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Resources for Distribution Systems Research

You can find useful information regarding our research, team, and capabilities here

1 - Updates

Updates on supplemental projects and new happenings

2022 Research Plans Available

The research team is happy to share our plans for next year’s R&D. Thanks to all of our utility advisors that have given input throughout the planning process. We are excited to continue working together!

Distribution resiliency research highlighted in the EPRI Journal

The EPRI journal recently published an article highlighting EPRI Distribution resiliency research and testing that we performed at the Lenox lab. This research was also recognized with an EPRI Technology Transfer Award in 2020.

Artificial intelligence research kicks off in distribution

Dexter Lewis has kicked off a research project focused on how to use imagery and AI to perform distribution inspection.

Urban Underground Event Scheduled

John Tripolitis leads the North American Dense Urban Utility Working Group each year. It is a great chance to interact with peers focused on urban underground distribution networks.

2021 Distribution Systems Overview published

Click here to get a preview of our research planned for 2021

New research begins to investigate new technologies for backup power for automation

Jason Anderson is leading a research project that is focused on reducing the largest O&M expense associated with distribution automation systems: batteries and backup power. Click here to read more

Conversations with Experts - How Drone Research Evolved and What is Next

Drones have moved into the mainstream, how did we get here, and where do we go from here? In this installment of our discussions with leaders in tech, we sat to learn more about how drones and drone R&D have evolved over the last several years.

1.1 - 2022 Research Plans Available

The research team is happy to share our plans for this year’s R&D. Thanks to all of our utility advisors that have given input throughout the planning process. We are excited to continue working together!

1.2 - 2024 Research Plans Available

The research team is happy to share our plans for this year’s R&D. Thanks to all of our utility advisors that have given input throughout the planning process. We are excited to continue working together!

1.3 - Conversations with Experts - How Drone Research Evolved and What is Next

Drones have moved into the mainstream, how did we get here, and where do we go from here?

In this installment of our discussions with leaders in tech, we sat to learn more about how drones and drone R&D have evolved over the last several years. This is a transcript of the conversation that has been edited for clarity and readability.

Have an idea for a future episode, or want to contribute? Email Drew McGuire ( with your ideas.

Podcast Transcript

Drew McGuire [00:00:05] : Hi, this is Drew McGuire at EPRI, thanks for joining me. Today, I want to sit down and learn more about EPRI’s research and the history of research into drones for the T&D industry.

To help me with this, I’m going to sit down with Dexter Lewis. He’s part of the EPRI team. Many of you know Dexter, he has been around leading UAS research for several years. He’s known across the industry as one of the leaders in this space. So it should be an insightful conversation. To get things started, let’s just start from the very beginning.

Dexter, can you tell us why we started UAS research and what were we trying to accomplish in the beginning?

Dexter Lewis [00:00:40] : All right thank you Drew. Well, I’ll start by saying that EPRI’s first drone report was published 20 years ago in the year 2000. But it wasn’t until 2014 that things really took off. Around that time, low cost, high quality, easy to operate drones were emerging for the hobbyist and consumer market. Now, we recognize that a lot of T&D inspection work is done from the air using manned aircraft.

These aerial inspection methods have advantages over ground-based approaches, primarily in speed, but also introduce risks when operating that close to overhead infrastructure. Recognizing the risks of those traditional inspection processes, I guess EPRI and several leaders in the utility industry thought that drones could be an attractive replacement option. But in all honesty, we had more questions and unknowns than we did answers.

To answer your question about what we were trying to accomplish: at the simplest level, we were trying to perform a better inspection with drones. We were looking for improvements with drones over traditional methods: in terms of safety improvements, were they a cheaper inspection method, were they faster, or did they give us just an overall better quality of inspection? And I’ll say that these are fundamental questions we try to answer before we integrate any new technology or approach. And I believe EPRI was and still is in a unique position to help our members answer these questions through lab testing, real world field studies, and overall shared experiences.

Drew McGuire [00:02:33] : Yeah, I think you’re right. EPRI is at a unique position in the industry where we can see a pretty broad range of what’s going on and help work together to address the problems.

