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Lightning Protection Measurement for Wind Turbines
Due to their exposed location, wind turbines are particularly vulnerable to lightning strikes. An electrical measurement of the lightning protection system can provide important information about the condition of the system — whether and when it is useful depends on the turbine, location and operator objectives. Here we answer the most important questions.
What is the difference between a visual inspection and an electrical lightning protection measurement?
During a visual inspection, lightning receptors, down-conductors and connection points are examined visually for damage, corrosion or wear — it is part of the recurring inspection (WKP). The electrical measurement goes further: earthing resistance and down-conductor resistances are measured and compared with target values. Only the measurement provides a standards-compliant test protocol according to DIN EN 62305.
What limit values apply to lightning protection measurements on wind turbines?
The relevant standard is DIN EN 62305 (VDE 0185-305): The earthing resistance should typically be below 10 Ω (IEC 61400-24). The down-conductor resistances on rotor blades depend on manufacturer specifications — typical values range from 0.5 to 2 Ω per blade segment. Exceedances indicate interruptions in the down-conductor system and must be rectified promptly.
When is a lightning protection measurement worthwhile even without an insurance requirement?
A measurement is particularly advisable after a confirmed lightning strike, before selling or refinancing a turbine, if the last inspection was more than 4 years ago, or if the operator wishes to avoid increased downtime costs from unplanned repairs. It provides legal protection and planning certainty — even without a formal obligation.
How does an on-site lightning protection measurement work?
The measurement is carried out while the turbine is shut down. Depending on the turbine type, a complete measurement takes 2 to 4 hours. On site, the earthing system, down-conductors and rotor blades are measured. The operator should shut down the turbine for the measurement period and have access documentation ready. Reprojekt provides all necessary measuring equipment and produces the test protocol.
What does the lightning protection measurement protocol contain and who is it for?
The protocol documents all measurement points with measured values, evaluates the turbine according to DIN EN 62305-3 and VDE 0185-305, identifies defects and provides action recommendations. It is aimed at operators, insurance companies and licensing authorities. As proof of a standards-compliant inspection, it can be decisive in the event of a claim.
Can the lightning protection measurement be commissioned separately or only together with the WKP?
Both are possible. Reprojekt carries out the lightning protection measurement either as a supplement to the recurring inspection (WKP) or as a standalone service. Combined commissioning creates synergies through shared site visits and turbine downtime.
What to do after a lightning strike?
After a lightning strike, the turbine should be shut down immediately and inspected before restarting. In addition to the visual inspection for rotor blade damage (ideally by drone), a complete electrical lightning protection measurement is recommended — also to prove the condition of the turbine to the insurance company. Reprojekt coordinates both from a single source.
Does Reprojekt carry out lightning protection measurements?
Yes. As a DAkkS-accredited inspection body Type C (D-IS-21697-01-00), we carry out lightning protection measurements and produce a standards-compliant test protocol. It can be commissioned as a supplement to the WKP or as a separate standalone service.