength• 8 hour duration, both

vertical and horizontal directions

– Results• Damage to arm• Hole enlargement• Loose hardware

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FIBERGLASS CROSSARMSPECIFICATION

Testing Requirements• Wall Crush Resistance

– Pounds of force, – 2¼” x 2¼”, standard washer

with pin. • Surface splitting, cracking and

tearing.– 4” x 4” washers, wall to all arm

coverage• Corner strength and side wall

performance

• Could be done as a push or a pull load

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FIBERGLASS CROSSARMSPECIFICATION

Testing Requirements• Crossarm Pin Transverse Load

– Standard 6” leadhead crossarmpin

– 2¼” x 2¼” washer• Test results

– Pin tear out– Wall, insert or hole damage– Loading 900 lbs

• Considerations– Tightening torque probably

makes a big difference– Washer size probably makes a

big difference

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FIBERGLASS CROSSARMSPECIFICATION

Testing Requirements• Post Insulator

– 35kV insulator test– Polymer or Porcelain– 4” x 4” washer – Angle pin

• Results– End collapse– Crushing or tear out

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FIBERGLASS CROSSARMSPECIFICATION

Testing Requirements• Torsional Loading

– Simulate non-equal loading– Span length differences– Ice drop

• Test setup– 45 degree load longitudinal on

post insulator