21. 06/11/02 - Nacelle Compartment

Total Weight (w/o rotor and tower) app. 24.5 tons.

The unit is completely sealed against the environment and cooling is provided by a radiator which supplies liquid for cooling the generator and gear oil.

22. 06/11/02 - View of Inside of Nacelle

The generator is a two-speed, water-cooled engine specifically built for wind turbine applications. Two generator sizes are integrated into the same housing. A main generator "G" with a speed of 1800 RPM/60 Hz and a low wind speed (small) generator "g" that operates at 1200 RPM/60 Hz.

23. 6/11/02 - The First Tower Section Arrives.

A total of 3 sections are needed for the tower. The three sections of the tower will stand nearly 232 ft. high with a top diameter of 5.75 ft, a bottom diameter of 13.78 ft, and weigh 98.3 tons. Shown is the lower or base section. Note the access door on top.

24. 6/11/02 - Inside a section of the tower.

View is from the top of the topmost section of the tower as it lies horizontal on the ground. Shown is the access ladder that extends the full height of the tower. Two fluorescent light modules per section light the way. Cables are for control and monitoring of the unit.

25. Upper Ring and Connecting Bolts

A closeup view of the upper ring with connecting bolts being lowered into the base excavation. Close observation shows the bolts are positioned between the two casings.

26. Filling the Cylinder

Once bolts and ring assembly has been put in place and secured the center of the cylinder is filled with earth. A 12 inch concrete floor is then poured over the earthen center to complete the base as shown in the next photo.

27. 6/13/02 - The Completed Tower Base.

The ring with connecting bolts is held in place between the two casings with concrete. The tower structure will be anchored to the foundation using the bolts seen protruding from the base. The concrete will cure to 3000 PSI break test within 3-4 days. At that time the concrete will be pre-stressed. Using large hydraulic rams the bolts will be "stretched" approx. 3" beyond their current length. The nuts will then be tightened and tension released. The bolts "snap" back much as a rubberband that has been stretched and then released. Pre-stressing in this manner is what gives the concrete its strength to withstand the enormous forces of weight and movement.

28. 6/13/02 - Break Test Samples

These cylinders contain concrete samples taken during the pouring process. They will be subjected to "break tests" to determine when the concrete base has cured sufficiently that construction may continue. Quality Assurance personnel remain on site during the entire construction phase to insure that construction standards are maintained.

29. 6/13/02 - Three tower sections.

All three sections for a single tower are ready for assembly.

30. Rotor blades and rotor hub assembly.

The rotor blades are attached to the rotor hub. The rotor hub and three blades are assembled as a unit on the ground. One blade is already attached and the second blade is shown being placed into position on the rotor hub.

31. 6/17/02 - Construction of the First Tower Begins

The crane being used to hoist the tower components into position has a 300' boom capable of lifting several hundred tons to a height of 300 feet. The crane itself, when fully assembled, will weigh approx. 1,000,000 pounds and negotiates terrain at a speed of 1 mph. The crane, as pictured here, does not yet have the full length boom attached.

32. 6/17/02 - Guiding the First Tower Section in Position

The base tower section is guided onto the bolts embedded in the concrete base. "Leveling nuts" have been placed on to each bolt prior to constructing the tower. These nuts together with leveling shims are used to level the giant structure.

33. 6/17/02 - A "concrete" gasket.

A layer of mortar is placed between the foundation and the first tower section. This layer serves as a concrete gasket, and together with the shims and leveling nuts, helps level and seal the section with the foundation (recall the grout trough in the foundation drawing Photo #13). Level is determined with a standard builders transit.

34. 6/20/02 - Placement of The Lower Tower Section

The first section is in place and the second section is being prepared for placement.

35. 6/20/02 - Adding the Second Section

The second section of tower is moved into position. Workmen standing on small platforms inside the first section guide the section into proper position and then secure it to the lower section. Each component and tower section is secured by several large bolts before the crane will release its payload. The bolts holding the component in place are then torqued to specifications.

36. 6/20/02 - Adding the Third Section

The third section is being lowered into place. The assembly of the tower and its components takes approximately 5-6 hours. The workmen usually remain inside the tower the full time.

37. 6/20/02 - Raising the Nacelle

After all tower sections are secured in place the nacelle is raised for mounting.

38. 6/20/02 - The Nacelle in Place

The nacelle is guided into place and fastened to the top section.

39. 6/20/02 - The Rotor and Blade Assembly

The rotor and blade assembly is carefully lifted into position. Due to the fragile nature of the flexible blades a great deal of care is taken while the blades clear the ground.

40. 6/20/02 - Attaching the Rotor and Blade Assembly

The rotor and blade assembly is guided into position by the workmen who have moved from the tower to the inside of the nacelle. They will fasten the assembly to the nacelle hub to complete the tower assembly.