Testing according to regulations
Nationwide locations
Sophisticated testing methods
We have the right service for every requirement.
Wind turbines are subject to regular inspection cycles to identify damage at an early stage and guarantee safe operation.
The inspection intervals and scope are determined by the specifications of the relevant type or individual inspection, the provisions of the approval notice, financing requirements, and insurance conditions. Advanced inspection methods allow for more detailed assessments of the condition of individual main components.
Inspections may focus on the following aspects:
Commissioning
- Expiry of warranty periods
- Technical condition during operational life
- Continued operation after 20 years
- Expert reports for legal proceedings
Our locations
Eight certified experts are available at various locations to carry out inspections. Through our shared network of five offices, we have a total of 17 experts based throughout Germany.
We are at your service for:
- Companies operating wind turbines
Authorities
- Wind turbine manufacturers
Maintenance companies
- Financing banks
- Courts
Our inspections are carried out according to the following regulations:
- “Principles for the Recurring Periodic Inspection of Wind Turbine Generator Systems”, German Wind Energy Association (BWE)
- “Principles for Condition-Based Maintenance of Wind Turbines”, German Wind Energy Association
- “Guideline for Wind Turbines – Load Effects and Structural Safety for Tower and Foundation”, German Institute for Structural Engineering (DIBt)
- DIN EN 61400 “Wind Turbine Generator Systems”
- DIN EN 50308 “Wind Turbines – Protective Measures – Requirements For Design, Operation and Maintenance”
- Type testing for wind turbines, including expert assessments of safety systems, rotor blades, mechanical components, user manuals, etc.
- System specification, maintenance manual, on-site wind turbine documentation
- Soil investigation reports
- Turbulence assessments (during commissioning and continued operation after 20 years)
- Inspection reports from previous inspections to check for conditions, logbooks etc.
- DNV GL Guideline “Lifetime extension of wind turbines”, Germanischer Lloyd
- “Principles for assessment and inspection regarding continued operation of wind turbines (BPW)”, German Wind Energy Association, version 05/2017
- German Statutory Accident Insurance Regulations (DGUV)
- Operational Safety Ordinance (BetrSichV)
- Workplace Ordinance (ArbStättV)
We offer the following services to our customers:
[Commissioning inspection]
Ensuring safety and function after trial operation
Commissioning inspections verify that contractual obligations and official requirements are met from a technical perspective.
The following are inspected in detail:
- Functions of the wind turbine, including safety procedures
- Compliance of the wind turbine with technical documentation for the foundation, tower, bolts, mechanical components including gearbox, welds of load-bearing parts, and safety-related equipment
Any defects that prevent acceptance or safe operation are identified. The result is documented in a comprehensive report.
The commissioning inspection includes the scope of periodic inspections.
[Warranty inspection]
Economically valuable thanks to preventive defect detection
At the end of the warranty period, risks from hidden defects in the wind turbine pass to the operating company.
If defects are not reported to the wind turbine manufacturer before the end of the warranty period, the operating company loses its legal right to a free repair.
To detect defects, the following documents and components undergo intensive inspection:
- System documentation and maintenance records
- Foundation, tower, machine support
- Check of critical bolted connections (sampling)
- All mechanical and electrical components
- Drive train and, including if necessary, measurements, gearbox video endoscopy, and vibration diagnosticsanalysis
- We inspect all safety-critical components and their functionality. Rotor blade inspection is carried out both externally and internally (where accessible).
If necessary, the inspection scope can be expanded to include additional components. All defects are documented in a detailed report, which serves as the basis for corrective action and may be submitted to the turbine manufacturer.
The warranty inspection includes the scope of periodic inspections.
[Periodic inspection]
Verifying structural integrity, functionality, and operational safety of all components
The technical condition of a wind turbine is of interest not only to the operator. Due to requirements from authorities, insurers, financing banks, and others, wind turbines in Germany are subject to a prescribed inspection cycle.
The periodic inspection focuses on critical safety aspects. It determines whether structural defects or operational malfunctions pose any risks.
