Classifi cation: CLASSCUP (Report: Risø-R-1348 (EN))
Reference report
Measnet-calibrated anemometer
Low threshold speed
Low distance constant
Negligible overspeeding
Angular response independent of wind speed
Fully tested temperature performance
Symmetrical geometry
The P2546A-OPR Cup Anemometer is a sturdy wind sensor solely construct-
ed by durable materials such as anodized aluminium and stainless steel. The
wind speed is sensed by a three-cup one-piece rotor (OPR) assembly. Perma-
nent magnets mounted on the shaft causes a switch to close and open two
times per revolution. The switch has no bounce and it is equipped with a spe-
cial built-in mechanism, which reduces the variation in operating time over
the frequency range. This feature provides the possibility of obtaining the
instantaneous wind speed by measuring the time interval of each revolution.
Anemometer WindSensor (Risø) P2546A-OPR
Dimensional drawing
page 1/2
Specifi cation
The speci cations are based on 80 wind tunnel calibrations per-
formed according to the Measnet Cup Anemometer Calibration Pro-
cedure. The speci ed offset and gain gures represent the mean
values of these calibrations. Variation among units designates the
maximum deviation of any unit from the straight line representing
these mean values.
All units are run-in for 225 hours at 9 m/s, in order to reduce the ini-
tial bearing friction to a level close to the steady state value.
After run-in, bearing friction is tested at -15 °C and at room tempera-
ture. The allowed limits for this test assures that the temperature
in uence on the calibration is within the speci ed limit.
The inner diameter of the anemometer base is 25.5 mm. The diam-
eter of the connector itself is 20 mm. Thus the diameter of the tube
should be at least 21 mm. Please consider the dimensions when
mounting the anemometer on the tube. We recommend using tubes
with material thickness of 1.5 mm. See dimensional drawing.
Note: The WindSensor P2546A-OPR anemometer (reed switch) contains
40 mg of mercury and is not available for sale in some US states. The following
states ban selling mercury switches: California (CA), Illinois (IL), Maine (ME),
Massachusetts (MA), Minnesota (ME), New York (NY), and Vermont (VT). Refer
to for further details.
Connector diameter: 20 mm
Anemometer WindSensor (Risø) P2546A-OPR
Characteristic Description / Value
Measurement range 0 ... 70 m/s
Slope 0.6201 m
Offset 0.027 m/s
Starting threshold < 0.4 m/s
Distance constant
λ0= 1.81 ± 0.04 m
Standard deviation of offset 0.014 m/s
Standard deviation of gain 0.027 m
Variation among units ± 1%
Non-Linearity < 0.04 m/s
Temperature inuence < 0.05 m/s (-15 ... +60 °C)
Switching chararacteristic
Signal Type potential free contact closure
Duty cycle 40 ... 60 %
Max. switching voltage 30 V
Max. recommended switching current 10 mA
Series resistance 330 Ω, 1 W
Operting temperature range -35 ... +60 °C
Reference report RISØ-R-1364 (ed. 2) (EN), Mar 2004; IEC 88/185/CDV
Manufacturer WindSensor
Accessories Module M83570 or M83200 (pull-up resistor required)
page 2/2
Sensor connection to Ammonit Meteo-40 data logger
Sensor Ammonit Wire Color Meteo-40 Counter Supply Sensor
Signal, high white Counter CNT, 6k8 (Switch: 5 V via 6k8 to CNT, Pull-up resistor)
Signal, low black Main Ground
Connect the shield logger-sided to Ground (GND)
Cable type: LiYCY 2 (3) x 0.25 mm²