Novawind 6 turbines are dangerous when operated in high winds, and cannot survive the loss of braking, irrespective of the reason for the triggering of a braking event. In high winds the brakes fail, and once this has happened there is no way for the turbine to survive intact. By throwing blades, the turbine cannot be installed in “public” areas, and must be sited well away from buildings and people. Severe damage, injury or even death could result from the operation of these turbines, and in my opinion they need to be recalled by the manufacturer to be upgraded to a much higher and safer standard.
The failure of these turbines has helped us to identify the weaknesses of the current design.
· The brakes are insufficient for safe operation and must be re-designed as a matter of urgency.
· The generator mounting structure does not have sufficient strength to prevent the generator assembly from becoming detached from the tower.
· The blade root assembly is not designed to cope with a brake fail event, and hence the blades can become detached.
· The blade pitch control system does not offer a “safe” operating range in all wind speeds, and needs to be re-designed.
· The tail fin is not securely attached to the tail arm, and can become detached.
· The tail arm is not sufficiently strong as to prevent the loss of the tail fin in extreme wind conditions.
The fact that the tower on one of these turbines has collapsed should, in my opinion, ring any alarm bells as far as the tower durability is concerned. Instead, with the loss of a single blade from a 4-bladed turbine, followed by the out of control rotation of the turbine rotor, some very severe oscillations would be set up in the tower, ultimately resulting in the failure of the welds at the flanges of the tower. If the turbine were to have a “fail safe” mode which prevented any rotor rotation once a blade had been shed, then no such oscillations could be transferred to the tower, thus keeping the structure safe.