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Wind Turbine Terminology

Modern innovations and improvements in wind turbines have made wind one of the most viable renewable energy options currently in use. According to the American Wind Energy Association, “every state in the United States has either an operational wind energy project, a wind-related manufacturing facility, or both.” There are nearly 49,000 wind turbines spread across 40 states, as well as Guam and Puerto Rico, representing over 74,000 megawatts (MW). As far as the manufacturing of wind turbines, there are over 500 facilities across 43 states.

As impressive as these figures already are, the U.S. Department of Energy anticipates the energy generated from land and offshore wind turbines will grow from the 2013 output of approximately 61 GW (Gigawatts) to 404 GW by 2050 — an eight-fold increase! However, none of this can happen without maintaining and upgrading existing wind turbines and constructing new wind turbine projects, as well as wind manufacturing facilities — and that means significant job opportunities for certified wind turbine technicians, manufacturers, and other wind energy workers.

How Is Wind Converted to Electricity?

Wind energy is the conversion of the energy that moves air particles into the mechanical energy that turns the rotor of an electrical generator. The result is electricity, which is a more consumable, practical form of energy. The basic principle works like this:

  1. Wind interacts with the vane, which acts as a rudder to turn the blades to face the wind.
  2. The wind spins the blades which are attached to a hub. The hub is fixed to a shaft, referred to as a rotor shaft.
  3. The other end of the rotor shaft is connected to a power generator. The rotor shaft spins magnets within the generator creating an electric current.
  4. The electric current follows a conductor to a power grid or a battery. Most wind projects are connected to a power grid.

While the principles behind wind turbines are simple to understand, there are a lot of factors that go into achieving the optimal energy yield from wind. Because wind turbines by their very nature are subjected to exposure to the elements, including high-speed winds, they must be designed and maintained in a way that enables them to continue reaping wind energy benefits when conditions are right.

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There are mechanisms and safeguards to ensure blades transfer the maximum desirable rotation, but also to make certain they aren’t torn from their hubs while doing so. There are braking systems to prevent the generator from overloading the system with electricity. Anchor points on the wind turbine structure and the ground connect cables to stop them from leaning or toppling over in high winds. But even the strongest parts of a wind turbine can be bent, broken, become fatigued, or otherwise worn out, which is why there are so many job positions near wind power projects for skilled technicians — particularly those with NFPA/70E Arc Flash training.

Why NFPA/70E Certification Is Vital to Wind Projects

Wind turbines are a clean and relatively safe source of electrical power, but it’s important to keep in mind that whenever dealing with electricity, there is the risk of shock injury and electrocution. If you include the height factor — wind towers are often hundreds of feet high — there’s an additional risk of a long fall complicating an electrical accident. OSHA (Occupational Safety and Health Administration) has established safety standards for wind power projects, and there’s an emphasis on electrical safety. This has created an increased demand for wind turbine technicians with NFPA/70E Arc Flash certifications. Fortunately, NFPA/70E Arc Flash training is available via online courses for those seeking work in the wind power industry.

The Distinction Between Wind Energy and Wind Power

While most people outside of the wind turbine field use the terms “wind energy” and “wind power” interchangeably, they have significantly different meanings. In simple terms, energy is the ability to do work. Therefore, a functioning wind energy definition, is the ability of wind to do work — in this case, the work the wind is doing is spinning blades.

Electricity is usually measured in watts, or because watts are relatively small units, kilowatts (1,000 watts), megawatts (1 million watts), and gigawatts (1 billion watts). Power is the rate of energy, or the amount of energy, over a given period of time. Electrical power is usually measured in kilowatt-hours, megawatt-hours, or gigawatt-hours. So, when someone asks the simple question, “What is wind power called?” the answer should be “wind power” because there is no substituting term.

