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Our normal wind speed cup assemblies are rugged, but engineered to read very light winds as well as to stand up under and read heavier winds. They are available for special applications with a voltage or a pulse output for a variety of uses. They are used as controls to switch on and off large garden fountain displays such as the Olympic Fountain in Atlanta, GA. They are used on wind mill electricity generating towers. They are also used to collect input for agricultural, sceintific data purposes.

Wind Direction sensors are available with voltage or pulse output for similar purposes.

Contact Downeaster Customer service at 888-806-6300 for more information related to your company's needs.

Wind Velocity System

Two wind speed transmitters are available which share the same housing and cup configuration. Three 2-inch cups rotate on a vertical axis at a radius to the cup center of 2.25 to 2.26 inches. The calibration of these units is given by the equation: Wind Speed, miles per hour = 0.9306 = 0.0420 (cup rotor revolutions/minute).

Therefore, one revolution of the cups is caused by the passage of 3.75 ft. or 1.143 meter of wind. The cups revolve at 1800 RPM at a wind speed of 76.27 mile per hour or 34.107 meters per second.

This calibration averaged 47 test points on 7 anemometers at wind speeds between 7.2 and 116 mile per hour in the Wright Brothers Wind Tunnel at the Massachusetts Institute of Technology. The coefficient of determination, a measure of how close the data points were to the line described by the equation above was: r2 = 0.99928 where 1.0000 represents a perfect fit.

P000111 Transmitter
This is an alternating current (A.C.) generator with a 4-pole rotating permanent magnet and air core pick-up coils, which give 2 cycles per revolution. The alternating current frequency and voltage are both linearly proportional to wind speed between 0.93 and 100 miles per hour. The generator output voltage is adjusted with a high resistance shunt to 9.00 volts RMS (root mean square) at 1800 RPM no load, to compensate for coil and magnet variations. The generator internal coil resistance is approximately 1300 ohms and the output voltage although lower, remains linear with speeds at meter loads of up to 2 milliamperes, at 100 miles per hour.
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P000112 Transmitter
This is a contact anemometer with a single bar magnet rotating above either one or three reed switches to give three pulses per revolution. The ON and OFF intervals are adjusted approximately equal in time but they can be varied by changing the magnet position. The reed switches have a maximum contact capacity of 10 volt-amperes, a maximum conductive current of 1 ampere and a maximum voltage of 100 volts. Typical long life operating conditions call for 5 ­ 15 milliamperes and 2 volts or less (from unpublished text). We cycled 32 of these reed switches at 2000 closures per minute, for over 270 million cycles with no failures. They switched a direct current on and off to light a 9 or 18 milliamperes light emitting diode for each switch.

For the one reed switch transmitter
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For the three reed switch transmitter
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Wind Velocity Meter
All of Downeaster's meters have high torque 500-microampere movements. These meters indicate the wind speed within the precision of the meter, which is plus or minus 2% of the full scale of the meter.

Frequency counters or digital volt meters with a higher built in precision give correspondingly more precise wind speed measurements. Wind speed recorders are also suitable where permanent records are needed.

P000112 transmitters are usually customer connected to data storage counters, computers, or remote modem data collection systems.

Wind Direction System

P304 Wind Direction Transducer ­ Voltage
The P304 transmitter uses a continuous rotation 1000-1100 ohm potentiometer rated at 1 watt maximum below 70 degrees C. This has a standard life expectancy of 5 million revolutions. Its resistance linearity is 1%, which should resolve to within 3.6 degrees of angle between 0 and 340 degrees. There is an open space of 20 degrees, which we positioned between south-southeast and south on the mast.
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P001011 Wind Direction Transducer ­ Reed Switch
The reed switch vane assembly utilizes contains 8 reed switches of the same type described for contact anemometers. The reed switches were selected for the pull in/drop out range and the operating magnet was angled so that the on-off resolution or scatter should be less than 1/3 of the 22.5degree interval the indicators show. The five-wire system uses about 6V AC and is tailored to Light emitting diode indicators only, as they have two diodes in the transmitter. Each wire operates a pair of side-by-side reed switches. Our standard color-coded wire connections correspond to the following sequence: black- NE and N; red- E and SE; orange- S and SW; green- W and NW. The white wire is the common power wire for the system.
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Wind Direction Meters
Eight light emitting diodes indicate 16 compass points, lighting alternately one or two lights over 22.5o degree intervals around the compass. These diodes are current-limited to either 10 or 20 milliamperes, depending upon type, provided the prescribed power plug is used. This assures long life of both the reed switches and the light emitting diodes.

The meters use a 6-volt AC transformer that is tailored to light emitting diode indicators that have two diodes in the transmitter.

Accessories

Combination Mast
This 14" aluminum mast allows mounting of OEM wind direction and OEM wind speed transducers (one each).
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