Transtech AS

Wind Energy Drives (WED) are a new range of gearboxes for wind turbines which ensure low maintenance and long operational reliability. Our range of wind turbine gearboxes use epicyclic gear trains which employ a proven flexible pin technology. This ensures equal load distribution along the gear teeth, and between the multiple meshing points. Using a flexible pin system gives optimal gear meshing between the planet gears and respective sun and ring gears, and reduces friction, wear and noise levels.

Our solution allows the maximum number of planet wheels and differentially divided power flow via two paths through the gearbox. This compact gearbox design significantly lowers mechanical stress on the gear teeth and bearings as well as makes a torsionally flexible transmission.

 

 

     
DESIGN HISTORY

The original design has proven its reliability for several years in service in one of the oldest and largest turbines in the world. In 1987 at Burgar Hill in Orkney, Scotland, an experimental three megawatt wind turbine was installed using flexible pin technology. 13 years later (due to generator failure), the entire turbine was dismantled. It held the record for the most powerful onshore machine in the UK.

The flexible pin concept was invented back in the early 60’s. The final analysis in 2000 of the Orkney turbine’s gearbox showed no damage or unexpected wear in the gear trains. Based upon these findings and our extensive experience with supplying epicyclic gear systems for offshore and marine applications, we decided to pursue the wind turbine market.

Principle sketch showing the Flexible Pin System

Transtech has further improved the flexible pin technology and today we feel that we have the optimal gearbox design for wind turbines.

 

VARIABLE RATIO SYSTEM

The variable ratio system (VRS) keeps the generator at a constant regardless of the wind speed. The mechanical/hydraulic method of achieving this constant speed makes the installation cost effective. In addition, the VRS performs as a safety device in the drive train by actively controlling the transmitted torque.

Because of the way modern turbine rotor blades react during wind gusts, transient speed changes occur which induce torque fluctuations in the gearbox. The referred generator inertia and the magnitude of such torque transients is likely the cause of the high rate of failure in traditional rigid gear driven turbines. Take also in to account the turbine’s rotor diameter, the larger it is, the slower it rotates and the more aerodynamic power transients will occur. A lower rotor RPM requires a higher gearbox ratio to keep the optimal generator speed. As the referred generator inertia is calculated by multiplying the generator inertia by the square of the gearbox ratio, it is evident that the problem increases exponentially with the size of the wind turbine.

 

PRODUCTION

Currently, we have three models available:

WED 650 (650 kW) WED 1400 (1,4 MW) WED 3400 (3,4 MW).
The 650 and 1400 have a fixed ratio and the 3400 is variable.

The Transtech WED gearbox is designed for long operational reliability and has a large number of advantages:

• Smooth power transfer from turbine to generator.
• Minimal maintenance requirements.
• Compact, can be place in existing nacelles.
• Shaft mountable.
• Hydraulic operated inching.
• Forced lubrication including cooling system.
• Light weight.
• Temperature sensors.
• Economical to produce.
• Adjustable peak limiter.
• Optional variable ratio system. 

The range of Transtech WED gearboxes can easily be modified to fit into any existing or newly designed wind turbine.