Denmark

Denmark

Gear box and blade retrofits ready -- NEG Micon and Vestas

Both of Denmark's top wind turbine manufacturers, NEG Micon and Vestas, announced the start of major component retrofit programs last month. After a false start, NEG Micon has decided exactly how it will retrofit the gear boxes on 1250 of its turbines. Pitting on the gear teeth of Peac 4300 and Peac 4280 gear boxes showed up last year and NEG Micon and Flender agreed on a DKK 400 million (EUR 53.7 million), two-year retrofit program to replace the planet gears and bearings on all NEG Micon turbines which could potentially give problems (Windpower Monthly, November 1999).

The Peac 4300 gear boxes will be retrofitted with a double row of double-cylindrical roller bearings, according to NEG Micon's managing director Torben Bjerre-Madsen. The company had previously considered using spherical bearings for the Peac 4280 gear boxes, but both Danish and American experts warned against the solution. Instead, the Peac 4280 gear boxes will be retrofitted with a single row of double-cylindrical roller bearings. Even though there is not room for a double row, Danish wind consultant Strange Skriver says the solution is a "clear improvement" on the earlier proposal. Det Norske Veritas (DNV) has type certified the new gear boxes for use in the retrofit and in new wind turbines.

Meanwhile, Vestas has begun a DKK 25 million (EUR 3.4 million) program to replace the outer gel coat on 1100 blades, according to the company's Hans Laurids Pedersen. All the blades are on 660 kW Vestas units erected before March 11, 1999 in Denmark, Sweden, Germany, Netherlands and the United States.

The re-coating is necessary due to an error in the blend of the original three-component gel. This has caused the blade surfaces to become porous and absorb moisture -- bad news in damp climates like Denmark, Pedersen says. "Even though this is causing no problems, we fear it can affect the blades' lifetime in the long run," he adds.

The retrofit news comes as Vestas has opened its new blade factory in Nakskov, Denmark, the home of a former shipyard and an unemployment blackspot (Windpower Monthly, June 1999). At full capacity, the huge facility will be able to produce 900 blades a year. Only 39 metre blades for 2 MW turbines and 32 metre blades for 1.65 MW units will be built at the 22,000-square metre plant, the company says.

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