But the way you describe that, that’s a big, broad challenge that we’re facing here from the ground up, from consumer grade equipment all the way to deployed systems in utility environments. So how did you even get started? How did you approach this problem from the beginning?

Dexter Lewis [00:03:00] : We started by building a team of interested utilities to begin a discussion. And a lot of our early engagements were focused on EPRI listening to our members. And it turns out that many utilities were asking the same questions. How does this drone technology work? How does it compare to our traditional or current methods and even things like how close can you fly a drone to a high voltage transmission line? How well do these things work in electromagnetic environment?

And I believe, you know, by listening to our members, we were able to really leverage our collaborative research model to target research projects that best answered these questions.

We started in our lab environment where we have the ability to test this technology safely and in a controlled manner. We still have projects where we do that. Then we moved into the field and at that time there was a ton of hype around the potential of the technology through listening to vendor presentations or service provider presentations or discussions.

There were a lot of anecdotal stories about how well this technology works, but not many documented scientific studies on the project. So we designed field tests where we compared drone inspections to manned aircraft inspections. We collected all kinds of data through this work where we really focused on trying to answer the question if drones can perform a better inspection.

I’d say fundamentally we did what we try to do with all our EPRI research. We try to provide our members knowledge based on nonbiased objective analysis to help them make informed decisions.

Drew McGuire [00:04:58] : That’s important because utilities have been making a lot of decisions around the technology in the last few years. It’s moved so quickly, you said we started back in the mid teens. Just in a few years we’ve made a lot of progress, and the landscape has changed so much around drones since then. There’s the new regulations, the technology has changed quickly, and utilities have really established drone programs by this point, in many cases.

You just described a lot of work that you’ve done so far. Can you summarize some of the key takeaways that you found?

Dexter Lewis [00:05:35] : I’ll start by saying that not all drones behave predictively in energized environments, testing in a controlled environment first can really help lower your risk before deploying on a real line. Also, drone inspection costs in the beginning were significantly more than inspection costs for traditional methods. If you look on a cost per mile basis. We’re still looking for ways to make that process more efficient.

One of those ways is through automation. Automation can help improve your inspection efficiency, but usually translates into more work on the back end in terms of reviewing your imagery.

You really need a way to efficiently handle the amount of imagery that these drones can collect, especially if they’re operating autonomously.

And finally, I’ll say that just giving a drone to an inspector or a field employee doesn’t always translate to a more efficient process. We learned you need to be smart about how you deploy this new aerial functionality to really capture all the value that it can provide.

Drew McGuire [00:06:55] : A lot of the unknowns that you discussed earlier are knowns now. We’ve answered those already, or at least we’ve begun to understand some of them. With that in mind, what does the future look like around drone research? What’s coming up next?

Dexter Lewis [00:07:06] : I suppose I’ll say that drones have made it through the hype cycle. They are tools that are here to stay and that are providing value to utilities today. However, I also think there is a lot of work that still needs to happen before we can fully realize the potential of this technology.

You mentioned how things have changed and continue to change. You know, the technology, the regulations, and the applications are evolving so fast. And it seems like a totally new landscape every six months. But we still can’t operate our drones long distances due to line of sight restrictions. And even if we could, we may likely be limited by our flight time or our wireless link limit.

And that’s a really big deal for our industry because we have so much linear infrastructure. A lot of our ongoing and future research is focused on being ready to take advantage of those beyond visual line of sight operations whenever they can be performed safely, and researching how best to deploy our drones in our current and future environment.

And kind of hinting at that, a lot of the work that we’re doing is focused on making our drone inspections more efficient through automation. There’s no doubt that drones can fly autonomously around the structure to capture imagery to perform an inspection. However, it’s really important that we understand when we’re leveraging those automated inspections that we’re getting the right picture to do a sufficient inspection.

We can’t jeopardize inspection quality for efficiency, and we have a project focused on that, where we’re trying to identify these data capture specifications to build confidence in these automated inspection models.

Now, through these automated inspections, a lot of times they generate a whole bunch of imagery and data. And the question is, what do you do with it? Because we don’t want to be building efficiencies on our data collection process, but then spending a lot of time reviewing imagery and data in the back office.

So drones have been a big driver in our push into artificial intelligence and image processing research. This is an area that we’ll be engaged with for many years to come.

