Determines the design of the turbine. Upwind turbines—like the one shown here—face into the wind while downwind turbines face away. Most utility-scale land-based wind turbines are upwind turbines.

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Part of the turbine's drivetrain, the main bearing supports the rotating low-speed shaft and reduces friction between moving parts so that the forces from the rotor don't damage the shaft.

The yaw motors power the yaw drive, which rotates the nacelle on upwind turbines to keep them facing the wind when the wind direction changes.

Thrustbearing

The wind vane measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.

The controller allows the machine to start at wind speeds of about 7–11 miles per hour (mph) and shuts off the machine when wind speeds exceed 55–65 mph. The controller turns off the turbine at higher wind speeds to avoid damage to different parts of the turbine. Think of the controller as the nervous system of the turbine.

Axial load bearingtype

The yaw drive rotates the nacelle on upwind turbines to keep them facing the wind when wind direction changes. The yaw motors power the yaw drive to make this happen.

Bearing axial loadcalculation

However you refer to these bearings in the axial bearing vs thrust bearing debate, it is important to use the correct type of miniature thrust bearing based on the direction of the thrust load. Some have a raceway or groove on each washer. In these instances, one washer has a slightly larger inside diameter so that it is located in the housing and the shaft can rotate inside it. These bearings can accommodate thrust loads in one direction only and must be installed according to the load direction.

Turbine brakes are not like brakes in a car. A turbine brake keeps the rotor from turning after it's been shut down by the pitch system. Once the turbine blades are stopped by the controller, the brake keeps the turbine blades from moving, which is necessary for maintenance.

Regardless of the loading type required, all bearings have their limits. When determining which bearing to choose, it is important to consider several factors; load direction, load size, turning speed of the application. It is also crucial to ensure the bearings are manufactured to high quality standards, which enables the highest levels of rollability even with heavier axial forces.

Radialloadvsaxial load bearing

The drivetrain is comprised of the rotor, main bearing, main shaft, gearbox, and generator. The drivetrain converts the low-speed, high-torque rotation of the turbine's rotor (blades and hub assembly) into electrical energy.

The pitch system adjusts the angle of the wind turbine's blades with respect to the wind, controlling the rotor speed. By adjusting the angle of a turbine's blades, the pitch system controls how much energy the blades can extract. The pitch system can also "feather" the blades, adjusting their angle so they do not produce force that would cause the rotor to spin. Feathering the blades slows the turbine’s rotor to prevent damage to the machine when wind speeds are too high for safe operation.

The nacelle sits atop the tower and contains the gearbox, low- and high-speed shafts, generator, and brake. Some nacelles are larger than a house and for a 1.5 MW geared turbine, can weigh more than 4.5 tons.

Wind power plants produce electricity by having an array of wind turbines in the same location. The placement of a wind power plant is impacted by factors such as wind conditions, the surrounding terrain, access to electric transmission, and other siting considerations. In a utility-scale wind plant, each turbine generates electricity which runs to a substation where it then transfers to the grid where it powers our communities.

The rotor bearing supports the main shaft and reduces friction between moving parts so that the forces from the rotor don't damage the shaft.

Part of the turbine's drivetrain, the low-speed shaft is connected to the rotor and spins between 8–20 rotations per minute.

The drivetrain on a turbine with a gearbox is comprised of the rotor, main bearing, main shaft, gearbox, and generator. The drivetrain converts the low-speed, high-torque rotation of the turbine’s rotor (blades and hub assembly) into electrical energy.

Axial loadexample

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Direct-drive turbines simplify nacelle systems and can increase efficiency and reliability by avoiding gearbox issues. They work by connecting the rotor directly to the generator to generate electricity.

The pitch system adjusts the angle of the wind turbine's blades with respect to the wind, controlling the rotor speed. By adjusting the angle of a turbine's blades, the pitch system controls how much energy the blades can extract. The pitch system can also "feather" the blades, adjusting their angle so they do not produce force that would cause the rotor to spin. Feathering the blades slows the turbine's rotor to prevent damage to the machine when wind speeds are too high for safe operation.

Wind turbines harness the wind—a clean, free, and widely available renewable energy source—to generate electric power. This page offers a text version of the interactive animation: How a Wind Turbine Works.

