RotaBolt® tension control technology has been chosen by french wind turbine manufacturer Vergnet for its unique GEV HP 1MW turbine.
This model is specifically designed for ease of transport and installation and offers ground-level maintenance TM thanks to its patented birdlike system, which enables the upwind nacelle to be lowered to the ground.
M90 RB1 RotaBolts have been chosen for the critical bolting of the upwind nacelle and rotor to the downwind nacelle, in order to ensure that the correct bolting tension is achieved on installation and then maintained throughout turbine operation.
The fact that each of the 30 RotaBolts used in each turbine has been individually load calibrated to within ±5% of design tension makes them ideal for such a critical role, as these bolts are required to be installed and re-tightened each time the upwind nacelle is returned to its operating position after being lowered for maintenance or in case of extreme winds.
Thanks to this unique and patented lowering system, servicing and blade cleaning can be performed at ground level without cranes and specialised teams being required. The upwind part of the nacelle lowers smoothly to the service position in a rapid, easy and secure operation.
The Vergnet GEV HP 1 MW can also be installed in high wind-prone areas (where previously only reinforced class-1 conventional wind turbines could be installed) and can sustain hurricane-force winds of up to Category 5 (250km/h). In the case of a hurricane alert, the upwind nacelle, including the rotor blades, is lowered to the landing platform and secured to the ground.
120 wind turbines of this type are currently under construction for the Ethiopian National Electricity Company (EEPCo).