# Why Wind Turbine Has Only Three Blades Not More or Less

### Why Wind Turbine Has Three Blades?

Wind Turbines are used to convert the wind kinetic energy into electrical energy. Normally Wind turbine start rotating very slowly and then begin accelerating faster and faster. You can see the wind turbine has only three blades not two blades not more than three blades. About 95% of the wind turbine has only three blades, Actually why?. Let see

• Construction of wind turbine blades are much costlier. Wind turbine has around 170-meter height and each blades has around 50 to 80-meter length. Wind turbines under 100 kilowatts cost roughly \$3,000 to \$8,000 per kilowatt of capacity. A 10 kilowatt machine (the size needed to power a large home) might have an installed cost of \$50,000-\$80,000 (or more). Since increasing the size of the wind turbine increases the cost as well.
• Increasing the number of blades decreasing the speed of the turbine and increase the torque produced in the turbine rotor. But we need to operate the wind turbine high speed to produce power. Hence fewer blades are enough for better operation.
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• Directly we can neglect the single blade turbine even it produces high speed. Because in single blade turbine has only one blade, and it create heavy vibration and wobbling phenomenon. Since the absence of counter weight to balance the operation. Therefore, it is practically not possible.
• Let’s take three blade and two blade. Two blade has high speed as compared with three blade turbine but coming to the yaw control the two blade system resist the wind heavily in vertical motion so that heavy stress fall on the turbine rotor. As a result, the yawing motion starts and stops twice per revolution, and this leads to stress on the turbine due to blade chattering.
• But in Three blade turbine has three blades with very little vibration or chatter. This is because when one blade is in the horizontal position, its resistance to the yaw force is counter-balanced by the two other blades. So, a three-bladed turbine represents the best combination of high rotational speed and minimum stress.
• At the same time the efficiency of the two blade turbine is slightly higher than three blade wind turbine. So Comparing all points We get better results in three blade turbine.
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That’s why almost three blade uses in wind turbine.

Note: What is Yaw control?

Turning the wind turbine according to the direction of the wind is called yaw control.