Wind Turbine Terminology

Learning the nomenclature of wind turbines and the wind industry jargon can be advantageous to individuals who are looking to make a living in this explosive-growth industry. As an institution that trains skilled workers for the wind turbine industry, we’ve assembled a list of commonly used terms. Where a simple wind turbine definition will not suffice, we’ve included a brief narrative explaining how each term relates to wind turbines and wind power:

Aggregation – This occurs when several wind projects are pooled together to achieve improved wind power output and/or reduce costs.

Airfoil – The shape of the wind turbine blade that provides lift and reduces drag.

Anemometer – Any instrument used to measure the speed of wind. This is also referred to as a “wind speed device.”

Angle of Attack – Is a term used to describe the direction (angle) from which wind interacts (attacks) with the turbine.

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Armature – This is the moving part in the generator portion of a wind turbine. The rotor turns the rotor shaft, which spins the armature, allowing the spinning magnets to generate electricity.

Availability Factor – Wind turbines sometimes come offline for maintenance and repairs. The availability factor measures the time the wind turbine actually functions to produce electricity.

Average Wind Speed – The average/mean wind speed over a particular time.

Balancing – A maintenance operation to keep the wind turbine rotating smoothly. If a wind turbine isn’t properly balanced, friction and vibration result, damaging the unit.

Betz Coefficient This is the optimum capacity at which a wind turbine can convert wind into electricity. Because of the design of wind turbines, some wind passes between the airfoil blades without interacting with their surfaces. The optimal Betz coefficient is 59.3%. To further explain, a solid disk would have a Betz coefficient of 100%, but it wouldn’t spin, which is why blades are used.

Blades – The panels extending from the hub. Wind turbine blade designs are selected based on a number of factors, including the anticipated angle of attack and maximum Betz coefficient.

Braking System – These prevent turbines from spinning too fast, which can damage the turbine or overload the electrical system.

Capacity Factor – Also known as Average Capacity, this is the amount of electric power produced by an individual turbine over a set period of time.

Chord – This is the width of a blade at any given point along its surface.

Commercial Scale Wind – Wind energy projects that produce more than 100 kw (kilowatts) of electricity for sale — not to be used on site.

Cut-in Speed – Turbines are designed to turn when wind reaches a certain speed, and 10 mph is a standard cut-in speed.

Cut-out Speed – The maximum wind speed in which a turbine can operate before the braking system stops it to avoid damage.

Distributed Generation – An alternative source of power to traditional large-scale utilities. This is a small-scale, local source of power. The term can be used to refer to a self-sufficient wind energy project.

Downwind Turbine – A turbine where the hub and blades point away from the wind direction.

Furling – When a wind generator adjusts its position to protect itself from high speed winds.

Gigawatt – One billion watts.

Green Pricing – A premium built into the price of energy to purchasers who are willing to pay extra to for clean, renewable power.

Grid – A system to collect and distribute electricity.

Guy-Anchor – The base by which the guy-wire is secured to the ground.

Guy-Wire – A strong metal cable that attaches to the wind turbine and the ground to provide stability.

Hub – The center of the wind turbine blades. The hub is connected to the blades and a rotor shaft, which connects to the generator. Also referred to as a “wind hub.”

Hub Height – The height of the center of the hub from the ground.

Hybrid System – A system that draws power from multiple sources, such as wind and solar.

Installed Capacity – In wind, the total electrical output a wind turbine project is capable of producing.

Inverter – A device that converts direct current to alternating current.

Kilowatt – 1,000 watts.

Kilowatt-hour – A consumption measure that is equal to 1,000 watts used over an hour’s time.

Megawatt – One million watts.

Met Tower – A tower platform that contains instrumentation and devices to measure wind direction, speed, and temperature at different heights from the ground.

Nacelle – A housing connected to or adjacent to the wind hub that protects the rotor shaft, gearbox, and generator.

Net Metering – A system where the flow of electricity is between the producer and consumer. Electricity is measured in both directions.

Payback Period – The time before the break-even point when the purchase price of the system is offset by savings.

