Drone Powerline Inspection: What to Consider and How to Choose the Best Drone

Utility companies are beginning to find that drones, also referred to as unmanned aerial vehicles (UAV) and unmanned aircraft systems (UAS), can be a valuable tool when it comes to powerline and substation inspection.

The benefits of drone-based inspections include:

  • human personnel maintain a safe distance from electrical hazards
  • safer and more efficient storm damage surveillance
  • eliminates the need to climb poles
  • eliminates the need for bucket trucks and helicopters
  • allows for more accurate and detailed inspection data (images)
  • can increase productivity and reduce cost

Safety is the top-selling point when pitching drones to utility company decision-makers.

“My business partner and I each knew people who lost their lives in helicopter accidents while inspecting powerlines,” says Jeremy Highhouse, Founder and Chief Technology Officer at Union Robotics, an Oregon-based manufacturer of drones for the utility industry. “That is why we started this company. Linemen are unsung heroes and deserve all the tools they can get.”

There is also an environmental aspect that could lead to financial implications.

“If a line came down and ended up burning tens of thousands of acres of land, there could be some pretty severe lawsuits,” says Robert Henley, Vice President of Energy Solutions at PrecisionHawk, a North Carolina-based provider of geospatial data analytics services and tools. “A drone is by far the safest way to inspect powerlines. If a lightweight plastic drone happened to hit a line, the probability of anything bad happening to a person or the environment is as close to zero as you can get. Plastic usually doesn’t start on fire. So the drone would just absorb some damage and drop to the ground.”

The economics of using drones

Convincing utility companies to implement drone-based inspections largely comes down to economics.

“We know linemen like the idea of using drones because they tested our products and told us so,” Highhouse relates. “But the bean counters at some of these utility companies can be a tough sell. They’ll keep pumping money into helicopter inspections because that is what they’re used to. But flying a helicopter on a line typically costs at least $10,000 a day. Our aircraft is $40,000 fully loaded. And if it crashes, nobody dies.”

When evaluating the economic benefit of drones, Henley says utilities should scrutinize three key areas: safety, productivity, and risk.

“Think about how much money might have to be spent in the aftermath of a catastrophe,” Henley says. “A utility could invest in a huge fleet of drones for that kind of money. I know that is a hard thing to ‘put on the books’ because it is speculative and subjective, but it is something that should be considered.”

Here is something more objective to consider. “In my past experience working for a utility, I found that the typical lineman could perform two detailed climbing inspections per day,” Henley says. “On the other hand, a drone could perform anywhere from 10 to 20. So from a productivity standpoint, the math speaks for itself.”

Helicopters can cover a lot more ground and can be a good solution for checking vegetation, but powerline inspection data is not as good as what a drone can collect.

“A helicopter can inspect hundreds of miles of powerline in a day, but rarely stops unless something is grossly wrong,” Henley says. “A helicopter is also 50 to 100 feet above a structure, so there is often a problem with taking the right pictures at the right quality level.”

Highhouse concurs, adding that a drone can hover in place longer and in closer proximity to whatever it is inspecting.

When contemplating the potential productivity gains of using drones, Henley reflects on an experience he once had when working on a large project in California.

“We were mandated to do our traditional means of inspection, which included a climbing lineman and a helicopter,” Henley tells. “But we also decided to introduce drones into the project. Our drone teams found 30-70% more defects. A lot of that varied based on geography where it was difficult for a lineman or helicopter to operate. In those types of environments, the drones really stood out.”

Choosing the right drone for inspections

A lineman could utilize either a fixed-wing or quad-copter drone. “We lean toward copters that are under 55 lbs. so you don’t need a waiver from the FAA,” Henley says.

Smaller drones (under 2 lbs.) can be ideal for inspecting distribution poles on properties. “They can get within 6 feet or so without electrical interference, and can also take good pictures,” Henley points out.

On larger structures of 60 kV and above, a mid-size drone that can carry two cameras is a good match. That way the drone can capture both RGB photos and infrared imagery. According to Henley, a mid-size drone typically requires a two-person operation. One person uses a controller to operate the drone while the other uses a controller to operate the cameras.

A utility company’s inspection data needs to drive drone and camera selection. For instance, if a utility doesn’t want the drone to get closer than 60 feet from a structure, a higher-resolution camera will be needed. If the utility wants to inspect smaller components such as cotter pins, a high-resolution camera with excellent zoom capability will be needed. On the other hand, if the drone is allowed to get within 12 feet of the structure, the camera doesn’t need to be quite as good. Additionally, a smaller drone allowing for one-person operation may be an option.

Highhouse says it’s also important to look for a drone that is designed for the utility industry.

“Flying high-kV lines can be a challenging environment for the sensors on an aircraft,” Highhouse explains. “The compass must have a decent idea of what is going on in order to keep the heading of the aircraft. In a high-kV environment, you end up with a lot of crazy magnetic fields everywhere. The compass freaks out. The solution is to use a drone that is ‘hardened’ for an EMI-rich environment.” EMI stands for electromagnetic interference.

Security is also something that should be considered when selecting a drone.

“If you want to use your drone on a utility that’s sensitive to national security, it has to be NDAA-compliant,” Highhouse points out. The NDAA is the National Defense Authorization Act which includes language limiting the use of drones made in certain countries, particularly China.

Henley says that regardless of where the drone comes from, security protocols need to be implemented in order to protect against a hacker taking over control or stealing data. To that point, PrecisionHawk never flies drones while connected to the internet. Secondly, firmware in the drone is never updated when an SD card containing images is inserted.

More ways drones help discover defects

A drone can take a lot of photos. Sorting through all of them takes expertise and time. Technology can help.

PrecisionHawk’s software has AI algorithms that allow it to geotag images and apply additional tags based on defects that are recognized. “The concept is to package all of that up so no single person has to look at a million pictures,” Henley says. “Rather, the person just has to look at those hundred pictures that are really an issue. An image database of the utility’s assets is also created which can help if there ever is a legal issue.”

Drone-based inspections can also span beyond imagery. For instance, Union Robotics’ drone has a cargo hook that allows the operator to drop a line over a powerline to conduct a ground fault test. “We are also developing some special tools for lubrication,” Highhouse adds.

Union Robotics has also worked with a company called Linebird. The Linebird Osprey NPS (non-conductive payload system) allows lineman tools to access live lines via a drone. The Osprey NPS currently integrates the Sensorlink Ohmstik to enable resistance measurement of transmission conductor splice and dead-end connectors while the drone operator is safely on the ground.

Realizing the potential of drones

Establishing a drone-based inspection program isn’t as simple as running to an electronics store and purchasing a bunch of drones.

“If a utility is going to do this right, it needs to establish the equivalent of a flight program,” Henley says. “It doesn’t have to be of the same scale as helicopters, but it has to have the key elements the FAA requires.” That includes pilot qualifications, certification, and retraining, as well as processes for maintaining equipment and other standard operating procedures.

“We’re still pretty early in the maturity curve,” Henley says. “The early adopters in the utility industry have only had drone programs for about five years. And you can probably count the companies with a really robust program on one hand. This is still pretty new.”

But the potential is enormous, for both the linemen tasked with completing inspections and the utility companies that employ them.

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