Recurring Inspection (WKP) of Wind Turbine Structural Safety
All wind turbines must be inspected at regular intervals by an independent expert. The recurring inspection (WKP) of structural safety every 2 to 4 years is the responsibility of an appointed expert.
As an inspection body Type C, the requirements for WKP are met in accordance with DIN EN ISO/IEC 17020:2012.
The basis in Germany is the structural safety guideline of the German Institute for Building Technology (DIBt). This standard applies to towers and antenna structures, which also include wind turbines.
What must be considered in the recurring inspection?
As part of the recurring inspection, the manufacturer provides calculations and drawings, which are used to verify whether the structure is safe for the design service life under categorised site conditions.
Since 2007, the expert advisory board of the BWE has formulated principles to specify the quality and scope of the inspection.
Scope of WKP
The recurring inspection serves to assess the current condition, identify damage potential, and reduce risks. The focus is on evaluating the structural and operational safety of the wind turbine.
What is inspected during the WKP?
Structural Safety
Static and dynamic structural safety in accordance with the DIBt guideline for wind turbines.
Document Review
Manufacturer calculations, drawings, and type-approval documents are fully reviewed.
Visual Inspection
Visual inspection of tower, foundation, nacelle, rotor blades, and lightning protection system.
Lightning Protection
Measurement of earth resistance and discharge resistances in accordance with DIN EN 62305.
Inspection Report
Standards-compliant report with condition assessment, deficiencies, and recommendations.
DAkkS Certificate
Accredited inspection certificate as a Type C inspection body – recognised by authorities and insurers.
Lightning Protection Measurement on Wind Turbines
Lightning protection measurement can be commissioned on request as an optional supplement to the WKP. Earth resistance, discharge resistances, and the continuity of the entire lightning protection system on rotor blades, nacelle, and tower are tested. The lightning protection report is issued separately and serves as documented proof for insurers and authorities.
- Earth resistance at foundation and earthing system
- Discharge resistances at rotor blades, nacelle, and tower
- Documentation in accordance with DIN EN 62305-3 and VDE 0185-305
- Optional lightning protection report available on request as a supplement to the WKP report
Your benefits from an accredited WKP
Legal Certainty
Fulfilment of the statutory inspection obligation under state building law and DIBt structural safety guidelines.
Independence
As an accredited Type C inspection body, we act independently – free from manufacturer or operator interests.
Complete Documentation
DAkkS-accredited inspection certificate for insurers, approval authorities, and turbine operators.
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