TOWERS

TOWERS

Selecting  the correct tower is an important first step in the installation of a wind turbine. The Tower must be of sufficient height to position the turbine in unobstructed airflow and be designed to withstand the loadings produced by extremes in weather. Since many wind turbine installations are in remote locations the ability to erect a tower without cranes or heavy lifting equipment is a great advantage. This will reward the installer and maintainer with large cost savings.

PROPERTIES OF A WELL DESIGNED TOWER

  1. Be high enough to give the turbine access to good turbulent free air.

  2. Enable the turbine to be easily lowered to the ground for servicing.

  3. Strong enough to resist high wind thrust on the turbine as well as able to support the wind turbine when the tower is lowered for servicing.

  4. Have natural frequencies that do not coincide with excitation frequencies of the turbine.

  5. Be Corrosion resistant.

  6. Be visually non intrusive.

WESTWIND TOWERS 

To meet all these requirements Westwind manufacture a range of guyed tubular and stand alone 'mono pole' wind turbine towers of heights 12m and above. These towers use a gin pole and sheave assembly to enable the turbine to be easily and safely lowered to ground level for easy installation and servicing. Westwind towers can generally be lowered to the ground in around 15 minutes using a suitable tow up vehicle or winch. All towers are galvanised to reduce corrosion especially in coastal environments and have been designed with natural frequencies away from that of the turbine.

As shown right, the guyed tower requires five concrete foundation blocks. Each of these have cast in fixtures that are supplied with the tower. A standard Westwind tower comes with all the parts required for installation except the turbine power cable, lightening protection spikes, concrete and reinforcing mesh. Power cables and lightening protection varistors can be supplied upon request.

A Typical Westwind Tilt Tower
 

The following guyed tower heights are available from Westwind:

Turbine Sizes

(kW)

Tower heights available

Approx tow path length required
3 kW 18m & 24m 18m = 40m, 24m = 50m
5 kW 24m 50m
10 kW 18m, 24m, 30m

18m = 50m, 24m = 60m, 

30m = 75m
20 kW 30m  80m 

A WESTWIND GUYED TOWER KIT

Westwind's towers are specifically designed to make installation and maintenance of the turbines as trouble free as possible. All tower kits are supplied with full instructions and all components necessary for complete installation (except for the foundation concrete).

 

A tower kit includes.

  • Hot-dip galvanised, tubular, tower sections with bolted flange ends.

    • Upper and lower tower sections incorporate terminal boxes to allow for easy cable termination between the turbine and tower power cable and from tower cable to the site power cable.

    • Circuit breaker located in the terminal box at the base of the tower and accessory for short circuiting the turbine during lowering and maintenance.

  • All manual furling hardware.

  • All necessary bolts and hardware. (all galvanised).

  • All rigging including high tensile galv. guy wires, adjusting turnbuckles.

  • Components for casting into the concrete foundations.

  • Gin pole and sheave assembly

  • Tow up cable

  • Steel trestle for lowering the turbine onto for servicing & assembly.

Note : the tower electric cable is not included in the tower kit. Westwind can supply this cable with a special suspension lanyard for mounting inside the tower upon request.

TOWING UP THE TOWER

Towers are raised and lowered using a winch or a vehicle of the appropriate size. Winches for this purpose are usually expensive and therefore not commonly used but may be necessary for inaccessible sites. For the 2.5kW and 5kW towers a moderately sized four wheel drive is adequate but for the 10kW and 20kW machines a small tractor or four wheel drive truck is required. The diagram below shows how a turbine is raised from horizontal to vertical with a tow  vehicle.

Tow up can occur in any of the directions  as shown in the diagram below.  This enables the tow path to be optimised for the chosen site. Tow path lengths for the various towers are detailed in the table above.

 

POSITIONING YOUR WIND TURBINE

It is essential that the wind turbine is exposed to a clear run of wind from the prevailing wind direction. Installation near steep slopes or precipices is inadvisable, due to the high degree of turbulence in such locations.

As a general rule, the tower should be as high as possible and any nearby obstructions should be less than half the height of the tower.

A level site is always preferred. If a level site is not available, the next preference is for a uniform slope or a slight ridge where the two side anchor lugs are in line with the axis of the tower hinge pin. These two arrangements are shown in the sketch below. In either of these situations, the tower can be lowered from its standing position with no need to adjust the length of the side guy wires during lowering or raising.

A Ridge

A Uniform Slope
 

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Site Created By: Julian Ilich, ilichj@ausi.com