Proving the applicability of sUAS on Electric Transmission Construction Projects
Sky Scape Industries, LLC (SSI), an airborne remote sensing technology company specializing in the utilization of small Unmanned Aircraft Systems (sUAS) for electric utility inspections, has successfully used unmanned aircraft to replace two static line segments on a 230 kV transmission circuit.
In 2020, utilizing a multi-acre in-house utility training yard, SSI began developing the proof of concept for powerline pull operations. Following months of process development, enhancement, and refinement, SSI was tasked with the first real-world scenario – proving that unmanned aircraft can be used in place of helicopters for the installation and replacement of high voltage electrical utility transmission and distribution lines.
While risks are present in any operation, using unmanned aircraft significantly diminishes the risk of significant injury or death to the participants, while simultaneously reducing costs.
One of SSI’s utility customers experienced damage to a 230 kV circuit which resulted in a pair of static lines between two wooden H-frame structures, 1,600 feet apart, to require replacement. The structures are separated by a ravine, two-lane roadway, and drastically changing topography.
As a result of the remote location, which would have made helicopter operations prohibitively expensive, as well as the client’s ongoing commitment to safety and innovation, SSI was tasked to execute the operation using small Unmanned Aircraft (sUAS). Due to outage schedules on the system, the SSI team was given a two-day outage window to complete the operation.
Concept of Operations (CONOPs)
After assessing the SOW requirements, Sky Scape was tasked with deploying drone technology to re-string new static wires.
Due to the weight of standard pull line, the team opted to perform the mission in multiple stages – first passing an ultra-lightweight “messenger line” via unmanned aircraft, then using ground-based equipment to pass the thicker “p-line”, which was then used to pull the static wires, completing the mission objective.
Referencing the extensive training and use-case development, the flight crew first got to work planning the Concept of Operations (CONOPs) for this operation, starting with the most important consideration – safety.
The flight crew considered all applicable risks and applied job-specific mitigations to the CONOPs, reviewing the plans in detail with the utility prior to the operation. In addition, factors such as environmental, meteorological, human-factor, cross-discipline personnel, and flight profile characteristics were considered. The risk mitigation portion of the CONOPs were only accepted by SSI when the customer signed off on the risk mitigation assessment.
Extensive preplanning was required for every aspect of the mission. Factors such as line characteristics, weather (i.e. wind-loading), environmental limits (adjusted for mission), human factors, structure composition, and subsystem equipment capabilities were all considered and addressed. SSI’s approach to the mission resulted in a detailed, carefully analyzed, comprehensive safety plan which addressed every conceivable hazard possible for this project.
This mission called for two flight operations, one for each static line placement. The Pilot in Command (PIC) was positioned at the first structure, together with supporting resources. As the aircraft ascended with the rope attached, a lineman positioned on the top of the first pole secured the line into a block after being signaled it was safe to do so.
The drone then traveled towards the second structure, carrying the line across the ravine. When the aircraft approached the roadway, the designated traffic detail was alerted to temporarily halt traffic while the aircraft passed overhead.
As the drone approached the second structure, radio communications were used between SSI personnel to position the drone in a suitable location. Once positioned, a second lineman, on top of the second structure, secured the line into the respective snatch block.
Upon successful connection to both structures, the PIC released the rope from the aircraft and returned for a landing at the first structure. The ground crew retrieved the dropped line and prepared it for a return trip, with the industry standard p-line connected. This flight operation was completed a second time, to complete the successful stringing of both static lines. The average flight time to complete each string operation was ~4 minutes and 30 seconds.
SSI has developed an efficient and repeatable procedure for safely connecting utility assets over inhospitable terrain. Careful planning, proactive communication, and a safety mindset all contributed to the success of the mission and have laid the groundwork for positive outcomes during future projects. While the project was a complete success, there were a significant amount of lessons-learned and improvements to be made.
“I am incredibly proud of the SSI flight crews who came together to make this mission a complete success. The theory of performing this operation sounds simple. In reality, it is incredibly complex and requires a team of highly technical flight crew members. Aside from the improvements we will be making to our workflow, we learned a valuable lesson; sUAS [drones] are a valuable tool for powerline pull projects,” said Nate Ernst, President of SSI.
SSI is currently developing a purpose-built system for sUAS powerline pulls which include enhanced aircraft capabilities, greater failsafe systems, and higher performance winching systems. As industry begins to tap into the potential of sUAS, SSI looks for to implementing this capability on a routine basis.
Sky Scape Industries, LLC (SSI) is an airborne remote sensing technology company specializing in the integration of small Unmanned Aircraft Systems (sUAS) into the critical infrastructure sector. A service provider, integrator, developer, and subject matter expert in the unmanned aviation industry, SSI performs flight operations for Electric Utilities nationwide.
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