Environmental Engineering Reference
In-Depth Information
In spring 1981 a young German, Aloys Wobben, then long
haired, rolled into Sparkær in his old Mercedes with a trailer
behind to pick up a set of 5 m blades and a spinner for his first 22 kW
prototype turbine. Later he purchased 7.5 m blades for a 55 kW
turbine and his company's name is now Enercon.
8.6
The Second Serious Blade Failure
After having delivered 7.5 m blades for 20 Vestas turbines, my
company, and Vestas as well were suddenly shaken by a blade
failure on a Vestas 55 kW turbine in Hinnerup in Denmark. The
accident happened only nine days before Christmas in 1980. At
that time a 7.5 m blade was considered big, and no test rig was
ready for the test of the blade. Consequently, in less than a week
we constructed and built a blade test rig. Another 7.5 m blade was
bolted to the test rig and sandbags were stacked on the blade in
an ultimate test. My blacksmith, the manager of Vestas and myself
performed the test on a late evening. The test clearly showed that
the blade did not have sufficient buckling strength, it collapsed
two metres from the root, and I was responsible.
During that night the manager of Vestas tried, two times to
persuade me to sell my company to Vestas. I knew that the price
would be low, taking in consideration, my obvious design fault in
the 7.5 m blade. At the same time my other good customers, such
as especially Nordtank and Bonus, would be left out with no blade
supplier. My lawyer helped me to avoid the takeover of my company
by Vestas. Økær Vind Energi now was in a bad situation as we
used all our resources in redesigning the blade in a common efort
with the Risø Material Research Department and a Vestas
engineer. The production of our main product, the 7.5 m blade was
temporarily halted, sales and incomes were small, and my 13
employees still had to get their salary.
In early spring, around Pentecost time, we were no longer
able to pay our electricity bill. On the Friday before Pentecost, the
electricity company cut the power supply to our home and at the
same time to the production site in Mønsted. I drove to Viborg and
rented a 27 kW emergency power generator, which was installed
at the production hall on Saturday, and the tank filled with diesel.
On the next working day my employees were more than surprised,
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