Peak Wind Speed – The maximum wind velocity that occurs within a specific time frame.

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Power Curve – A graph showing the instantaneous power output for a wind turbine at different speeds.

Production Tax Credit (PTC) – The Energy Policy Act of 1992 provides a tax credit to wind facilities based on the amount of energy produced.

PURPA (Public Utilities Regulatory Policy Act)A law requiring utilities to purchase a portion of their power from renewable energy producers. The law was enacted in 1978.

Renewable Energy Certificates – Vouchers to offset the increased cost of producing clean, renewable energy. Also referred to as “green tags.”

Rated Wind Speed – Wind turbines come with nameplates listing their optimum level of energy production. The rated wind speed is the corresponding wind speed that allows a turbine to achieve its nameplate rating. This is usually 30-35 mph.

Rotor – The turbine blades and the wind hub. This is the visible spinning part of the wind turbine.

Start-Up Speed – This is the speed at which a turbine starts to rotate. Power is not produced, however, until the turbine reaches cut-in speed.

Thrust Bearing – A bearing that supports the centerline of the shaft against the force of the wind against the turbine blades.

Tower – The supporting structure for the wind turbine rotor and the nacelle.

Turbine or Wind Turbine – A device that allows wind to be turned into mechanical energy, which is used to power an electrical generator.

Twist – This refers to the curvature in wind turbine blade designs.

Utility-Scale Wind – A wind energy project that has a capacity of at least 100 kilowatts. This is not dependent on other size considerations like the number of turbines or whether they are commercially or privately owned.

Vane – A flat piece of metal attached to a turbine that acts as a rudder to point the turbine rotor into the wind. It is sometimes referred to as a “tail.”

Variable Pitch Turbine – A wind turbine rotor design where the blades can be adjusted to the angle of attack. Variable pitch turbines can be manually or automatically adjusted.

Variable Axis Wind Turbine – A type of rotor design where the axis of rotation is vertical instead of horizontal.

Watt – Is a measure of electrical energy transfer. A watt equals 1/746 Hp (horsepower). See also, kilowatt, megawatt, and gigawatt.

Watt-Hour – A consumption measure that is equal to one watt used over an hour’s time.

Wind Monitoring System – Instrumentation that measures meteorological conditions, like the speed, direction, and temperature of the wind at different heights.

Wind Resource – The anticipated wind available to drive wind turbines. This is calculated by historical wind data and topographic conditions that affect wind availability.

wind-resource-is-the-anticipated-wind-available-to-drive-wind-turbines

Wind Resource Assessment – The process of measuring and mapping wind resources.

Wind Rose – A graphical representation of wind speed and direction at a specific geographical location.

Wind Shear – With all other factors being equal, wind speed increases as it gets higher with respect to the ground. Surface terrain can also affect the velocity of the wind. It’s important not to confuse wind shear with wind speed.

Wind Speed – The measure of how fast wind is moving. It is calculated by determining the distance that air particles move in a particular amount of time. In the United States, miles per hour (mph) is the standard unit of wind speed measurement.

Wind Speed Device – See Anemometer.

Wind Turbine – A system designed to convert wind into mechanical energy (rotation) to power an electrical generator.

Wind Vane – An instrument that measures the direction of wind. See also Vane.

Windmill – A structure that converts wind to the mechanical energy used to grind grain into flour.

Yaw – This refers to the adjustment a wind turbine will make about the vertical axis of its tower.

Wind Turbine Employment and Training in Your Area

Because wind power is still in its early growth stages, there are many areas of the country that are not near wind power projects. Before you seek out training in the field, make certain there are potential opportunities in your area or in a geographic location where you want to move. Not all areas are suited for wind turbine projects, so do your research before committing to a career in wind power. We offer NFPA/70E Arc Flash Training online to current and potential wind industry technicians. Contact us if you have any questions regarding training for career opportunities in wind power.