New Developments for Wind Turbine Service Lifts
DualLift GmbH, a company based in Osterholz-Scharmbeck, Germany, is a manufacturer of drive systems for wind turbine service lifts. With its new development of a roller-chain-based drive system instead of one using a wire rope, the company offers a new technology for the industry that improves safety and comfort.
By Fabian Kern, DualLift, Germany
DualLift is a privately owned company and operates in four business units: Wind, Building Industry, Service/Rentals and Home Lifts. The company is a global player in person and material carrying traction hoists. Since 2008, DualLift has delivered hoist and overspeed safety devices as well as accessories for access at height to the wind industry. Nearly 10,000 wind turbine service lifts worldwide use DualLift wire rope traction hoists and overspeed safety locks.
The model range UpPro and UpPro S for transporting people can carry payloads of 400 to 2,000kg, while the UpLite Cargo and UpPro Cargo range for material handling can cope with weights from 100 to 2,500kg.
The company prides itself on its core values: quality, reliability, aftersales service, cost reduction and short delivery times. With more than 20 employees – a quarter of them engineers – DualLift drives new developments and changes in the industry, as several patents and utility patents prove. DualLift provides worldwide services with its service partner network and is committed to quality and engineering; every product that leaves the factory is 100% tested by specialised engineering staff.
What is New for Wind Turbine Service Lifts?
In the past, wire rope traction hoists have been the dominant drive system for wind turbine service lifts. However, DualLift saw that there was a great potential for improving the safety of the system and comfort for the users at the same time as reducing the costs of investment and maintenance. Therefore, focusing on new developments, DualLift’s engineering team led by Chief Technology Officer Frank Luelfing invented a completely new design of drive system for turbine service lifts. International patents are pending for this core innovation in the market.
The DualLift UpMax system uses roller chains instead of wire ropes to climb up the wind turbine. The technical characteristics of roller chains are an optimum solution for the demands of wind turbine service lifts: roller chains are constructed to withstand millions of bending cycles, based on the form fit, and there is no measurable wear within the expected lifetime of a turbine service lift. This reduces maintenance service costs by up to 80%, because there is no necessity to change the chain within the 20 years of expected use. Easier installation and safety checks compensate for the slightly higher investment costs for the roller chains.
By using two completely redundant drive systems, instead of one traction hoist, the system doubles its safety. In most wind turbine service lifts, the overspeed safety lock is a critical part, due to its life-saving character, but it creates some challenges in safety checks during operation. The new design makes life easier for the people climbing up the wind turbine, by reducing the number of maintenance checks and tests needed for the safety equipment.
With the 100% redundant drive system, there are possibilities for emergency descent even if one chain is broken or there is no power to the service lift. Improving safety for the users was a big goal for DualLift in developing this system, and the company wanted to ensure that the demands of the EN1808 standard were fully met. Shock factors and the catching speed of the EN1808-based safety devices are no longer an issue, because, due to the built-in redundancy, any problem of the drive system is detected automatically and there is no shock factor at all. This reduces the forces for the people in the turbine service lift and also the forces on the static structure of the top beam in the wind turbine, which has to carry a significantly lower load.
The combination of a redundant motor system which runs with chains instead of wire ropes brings a lot of advantages in terms of both economics and safety:
- Economics: The investment in an UpMax drive system for a turbine service lift is lower than that for the existing combination of hoist and safety lock. The maintenance costs are up to 80% lower than the existing solutions. This reduces the total costs of ownership for the OEM and the user and fulfils the needs of an industry that is under cost pressures.
- Safety: The UpMax roller chain drive system provides better safety due to the absence of the shock factor, the compliance with the EN1808, the redundancy of the drive system and the ability for much easier emergency descents. There is no overspeed safety lock to test and the built-in safety mechanism of the 100% redundant system works at any time.
These advantages of the DualLift UpMax drive system make it a new and notable innovation for the wind industry, with potential to save people’s lives and money.
The system is very flexible and could also be retrofitted to existing wind turbine service lifts or wind turbines. The service lift itself could be – as today – guided by ropes or the ladder so that there are no changes necessary in the fixing points or other installations within the wind turbine.
A cold climate version (CCV) comes as standard with the system so this drive system could be used anywhere in the world, both onshore and offshore.
The technical details of the DualLift UpMax are as follows:
Power connection: 400V 3-phase, 50 and 60Hz; 690V 3-phase, 50 and 60Hz; other voltages customised
Control box: Customised
Size of the lift: Customised
Speed: 18 metres/minute; other speeds as customised
Payload: 600 to 1,000kg
Temperature range: -40 to +60°C