It is also easy to think about the positive uses of drones, but they could also pose a threat or challenge to our industry. There are some unknowns related to the physical and cyber aspects of this technology. So how can we protect our infrastructure from malicious drone actors? And how can we be confident that the drones we’re using have adequate cybersecurity protections in place? We have active research in these areas as well.

In summary, there has been so much work from EPRI and the utilities over the last few years. This technology can really change the way that we as an industry perform work. And it’s exciting to think about what we will be able to accomplish in the future.

Drew McGuire [00:10:25] : Thanks, Dexter. I think that’s a really interesting way to see how we’ve started from the beginning of this research and where we are now and what’s coming up next. It’s good to back away from it sometimes and see the big picture. Thanks for walking us through it today.

So if you’re listening to this and have more questions, you can reach out and talk to Dexter at any point. Shoot him an email at, or you can get in touch with me via email as well,

If you have questions, feel free to reach out. Thanks for joining us today and we’ll talk with you later. Thank you.

2 - Applications

Opportunities to apply EPRI expertise and results for immediate impact

2.1 - Reduce Outages by Designing Better Structures

Lab testing is a critical step to improve resiliency

One of the best ways to understand how a structure performs is to see it in action. Normally, this would require you to be in the field when a tree or branch falls on a line. EPRI’s laboratories are able to perform this test safely, repeatably, and with full data and imagery collection.

The purpose-built test site at EPRI’s High Voltage laboratory in Lenox, Massachusetts gives utility designers and engineers the ability to see their designs in action and identify opportunities to improve the design in real-time. The researchers construct full-scale structures built to your specifications, then subject the structure to the impact of a mid-span tree-strike or falling branches. Sensors and cameras capture the action so that the test team can analyze performance and identify design changes that could improve performance.

Major weather events necessitate improved resiliency and reduced restoration time. EPRI collected data to identify time consuming restoration tasks. Replacing broken poles was, by far, the most time-consuming task

Design characteristics to improve through testing

EPRI can test multiple characteristics of designs and components. Two of the main objectives of the testing are to reduce restoration time by pole saving and increasing reliability through branch deflection.

Pole Saving

EPRI’s resiliency research results have shown that a key to reducing restoration time is predictable and consistent structure performance during storms. Put simply, it is important to know the order in which components will fail, and it is important that the pole itself is not the first component on that list.

One approach is to apply the concept of mechanical coordination to your designs. Coordination is well understood in power system protection, and the same concept can apply in structure performance. Unlike protection system coordination, however, structures are made up of physical components with unknown or unpredictable performance characteristics. This makes it very difficult to model or simulate structural performance.

EPRI’s resiliency research results have shown predictable and consistent structure performance is key to reducing restoration time after storms. Put simply, it is important to know the order in which components will fail and that the pole itself is not the first component on that list.

The Test Site

Explore the test site by hovering over the green highlighted areas.


How it works

Watch a virtual tour of the test site with EPRI Project Manager Joe Potvin below.

The EPRI test site is designed with the flexibility to meet your needs. We have tested many types and sizes of structures. Call us to talk about how we test your structure!

Utilities use the full-scale test facility to assess potential resilient design improvements. The failure mode of this structure was typically a broken pole. Testing demonstrated the need for an improved design.

Branch Deflecting

Fallen tree branches cause many outages, often by getting stuck on the line and creating an electrical fault. This test helps identify conductor configurations that are less likely to cause reliability issues when branches fall on them. Testing includes multiple combinations os configurations, as well as branch species and types that are representative of your utility’s service territory.What if we could identify conductor configurations that branches are less likely to get caught on?

EPRI can simulate fallen branches on overhead lines by literally dropping branches from above. However, this requires careful consideration of representative tree species, review of outage data, and discussions with utility vegetation experts.


Branch deflection vs capture depends on many factors, including branch shape, line configuration, and how the branch contacts the line. The results rely on many individual tests to generate statistics.


Results can also demonstrate branch species that may be more problematic and require more management.

How to get involved

If you would like to schedule testing of your designs, please contact our research leader, Joe Potvin, at

Find more information here.

