Turbines with Power Ratings above 1 kW to 30 kW

Turbines in this size category represent a more significant investment of both time and money compared to sub-1 kW wind turbines. Sales volumes are also not as high, and the machines tend to be made in smaller production batches with more complex parts (for example, extruded blades rather than moulded). On the installation side, they require more extensive planning with regards to land area, tower erection, height clearances and, in some cases, permitting. In most cases the turbines are installed by professionals, and require regular inspection and on-site maintenance. They typically provide power for single-family dwellings or larger off-grid applications (e.g. a hunting lodge). The most common wind turbines in this category are 3-bladed, horizontal axis, up-wind machines. Variations on this design include 2-bladed and down-wind machines. Some manufacturers also offer the century-old multi-bladed wind pumper, or ‘American windmill’, design that has been updated and modified for electricity generation.

While most of these turbines employ direct-drive permanent magnet alternators, some use asynchronous induction generators and gearboxes. Different electrical controls and power conditioning equipment packages are available depending on whether the turbines are intended for stand-alone battery charging or for grid-connected applications.

Most of these wind turbines are variable speed machines that employ passive stall regulation and furling for overspeed control, although some use electrical controls to slow down the generator rotor. No turbines in this size range are known to use active (i.e. motorized) pitch control. Typical rotor diameters for these turbines range from 2.5 to 10 m while tower heights are usually from 18 to 40 m. Because of the significant weight and loading of these machines, special attention has to be paid to proper tower design and installation.

The life expectancy of well-built and well-maintained wind turbines is generally expected to be over 20 years. This may vary significantly however depending on operating conditions (e.g. high turbulence winds, extreme dust or cold). Some non-integrated turbine designs allow for the replacement of virtually all major components, allowing the system’s life to be extended indefinitely.

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