To: Hugh Piggott
Proven decided to improve blade lifetime on our WT2500 and WT600 wind turbines by going to a higher performance blade hinge material back in late 1998. The blades at that time featured zebedee hinge material the same as that of the blade (polypropylene).
This had a working life of 3-5 years depending on site severity and average wind speed. While replacement costs were low (~£200 if metal fixing plates from old blades were recycled) often machines in the field are in difficult locations and many Proven machines are not maintained as per manufacturers recommendation! The development of a blade hinge with a higher lifetime was started.
After extensive bench and field testing the Proven PU blade hinge was introduced to all 3 turbines in the Proven range in early 2000.
It features a specially formulated polyurethane (PU) hinge with integral nylon rope strengthening. The rope patterns are wrapped around the fixing bolt locations at either end of the hinge.
Figure 1: Proven WT2500 Blade PU Hinge
Figure 2: PU Hinge separate and integrated into the blade root.
Another element built into the PU selected for the hinge was excellent performance over a wide temperature range from –40 to +50 deg C. This makes the turbine suitable for operation in more extreme climates.
We have to a fair no. of years before finding out! From the testing we have done we are confident of 10-15 years for the PU hinge. We have had no problems with any of the PU blades in operation so far. This has effectively removed this maintenance issue. When the PU hinge does wear out then just this small section of the blade will need to be replaced. This will typically be a field retro-fit.
Sets of PU blades are available for retrofit to existing wind turbines – all fixing points for the blades are unchanged from the previous polypropylene versions.
PU2501 (1 set of PU blades) replaces the BL2501 (1 set standard polypropylene blades)
PU601 replaces BL601
PU6001 replaces BL6001