Tower Guidelines for Alizé
| Tower Height: | Site-specific, but must be at least 30 ft (9.1 m) taller than the tallest trees or buildings located within 500 ft (152 m) of the tower. Minimum recommended tower height = 100 ft (30 m). |
| Design Wind Speed: | Site-specific. The tower designer must consult local building codes. Minimum recommended design wind speed = 90 mph (40.2 m/s). |
| Total Weight of Assembled Turbine: | 847 lb (385 kg) |
| Maximum Turbine Thrust Load: | 2923 lbf (13000 N). This value assumes a 10x safety factor over the calculated thrust load at rated power (13 kW @ 15 m/s = 34 mph wind speed). Minimum recommended design value = 2000 lbf (8900 N) - based on IEC 61400-2 calculations. |
| Blade Clearance: | The diameter of the adapter plate at the top of the tower should not extend beyond a 24 in (610 mm) radius from the tower center line. NOTE: The camber of the rotor will allow the tower to become slightly wider with increasing distance from the top of the tower. Tower designers should contact us for detailed specifications. |
| Dynamic Loads: | The significance of dynamic loading should be assessed by the tower designer and accounted for if deemed necessary. |
| Stiffness: | This is left to the discretion of the tower designer. However, we generally recommend that the tower top should not deflect more than 2.0%; of the tower height at 90 mph (40.2 m/s) or 1.5% of the tower height at 50 mph (22. 4m/s). |
| Turbine Mounting: | An turbine adapter plate must be specified by tower designer to accommodate bolt pattern on turbine powerhead flange (drawing available on request). |
| Wiring Strain Relief: | Downtower wiring must be protected in liquid-tight metallic conduit or, in the case of enclosed tubular towers, be provided with strain relief with a suitable cable grip assembly (e.g., Kellem Grip). |
| Access Hole: | On enclosed tubular towers, we recommend that a 6 in (152 mm) diameter hole be provided approximately 6 in (152 mm) below the top of the tower to allow access to turbine wiring and slip rings. |
| Tower Climbing: | The tower must be climbable for inspections and maintenance, although anti-climb devices may be added depending on requirements of the end user. Climbing pegs should be removable if they do not meet the blade clearance requirement (see above). We recommend that climbing pegs be doubled in the top 20 ft section(s) of the tower to allow for foot placement at the same level for ease of maintenance. |
| Materials: | This is left to the discretion of the tower designer. However, in general, we recommend low-carbon steel, with careful attention given to weld quality. Stress risers and brittle materials (such as aluminum) must be avoided because of the possibility of fatigue cracking. All fasteners should be Grade 5, since Grade 8 is too brittle. |
| Finish: | This is left to the discretion of the tower designer. However, for most conditions, we recommend hot-dip galvanizing after tower fabrication. Dealers are encouraged to contact us with questions about tower suitability or any of the design guidelines presented here. Please note: We have modeled our tower recommendations after a similar document distributed by Bergey Windpower in order to facilitate constructive comparisons. |