DC21 Provides Competitive Overhaul Package for Endurance Wind Turbine Owners

November 9, 2021

Endurance Wind Turbines - DC21 Provides Competitive Overhaul Package for Endurance Wind Turbine Owners

Endurance Turbine Owners

DC21 own a fleet of 12 wind turbines and provides monitoring, maintenance, and overhaul services to owners of Endurance wind turbines.

Matthew Tidmarsh, General Manager at DC21, has been involved in the wind industry for over 12 years, predominantly focussing on the Endurance E-3120 of which there are over 800 in operation in the UK.

The manufacturer, Endurance Wind Power Inc., went bankrupt in 2016 due to a sudden market decline and a wave of large warranty claims. This was due to defects in the E-3120 design, with the bedplate and the low speed shaft being the prominent failures

Challenge Accepted

In 2019, DC21 directors Kevin Dare, and Mark Ashton challenged Matthew to come up with a cost-effective overhaul package for the Endurance E-3120. Having just spent over £100k on DC21’s oldest E-3120, it was clear a more economical solution was needed, especially for turbines on less productive sites and/or with lower subsidy levels.

In April 2020, after Matthew successfully answered the challenge, DC21 relocated to a 3,000ft² facility in Slaithwaite, Huddersfield, dedicated to the overhaul of the Endurance turbines. Using DC21’s exclusive cost-effective solution, five overhauls were completed in 2020 and, as of September 2021, a total of 18 have been completed, with a further 10 booked/in progress.

DC21 now offer any E-3120 owner in the UK a complete turbine overhaul at the most competitive price available.

Answering the Challenge with Carbon Fibre

Matthew’s idea to answer the challenge came from somewhat of a ‘Eureka moment’ after reading articles on “light-weighting” technology used in the automative sector. After researching the concept, Matthew set to work adapting the technology for the Endurance wind turbines, exploring established methods of reinforcing steel found across various industries.

The application of this technology to repair the E-3120 bedplate took significant time and investment to develop. The main challenge was to develop a system that could be used to effectively bond the carbon fibre parts to the steel structure in such a way that the desired improvements were ensured.

The development process included small scale testing. The results, to say the very least, were very encouraging. This gave DC21 sufficient confidence in the design concept to invest thousands of pounds in engineering design and prototype manufacture.

DC21 worked with several design engineers to develop and validate the Finite Element Analysis model. This was used to develop the carbon fibre reinforcement and was validated against known failure mechanisms in the existing bed plate. The outcome has been a 77% reduction in peak stresses seen in the bedplate.

The process of reinforcing the E-3120 bedplate is now established and has been deployed on over 20 turbines, including four of DC21’s own machines.

Eliminating E-3120 Low Speed Shaft Problems

Several other companies have developed new low speed shaft designs for the E-3120. These have not been without issues. DC21’s remit was to keep it simple and only change the problematic areas.

The original E-3120 shafts were made in China, something DC21 was keen to avoid. Ultimately the steel was sourced from Sheffield, UK.

The new shaft design had to work with the existing bedplate and that also meant the existing bearing housing design. It was, however, possible to increase the shaft diameter to 150mm and use bearings with approximately 10% greater capacity.

The new design, crucially, eliminated the shaft keyway and the separate rear taper sleeve. This removed the main source of failure in the existing design. The new design also reduced the peak stress in the shaft by 50%.

DC21’s design included a unique hub locking system that significantly reduced the risk of hub slip, another issue in the original design that led to many failures.

Matthew Tidmarsh said, “With the new design I simply cannot envisage how we would get hub slip. That is a huge improvement over the original and is probably unique to our design”.

The billets are machined into the final shaft by CNC in the UK, ahead of assembly at the DC21’s facility in Slaithwaite, Huddersfield.

Endurance Hub Refurbishment

The original Endurance hub design includes a 1.5” pin passing through the hub arm. There is no lubrication on this steel/stell junction, and it inevitably wears.

Endurance did develop a system involving drilling the hub up the tower to try to address this problem. However, the accuracy of the drilling leaves a lot to be desired and even when done well it just moves the wear into the (expensive) nyloil blocks . Worse, if not done accurately, the blade pin stresses the spring tube, leading to failure and very costly repairs to the blades..

DC21’s hub refurbishment creates an economically maintainable system. Unlike the Expander Pin system which wears a £400 nyloil block, the wear item is a £65 bush. At this time, having used the system for two years without finding a worn bush, we don’t have service life data but would anticipate a minimum of two years.

The refurbishment is carried out using a precision jig to ensure the hub arm holes are correctly positioned; something that cannot be achieved with any up tower processes.

Condition monitoring

Several of the turbines that have benefited from the DC21 upgrades are also fitted with the condition monitoring system from Turner ICENI – M-HAS. The data shows significant improvements in the health of the machines compared to their condition before overhaul.

Windy location

One of DC21’s turbines, known as Grace, has had the DC21 upgrade package. This site has already gone through two original E-3120 nacelles, the first one, and a subsequent one provided under warranty by Endurance.

This site sees very high wind speeds (average of 8.5m/s) and is proving very useful for demonstrating the improvements that the DC21 upgrade package delivers.

Transporting E-3120 Nacelles

E-3120 Wind Turbine Nacelle Trailer
1. Turbine Nacelle Trailer.

To complement the refurbishment facility in Slaithwaite, Huddersfield, DC21 has invested in a bespoke trailer that allows the transportation of E-3120 nacelles without the need for heavy goods vehicles (HGV). This is not only more cost-effective it is also much easier for access to turbine sites. The transport vehicles are legal, and turbines are fully insured.

Competitive, Cost-effective E-3120 Overhaul Package

Matthew Tidmarsh said: “I am immensely proud of the package we have developed; it gives E-3120 owners a much more cost-effective package than any of our competitors. We’re not done yet though. The braking system on the E-3120 is brutal, as any owner will know if they have watched the turbine stop. I’m particularly concerned about the stress this imposes on the gearbox. Over the last year, we have been busy testing a new braking system on one of our turbines, and it will soon be released.”

New Endurance E-3120 Wind Turbine Braking System

Video new braking system for E-3120 Wind Turbine

See the new Endurance E-3120 braking system in action in this video. Developed by DC21, the new system is designed to reduce the severity of braking events on various turbine components.

Is your wind turbine in need of an overhaul?

To find out more about our overhaul package and how DC21 can save you money, call us on +44 (0) 1484 702702 or email info@dc21group.com.

Matthew Tidmarsh - General Manager, DC21 Operations Ltd

Matthew Tidmarsh

Matthew Tidmarsh is the General Manager of DC21 Operations Ltd. He graduated from the University of Leeds in 1997 with a degree in Chemical Engineering. He spent the first 12 years of his career working with various companies on projects in the UK, India, and North America. In 2009 the opportunity arose to join DC21 as General Manager and drive the business forward on renewable energy with a focus on wind turbines.

Contact Matthew and his team today or follow us on LinkedIn:
Matthew Tidmarsh - LinkedIn
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