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Cable Rehabilitation Program
By Lee MaurerMaintenance Planning
SWEDE ConferenceApril 26, 2011 - Bastrop, Tx
(Second Responder Cable Treatment Program)
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27,000 Square Miles of Territory
3.2 Million Electric Service Points
3,000 Circuits
Miles of Underground Primary
17,218 Cable Miles – URD
4,641 Cable Miles – Feeder
21,859 Total Miles.
(Networks not included)
Miles of Overhead Primary
10,608 Mainline Primary
13,026 3ø Non-Mainline
5,006 2ø Lines
27,212 Single Phase Lines
55,852 Total Miles
Oncor System Overview
630 miles
390 miles
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Cable Components
Tinned Copper Concentric Neutral
Insulation Shield
XLPE or HMWPE
Insulation
Conventional Conductor Shield
Aluminum Conductor
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Aluminum
Conductor
(Strand-filled)Jacket Bare Copper
Concentric Neutral
Insulation Shield
TRXLPE Insulation
Super Smooth Conductor Shield
Pre-1990 Since 1990
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Previous specification cable Current specification cable
Primary Underground Cable (Network Excluded)
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Primary Cable Faults
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Cable Rehabilitation Program - Background
System wide maintenance plan (Second Responder) for extending the life of aging infrastructure
Pre-1993 PE cable issues
8,000 cable miles – Pre-1993 PE cable
– 7,000 cable miles – URD
– 1,000 cable miles – Feeder
Cable Manufacture 1980 - 1995
– General Cable, Hendrix, Pirelli (Now Prysmian), Southwire
Capital Rehabilitation method for aged cable
– 235 cable miles rehabilitated (By Utilx)
Cost effective alternative to replacement of cable
Additional 600 cable miles rehabilitated in other programs
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Second Responder Process
When a cable faults, the troubleman (first responder) determines if the cable is loop fed and if the faulted cable can be switched out.
Padmount Transformer Pole Riser
Normal Open PointFault
Isolated Faulted Cable
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Second Responder Process (cont’d)
If the cable can be switched and service restored to the customers, the location of the faulted cable is sent to Oncor Program Services.
Program Services will then schedule a Utilx cable repair/rehabilitation crew to the cable.
The crew will attempt to repair and inject the cable with rehabilitation fluid.
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2nd Responder Process
4,291 sections of failed cables came through the process since 2008
– 65% were able to be injected successfully.
235 cable miles have been rehabilitated using 2nd responder process since 2008.
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Business Comparison
Cable Repair - Splicing $ X
– O&M Cost
– Same old cable
Rehabilitation of Span $ 4X
– Capitalized Cost
– Added 20+ years of life
New Cable (Bore) $ 15X
– Capitalized Cost
– New 40+ year asset
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Business Considerations that Prevent Rehabilitation
Cable installed in conduit (except preventative)
Corroded concentric neutral of 25% or less remaining
The faulted cable section must not have been de-energized more than six months.
There cannot be more that one joint per 100 feet of cable. (Business Case)
Other Technical Reasons
– Butyl rubber cable
– Cable with tape conductor shield
– Loss of insulation shield conductivity
– Insulation shield with no adhesion
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Questions
Oncor Contacts
Lee MaurerSenior Manager
Maintenance Planning 817-215-6128
Mark Darilek Project Manager
Maintenance Planning 817-215-6809
Richie Harp Consulting Engineer
Distribution Standards817-215-6008
Fort Worth, TX
Mike Sulak Program Manager
Operations/Program Services817-215-6151
