A Power Cable Reliability Solution

Transcription

1 A Power Cable Reliability Solution IEEE Insulated Conductors Committee Subcommittee C October 30, 2006 Benjamin Lanz Some of the technologies referenced herein are patented and proprietary IMCORP technology. Power Cable Reliability

2 The Need for a Cable Reliability Solution Raw material costs are increasing exponentially Cable manufacturer supply is likely to be outpaced by need* Many rehabilitation budgets can not keep pace with failure rate increase** Public requiring evidence of prioritization before awarding funding*** * Recent study by a major US utility research organization ** Based on cable owner data *** Wall Street Journal article 8/18/06 2

3 The Strategic Value of Prioritization Defect Specific Diagnostics (Type 2) IEEE 400 Definitions Type1: Destructive Withstand Type 2: Non Destructive Diagnostic Test General Diagnostics (Type 2) Withstand Test (Type 1) 3

4 Utility Reliability Solution Options for Underground Residential Distribution (URD) Continue to run assets to failure Traditional wholesale replacement Cable rejuvenation Strategic replacement with DSD 4

5 What if you had a URD cable reliability solution which provided a 20-year life extension and would enable you to eliminate the risk of rejuvenating or replacing up to 80% of good cable, dramatically improve the reliability of your cable system, and defer significant costs, allowing you to extend the reach of your budget? 5

6 A Qualitative Overview of the Cable Reliability Challenge $ Unchecked Failures Typical Utility Budget Increase Standard Replacement Standard Distribution Curve Failures 20 yrs 30 yrs Prioritized Replacement 40 yrs 6

7 The Budget vs. Reliability Failures/100miles/year on ~7700 of XLPE & HMWPE Cable 41% of the population is causing 95%+ of the failures Failure rate Increasing at 7% + 5% per year Budget increase 3% per year Data provided by cable owner 7

8 6-Year Correlation Study Parameters 2000 & Early , 20+ year old, 3 phase cables 15 & 25kV, 1000kcmil XLPE cables Each cable had failed at least twice All cables tested with 1 st generation Defect Specific Diagnostics and put back in service 8

9 Dispelling the Myth Myth: Once an electrical tree is initiated in extruded cable insulation complete failure is imminent Reality: Electrical trees in XLPE cable systems have been monitored for up to 6 years with out failures IEEE Electrical Insulation Magazine -peer reviewed article Medium Voltage Cable Defects Revealed by Off-Line Partial Discharge Testing at Power Frequency July/August 2006 Vol. 22, No. 4 9

10 6-Year Correlation Study Lessons Learned Most partial discharge (PD) associated defects in aged XLPE insulation are electrical trees, not voids Electrical trees do not necessarily go to failure immediately after initiation and can last for several years DSD is highly effective for separating reliable Good from unreliable Bad cable 10

11 6-Year Correlation Study Lessons Learned 95% of GOOD cable (PD free) survives 6 years Failed 5% Survived 95% On the basis of: 108, 3-phase cable sections tested with 3 generations old technology 4 th gen. tech is likely to significantly outperform 1 st gen. tech. 11

12 The Story of Good URD Cable Connecting the dots Utilities have suggested that the industry may be replacing and/or rehabilitating a significant amount of good cable. Review of knowledge base and cable autopsies agrees that the majority aged URD cable is still serviceable. Past URD experience coupled with recent URD projects show that DSD determines up to 80% of cable is still in good condition. 12

13 Sample of Utility URD Pilot Studies 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Def er Repair Replace Utility A Utility B Utility C-1 Utility C-2* *DSD results from URD cable 10 years after rejuvenation 13

14 Investment Comparison * 100 miles of single phase URD cable Average length of 300 ft 20-yr investment period Based on 80% PD free cable Wholesale Replacement $21.1M Rejuvenation $10.6M DSD Program $6.7M 20-year life extension 20-year life extension * Based on cable owner data 14

15 DSD Based URD 20-yr Life Extension Program Highlights 65% savings compared to wholesale replacement 35% savings compared to rejuvenation 60% deferred capital in first year compared to rejuvenation 3X reduction in failures compared to wholesale replacement Cable owner data used in model Years 15

16 Cable Reliability Improvement 5-Step Implementation Process Survey, Scope, & Plan Diagnostics Implementation Results & Analysis Corrective Action Continuous Reliability Improvement 16

17 Summary Current market, economic, and political pressures are driving the demand for a cable reliability solution 6-Year correlation study on 195 cables indicate Many electrical trees can survive several years in XLPE cable PD free (good) cable is likely to last more than 6 years DSD based program can reliably find good cable DSD results show up to 80% of URD cable is good A DSD based reliability program with a 20-yr life extension is an economic alternative to wholesale replacement and rejuvenation 17