User Perspectives PD Testing Some Perspectives from Users

User Perspectives PD Testing Some Perspectives from Users Josh Perkel and Nigel Hampton NEETRAC

User Perspectives Outline • How often is PD testing used by Utilities? – What are the ways PD is used – HV/EHV & MV • Why do so few Utilities use PD? – Complicated § No consensus § Confidence in Diagnosis – Value / Benefit – Drives Unexpected Practices 2

User Perspectives Cost Chain – cable system Cable Materials Metallic Non-metallic Accessory Materials Metallic Non-metallic Cable Production Delivery Cable Construction Installation FIRST COST Accessory Production Delivery Accessory Maintenance Repair Lost power End Of Life Construction Installation Commissioning How often is PD testing used by Utilities Health

User Perspectives Ways the PD Tests are Used by Utilities System Commissioning Health of Aged Systems • As part of the project handover / acceptance • Part of a coherent program • Opportunistically funded • Pilot Study • Management Directive How often is PD testing used by Utilities 4

User Perspectives Outline • How often is PD testing used by Utilities? – What are the ways PD is used – HV/EHV & MV • Why do so few Utilities use PD? – Complicated § No consensus § Confidence in Diagnosis – Value / Benefit – Drives Unexpected Practices 5

User Perspectives What has Failed? Collated in 2014 How often is PD testing used by Utilities – HV/EHV ICC Sub A Fall 2015

User Perspectives Bathtub Curve - Times of Failure Shape Parameter = 0. 3 Infant Mortality Shape Parameter = 1 Random ICC Sub A Fall 2015 How often is PD testing used by Utilities – HV/EHV

User Perspectives Use of PD HV/EHV How often is PD testing used by Utilities – HV/EHV CIGRE B 1. 28 8

User Perspectives Why use PD – HV/EHV How often is PD testing used by Utilities – HV/EHV CIGRE B 1. 28 9

User Perspectives Evolution at HV & EHV Hi. Pot Only Hi. Pot with PD No reported use of PD Only How often is PD testing used by Utilities – HV/EHV CIGRE B 1. 28 10

User Perspectives Outline • How often is PD testing used by Utilities? – What are the ways PD is used – HV/EHV & MV • Why do so few Utilities use PD? – Complicated § No consensus § Confidence in Diagnosis – Value / Benefit – Drives Unexpected Practices 11

User Perspectives PD use MV in Utility Distribution programs How often is PD testing used by Utilities - MV CDFI 12

User Perspectives PD use MV in Nuclear Plant programs 90% CI Concerns over neutral degradation How often is PD testing used by Utilities - MV Practitioners 13

User Perspectives CDFI / NEETRAC Experience Base 10 Utilities 50 Test Locations >1, 120, 000 ft Optimal opportunities for utilities to see different diagnostics at work on their system 14

User Perspectives Outline • How often is PD testing used by Utilities? – What are the ways PD is used – HV/EHV & MV • Why do so few Utilities use PD? – Complicated § No consensus § Confidence in Diagnosis – Value / Benefit – Drives Unexpected Practices 15

User Perspectives PD Tests are Complicated • Difficult to employ – – – Access Crews Equipment Time Neutrals PD tests become increasingly problematic as more of the neutral corrodes • Impenetrable Interpretation – If we don’t understand how it is done how do we know it is done consistently – Black Box / Proprietary Methods – Expedient Interpretation Why do so few Utilities use PD - Complicated 16

User Perspectives PD Tests are Complicated • Difficult to interpret • Tests on “Components in Factories” ≠ “Test on System in Field” Physical Factory Tests Dimensions Electrical Routine AC Hipot PD PD • Apart from new installations, no clear metric of severity: Number Magnitude Level Location • Evolving PD Test Levels Why do so few Utilities use PD - Complicated 17

User Perspectives Unexpected Outcomes • The ones that were identified as critical: – “Never failed” – “Were fine when I took them out and dissected them” • “The ones that were identified as less critical failed way before the ones that were most critical” Old Accessories / Cable PD shows acceptable Within 5 yrs expect: % • 0 -1/3 very bad to failing • 0 -1/7 bad to fail in 5 yrs • 2 -3/90 acceptable to fail 3 PD shows bad 10 PD shows very bad 25 Not so unexpected! Certainly complicated!! Why do so few Utilities use PD - Complicated 18

User Perspectives Outline • How often is PD testing used by Utilities – What are the ways PD is used – HV/EHV & MV • Why do so few Utilities use PD – Complicated § No consensus § Confidence in Diagnosis – Value / Benefit – Drives Unexpected Practices 19

User Perspectives Drives Unexpected Practices • Currently: Longevity / Reliability comes from following training / instructions – Dielectric – Connector – Jacketing • Evolves to: Passing a test • Outcome: Develop methods / skills to pass the test, which may only address one element Why do so few Utilities use PD 20

User Perspectives Outline • How often is PD testing used by Utilities? – What are the ways PD is used – HV/EHV & MV • Why do so few Utilities use PD? – Complicated § No consensus § Confidence in Diagnosis – Value / Benefit – Drives Unexpected Practices Not presented - - Lack of Time 21

User Perspectives Conclusions • PD tests deployed on MV and HV/EHV for different reasons and at different times in the life cycle – now routine at HV/EHV – presence & approx locn of PD is paramount • Complication is higher for PD as compared to other diagnostic techniques employed by utilities – Interpretation is difficult – no clear way of assessing severity – Different embodiments – voltage sources, bandwidth, etc. – Technologies continue to evolve • Value/Benefits can be estimated using probabilistic principles – Have to be comfortable with ranges / imprecise outcomes – Benefits are driven by sizeable Intangible costs • PD is a useful tool in the cable diagnostic toolbox 22