2.2 - EPRI T&D Asset Forensics & Failure Analysis

Transmission and Distribution (T&D) asset failures can significantly impact system operation, reliability, and safety. These failures are frequently difficult or impossible to predict, and they can sometimes seem random. In reality, these failures are driven by degradation mechanisms and stressors that lead to specific failure modes. Even sophisticated online monitoring data may not tell the whole story. A forensic analysis may be the best opportunity to learn why a component failed. This helps you prepare for the future by improving specifications, inspections, or maintenance practice.

Use the Past to Improve the Future

The pace of utility operations is fast – especially when you are responding to an equipment failure. By using the EPRI team to perform a forensic analysis, you not only free your team to focus on the critical work of preparing for the future, but you are also equipping them with lessons from the past. Learning from past failures gives you new insights so that you can:

  • Improve specifications – Whether it is a design issue, a materials issue, or an environmental issue, there may be an opportunity to prevent future failures by updating your specifications based on causes of previous failures.
  • Improve work practices – Workmanship issues during installation, operations, and maintenance are difficult to diagnose and correct without data from a forensic analysis.
  • Improve inspection capabilities – A forensic analysis is a critical step in understanding how assets age and fail. This information directly informs inspection tools and practices that can improve performances.

The Forensics Process


A proper forensic analysis of a transmission or distribution component is a multi-disciplinary exercise that requires deep expertise across a broad range of engineering and material science. While each investigation is unique, EPRI applies a rigorous, scientific method that can include a multitude of approaches such as:

  • Materials analysis – Even simple components can be made of complex materials with unique performance characteristics. A thorough analysis of each material not only increases understanding of the component itself, it can also expose byproducts produced during failure.
  • Mechanical & Electrical Testing – Depending on the component, a series of mechanical & electrical tests can begin to identify and locate the point of failure.
  • Detailed dissection – In many cases, a thorough and methodical dissection of the failed component can expose evidence of design, manufacturing, or installation errors. It takes time, dedication, and an eye for detail, but the effort is typically worthwhile.


EPRI engineers test and analyze T&D assets every day. The team has decades of experience in understanding asset design, performance, degradation, and failure. We have experts across many assets and scientific disciplines, such as transformers, circuit breakers, connectors, corrosion, underground equipment, and distribution automation. This expertise, coupled with the EPRI labs, means that the team can perform the forensic analysis, and put the results into context to help you understand how to turn the insights into action.

Examples of T&D Asset Forensics & Failure Analysis

Tools and Capabilities

The EPRI laboratories can analyze a wide range of components and assets. We have a vast array of advanced inspection and analytical tools at our disposal, such as:

  • Stereo microscope
  • Scanning electron microscope
  • Sectioning and dissection equipment
  • Partial discharge test equipment
  • Gas chromatograph – Mass spectrometry
  • Energy-dispersive X-ray spectroscopy
  • Materials hardness mapping
  • X-ray scanning and imaging

Example of a transformer that failed in-service. The failure event was detected by an online diagnostic system, but the detection could not be classified for action. The forensic analysis identified the root cause, which strengthens the future effectiveness of the online diagnostic.

Surge arresters were found to be heating in service, but the utility did not have a clear replacement criteria. The forensic analysis showed that the heating was likely due to design and material selection and that continued heating would cause further degradation. As a result, the utility had confidence to quickly remove heating arresters from service.

Distribution switches were found to be heating in the field. A forensic analysis identified corrosion at the contact points that was the cause of the localized heating. Further analysis identified a design issue as the root cause, leading to improved utility specifications to prevent this issue in the future.


The EPRI team is known for deep technical expertise that is applied to practical problems. Our engineers are passionate about understanding asset performance and failure and using those results to help improve power system performance. We take pride in high-quality results and are committed to technical excellence. EPRI has earned a reputation for objectivity, meaning that you get results that you can count on from the team that you trust.

3 - Capabilities

EPRI - PDU Lab capabilities

3.1 - Lenox T&D Lab

A look into EPRI’s Lenox Transmission & Distribution Laboratory

The Transmission & Distribution laboratory in Lenox, MA provides a unique test facility for a variety of T&D research topics. Explore the laboratory below by clicking the popover (red dots) at a selection for the test sites. Click the popover to keep the popover open.