1. Paul Dyer Condition Criticality Risk Rating and Condition Monitoring in a Distribution Network PAUL DYER DAVE OPENSHAW London Electricity Group

2. Paul Dyer What am I going to talk about ? Risk Management Maintenance strategies Plant specific diagnostics What are the benefits Summary

3. Paul Dyer n n Ensure safety of staff and members of the public n n Prevent interruption to supply n n Extend the useful life of the asset n n Ensure that the most cost effective solutions in place n n Enable informed asset replacement policy

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5. m = Maintenance or Replacement Window f = Critical Failure (or Uncertainty) Period m + f = ‘P-F’ Interval Asset Condition Time or Duty Functional Failure As New Potential Failure (Fails Condition Acceptance Criteria) Unacceptable Risk of Failure mf Risk-Averse Maintenance / Replacement Strategy Hi-Risk (Reactive) Maintenance / Replacement Strategy Optimum Maintenance / Replacement Strategy

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7. Reactive FOR n Considered to be cheap n No policy to develop n No routine maintenance to budget for AGAINST n Safety risk n Unscheduled down time n Damage to plant n Teams always to be ready n Loss of confidence

8. Paul Dyer FOR n Easy to predict labour and plan n Can ensure maintained before failure AGAINST n Not easy to predict failure n Easy to over or under maintain Time based

9. Paul Dyer Duty based FOR n Tailored to actual usage n Minimises work AGAINST n Needs development work to set duty levels n Requires hours run or other duty counters

10. Paul Dyer Condition based FOR n Tailored to plant condition n Minimises work and knowledge of plant condition AGAINST n Needs development work to set condition levels n Requires diagnostic equipment n Requires some skill to assess condition

11. Paul Dyer Transformer diagnostics n Moisture and dielectric tests n Dissolved gas in oil analysis n Furfuraldehyde analysis n Hydran on/off line n Metal in oil n Particle analysis

12. Paul Dyer Maintenance strategies Switchgear So what diagnostics do we have available? 1. Discharge n Transient Earth Voltage monitoring n Ultrasonic detection n Radio frequency detection n Discharge sensitive gel

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14. Maintenance strategies Cable diagnostics Why are we interested in cables? n Main cause of loss of supply n Failure is common n Adversely affects KPIs n Main nuisance to customers

15. Paul Dyer Maintenance strategies Cable diagnostics So what can we do? n Monitor failures n Off line partial discharge tests n On line partial discharge monitoring

16. Paul Dyer SUMMARY n What measurements are important? n Evaluate the risk to the system n What data tells me most about equipment operating condition? n Do I need to take measurements from each item n How much will it cost ? n How much time interpreting the results? n Will the measurements be acted upon?

17. Paul Dyer Maintenance strategies THE END Any questions?