The calibration of propeller anemometers must comply with national or industry-specific metrological technical specifications. In China, the main basis isJJF 1903-2021 "Calibration Specification for Propeller Anemometer"(released in 2021, replacing the old version), this specification specifies in detail the calibration conditions, methods, items, and result processing for propeller anemometers. The following is a summary of the core regulations:

1、 Verification basis

• Core specifications：
  JJF 1903-2021 "Calibration Specification for Propeller Anemometer"
  (Suitable for propeller anemometers in wind farms, meteorology, environmental protection and other fields)

• Other references：

• JJG 431-2014 (including wind direction function)

• GB/T 35226-2017 "Specification for Ground Meteorological Observation"

• Manufacturer's Technical Manual

2、 Verification conditions

1. Environmental Requirements：

• temperature(20±5)℃

• humidity≤85% RH

• Air pressure:86~106 kPa

• No strong vibration or electromagnetic interference, stable airflow.

2. Standard equipment：

• The accuracy level is three times better than that of the tested instrument (such as a standard tolerance of ± 0.1 m/s and a tested tolerance of ± 0.3 m/s).

• Flow field uniformity deviation≤1%Turbulence intensity≤0.5%

• The wind speed range covers the range of the tested instrument (usually0.5~60 m/s）.

• Wind tunnel device：

• Standard anemometer：

• Auxiliary equipment such as temperature/humidity sensors, barometers, timers, etc.

3、 Verification items and methods

4、 Data processing and judgment

1. Calculation of indication error：
   $E_v=v_i-v_s$

• $E_v$Wind speed indication error;

• $v_i$The displayed value of the tested instrument;

• $v_s$Standard wind speed value.
  judgmentThe error of each point shall not exceed the maximum allowable error (MPE, such as ± 0.3 m/s or ± 3% reading).

2. Repetitive calculation：
   $RSD=\frac{\sigma }{\bar{v}}\times 100\mathrm{\%}$

• $\sigma$: Standard deviation of 6 measurements;$\bar{v}$: Average value.
  judgmentRSD ≤ instrument nominal repeatability (e.g. 1%).

3. Expression of calibration results：

• Issue a Calibration Certificate, including correction values/curves for each point, uncertainty (usually expanded uncertainty)$U\le 0.2\text{m/s}(k=2)$）.

5、 Verification cycle

• Regular cycle：1 year(Frequent use or harsh environments can be shortened to 6 months).

• Re examination conditionsImmediate re calibration is required in case of instrument maintenance, collision, or abnormal data.

Precautions

1. Blade maintenanceRegularly clean the blades to avoid dust or frost accumulation that may affect balance.

2. Bearing lubricationUse specialized lubricants to prevent low-temperature solidification (special treatment is required for environments below -30 ℃).

3. Dynamic calibrationWhen used in wind farms, precision testing under turbulent intensity needs to be increased.

prompt：

• Imported equipment can refer to IEC 61400-12-1 (wind turbine power characteristic testing) or ISO 17713-1 (meteorological applications).

• Explosion proof anemometers must additionally comply with the safety verification of GB 3836.1 "Explosive Environments".

It is recommended to contact provincial metrology institutes or national meteorological metrology stations for professional verification to ensure the legal validity of data.