The Wind Turbine

Jeffreys Bay Wind Farm consists of 60 wind turbines – model Siemens SWT 2.3 MW. These turbines were selected based on the technology’s quality and compatibility with the local wind regime and its proven track record of over 5170 units installed worldwide as of October 2012.

A diagram illustrating key turbine components

A diagram illustrating key turbine components


Wind Turbines – Height & Weight

Jeffreys Bay Wind Farm has sixty Siemens 2.3 Mega Watt machines. See their height and weight statistics below:

  • a hub height of 80 meters
  • a blade length of 49 meters
  • a rotor diameter of 101 metres
  • the rotor weighs in at 60 tones
  • the nacelle weighs 82 tones
  • the tubular steel tower weighs 162 tones

What happens when the wind doesn’t blow?

By its very nature, wind varies and does not blow consistently all the time. This is why the where the wind turbines are sited is so important; erecting them in an area with prevailing winds ensures that the turbines can generate energy and provide energy to the grid about 90% of the time.

The wind turbine only start operating when wind speed reaches approximately 13km/h.

How do wind turbines operate?

Wind turbines are sophisticated machines with computer controls.
A typical operating sequence is as follows:

  • when the wind speed reaches around 4 metres per second, the turbine blades will spin up to operating speed, usually around 14 to 29 rpm (varies by turbine model), and start generating electricity
  • as the wind speed increases, the generator output increases
  • when the wind speed increases to the rated wind speed (usually around 12-13 metres per second), the generator will output its nameplate-rated capacity (i.e. a 2.3MW turbine would now output 2.3MW)
  • as the wind speed continues to increase, the generator output will remain at the rated capacity (i.e. 2.3MW) until the wind reaches the cut-out speed (usually around 25 metres per second)
  • at this wind speed, the turbine will deploy its tip-brakes and then apply its disk brake, stopping the blades in a few revolutions
  • it will then rotate itself 90 degrees out of the wind and park itself
  • if the wind speed drops to a level below the cut-out speed for a sufficient length of time, the turbine will point itself back into the wind, release the brake, and resume power production.

Can wind farms affect airport and military radars?

Jeffreys Bay Wind Farm doesn’t fall within the ‘radar buffer distance’ and therefore can’t affect any airport or military radars.

What happens if turbine throws a blade or a tower collapses, maybe on neighbour’s property or a power line?

When designing the site layout, our team ensure that turbines are located with ample clearance from the border of the property, main roads and power lines so that, in the highly unlikely event that a tower collapses, it will not traverse the border of the property.

Do wind turbines kill birds?

In answer to the concern that wind turbines kill birds, studies show that birds are seldom bothered by wind turbines and in fact, the number of birds killed by wind turbines is negligible compared to the number that die as a result of other human activities.

Studies from the western part of Denmark, show that birds – by day and night – tend to change their flight route some 100 – 200 metres before the turbine and pass above the turbine at a safe distance.

Bird studies formed an integral part of the Environment Impact study done at the Jeffreys Bay Wind Farm site. A 12 month pre-construction study was done, and another 12 month post-construction study will be done to assess impact.

Are wind turbines noisy?

Modern wind turbines are not considered noisy; the mechanical (gearbox/ generator) noise and vibration is almost undetectable with the main sound being the aerodynamic swish of the blades passing the turbine tower.
Animals and livestock ignore wind turbines, and continue to graze as they did before wind turbines were installed.

Monday 17/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Tuesday 18/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Wednesday 19/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Thursday 20/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Friday 21/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Majority shareholder, Globeleq is jointly managing the construction of Jeffreys Bay Wind Farm and will play a key role as the management company during operations.