8.2.1 Wind Speed
This
section provides guidance for the acceptance testing of anemometers (i.e.,
mechanical wind speed sensors employing cups or vane-oriented propellers)
which rely on the force of the wind to turn a shaft. Guidance for the
acceptance testing of remote sensors for the measurement of wind speed is
provided in Section 9. Other types of wind speed sensors (e.g., hot wire
anemometers and sonic anemometers) are not commonly used for routine
monitoring and are beyond the scope of this guide.
A
technical acceptance test may serve two purposes. First, it can verify that
the instrument performs as the manufacturer claims, assuming the threshold,
distance constant and transfer function (rate of rotation vs. wind speed)
are correct. This test catches shipping damage, incorrect circuit
adjustments, poor workmanship, or poor QA by the manufacturer. This level of
testing should be equivalent to a field performance audit. The measurement
system is challenged with various rates of rotation on the anemometer shaft
to test the performance from the transducer in the sensor to the output. The
starting torque of the bearing assembly is measured and compared to the
range of values provided by the manufacturer (new and replacement).
The
other purpose of a technical acceptance test is to determine if the
manufacturer really has an instrument which will meet the specification.
This action requires a wind tunnel test. The results would be used to reject
the instrument if the tests showed failure to comply. An independent test
laboratory is recommended for conducting the ASTM method test.
The
specification most likely to fail for a low cost anemometer is threshold, if
bushings are used rather than quality bearings. A bushing design may degrade
in time faster than a well designed bearing assembly and the consequence of
a failed bushing may be the replacement of the whole anemometer rather than
replacement of a bearing for a higher quality sensor. A receiving inspection
cannot protect against this problem. A mean-time-between-failure specification
tied to a starting threshold torque test is the only reasonable way to
assure quality instruments if quality brand names and model numbers cannot
be required.
8. QUALITY ASSURANCE AND QUALITY CONTROL
8.1 Instrument Procurement
8.1.1 Wind Speed
8.1.2 Wind Direction
8.1.3 Temperature and Temperature Difference
8.1.4 Dew Point Temperature
8.1.5 Precipitation
8.1.6 Pressure
8.1.7 Radiation
8.2 Installation and Acceptance Testing
8.2.1 Wind Speed
8.2.2 Wind Direction
8.2.3 Temperature and Temperature Difference
8.2.4 Dew Point Temperature
8.2.5 Precipitation
8.2.6 Pressure
8.2.7 Radiation
8.3 Routine Calibrations
8.3.1 Sensor Check
8.3.2 Signal Conditioner and Recorder Check
8.3.3 Calibration Data Logs
8.3.4 Calibration Report
8.3.5 Calibration Schedule/Frequency
8.3.6 Data Correction Based on Calibration Results
8.4 Audits
8.4.1 Audit Schedule and Frequency
8.4.2 Audit Procedure
8.4.3 Corrective Action and Reporting
8.5 Routine and Preventive Maintenance
8.5.1 Standard Operating Procedures
8.5.2 Preventive Maintenance
8.6 Data Validation and Reporting
8.6.1 Preparatory Steps
8.6.2 Levels of Validation
8.6.3 Validation Procedures
8.6.4 Schedule and Reporting
8.7 Recommendations