Wind turbine frequency converter repair

Converter repair for Woodward, GE, ABB, Vestas, Ingeteam, and more

This lineage means our engineers carry original design knowledge for the converter platforms most widely installed in the global wind fleet. We do not just repair these converter parts. We know exactly how they were engineered.

Our repair service covers frequency converter components across all major platforms:

ConverterTec / Woodward platforms

MP1 IGBT & Capacitor Banks, CSC4 & DCU controllers, IMC & DC Limiters / Choppers, NGx & NG03 IGBT modules, MFR300 protection relays, IDS rack controller boards, IDS IGBTs and Capacitor Banks, Main Circuit Breakers & Contactors.

Components we repair

Wind turbine converter components and assemblies we repair

Our repair capabilities cover the full range of frequency converter assemblies and sub-components. Each unit is treated as a system — not just a failed part — with inspection extending to all wearing and associated components.

Power stacks & IGBT modules

We repair and refurbish power stacks for both rotor-side and line-side converters, including MP1, NGx, NG03, and Skiip-based IGBT phase modules. Repairs extend to transistor-level inspection, gate driver board replacement, and thermal interface restoration. Where applicable, we replace original IGBT modules with state-of-the-art technology — delivering improved cooling efficiency and extended component lifetime.

Capacitor banks & chopper modules

Capacitor banks are replaced as standard during full converter refurbishment. We cover C-Bank assemblies across all ConverterTec platforms as well as multibrand capacitor assemblies. Chopper modules — including IMC limiters, DC limiters, and brake choppers — are repaired and tested under load conditions to verify surge protection and switching performance.

Control boards, controllers & driver circuits

We repair and refurbish CSC4 and DCU controllers, DCU3L decentralised control units, IDS rack controller boards, and driver circuits across all supported platforms. Software version compatibility is verified and updated as needed. For CSC3-equipped systems, we also offer a direct upgrade path to CSC4 controller technology — improving system reliability without converter replacement.

Rotor-side & grid-side converter sections

Repairs cover both rotor-side and grid-side converter assemblies, including the electrical systems that interface with the generator and the grid connection. Each section is inspected, repaired, and tested independently before full-system validation.

Protection relays & auxiliary components

MFR300 protection relays, thyristor switches, stator crowbars, main circuit breakers, contactors, and auxiliary power supply assemblies are all within our repair scope. These components are critical to converter safety and grid stability and receive the same rigorous testing as primary power electronics.

Repair process

Our repair process — from incoming inspection to validated return

Every repair at ConverterTec follows a defined, documented repair procedure — from the moment a component arrives at our dedicated repair center in Bulgaria to the moment it is returned to service. Our facility is purpose-built for frequency converter power electronics, equipped with advanced diagnostic systems, dedicated test benches, and application-specific test stands.

Step 1: Incoming inspection & diagnostics

On arrival, each unit undergoes a structured incoming inspection covering visual assessment, mechanical integrity, and preliminary electrical checks. We record the unit’s condition, identify visible damage or contamination, and log all relevant data before any work begins. Proprietary diagnostic tools are used to detect faults at component level — including conditions that would not yet have caused failure in service but are likely to do so.

Step 2: Root-cause analysis

We do not repair symptoms — we repair causes. Every fault is traced to its root cause before any component is replaced. This involves detailed electrical systems analysis, static and dynamic testing, thermal imaging to detect overheat conditions, and where relevant, assessment of environmental factors such as humidity and vibration exposure. This step ensures the repaired unit does not return with the same failure mode.

Step 3: Component replacement with qualified parts

Replacement is carried out using only qualified parts that meet or exceed original specification. Where state-of-the-art IGBT technology is available as a direct replacement, we use it — delivering improved thermal performance and longer component lifespan compared to original parts. Capacitor banks are replaced as standard in full refurbishment. All replacement parts are traceable and documented.

Step 4: Functional testing & test report

Each repaired unit undergoes comprehensive functional verification on dedicated test benches under simulated operating conditions. Both static and dynamic testing is performed, replicating real converter environments to confirm performance, stability, and safe operation. A 24-month warranty is provided on all repairs and replaced components.

Step 5: Return & lifecycle integration

Repaired units are returned in custom-designed wooden transport packaging, purpose-built for power electronics components, to ensure safe delivery to site. The repair service connects seamlessly with ConverterTec’s broader aftermarket portfolio — spare parts supply, field service, retrofit engineering, and condition monitoring — supporting a complete repair and maintenance strategy across the full converter lifecycle.

Converter refurbishment

Repair and refurbishment are not the same thing — and the distinction matters for long-term fleet planning.

A repair addresses a specific fault: we identify what failed, fix it, and return the unit to operation. A refurbishment goes further. It involves a full overhaul of the converter assembly — replacing all wearing components, including capacitor banks, IGBT modules, driver boards, and thermal interface materials — regardless of whether they have yet failed. The result is a unit that performs like new, with an extended lifespan and significantly reduced risk of secondary failure.

For wind farm operators managing aging fleets or planning ahead of scheduled maintenance windows, refurbishment offers a cost-effective solution that avoids the supply chain delays and costs associated with replacement converters. Refurbished units from ConverterTec are returned with a full test report and 24-month warranty — the same standard as a new component, at a fraction of the cost.

Our multibrand refurbishment capability covers all major converter platforms. Whether you are managing a mixed fleet or a legacy system approaching the end of support, we apply the same validated refurbishment process and quality standards across all repairs.

Why operators choose ConverterTec

Why wind farm owners and operators choose ConverterTec repair

There is no shortage of independent service providers offering wind turbine component repair. What there is a shortage of is companies that actually designed the converters they are repairing.

ConverterTec traces its origins to SEG, founded in 1969, and later Woodward SEG — one of the most widely deployed frequency converter platforms in the global wind industry. Our engineers carry that accumulated design knowledge into every repair. We have access to original documentation, proprietary diagnostic tools, and decades of field experience with these specific systems. That is a level of expertise no independent service provider can offer.

For wind turbine owners and operators, this translates into faster fault diagnosis, fewer repeat failures, and repairs that perform reliably under the demanding conditions of real turbine environments — including remote locations, extreme temperatures, and continuous load cycling.

Proven scale and reliability

With over 24,500 converters installed globally, 45GW+ of installed power supported, and 237 customers across 50 countries, ConverterTec’s repair service is not a secondary offering — it is a core part of how the wind industry keeps its converters running. Our repair center has capacity for 1,200+ converter component repairs per year, supported by ISO 9001 certified quality processes and a 24-month warranty on all work completed.

Cost efficiency and downtime reduction

Replacing a frequency converter assembly is expensive and time-consuming. Our repair service provides a reliable alternative — restoring components to full performance at a fraction of replacement cost, with turnaround times designed to minimise downtime and protect energy production. By choosing repair over replacement, wind farm operators can reduce OPEX, extend turbine lifetime, and support more efficient maintenance planning across their fleet.

Frequently asked questions