1. Josh Perkel and Nigel Hampton NEETRAC
Some perspectives on the aging of the Devices that make up our Infrastructure
Josh Perkel and Nigel Hampton
NEETRAC

2. Outline
What do we say?
What does this mean?
How can we do better?

3. What do we say?
The existing electric power delivery relies on an aging infrastructure and largely reflects technology developed in the 1950’s that struggles to meet today’s demand. In a recent survey, 147 investor owned utilities reported that between 35% & 48% of their T&D assets either currently need or will soon need replacement.
Source: EEI / Harris Williams Co, Summer 2014

4. What do we say?
.. Utilities built lines at a significantly faster pace during the 1950’s, 60’s & 70’s … The result is a “Baby Boomer” like asset curve. … The “perfect storm” depicted by some combines increasing risks to reliability and safety together with increased costs ….
Source: Osmose 2016
The impact of any “perfect storm” is different if your assumed “end of life” is at 50 or 65 years

5. What do we say?
The US Department of Energy (DoE) estimates 70% of transformers and 25 years old or older and 60% of circuit breakers are more than 30 years old compared to useful lives of 25 years and 20 years respectively.
Source: DoE / Harris Williams Co, Summer 2014
Impacted if the
“useful llfe”
is 25 years

6. What does this mean?
What do the numbers “Useful Lives of 25 years and 20 years” mean?
What are the implications of a 25 year “Useful Life”?

7. What do the numbers “useful lives of 25 years and 20 years” mean?
Good for 25 years but 50% are gone by age 38?
Pretty much good for years but 50% are gone by age 25?
If we are not precise, we cannot be certain of the interpretation

8. What are the Implications?
Predictions do not fit with current reality
Estimated Failures
Installed

9. Where does this leave us?
We have “Useful Lives” that are open to multiple interpretations
We cannot readily explain where they come from
The consequences that arise do not match with reality

10. It matters how we frame our Life Expectancies
Given the impact of Life Expectancies, it would be valuable to be as clear as possible
Life Statement

11. “Lifetime” Statement Lifetime statements are needed to:
describe what a utility needs
AND
what the manufacturer has designed.
They have three elements:
Time
Survival Rate
Conditions
Under _________________, ___% survive to ________years.

12. Returning to Transformers an example of how we might do this
Transformers fail due to a variety of different failure modes.
Overheating
Dielectric
Moisture Ingress
Corrosion
As an example – lets consider Corrosion of the case

13. Corroded Transformers
Device “Assessment Audit”
Corrosion Scheme
1) Construct an “Assessment Scheme”:
New, Good, Moderate, Severe, Replace
2) “Audit “ (representative, random) to determine “Ages of units in the Sub Populations”

14. Ages for the Sub Populations
Moderate Corrosion
Good
Severe
Example

15. Survival Curve – Moderate Corrosion
Now have a clear way of establishing
How long things last
The manner in which they age
Example

16. Corroded Transformers
It’s pretty clear when they reach “Replace”

17. Transformers in Highly Corrosive Areas
Replace
Severe
Corrosion
In areas subject to corrosion, expect 10 % of the population to require replacement by age 17 years
In areas subject to corrosion, expect 95 % of the population to show Severe Corrosion by age 30 years
Source: NEETRAC Research

18. Maintainable Devices – Switch Controllers
5 % of Control Boards will require replacement before age 30 years
Consider the challenge of managing the inventory of replacement Control Boards for a population of several thousand switches over tens of years
Source: NEETRAC Research

19. Conclusions
Much of the currently operating infrastructure is labeled with “Useful Lives” of 20, 25, 40 years
Device “Life” is used but is ambiguously defined
“Life Statements” including conditions, survival rate, & time frame are useful / needed to define the life of a device
“Assessment Audits” allow us to get Survival Curves
Whatever we mean by “Life” will continue to be important for the devices in our infrastructure: drives development, procurement, operation and maintenance