Things that Work! Trade Wind's Wind Odometer Mick Sagrillo copyright 1991 Mick Sagrillo Folks who want to do an extensive wind site analysis are usually stunned by the prices of recording anemometers. Wind odometers or recording anemometers start at around $350, but most cost $1,200 and up. That's affordable for a wind farm, but what, you may ask, is available for the homeowner? For years, I tried to find affordable wind recording equipment. I finally stumbled onto the Wind Odometer made by Trade Wind. Hardware I have many expensive wind recording instruments, so I was skeptical when I found this budget model. I have been selling Trade Wind anemometers for years, and am familiar with the high quality of their relatively inexpensive equipment. But somehow this odometer had escaped my attention. Unable to pass up the temptation, I ordered one. It arrived promptly via UPS. It was well packed, preventing damage by overenthusiastic truck stuffers. The unit consists of the odometer, a 3-cup plastic anemometer head, a ten inch PVC mast for the anemometer, sixty feet of two conductor cable, and some brief instructions. The odometer comes with a small power supply (wall cube) for use with a standard 115 vac power outlet. No 120 vac available? No problem. The instructions indicate that you can simply cut the wires to the wall cube and reconnect to any 12 VDC power source. Be sure to get the polarity right. The odometer consumes only 1 milliAmpere of current at 12 VDC. When operated by the wall cube, the odometer is much less efficient due to losses in the power supply. The odometer can actually be powered by D sized flashlight batteries for remote applications. Installation The set up is simple. Mount the anemometer somewhere high, and connect the two conductor cable to the anemometer. Connect the other end of the cable to the odometer and you're ready for business. The anemometer can be mounted as far as 500 feet away from the odometer. If you are collecting data for a future wind generator, then place the anemometer at the hub height of the planned generator. The higher the anemometer, the greater the average wind speed. See HP#21 article on Wind Generator Tower Height. How It Works The Wind Odometer is an event totalizer that counts pulses. Operation is simple. The anemometer head generates an electrical pulse every time it spins around. The electronics in the Wind Odometer counts these pulses. The display of the odometer shows an accumulative count which increases as the wind blows. The five digit display of the Wind Odometer looks just like the odometer on your car and works the same way. In a car's odometer, to find the distance between two points simply subtract the starting odometer reading from the reading when you reach your destination. This gives you the number of miles you have driven. The Wind Odometer works similarly, but reads wind speed in miles per hour. If you take the number of counts displayed by the odometer, subtract the previous odometer reading and divide by the number of hours between the readings, then you will get the average wind speed in miles per hour for that period. The main difference between the Wind Odometer and more expensive data loggers is that the data loggers keep track of the elapsed time, and do the necessary calculations, for you. What expensive data loggers accomplish electronically, the Wind Odometer's user does manually with a watch, calendar, and a piece of paper. Simply jot down the count on the odometer, the date, and the time. I suggest writing down the count on the odometer daily at the same time of day. Simply subtract yesterday's reading from today's and divide by 24 (hours per day). The result is the average wind speed in miles per hour for the preceding day. You can also use a running time meter to keep track of the elapsed hours. There is an LED on the odometer that can be used to measure wind speed in miles per hour. Simply count the number of times that the LED flashes in a sixty second period. That's the wind's speed in miles per hour. While the anemometer is waterproof and designed to live outside, the odometer is not. If you are going to use the odometer in an outside location be sure to put it in a waterproof box such as a Hoffman enclosure or NEMA class 3 box. Conclusions The Wind Odometer lists for $153.50. It comes with a one year factory warranty. At various times, I have looked into building a wind odometer or recording anemometer. Between the electronics to do the counting, the actual anemometer (which must live outside in the wet and wind), and the display, I figure that it would cost well over $150 in parts. Not to mention the time and R&D involved. Homebrew anemometers using panty hose containers or split ping pong balls aren't worth the trouble of building. For my time and money, the Wind Odometer is a bargain. Access Author: Mick Sagrillo, Lake Michigan Wind & Sun, E3971 Bluebird Road, Forestville, WI 54213 ù 414-837-2267. Manufacturer: Trade Wind Instruments, 1076 Loraine Street, Enumclaw, WA 98002 ù 206-825-2267. The Wind Odometer is available directly from Trade Wind or from your wind generator dealer.