High-voltage power line tower at high altitude with aurora borealis and electrical arcs.

Voltage Correction Factors: The Shocking Truth About High-Altitude Power Lines

Nico Varela in Tech & Innovation September 2025 • 4 min read.

"Uncover the hidden challenges and necessary adjustments for maintaining safe and efficient air-insulated transmission lines in mountainous regions."

As the demand for electricity grows, so does the need to transmit power across increasingly challenging terrains. High-altitude regions, with their thinner air and harsh climates, present unique obstacles for air-insulated transmission lines. Designing and maintaining these power lines requires careful consideration of atmospheric conditions to prevent failures and ensure reliable performance.

One critical factor is the dielectric strength of air, which decreases with altitude due to lower air density. This reduction can lead to corona activity, an electrical discharge that wastes energy, generates noise, and can even damage equipment. To combat these effects, engineers apply voltage correction factors, adjusting the operating voltage to account for the altitude.

But how accurate are these correction factors? Are international standards keeping pace with the challenges of high-altitude power transmission? Recent research has revealed substantial differences among various correction methods, particularly at higher altitudes. This raises concerns about the adequacy of current testing procedures and the need for more detailed information to ensure the safety and efficiency of power lines in mountainous regions.

Decoding Voltage Correction: Why Altitude Matters for Power Lines

High-voltage power line tower at high altitude with aurora borealis and electrical arcs.

At altitudes above 1000 meters, the atmospheric conditions significantly impact the performance of high-voltage electrical systems. Air density decreases, reducing the dielectric withstand voltage – the ability of the air to insulate the conductors. This is crucial because the dielectric strength and transient overvoltage levels are critical for designing external insulation in power transmission systems.

Think of it like this: air acts as an insulator, preventing electricity from arcing or escaping from the power lines. As you go higher, the air becomes thinner, making it easier for electricity to jump. This is why voltage correction factors are essential; they compensate for the reduced insulating capacity of the air at high altitudes.

Reduced Dielectric Strength: Lower air density means air is less effective as an insulator.
Increased Corona Activity: Electrical discharges (corona) become more likely, leading to energy loss and potential damage.
Overload Capacity: High altitude can impact overload and thermal ampacity ratings.
Pollution and Icing: The potential for pollution and icing in high-altitude environments can further degrade dielectric performance.

These factors make it imperative to understand and apply the correct voltage correction methods. International standards provide guidance, but recent studies show that these standards may not always be sufficient, particularly at very high altitudes. This is because most high-voltage labs aren't equipped to simulate conditions that the high-voltage devices installed in high-altitude regions must handle.

Powering the Future: The Need for Updated Standards

The existing altitude and atmospheric correction factors within current International Standards require a thorough update and/or revision. By doing so, there is a chance that testing high-voltage components destined for high-altitude deployment will increase, while taking into account their unique insulation design. More research must continue on the challenges encountered in air-insulated transmission lines and high-voltage electrical system.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.3390/en11071908, Alternate LINK

Title: Voltage Correction Factors For Air-Insulated Transmission Lines Operating In High-Altitude Regions To Limit Corona Activity: A Review

Subject: Energy (miscellaneous)

Journal: Energies

Publisher: MDPI AG

Authors: Jordi-Roger Riba, William Larzelere, Johannes Rickmann

Published: 2018-07-21

Everything You Need To Know

Why is the dielectric strength of air so important for high-altitude power lines?

At higher altitudes, the air's dielectric strength decreases because the air becomes less dense. This reduction in dielectric strength means the air is not as effective at preventing electrical discharges, known as corona activity, which can lead to energy loss and potential damage to the equipment. Therefore, voltage correction factors are applied to adjust the operating voltage and compensate for this reduced insulation capacity.

What is the purpose of voltage correction factors in air-insulated transmission lines?

Voltage correction factors are used to adjust the operating voltage of air-insulated transmission lines to account for the reduced dielectric strength of air at higher altitudes. By applying these correction factors, engineers can maintain safe and efficient power transmission, preventing issues like corona activity and ensuring that the lines can handle transient overvoltage levels. If these are not taken into account it can impact overload and thermal ampacity ratings.

Are the existing international standards sufficient for voltage correction at high altitudes?

International standards provide guidance on voltage correction methods, but recent studies suggest these standards may not be adequate, especially at very high altitudes. The standards might need updating because most high-voltage labs are not equipped to simulate conditions that high-voltage devices installed in high-altitude regions must handle, potentially leading to inaccurate assessments of insulation performance and the need for more detailed information.

What specific challenges do high-altitude installations pose for air-insulated power lines?

High altitude installations introduce several challenges, including reduced dielectric strength of air, which increases the risk of corona activity. This can lead to energy loss, noise, and potential damage to equipment. Moreover, the potential for pollution and icing in high-altitude environments can further degrade dielectric performance, impacting overload capacity and thermal ampacity ratings. Understanding and addressing these factors is crucial for ensuring the reliability and safety of power transmission.

Why is it important to update international standards for voltage correction factors?

Updating international standards for voltage correction factors is important because current standards may not fully address the unique challenges of high-altitude power transmission. Revised standards should lead to more thorough testing of high-voltage components destined for high-altitude deployment, considering their unique insulation design. Increased research on the challenges encountered in air-insulated transmission lines and high-voltage electrical systems is necessary to inform these updates and enhance the safety and efficiency of power lines in mountainous regions.