After lightning strike tests on electric vehicle charging stations for the company Indelec Mobility, and certification tests of insulating stands for external lightning protection installations for the company Constructions Tubulaires de l’Artois, LiRi LAB continues his adventure off the beaten track of Early Streamer Emission Air Terminals (E.S.E.A.T.) with isolation measurements of airfield runway edge beacons for the company Delta Box based in Douai (North, France).
These beacons are notably used in series in so-called “6.6 Amps” current loops to mark the edges of airport runways or taxiways. The electrical insulation of these loops is a concern for airport operators because they can be powered over long distances at up to over 4500 V AC. Indeed, excessively large earth leakage current losses are detrimental and can interfere with the automatic insulation measurement systems of the runway edge loop power system. These beacons, elements of the “6.6” loop, are therefore affected by this problem and must therefore present the highest possible insulation resistance. The company Delta Box, which has already carried out insulation resistance measurements in another laboratory, asked the LiRi LAB to validate a measurement protocol and to carry them out up to 5000 Volts, in alternative and direct voltage on a runway edge beacon designed by Delta Box. These products meet in particular recommendations of the American Federal Aviation Administration (F.A.A.) and the French Civil Aviation Authority (D.G.A.C.), as well as the recommendations of the International Civil Aviation Organization (I.C.A.O.) on the design of airfields.
These measurements are difficult to carry out due to the very low values of the leakage currents to earth. Particular care must be taken to measure a few microamps, or even a few nanoamps, without being disturbed by the electrical environment of the laboratory or the building.
The laboratory environment was therefore modified to recreate a test setup in agreement with the company Delta Box, with the aim of being as close as possible to the configuration of the installed equipment, while being able to measure with complete immunity very low earth leakage current values.
After joint validation of the test protocol with the customer, the measurements were successfully carried out thanks to very satisfactory values, of the order of approximately 6nA under 5000 Volts, which corresponds to an insulation resistance of approximately 800 GigaOhms.
Once again, the laboratory took great pleasure in participating and developing the measurement benches necessary for the completion of this service in a field of application different from that of lightning protection.