Direct-drive generators don't rely on a gearbox to generate electricity. They generate power using a giant ring of permanent magnets that spin with the rotor to produce electric current as they pass through stationary copper coils. The large diameter of the ring allows the generator to create a lot of power when turning at the same speed as the blades (8–20 rotations per minute), so it doesn't need a gearbox to speed it up to the thousands of rotations per minute other generators require.

When choosing a thrust bearing, it’s important to seek the right advice, as these bearings can be very unforgiving when axial forces are in play.

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Axial load bearingSKF

Turbine brakes are not like brakes in a car. A turbine brake keeps the rotor from turning after it's been shut down by the pitch system. Once the turbine blades are stopped by the controller, the brake keeps the turbine blades from moving, which is necessary for maintenance.

Transformers receive AC (alternating current) electricity at one voltage and increase or decrease the voltage to deliver the electricity as needed. A wind power plant will use a step-up transformer to increase the voltage (thus reducing the required current), which decreases the power losses that happen when transmitting large amounts of current over long distances with transmission lines. When electricity reaches a community, transformers reduce the voltage to make it safe and useable by buildings and homes in that community.

For low axial load applications, some radial bearings can be used. Thin-section deep groove ball bearings can support axial loads of between 10 and 30 per cent of the bearing's static radial load rating. Note — these figures are based on pure axial load. Additional radial loads or moment (misalignment loads) will have an impact on the axial load capacity.

Radialload bearing

The terms axial ball bearing or thrust ball bearing can be used interchangeably. Sometimes, they are even combined together, referred to as ‘axial thrust bearings’. This group of bearings has been designed to endure an axial load, also known as a thrust load, which is a force in the same direction as the shaft. The axial bearings should not be subjected to any radial load as they are designed for thrust loads only.

Most turbines have three blades which are made mostly of fiberglass. Turbine blades vary in size, but a typical modern land-based wind turbine has blades of over 170 feet (52 meters). The largest turbine is GE's Haliade-X offshore wind turbine, with blades 351 feet long (107 meters) – about the same length as a football field. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin.

Thrustload bearing

Transmission lines carry electricity at high voltages over long distances from wind turbines and other energy generators to areas where that energy is needed.

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Different applications put different load requirements on the bearings. For high axial load applications, heavy duty bearing types such as 6200 or 6300 series may take axial loads of up to 50 per cent of the static radial load rating. In cases where large axial and radial loads occur simultaneously, angular contact bearings may be required.

The more straight-forward type of miniature thrust bearing has identical washers and no raceway. These can accept endure axial loads in either direction but have reduced load and speed ratings compared with single-direction axial bearings.

The controller allows the machine to start at wind speeds of about 7–11 miles per hour (mph) and shuts off the machine when wind speeds exceed 55–65 mph. The controller turns off the turbine at higher wind speeds to avoid damage to different parts of the turbine. Think of the controller as the nervous system of the turbine.

Made from tubular steel, the tower supports the structure of the turbine. Towers usually come in three sections and are assembled on-site. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity. Winds at elevations of 30 meters (roughly 100 feet) or higher are also less turbulent.

A wind turbine turns wind energy into electricity using the aerodynamic force from the rotor blades, which work like an airplane wing or helicopter rotor blade. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin. The rotor connects to the generator, either directly (if it's a direct drive turbine) or through a shaft and a series of gears (a gearbox) that speed up the rotation and allow for a physically smaller generator. This translation of aerodynamic force to rotation of a generator creates electricity.

Most turbines have three blades which are made mostly of fiberglass. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin. Blades on GE's Haliade X turbine are 351 feet long (107 meters) – about the same length as a football field!

Think office chairs, lazy Susan turntables or bar stools, to name just a few axial load applications. While this group of bearings are unable to handle radial loads — they can be used in conjunction with radial ball bearings if required. A radial ball bearing’s rolling elements are designed to support radial loads, which is a load that is perpendicular to the shaft.

The wind vane measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.

The generator is driven by the high-speed shaft. Copper windings turn through a magnetic field in the generator to produce electricity. Some generators are driven by gearboxes (shown here) and others are direct-drives where the rotor attaches directly to the generator.

A substation links the transmission system to the distribution system that delivers electricity to the community. Within the substation, transformers convert electricity from high voltages to lower voltages which can then be delivered safely to electricity consumers.