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

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

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

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

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

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”?

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 5 - 10 years but 50% are gone by age 25? If we are not precise, we cannot be certain of the interpretation

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

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

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

“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.

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

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”

Ages for the Sub Populations Moderate Corrosion Good Severe Example

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

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

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

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

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