History of Danish Wind Power - Wind Power for the World: The Rise of Modern Wind Energy - page 74

Their first prototype from June 1978, financed with DKK
50 000 from a public fund for inventors, was a 22 kW turbine
with three 5 m Økær blades and electric yawing. The rotor hub
was mounted directly on an industrial standard gearmotor with
reinforced bearings. On the basis of the experience with this
turbine, they decided to make a 30 kW version. One of the hard
lessons from the test of the prototype was that the blades needed
an automatic braking, preventing runaway at high wind speeds.
After that, the Økær blades got revolving tip brakes after the
same principles as on Juul's Gedser turbine from 1957. The 30 kW
wind turbine with the designation “HVK-10” (HVK for Herborg
Wind Power—10 for the rotor diameter) was finished in the spring
of 1979.
Inspired by the work of the first pioneers—Riisager and
others—the NIVE turbine and the HVK-10 added new features for
the next generation of Danish wind turbines: Upwind rotor with
three self-supporting, fixed fibreglass blades, electrical yawing,
industrial gear and disc brake between rotor and generator. The
HVK introduced tip brakes and two generators (a 30 kW for
higher wind speeds and a 5.5 kW for lower wind). What later had
been named the “Danish Concept” for modern wind turbines was
born.

3.15 Establishing the New Industry: 1979-1981

In the 1970s, the company Vestas in Lem, near Ringkoebing,
was a small machine factory, mainly producing machinery for
the agricultural sector. As this market was in a deep crisis, Vestas
was motivated to look for new products and turned their interest
to wind power. Experiments were made in 1978 with several
types of vertical-axis Darrieus-type turbines, designed by the
innovative Danish engineer Leon Bjervig, but in the end the choice
was the more conventional HVK design. In the autumn 1979, a
contract was signed with Herborg Wind Power (Karl-Erik Jørgensen
and Henrik Stiesdal) and the 30 kW HVK wind turbine with the
designation “V-10” (with reference to the rotor diameter—as all
later Vestas wind turbines) became Vestas' entrance on the wind
turbine market.