Least Cost Cable System. Strategies to Reduce Cable and Infrastructure Costs When Transitioning to an All Conduit Systems

Transcription

1 Least Cost Cable System Strategies to Reduce Cable and Infrastructure Costs When Transitioning to an All Conduit Systems

2 Cost Sharing of Cable Systems Underground Extensions The Company will construct Extensions underground when requested by the Applicant or if required by local ordinance or conditions. The Applicant shall provide all trenching and backfilling, imported backfill material, conduits, and equipment foundations that the Company requires for the Extension.

3 Standard Advisory & Decision Process

4 Trenching requirements Direct Buried See Standard GA 211 Curb Backfill the trench with 6 inches of sand over the cables. An inspection may be required prior to covering the cables. Check with responsible Rocky Mountain Power (RMP) manager. Backfill both primary and secondary trenches another 12 inches with native soil then add red Danger Tape. (See Standard GB 101). As an alternative to certain trenching requirements, applicants may choose to install full conduit & vault systems. Check with the RMP manager for more information.

5 Pad Mount Transformer--Direct Buried Box Pad Install box pad after primary and secondary cables have been installed in the trench. Install box pad on level, compacted soil. Interior of the box pad is to remain free of dirt and debris. Backfill box pad leaving 3-4 inches above final grade measured from top of curb.

6 Vaults with Terminal Duct Entrances and Ground Grids

7 A transformer and sectionalizer side by side.

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9 Changing to an All Conduit System When changing the cable installation practices the CG-12 provides a guideline for a rationale way to minimize cable cost. The document discusses many cable design approaches that may be considered that control cost, yet assure reliability for a cable system.

10 Conductor Studies showed that even when the cost difference between aluminum and copper was near $0.30/pound that for a three circuit substation getaway (9 cables) installing 1000 kcmil aluminum cables with a fluidized backfill was less expensive than copper cables for a getaway system. The cost difference between aluminum and copper on the COMEX is now over $2.00/pound.

11 First Project near Bend, Oregon.

12 The first project in Bend, Oregon showing the fill.

13 Cable Structure Drives a Blueprint for Cable Design AEIC CG12, GUIDE FOR MINIMIZING COST FOR EXTRUDED DIELECTRIC SHIELDED POWER CABLES RATED 5 THROUGH 46 KV,

14 The West has soils with poor heat transfer rate.

15 An example of thermal runaway where the soil spreads!

16 This cloud blew east.

17 Dry Clay at this location had a RHO of PSI Concrete Backfill RHO dry 90

18 Core Samples taken near Bend, Oregon

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20 Fiberglass Riser in Yakima, Washington PVC and steel conduit for risers are being replaced by fiberglass. Prior this was the limiting factor for an ampacity rating.

21 Riser in Bend, Oregon

22 Fiberglass with lower COF allows for longer pulls. This reduces the number expensive vaults

23 Single Reel Trailers with Payout and Retrieve

24 What has been Gained With the reduction in cable cost and labor-hours, PacifiCorp s initial cost is close to the same whether in duct or direct buried. PVRR (Present Value Revenue Requirements) to implement all conduit is 1.38:1 over fifty years. This is from present system snapshot. This model does not include the salvage of 15 million pounds of copper and aluminum. Outage time reduced by ½ from 3 million to 1.5 million.

25 Continuing the Process Still in the process of implementing the concrete vaults. Need sources near our Districts. Post design to web. To fully implement will probably require meeting with the developers Need to Communicate to the field on Savings

26 National Documents--AEIC Went to Aluminum Conductor Changed Cable Packaging Reduced Concentric Neutral Size Thanks for your time. Any questions