identifying solutions 101 overhead reliability to
TRANSCRIPT
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Identifying Solutions 101
Overhead Reliability to Resiliency
Betsy Coppock
10.10.19
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Reliability to Resiliency
• Once you have a goal - Figure out the solution
• To find the solution, you need to figure out what’s the problem
• To figure out the problem you need to know what’s happening
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Reliability to Resiliency
• Goal - Xcel Energy wants a more resilient system
– Less damage in storms
– Easier and faster to repair
– Less hazards to the public
– Uniform and guided inspection
• Not much has changed since utilities began using wood poles and crossarms
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Finding the Problem - Testing with EPRI
• Did 13 tests
• Old line but almost all
poles sound at ground line
• Conductors
– Old #4 Cu solid
– Old and new #2 ACSR
– New 2/0 ACSR
• Crossarms
– Old existing wood
– Added new wood
– Added fiberglass
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Pole Failure
• Ground line pole failure difficult to achieve
• Top of pole failed frequently
• Pole top condition prior to test was a strong indicator if pole top would stay intact during test.
• Good inspection/ maintenance programs should limit storm damage
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Crossarm Failure
• Typically insulators and insulators ties were stronger than old cross-arms
• Broke tops off some porcelain pin insulators
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Conductor Size Impact
• Damage happens on impact but also on conductor breakage recoil
• Pole top damage common all conductors
• Old #4 Cu higher probability of conductor breakage
• New #2 ACSR conductor high probability of crossarm breakage
• New 2/0 ACSR broken pole at groundline
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EPRI Pole Strength testing
• Pole Strengths
– Class 2, southern
pine for mainline
– 4,000 lb strength
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EPRI Component testing
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EPRI Tie and pin insulator test
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Pole top pin and insulator test
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Post insulator testing and steel distribution tie
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Post insulator test and aluminum preformed tie
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Structure Loading
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Mechanical Strength Coordination
• Texas Ice Storm
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Structure Testing 2018
• Xcel Energy tangent structure 15kV
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EPRI Structure Testing 2018
• Coordinated release – 15/25kV
– PUPI 2000 Tangent Arm
– 336 ACSR
– 4” x 4” washers
• Damage – 15/25kV
– Steel top ties came loose
– Bent arm pins
– Some arm bracket bending
– Possible insulator damage
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Preformed Tie on Pin Holding Strength
• Release
– Insulator rotates
– Pins bend
– Ties came loose
• Strength
– Arm pins bend easier than pole top pin
– Release at a lower strength
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Structure Testing 2018
• Xcel Energy tangent structure 35kV
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Structure Testing 2018
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Structure Testing 2018
• PUPI Arm Strength 6400lb vertical
– 336 ACSR, distribution tie, 4” x 4” washer above and below
• Three tests, same results – tried weaker tie and stronger arm
– Cantilever is too much
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• Insulator doesn’t rotate and insulator pin doesn’t bent
• Arm does twist to help release
Preformed Tie on Post Insulator Holding Strength
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Fiberglass arm testing
• 35kV Polymer Post
– 4” x 4” top and bottom
– 16” tall polymer post
– Maximum force – 961 lb
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Structure Testing 2019
• Xcel Energy tangent structure 35kV
• Polymer clamp top insulators
– Force to slip around 1,000 lb.
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• Change in thinking about the Distribution System
• Automobile Industry
• Not selling 1950’s Chevy (Even if you like the styling)
• New models are better, more reliable, safer and efficient
• Utility Business
• Building 1900’s distribution isn’t going to take you further
• Inspect, maintain and replace exiting structures
• Build more resilient structures going forward
Conclusion
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