The Tech Corner is a place for engineers, contractors and maintenance personnel to connect with the technology experts at ADB on airfield lighting and industry related topics. Written from a technical point of view, our team provides answers to your questions and discusses reliability, efficiency and other key factors that impact your operations.

Latest Topic: What Do You Need To Know About Airfield Lightning Protection?

By John Chapman, ADB Airfield Solutions

Satellite data tells us that there are around 3 million lightning flashes per day throughout the world, or about 30 flashes per second on average. Most of those discharges are cloud-to-cloud, but about 30% end up as the cloud-to-ground discharge that we are most familiar with.

There are a number of websites that describe the atmospheric electrical discharge that we know of as lightning, but the average bolt carries 30 to 40 kilo amperes (kA) of current, at millions of volts. Current can exceed 120 kA, and reach temperatures of 20,000 °C (36,000 °F), with a stroke lasting around 30 microseconds.

In airfield applications, we are also very concerned with how far that current will travel in soil once a lightning bolt contacts the earth. The current will begin to dissipate as it travels from the contact point at a rate that varies depending on the soil conditions, but current can still radiate out 1-3 km (approx. 1 mile) from the strike…

The topics covered in this article are:

• Airfield Lightning Protection Specifications
• Counterpoise Lightning Protection System
• Protection from Lightning
• Use of MOVs in Airfield Lighting
• MOV Failure
• Degradation of MOVs
• Identifying MOV Failure
• Series Circuit Field Lightning Arrestor