Guide to Aerial Power Line Inspection

When electricity first appeared, technophobia reigned in humble homes and the White House alike. Benjamin Harrison, the first US president to have electricity in his residence, was so uneasy about the invention that he refused to flip the switches.

A hundred years later, electricity mostly causes frustration when it’s out. “After one hour without electricity, we were on the verge of panic,” recalled a resident of Montenegro after the major outage left the Balkans without power for several hours. Even short blackouts hamper critical operations of hospitals, fire departments, and police stations — and in the United States, they last almost 6 hours on average.

Aerial power line inspections with drones can help operators minimize shutdowns and shorten power restoration times. Drones can help identify infrastructure damages, vegetation hazards, and mechanical breakdowns, increasing the resilience of power grids. Similar to electricity, drones went from causing skepticism to becoming a standard infrastructure management practice.

Why Use Drones for Power Line Inspection

Unreliable power grids escalate beyond outages, leading to wildfires, environmental pollution, and even fatal accidents. That’s why authorities enforce annual inspections and penalize non-compliant companies. For instance, Australian operator Powercor owes $2.5M for failing to inspect and manage vegetation, which led to 185 hectares of bushfires.

If inspections are so important, why aren’t they done more often? The challenge lies in traditional inspection limits. Due to the massive size and remote location of power grids, helicopter inspections are expensive, and on-foot patrols are extremely time-consuming. The leading 10 U.S. power grid owners operate 2.2M km/1.4m miles of transmission lines — equivalent to the distance from New York to Miami. Imagine driving or walking across this distance, trying to pay attention to anything.

Much of the power infrastructure is aging and requires more in-depth inspections and repairs. In the USA alone, 70% of transmission lines are over 25 years old. Also, power line inspections are dangerous. Even when disconnected from live electricity, the grid may still have a residual charge that can injure or kill inspection personnel.

Given these factors, drones have taken off in the power line industry. They make inspections much faster and save thousands of dollars, enabling more frequent missions. Drones cover miles of power lines in one trip, collect precise data on asset conditions, and locate external hazards in real-time. All the while keeping your team on the ground and safe from all those kilovolts.

Advantages of Drone Power Line Inspection

• Cost-efficiency. Drone inspection cuts down on scaffolding, ropes, climbing poles, safety gear, and vehicle patrols. UAVs aren’t as expensive as chartering planes and require fewer man hours. Plus, they enable more frequent inspections, reducing the risk of hefty fines.

• Greater safety. Drones easily access overhead transmission lines and withstand high-voltage environments, leaving your climbing gear to gather dust. They can act as first responders during storm damage surveillance, providing relief teams with data for safe risk mitigation.

• Richer inspection data. Drones can be fitted with various payloads: different types of cameras, thermal imagers, sensors, and NDT probes. This allows for capturing valuable asset data, from temperature fluctuations and vegetation overgrowth to loss of coating and tower corrosion.

• Higher precision. Modern drones boast high-resolution cameras that can capture close-up images of even the smallest power grid elements. With NDT probes, you can detect corrosion, erosion, and loss of coating in their early stages.

• Minimal downtime. Power line inspection drones are EMI-resistant and carry flight missions even in GPS-denied environments. You can inspect transmission lines without powering them off and right after the coating application.

4 Aerial Power Line Inspection Scenarios with Drones

Power line infrastructure has many components, from conductors and insulators to transmission towers and concrete foundations. All these parts are prone to specific defects and thus require different inspection methods.

Steel transmission towers, for example, are vulnerable to corrosion and are often coated, so you’d want to measure the coating thickness. Cables and conductors should be inspected for stubs, discontinuities, internal corrosion, and the area around them — for corona discharge. In concrete foundations, look for cracks, debonding, or delamination.

Industrial inspection drones, fitted with cameras, thermal imagers, sensors, and NDT probes, can support a wide range of asset integrity management scenarios. Listed below are the top 4 cases where drones can have the greatest impact.

1. Visual Damage Inspections

Due to a growing demand for electricity (+2.2% in 2023), power lines are subjected to overconsumption and increased wear and tear. Vegetation growth, wind, excessive heat, ice build-up, and flooding exacerbate the problem, leading to service disruptions. In the USA, about 83% of major outages are weather-related. That puts pressure on inspection teams. Apart from routine inspections, they need to deploy teams to dangerous terrains after each storm. Drones solve the problem.

Drones with long battery lives, large bandwidths, and autonomous modes perform beyond line-of-sight (BVLOS) operations and inspect miles of power lines in one go. With high-resolution cameras, they reliably spot vegetation hazards, foundation aging, tower cracks, market ball falling, and line ruptures. No need to send expensive charter planes and bucket trucks.

Some models enable visual inspections at night, powered by thermal sensors and night vision cameras. Specialized apps and controllers enable real-time viewing of all inspection findings.

In one long-range demo, two ARA Robotics drones performed a BVLOS inspection of Viasat’s energy infrastructure in Canada. The drones captured HD video of facilities and brought back rich sensor data. Equipped with an extra Satcom payload, they could easily switch radio bands and ensure continuous operation under an 11-kilometer control distance.

Across the globe, Australian power distributor SA Power Networks partnered with Carbonix for the first BLVOS power line inspection. The pilot mission covered 150 kilometers of powerlines in remote, hard-to-access areas. Further deployments have the potential to cut 80% of operational costs and up to 98% of CO2 emissions.

2. Thickness Measurements of Protective Tower Coating

Transmission towers have protective coating or paint to keep them from corroding and eroding. The warmer the climate and the higher the humidity, the more likely corrosion and coating thinning are to occur. Global warming intensifies the risk and necessitates constant inspections.

