ea technology

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ea technology
Delivering your energy solutions
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The use of Health Indicesto determine end of
life and remnant life for distribution assets

• D T Hughes
• EA Technology UK

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Condition Based Risk Management

• Use of condition information to understand future
  performance
• Maximise the use of existing information
• Define additional condition assessment
• To enable specific decisions on replacement/EOL

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Context

• Ageing asset population
• Pressures to maintain/improve performance and to
  reduce costs
• Age (by itself) is not an acceptable reason to
  replace assets
• Must demonstrate need and consequences,
  condition and future performance
• DPCR 4, and Ofgem ARM

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A Health Index (To define proximity to EOL)

• A Health Index is means of combining varied and
  relatively complex condition information as a
  single number
• Define significant condition criteria, code
  information numerical, apply weightings and
  develop a simple algorithm to generate a HI for
  each asset.
• Rank and apply calibration

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Health Index
Condition
Remnant Life (years)
Probability of failure
100
At EOL (lt5 years)
Bad
High
Poor
5 - 10
Medium
Fair
10 - 20
Low
Good
gt20
Very Low
0
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From the health index to probability of failure
and beyond

• Defined a process to translate HI to probability
  of failure
• Estimate future health index values based on
  degradation processes
• Estimate future failure rates and effects of
  different intervention strategies

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Health Index Profile for 11kV OHLs
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Current and future failure rates
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Summary

• Process goes from condition information to
  probability of failure and future failure rate
• Assumptions/approximations however everything is
  related back to physical condition, degradation
  and failure processes and actual fault rates.
• Sanity checks and links to reality throughout
• Provides a vital input to overall risk models