Skystream 3.7
Wind Turbine Specifications - Skystream 3.7
Energy Potential ............................................ Up to 400 kWh/month*
Rated Capacity .............................................. 2.4 kW
Energy Monitoring ......................................... Skywiew wireless communication & monitoring system
Weight ........................................................... 205 lbs (93 kg)
Rotor Diameter .............................................. 12 ft (3.72 m) Swept Area: 115.7 ft2 (10.87 m2)
Type .............................................................. Downwind rotor with stall-regulation control
Direction of Rotation ..................................... Clockwise looking upwind
Blade Material ................................................ Fiberglass reinforced composite
Number of Blades .......................................... 3
Rated Speed .................................................. 50-325 rpm
Tip Speed ...................................................... 2113 ft/sec (66 m/s)
Alternator ...................................................... Slotless permanent magnet brushless
Yaw Control ................................................... Passive
Grid Feeding .................................................. Southwest Windpower inverter 120/240 VAC 50-60 Hz
Braking System ............................................. Electronic stall regulation with redundant relay switch control
Cut-In Wind Speed ......................................... 8 mph (3.5 m/s)
Rated Wind Speed ......................................... 29 mph (13 m/s)
User Control .................................................. Wireless 2-way interface remote system
Survival Wind Speed ...................................... 140 mph (63 m/s)
*Based on preliminary data measured at 12 mph average annual wind speeds. Actual output will vary based on site conditions & tower heights.
System Description - Rotor
Skystream is equipped with 3 carbon composite molded blades. They are naturally matched for an optimum rotor balance combonation straight from Flagstaff Arizona. The blades are roughly 6 foot a peice for a total of a 3.7 meter diameter. Skystream has acheived a very efficient airfoir and features one of the only turbines in the world with patented "swept" blades. The design is used to combat tower flutter associated most commonly with all down wind designs.
Generator
The generator converts the rotational energy of the rotor into electricity. The generator utilizes permanent magnets. The generator is configured such that the inside magnet cam rotates, while the external windings are stationary. It was specifically designed for the Skystream and produces power at low speed and also eliminates the need for a speed-increasing gearbox. Since it uses permanent magnets, the generator is generating voltage whenever the rotor is turning. Having a magnet cam inside of the of the stator allows the machine to have a very light rotor comparable to other turbines. The over inertia of the rotor allows for a very reactive and efficient machine. The configuration also allows the Skystream to utilize dynamic braking, bringing the rotor to a complete stall in the case the system loses grid power.
Mainframe
The mainframe is the structural backbone of the wind turbine. It serves as the attachment point for the yaw bearing and the housing for the yaw-axis slip-ring brushes. The yaw-axis is the full 360 degree pivot that allows the turbine to freely align itself to the wind direction.
Governing and Overspeed Protection
The Skystream has developed one of the world's most effective fail-safe turbines. By shutting down the rotor in dangerous high winds, Skystream protects itself (and your property) by utilizing redundant relay switch control. As a redundant measure of safety to guarantee stopping the turbine in case of a winding fault or a lost connection to the alternator, there are seven connections to the alternator windings, but only three are necessary to control or stop the turbine. Asa final measure of safety, if the inverter is unable ton control the rotational speed and skystream exceeds approximately 400 rpm, the rectified coltage will cause the relays to close and apply all the available electromechanical torque to the rotor, stopping Skystream completely. The inverter power path will also be disconnected from the grid by means of relay RL_G. This is the final level of control and is only applied when all methods have failed.
Skystream Inverter
The UL approved Addendum Inverter allows the Skystream to be connected to the wiring in your farm, home, or business. The output of electricity is identica to utility power. The inverter has an interactive wireless communication for reading grid faults, output, and other important operating parameters and characteristics of the inverter. Soutwest Windpower is developing a internet based communication system to allow users to access the data from any internet accessible computer in the world. This also gives the engineers at Southwest Windpower a hands on look on the operating characteristics of your Skystream. This is very innovative way to acquire wind data and performance data from your turbine. Southwest Windpower has long been known as the first guys to succesfully pull off mounting electronics in the air. The benefit is clean A/C power coming down the tower ready to connect to any breaker.
Slip-Rings and Brushes
The slip-rings and brushes conduct the electricity generated in the generator from the moving wind turbine to the fixed tower wiring. The slip-rings are enclosed in a metallic housing to help portect them from lightning.