MONITORING STATION INSTRUMENTATION AND MEASUREMENTS - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 36

Table 4-1. Specifications for basic sensors

Anemometer Wind vane Temperature

Specification (wind speed) (wind direction) probe

0 ◦ − 360 ◦ ( 8 ◦ deadband) 40 ◦ to 60 ◦ C

≤ − −

Measurement range 0-50 m/s

≤ . ≤ .

Starting threshold 1 0 m/s 1 0 m/s N/A

Distance constant ≤ 3 . 0m N/A N/A

Operating temperature range, ◦ C − 40 to 60 − 40 to 60 − 40 to 60

Operating humidity range, % 0-100 0-100 0-100

5 ◦ -10 ◦ ≤ 1 ◦ C

System error ≤ 1% (at 1 σ )

≤ 1 ◦ ≤ 0 . 1 ◦ C Recording resolution ≤ 0 . 1 m/s

Lifetime (service interval), yr 2 2-6 2-6

N/A = not applicable. Source: AWS Truepower.

Table 4-2. Basic measurement parameters

Measurement Example heights Example heights

parameters (60-m tubular tower) (83-m lattice tower)

Wind speed, m/s 57.2, 47.4, and 32.0 m 80, 60, and 40 m

Wind direction, degrees 53.5 and 43.7 m 80, 60, and 40 m

Temperature, ◦ C 3 m 3 m and/or hub height

Source: AWS Truepower.

the top priority of any wind monitoring campaign. Achieving this goal requires care-
ful attention to the choice of instruments, mounting configuration, and tower design.
Multiple redundant anemometers and measurement heights are strongly encouraged
to maximize data recovery and to accurately determine a site's wind shear. Sensor-
mounting recommendations and diagrams of typical monitoring configurations are
provided in Section 5.7.
Three anemometer types are used for the measurement of horizontal wind speed. Of
these, the cup anemometer is the most popular because of its low cost and generally
good accuracy. However, both propeller and sonic anemometers are used in some
settings.

• Cup Anemometer. This instrument consists of three or four cups connected to a
vertical shaft. The wind causes the cup assembly to turn in a preferred direc-
tion. A transducer in the anemometer converts this rotational movement into an
electrical signal, which is sent through a wire to the data logger. The logger
measures the frequency or magnitude of the signal and applies a predetermined
multiplier (slope) and offset (intercept) to convert the signal to a wind speed
(Fig. 4-1).
• Propeller or Prop-Vane Anemometer. This consists of a propeller mounted on a
horizontal shaft that is kept pointing into the wind by a tail vane. Like a cup
anemometer, a propeller anemometer generates an electrical signal whose fre-
quency or magnitude is proportional to the wind speed. This type of anemometer