Image:Urbine resistor glog.jpg

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2000 watt, 1/8 ohm variable resistor: cyborglog of installation

Variable resistor as installed, with metal housing, secured to structural pipes. This resistor is connected, by way of a PWM (Pulse Width Modulation) controller to the 12 volts D.C. of a wind turbine, for purposes of dynamic braking.
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Variable resistor as installed, with metal housing, secured to structural pipes. This resistor is connected, by way of a PWM (Pulse Width Modulation) controller to the 12 volts D.C. of a wind turbine, for purposes of dynamic braking.

Here is an example of a variable resistor, of the edgewound variety. Stainless steel strips are edge wound on ceramic core, mounted in a NEMA rated enclosure. Here the enclosure is open for setting the resistance value which can be easily done with a nut driver as shown. The bolts (1/4 inch, 20 threads per inch) are loosened and the bar can be moved from one coil to the next. Each coil has 41 turns of flat stainless steel bar on edge. Thus the variability of the resistance must be quantized to the nearest 1/41 of the total 1/8 ohm (i.e. approx. 0.003 ohm resolution). The two coils of 1/4 ohm each are connected in parallel to make the 1/8 ohm resistance that is desired for the end application which is the dynamic braking of a 12 volt Lakota wind turbine.

The resistor is mounted in the middle of the mechanical room upon which the turbine is mounted. This allows maximum ventilation on all sides of the resistor.

This picture was captured using an electric eyeglasses (wearable personal imaging system), and constitutes a cyborglog of the installation process. The entire cyborglog may be viewed at the urbine construction glog


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