Thorne & Derrick: Electrical Safety in Wind Turbines
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In 2021, electro mechanical engineering specialist Houghton International carried out the repair and rewind of a 850kW direct drive wind turbine generator. The Enercon E48 wind turbine had been erected and commissioned in 2019 on a farm in the village of Llanwnnen in Ceridigion, Wales by Grannell Community Energy, a locally-founded Community Benefit Society. It was purchased from a wind farm in the Netherlands, where it had previously been in operation.
In late 2020 the turbine failed in service due to an earth fault and Grannell Community Energy approached Houghton International to carry out repair work. Houghton International, based in North East England, was comfortably able to accommodate the 26 tonne generator in their large machine repair shop, which is specifically designed for large-scale projects.
Lindsay Thomas, Director at Grannell Community Energy commented: “As a community energy group, we have invested significant time, effort and funds into our wind turbine project so when it came to repairs it was particularly important to us to find a repairer that could offer the highest quality of service.
“From our first contact with Houghton International, we were impressed by their professionalism, enthusiasm and support for the project. Not only did they have the facilities to accommodate a project of this size, but they also gave us full confidence in their experience and technical expertise.”
Taking into consideration the age and condition of the asset, and previous works carried out, Houghton International’s project team recommended a full rewind of both the rotor and stator to minimise risk of further faults and extend the operational lifespan of the turbine.
Houghton International has developed a range of processes and intellectual property in-house, several examples of which were used during this project, as Chris Measor, Winding Assistant Manager at Houghton International, explained: “We agreed with the customer that we would make improvements to the insulation systems on both the rotor and stator to give them peace of mind of a long-lasting, quality repair.
“To rewind the DC pole shoes from the rotor, we used a system we had first developed for use on high speed trains, which is tried and tested with a proven track record. Whilst running on the railways, this system is exposed to high levels of moisture and temperature extremes, making it an ideal choice for the conditions the wind turbine is likely to see.
“We also uprated the insulation on the stator to a Class 3 enamel copper, which has a breakdown voltage of about 15,000V. The generator runs at around 480V, so this gives it a very high dielectric strength.”
The project was the first of its kind to be completed at Houghton International, requiring the manufacture of a bespoke frame and motorised jig for the winding of over 50 miles of continuous copper wire from three drums.
Houghton International provided regular reports and progress updates to Grannell Community Energy throughout the project and continued to deliver support after the turbine had been transported back to Wales for reinstallation.
Lindsay Thomas concluded: “The support from Houghton International even after the generator left their facility has been excellent. We were able to come back to them with further questions during the installation, and we are reassured to know they are on hand in future for any spares or maintenance support needed.
“Having recently reinstalled the generator, initial impressions are that it is generating exceedingly well and we are optimistic it will meet our most ambitious projections for power generation. As a result of the comprehensive and diligent work carried out, we effectively have a brand new turbine in operation and we have every confidence that it will meet its 20 year lifespan expectation.”
To find out more and watch the case study video, visit: https://www.houghton-international.com/case-study/grannell-community-energy/
Houghton International works with customers in power generation, renewables and other key sectors to improve the performance of their electro mechanical assets. They offer a high-quality monitoring, maintenance, repair and life extension service for motors, generators, pumps and all electrical rotating equipment.