PDF《Met One 034A-LC Windset》

0 to 360°, shorting to ground between 356° to 360° Threshold: 0.4 m s-1 (0.9 mph) Accuracy: ±4° Resolution: 0.5° Potentiometer Specifications: Resistance:

0 to

10 k? shorting at crossover General Specifications Operating Temperature Range: -30° to +70°C Weight:

907 g (2.0 lb.) The black outer jacket of the cable is Santoprene? rubber. This compound was chosen for its resistance to temperature extremes, moisture, and UV degradation. However, this jacket will support combustion in air. It is rated as slow burning when tested according to U.L.

94 H.B. and will pass FMVSS302. Local fire codes may preclude its use inside buildings. NOTE 3. Installation 3.1 Siting Locate wind sensors away from obstructions (e.g. trees and building). As a general rule of thumb there should be a horizontal distance of at least ten times the height of the obstruction between the windset and the obstruction. If it is

1 Met One 034A-LC Windset for MetData1 necessary to mount the sensors on the roof of a building, the height of the sensors, above the roof, should be at least 1.5 times the height of the building. See Section

9 for a list of references that discuss siting wind speed and direction sensors. 3.2 Mounting Tools Required: ? 5/64 and 1/16 allen wrenches ? compass and declination angle for the site ? small screw driver provided with datalogger ? UV resistance cable ties ? small pair of diagonal-cutting pliers ?

6 -

10 torpedo level Mount the 019ALU crossarm to the top of the tripod/tower. Orient the 019ALU north and south with the 3/4 x

1 inch Nu-Rail on the north end. Appendix A contains detailed information on determining true north using a compass and the magnetic declination for the site. Remove the alignment screw at the base of the 034A (Figure 3-1). Insert the 034A into the aluminum bushing provided with the sensor. Align the hole in the bushing with that in the 034A base and replace the screw. Insert the 034A/bushing into the 3/4 x

1 inch Nu-Rail on the 019ALU. Align the sensor so that the counter weight points to true south and tighten the set screws on the Nu-Rail. Remove the shoulder screw to allow the vane to rotate. Attach the sensor cable to the six pin male connector on the 034A. Make sure the connector is properly keyed. Finger tighten the knurled ring. Route the sensor cable along the underside of the crossarm to the tripod/tower mast and down a tripod/tower leg to the instrument enclosure. Secure the cable to the crossarm and mast using cable ties. 4. Connection The 034A-LC is attached to the MetData1 connector #2. 5. Datalogger Programming Information in this section is not necessary when programming the MetData1 with the Short Cut Program Builder software. NOTE The Pulse instruction, Instruction 3, with an option code of 22, is used to measure the wind speed. Instruction

3 counts the number of switch closures that have occurred during the datalogger'

s execution interval. When option code

22 is selected, the datalogger reports the counts as a frequency. In addition, counts beyond the execution interval, caused by table overruns, are discarded. The frequency is converted into wind speed using the multiplier and offset listed in Table 5-1.

2 Met One 034A-LC Windset for MetData1 The AC Half Bridge instruction, Instruction 5, is used to measure wind direction. The AC Half Bridge (P5) instruction provides a precision voltage to the potentiometer and measures the voltage between the wiper and ground. The voltage is linearly proportional to the azimuth and is converted to degrees by the multiplier and offset listed in Table 5-1. TABLE 5-1. Multipliers and Offsets for Wind Speed and Direction Units Datalogger Type Instruction Number Multiplier Offset m s-1 CR10(X) or 21X