Prove it or pay for it: Increased requirements for wind turbine lightning protection design and blade operation

As wind turbines age and new larger ones are installed in remote or harder-to-service areas, the focus of the wind industry shifts to risk-based management of turbine operation, dictating how to assess damage categories and how to qualify repairs; when root cause analysis is needed; and when monitoring is required. Managing this risk relies on accurate, blade-resolved data that guides inspections, informs, and documents decision-making throughout the turbine’s life.

An entirely new standard will come into effect in 2027. IEC 61400-32 will define how wind turbine blades must be operated and maintained, covering inspector qualifications, reporting practices, and risk-based responses to damage. The goal is to improve consistency and reduce repeat repairs. Some already refer to it as the rulebook for operating and managing a turbine.

Key elements of the standard include:

• Standardizing the qualifications for inspection and repair personnel

• Establishing uniform reporting practices for inspections and repairs

• Implementing a risk-based approach to evaluating and responding to damage

• Reducing repair failures and minimizing the need for repeat repairs

“We want to make informed decisions when damage occurs by standardizing damage definitions such as cracks or open trailing edges and by structuring the thought process behind risk assessment and repair selection, so service providers, operators, and OEMs can speak a common language,” says Lisa Carloni, Lead LPS Specialist, Electrical Engineering at Polytech and member of the Danish National Committee of the IEC.

One of the key drivers of damage and insurance claims is lightning damage. Lightning protection is becoming more challenging as wind turbines grow taller with longer blades, resulting in more lightning and more strike damages in the middle sections of the blades, which are less protected and structurally critical.

The other upcoming IEC 61400-24 Ed.3 standard (expected to be released in 2027) raises the bar and requires you to prove that the lightning protection works in these challenging conditions across the whole blade and over its service life.

IEC 61400-24 Ed.3 extends lightning protection to a full lifecycle framework with exposure assessment, design and validation, mandatory inspections, and clear LPS efficiency and wear criteria.

Key changes from the previous version include:

• Explicit verification of the numerical models used in blade or LPS design, with required correlation to test data and defined acceptance criteria

• Mandatory HV and high-current testing further inboard or mid-blade to address internal current paths and mid-span vulnerabilities

• A shift toward LPS condition monitoring (preventive maintenance), with reduced emphasis on one-time continuity checks

• A mandatory risk-based inspection program

Manage that risk by relying on reliable, blade-resolved lightning data that shows the actual lightning exposure, guides inspections, and documents decisions made across the turbine’s life.

The new monitoring rulebook IEC 61400-24 Ed.3 specifies, among other elements:

• What to capture (peak current, polarity, charge, specific energy, impulse class) with specified accuracy classes, dynamic range, bandwidth or sampling, and related requirements

• Sensor types and placement (down-conductor shunts, Rogowski coils, blade sensors), EMC and surge immunity, environmental qualification, and calibration or verification

• Rules for triggering, deduplication, classification, minimum datasets, storage or retention, cybersecurity, SCADA or CMMS interfaces, and optional correlation with external Lightning Location Systems

Polytech’s Lightning Key Data System (LKDS) is built for this direction and is fully compliant. It measures each blade independently with high fidelity. A recent case shows that blade-resolved data has reduced repair costs and downtime. Energy yield is up by approximately 3,500 EUR per MW per year.

It is a lot of information to process, so we have summarized what this means for OEMs and fleet operators.

Checklist for wind turbine manufacturers:

• Prove the design: Deliver a verified numerical model per IEC 61400-24 Ed.3 with defined acceptance criteria, traceable correlation to HV or HC tests (including inboard sections), and a complete certification package

• Expand the test scope: Cover HV and high-current tests beyond the first 5 to 10 m, validate worst-case current paths and stack-ups, and document clear pass or fail margins and retest logic

• Built-in monitoring: Specify IEC 61400-24 compliant LPS monitoring (sensor type, accuracy, time synchronization), SCADA or CMMS integration, event classification or reporting, and O&M trigger logic aligned with warranty terms

Checklist for asset operators:

• Contract for proof: Make IEC 61400-24 Ed.3 compliance deliverable. Require model verification reports, full HV or HC test evidence (including inboard coverage), and explicit acceptance criteria in as-built documentation

• Instrument for action: Require IEC 61400-24 monitoring with data ownership and retention rights, open interfaces, and inspection or repair triggers tied to measured strike severity and remaining life assessment

• Close the loop: Feed lightning events into management workflows and fleet analytics to optimize inspection and repair criteria, and align warranty or insurance language with IEC 61400-32 event definitions

For additional information on lightning protection solutions, click here. If you have any questions, do not hesitate to reach out. Our team of experts is ready to help.