The following are also inspected:
- Electrical systems, including lightning protection paths
- Safety system
- Parts and components with regard to condition and function
- Rotor blades
The following are inspected on the basis of the documentation:
- Maintenance and repair work
[Condition-based inspection]
Improved operational safety thanks to up-to-date insights
A condition-based inspection (ZOP) is required:
- for turbines with high operating hours
- in case of repeated damage
- when a wind turbine is sold
- when changing insurance providers or maintenance contractors (e.g., entering or exiting a full-service contract)
The goal of this extensive inspection is to determine the current technical condition of the turbine. We detect early damage to prevent future failures. This includes full drivetrain diagnostics using video endoscopy and vibration analysis, as well as rotor blade inspection.
The condition-based inspection includes the scope of periodic inspections. The inspection is carried out in accordance with the “Principles for Condition-Based Maintenance of Wind Turbines” by the German Wind Energy Association Expert Committee. The exact scope is ultimately defined by the contracting company.
[Continued operation]
Operation beyond 20 years is possible
The operational life of a wind turbine is usually defined by the design life in its type or individual certification – typically 20 years.
Operation of the wind energy installation beyond this period is possible, provided that a continued operation assessment (BPW) demonstrates compliance with the necessary conditions.
This assessment consists of an analytical and a practical part:
- The analytical part is used to calculate any remaining service life.
- The practical part expands on the periodic inspection with in-depth considerations on material fatigue.
The subject of the continued operation inspection is therefore an individual analysis of possible risks that may arise from the continued operation of the wind turbine, taking into account the operating time already achieved and the specific site conditions.
The continued operation inspection includes the scope of periodic inspections.
[Rotor blade inspections]
Maximum yield through accurate inspection
Intact rotor blades are a key factor in ensuring the reliable operation of a wind turbine. The quality of the manufacturing process determines both the aerodynamic performance and potential downtime. As such, any damage directly affects turbine output and the economic viability of the investment.
The rotor blade inspection is carried out at close range using rope access techniques or mobile elevated work platforms.
We inspect:
- The condition of the rotor blades (cracking, cavities, delamination, etc.)
- The functionality of drainage holes and lightning protection systems
- The operational status of the tip brake mechanism
- The condition and completeness of aerodynamic elements
- Unusual operating noise
The inspection of the interior of the blade is limited to the accessible area. Defects are documented. As a result, a statement is made as to whether safety concerns preclude continued operation due to the condition of the blades.
[Gearbox video endoscopy]
For planned maintenance
Gearbox damage can lead to costly repairs and extended downtime.
To detect defects in gearing and bearings, gearboxes are inspected using high-precision video endoscopy. Years of hands-on experience combined with up-to-date inspection and documentation technology ensure reliable results.
To determine the cause of damage, video endoscopy can be supplemented by other methods, such as:
- Tooth impression analysis with subsequent SEM examination (scanning electron microscopy)
- Laser-based alignment measurement
- Vibration diagnostics
- Material testing
- Metallographic investigations
The results of the video endoscopy are summarised in a detailed report.
[Video endoscopy of main and blade pitch bearings]
For planned maintenance
Gearbox damage to main bearings or blade pitch bearings can lead to costly repairs and extended downtime.
To detect defects in gearing and bearings, gearboxes main bearings and blade bearings are inspected using high-precision video endoscopy. Years of hands-on experience combined with up-to-date inspection and documentation technology ensure reliable results. The accessibility of the bearings must be clarified in advance.
To determine the cause of damage, video endoscopy can be supplemented by other methods, such as:
- Tooth impression analysis with subsequent SEM examination (scanning electron microscopy)
- Laser-based alignment measurement
- Vibration diagnostics
- Material testing
- Metallographic investigations
The results of the video endoscopy are summarised in a detailed report.
