WT10 Design
The WT10 is designed to be strong and power through anything mother nature can throw at it. Nearly every component on the WT10 is designed by APRS World and custom manufactured for us. Off the shelf components neither fit nor provided the reliability we require. Most components are machined from solid metal or engineered plastic. All components are sealed, plated, or otherwise designed to provide the most reliable service.
Blades
The WT10 uses three high strength, glass filled nylon, injection molded blades. The blades were designed in the mid 2000's for European micro wind turbine. More than 10 years of experience and thousands of deployed blades has proven that these blades are very though. The wide and thick inboard section of the blades allows them to start working in low wind speeds. The WT10 can be configured for bolt attached blades or for quick and no-tools-required blade attachment. The quick attach blade option allows the blades to be installed in less than a minute, even while wearing gloves.
Chassis
WT10 chassis start as solid sections of 6061-T6 aluminum. Much of the material is precision CNC machined away to make for light weight and strong components. The main section of the chassis holds the front bearing, provides a mounting location for the yaw assembly, and provides a precision face for attaching intermediate bearing and permanent magnet generator. O-rings and custom o-rings are used between all sections of the WT10 chassis.
Generator
To generate electricity, the WT10 has a three phase permanent magnet generator (PMG). The generator consists of a rotating shaft, called the rotor, surrounded with super high strength neodymium magnets. These magnets spin inside a stationary generator assembly called the stator. The stator is wound with coils copper wire. As the rotor containing magnets spins within the coils of the stator, electricity is generated. Special considerations were made in the PMG design to minimize "cogging" or mechanical pulsing of the generator. The complete generator assembly is housed in finned extrusion to provide generator cooling.
Tail
The anodized aluminum tail slides into the finned section of the WT10 and is held in place with tool-less quarter turn fasteners. High performance engineered plastic "grabbers" hold the tail in the heat sink and prevent it from vibrating. Tail vibration is a common cause of unwanted acoustics (i.e. noise) in small wind turbines. Installation of the tail takes just seconds and can be done with gloved hands.
The tail features a lifting hole that is located above the front to back center of gravity of the WT10. This allows the WT10 to be safely and easily lifted during installation. There is a drawing showing this operation in the documents section.
Yaw
The yaw component serves three purposes: allowing the turbine to turn, transferring electrical power and ground, and attaching the WT10 to a mast. The WT10 is available with two different types of yaws. A slip ring yaw and a Mercotac® based yaw.
The slip ring yaw uses four custom carbon metallic brushes that contact brass slip rings. The brush stay stationary with respect to the wind turbine and the brass slip rings stay stationary with respect to the mast. The brushes are electrically connected to the permanent magnet generator. The slip rings are connected to the turbine control panel or electrical system. The brushes are very thick and wide and would take many many years to wear out. A innovative slip ring mechanism allows for compact packaging and trouble free operation.
The Mercotac® yaw uses a mercury wetted rotary contact to transfer power from the turbine to the mast. The sealed Mercotac® module has three compartments containing a blob of mercury. Wires stick into the mercury blob and the mercury conducts electricity. Above approximately -40°F / -40°C mercury is a liquid and the Mercotac® yaw turns freely. Below that temperature the mercury can become solid and impede free rotation of the turbine yaw. Because of this, we do not recommend the Mercotac® yaw be specified for cold environments.
To prevent water buildup in the yaw, a drain hole is located at the bottom of the yaw assembly. A micro-porous sintered stainless steel plug allows water to escape but doesn't allow contamination in. A circular metal electrical connector on the bottom of the yaw provides the electrical connection from the generator. The electrical connector has a strong metal body and is used during the installation to hold the turbine in an easy to reach position. There is a drawing "WT10 Drop Cable Installation" showing this operation in the documents section.
Both versions of the yaw are compatible with APRS World's mast quick coupler to allow very quick mating of the mast at WT10 turbine.
Plating
Aluminum parts of the WT10 are anodized and dyed black. We have carefully selected an anodize process and vendor that results in dark black parts that stay black even after years outside in the sun. Only by very tight process control can we achieve this.
Stainless parts are passivated to eliminate any contamination or other molecules that may rust or stain. Our plating vendor uses a very effective but environmentally friendly citric acid solution for this.