Specialized NDT drones like Voliro T can now handle coating thickness measurements on all tower components, including those in hard-to-access, angled sections. They identify coating thinning and corrosion in the earliest stages. But most importantly, drones require no asset shutdown and can test the asset immediately after painting.

Voliro T facilitated a one-person inspection of 380 kV transmission towers. Outfitted with a DFT probe, the drone offered an unparalleled coating measurement range of 0 – 1.5 mm / 0 – 60 mils. By inspecting 10+ transmission towers per day without shutdowns and right after coating, Voliro T minimized service interruptions.

Austrian Power Grid (APG) also streamlines protective coating inspections. The transmission service operator has been deploying drones to visually assess high-voltage pylons for years. If the analysis shows mast damage, the company renews the protective coating and uses drones to ensure it is applied properly. Currently, APG plans to use AI to pre-plan drone missions and collect more than 2000 photos for realistic, 3D tower modeling.

3. Safe High-Voltage Power Line Inspection

Combine environmental hazards, continuous overconsumption, and high electric pressure and you get a sure-fire formula for power line breakdown. According to an Australian study, corrosion accounts for 30% of conductor malfunctions, joining failures — for 19%, and fretting fatigue — for 14%. Frequent inspections could prevent these damages, but they pose a serious danger.

Electric pressure of lower than 230V kills and injures people. High-voltage, long-distance transmission lines carry electricity with almost 500-3K times as much voltage, ranging from 115 kV to 765 kV. Therefore, traditional inspections always require shutdowns, lengthy preparations, and expensive equipment to prevent personnel injury.

EMI-shielded and maneuverable in GPS-denied environments, drones can inspect high-voltage power grids even when it is operational, reducing downtime to a minimum. Because the drones are lightweight and protected by natural insulators, they don’t catch fire in contact with the line. In worst cases, they absorb energy and fall to the ground — a sad loss, but less expensive than a downed helicopter or a wildfire lawsuit.

Fitted with visual HD cameras, they pinpoint physical damage, corrosion, and external hazards. Many models come with in-built or mountable thermal imagers, so they can detect hot spots and electricity leaks in real time.

The UK National Grid partnered with Manchester University to create a drone-mountable solution for electric field inspections at 600kV DC and 800kV AC voltage ranges. These fields have a unique footprint and, if evaluated correctly, can point out insulator defects that weren’t apparent before. In the long term, the technology can save the UK power grid operators £2.8M.

4. Land Surveying for New Power Line Construction Projects

To meet their climate goals and streamline energy resilience, countries will need to build or replace 80M km/50M miles of transmission lines by 2040, according to IEA. That’s almost equal to the current capacity of transmission lines.

The construction of such long power lines calls for careful planning, monitoring, and optimization. Vertical take-off and landing drones (VTLOs) can speed up the process and improve decision-making.

VTLOs are larger-sized, enterprise-grade UAVs that can take off and land on almost any terrain. They boast flight times of up to several hours, long data transmission ranges, and autonomous operation modes, which allow for continuous surveillance of large territories. With powerful LiDAR sensors and wide-angle, tele cameras, VTLO drones can gather data for BIM designs, dimension-accurate 2D and 3D models, colorized maps, and even digital twins.

With all these capabilities, VTLOs help you map out a power line route that:

• Allows for the shortest distance between the start and finish points
• Crosses minimal railroads, highways, bicycle routes, and densely populated areas
• Does not interfere with airplane and helicopter operations, where they are necessary
• Requires less extensive vegetation management (remote from protected habitats)
• Has the right geological features, like soil conditions, and topography

Additionally, VTLO drones can help you monitor and inspect active construction sites, allowing you to timely optimize designs and layouts based on unforeseen risks, environmental hazards, and operational inefficiencies.

3DroneMapping, a provider of aerial surveys in Africa, uses drones equipped with LiDAR sensors to inspect up to 10 thousand ha per day. The collected data is then used for creating dimensionally-accurate digital terrain models (DTM) and digital surface models (DSM). DTM and DSM later power up computational fluid dynamic modeling – a technology that can simulate oil, gas, and electricity flow and pressure conditions, allowing you to optimize power line placement and modify construction planning.

Best Power Line Inspection Drones

First and foremost, power line inspection drones need to navigate well in EMI-rich, high-KV environments – so consider options that are made of resistant materials and have redundant positioning sensors, auto-return and landing options, and AI-assisted autonomy.

Long flight times and BVLOS operation modes are important when it comes to inspecting miles of transmission lines in remote deserts, mountains, or rural areas.

Also, consider drone’s potential applications. There are models purpose-fit for early corrosion detection and coating measurements, thermal readings, or aerial mapping. For maximum flexibility, select options that have sufficient payload capacity, probe customization options, and open platform design.

Our top recommendations:

• Voliro: a lightweight drone purpose-fit for non-destructive testing and early defect detection. With a selection of six NDT probes, you can use Voliro to inspect ferrous and non-ferrous components at any height and orientation, detecting cracks, dents, corrosion, and coating thinning.

• DJI Matrice 350 RTK: a larger drone with an hour of flight time, 20 km transmission rate, and pre-planned flight missions. The drone can be fitted with either a Zenmuse four-sensor RGB and thermal camera, P1 payload for photogrammetry, or L2 LiDAR payload with an IMU system, and a 4/3 CMOS RGB mapping camera.

• Ranger Pro: a quadcopter that works great in high-voltage environments due to its carbon fiber frame, EMI-absorbing and dissipating protection, and strong connectivity. The model has an in-built anti-vibration control for higher-quality imaging.