[Vibration measurement and analysis]
Identify defects and avoid consequential damage
Vibration measurement and data analysis can be used to determine the technical condition of the bearings and gears of the entire drive train – main bearings, gearboxes, generators:
- Non-visible areas are examined and evaluated in this way
- Damage is detected at an early stage
- Costly consequential damage can be avoided
- Vibration diagnostics can be used to identify the following defects, for example:
- Local and rotating gear or rolling bearing irregularities, overrolling damage, smearing, breakouts
- Imbalances
- Loose parts
Vibration diagnostics is the perfect complement to gearbox video endoscopy. The evaluation is carried out by our in-house diagnosticians. The results are compiled in a report, including recommendations for any necessary actions.
[DGUV regulation 3 inspection]
Safety through inspected electrical components
According to the DGUV regulation 3 inspection, the operating company must ensure that the electrical systems and equipment are checked for proper condition before the first start-up, after a change or repair, before restarting, and at certain intervals.
This inspection is extremely important for operating companies in several ways:
The inspection fulfils their obligation to trade supervisory offices, professional associations and insurance companies.
As part of the inspection, all electrical equipment is subjected to an individual inspection. It comprises the following three steps, which are laid down in the relevant DIN VDE regulations:
- Inspection: Visual inspection for damage or improper use
- Testing: functional test
- Measurement: carrying out prescribed measurements
Modern and calibrated measuring instruments are always used for electrical inspections. The results of the inspection are summarised in a detailed report.
[Factory acceptance testing]
Our expertise – right from the factory
With increasing wind turbine size, the factory acceptance testing of wind turbine components such as towers, rotor blades, rotor bearings, gearboxes, etc. is becoming increasingly important.
The control of the production and the subsequent acceptance of the components directly from the factory helps to detect defects before the wind turbine is installed and commissioned.
Other objectives of factory acceptance testing include:
- Review of the production process and its quality level
- A smooth commissioning process
- Avoidance of consequential damage through early detection
- Fulfilling the conditions of investors, banks, and insurance companies
Expensive repair work or component replacement actions, combined with long downtimes, can thus be avoided.
The results are summarised in a detailed inspection report, in which all identified defects are named, described and largely documented with photos. The test report also contains necessary maintenance measures and recommendations for maintenance times.
[Due diligence inspection]
Safety through technical expertise
When buying or selling wind farms, the contractual object is thoroughly checked in advance in order to be able to carry out a well-founded assessment of the investment risks.
The focus of this inspection is to identify and evaluate the technical strengths and weaknesses of the wind farm project and the resulting opportunities and risks over the remaining lifetime.
The tax, legal and financial due diligence is carried out by specialised external service companies that support windexperts.
windexperts acts as an independent expert body to inspect wind turbine technology and prepares the detailed technical report entitled “Technical Due Diligence Report”.
The following points are inspected as standard:
- Consistency of the systems with the approval documents (type testing, individual testing, certification, operating license, grid connection, etc.)
- Foundations and towers
- Mechanical and electrical components
- Gear unit Gearbox
- Safety-critical components and their functions
- Rotor blades
[Damage and legal reports]
Recognised expertise – neutral and independent
The scope of potential “special damage” ranges from gearbox damage and lightning strikes on a rotor blade to major incidents such as the complete destruction of the nacelle by fire.
To clarify the cause and answer questions from all parties involved, we investigate the “special damage” on the basis of our many years of experience.
If necessary, we involve external experts in the investigation, for example, in the case of a fire.
In addition, testing laboratories or suitable institutes with the appropriate special equipment and testing resources are consulted to determine the causes of damage, e.g., for a material investigation in the event of a tooth fracture in the transmission, which have appropriate special equipment and use suitable testing equipment. broken tooth in the gearbox.
[Offshore inspection]
Special requirements for logistics and team
The experts at windexperts are familiar with the technology of offshore wind turbines through their previous work.
windexperts has been offering the entire range of services, taking into account the special conditions at sea, since 2005 – from commissioning inspections to condition-oriented inspections, to factory acceptance and due diligence inspections.
Thanks to specialised safety training, strong mental and physical fitness, as well as proven logistics, we meet the requirements for a safe and smooth inspection process.
We can carry out inspections of offshore wind farms with several experts. This reduces costs due to wind turbine shutdowns and service trips.
We offer a review of the foundation of offshore wind turbines in cooperation with experienced service companies, if necessary and desired.