User manual VAISALA WAA252 QUICK REFERENCE GUIDE PART 1

[. . . ] Optimum position yields < 0. 35 m/s starting threshold. 2) Standard Deviation 3) Typical error versus speed, when "simple transfer function" Uf = 0. 1 × R is used: RANGE (m/s) ERROR (m/s) 0-5 -0. 2 5-10 -0. 1 10-15 ±0. 0 15-20 +0. 1 20-24 +0. 2 24-29 +0. 3 29-34 +0. 4 34-39 +0. 5 39-44 +0. 6 44-48 +0. 7 48-58 +0. 85 Quick Reference Guide WAA252 Heated Anemometer Description and Technical Data 9608-037 · Non-freezing all-weather sensor · Lightweight cups with integral heaters · Non-contact heating power transmission · Low starting threshold · Excellent linearity even at low wind speeds · Fast response; distance constant only 2. 7 m The WAA252 Heated Anemometer is an optimum choice, when a non-freezing gauge is required. It offers the linearity and sensitivity of a well-designed cup anemometer plus the advantage of heating carried out right where it is needed - in the cups. Foil heaters are inserted in each cup and in the cup wheel hub. [. . . ] The optochopper type transducer consumes only some 10 mA from a 5. . . The WAA252 can be mounted on Vaisala's regular WAC151 crossarm and its output interface is compatible with that of the regular WAA151 anemometer. Therefore, updating to a heated-cup system is easy - just a wiring alteration is needed in the crossarm's junction box. Wind tunnel tests per ASTM method D5096-90 have been conducted on the WAA252 in order to define its aerodynamical behavior. The WAA252's power inputs and signal outputs are well protected against line transients and interference. The device itself emits no unacceptable electro-magnetic noise to the signal cables or the atmosphere. www. vaisala. com Mounting and Locating In mounting the WAA252 Heated Anemometer keep in mind the recommendations for locating the wind sensors. Following three cases are most typical: 1 Preferred location is on the top of a mast, at a site with open terrain. The recommendation is to have at least 150 m open area in all directions. Minimum distance to visible obstacles is 10 times the height of the obstacle. When the gauge is mounted beside the mast, the distance from the mast to the crossarm should be at least 3 times the diameter of the mast. If mounted on the top of the building, the gauge should be installed on top of a mast at least 1. 5 times as high as is the height or the largest width of the building, whichever is smaller. NOTE Following the recommendations for locating the wind sensors is essential for receiving reliable wind data. 2 3 Electrical The WAA252 operates from a single 25 VDC +10% power supply, at 3. 2-ampere maximum current (@ 25 V). Most of the current is consumed by the heating, typically enabled only at ambient temperature below +5 °C. With heating off, only some 40 mA is consumed. Table 1. WAA252 Connector A F+ Optional power input for transducer section, 5. . . 15VDC, 10mA typ. Signal Ground (also GND for optional power i/p and o/p at A and F) Signal Output, 0. . . 750Hz square wave (for 0. . . 75m/s), (HI>11V / LO<1V typ. ) Power Ground Power Input, 24VDC +10%, 3. 2 A max. Optional power output for external transmitter, 13VDC typ. , 75 mA max. The input power supply leads are connected to the terminals E(+) and D(-) of the I/O connector (presented in Table 1). The lead diameter should be such that no excessive power is wasted in the cable. Each 0. 3 ohms in the cable will cause a 1-Volt extra drop in the operational voltage, which in turn will decrease the applicable heating power. For instance, if only 20 V instead of the recommended 24 V is remaining at the anemometer end of the cable, only 70% of the specified heating power is gained. No separate power source is required for the WAA252's transducer section, since this is also fed by the heating supply, through a galvanically isolated voltage converter integral to the sensor electronics. Optionally however, if an external, no-break power supply should be applied for the transducer section only, this can be connected to the terminals A(+) and B(-), with a voltage range from 5 to 15 VDC. [. . . ] Those inputs are not necessarily needed, since the sensor can take its excitation from the integral, isolated 12V power supply fed from the 25V heating power line. Optionally, however, as described in the Electrical section, a no-break power supply can be applied to those terminals, for example, when a WT521 or WAT12 Wind Transmitter is being used. The power cable leads (ZZ45049 or equivalent) are applied to the terminals #2(+) and #3(-). In case the installation includes both the WAA252 and WAV252, the power line current exceeds 5 A. [. . . ]