Vaisala AWS330 - Manual (Page 179)

Chapter 6 ______________________________________________________________ Maintenance
VAISALA ______________________________________________________________________ 177
Visual Inspection
It is recommended that you carry out a yearly visual inspection of the
wind sensor to ensure correct operation and clean the wind sensor if it
becomes contaminated. If necessary, you can also test the operation of
WMT700 with an optional verifier, which is a small echo-free chamber.
If any of the transducers have been bent, twisted or rotated, the
measurement results might not be accurate.
To avoid errors caused by damaged array, check the following:
- Array has not been hit or bent. All transducers must be parallel to each
other.
- Transducers have not been scraped or touched with sharp objects. The
silicon rubber coating must be undamaged.
Cleaning
Regular cleaning of WMT703 is not required. If the wind sensor
becomes contaminated, you can clean it with a soft cloth moistened with
some mild detergent. Do not use solvents or a pressure washer to clean
WMT703 since they may damage the transducer coating.
Testing Proper Operation
WMT703 measures how long it takes for an ultrasonic signal to travel
from one transducer to receiver. Therefore, the accuracy of the sensor
depends on the distance between the transducers and the time-of-flight
measurement circuit, which uses a crystal oscillator for its time reference.
If necessary, you can verify the distance between the transducer arms
with the optional verifier. You can order the verifier from Vaisala as an
accessory (order code: WMT70VERIFIER).
It is recommended that you perform the test every 12 months or if you
suspect that the transducers may have been damaged. The test can be
performed either in the field or in a laboratory. Do not perform the test
when the wind speed is more than 10 m/s or when there is a risk of
thunderstorm in the area.
NOTE Disable heating before performing the verifier test. You can do this either
by disconnecting the heater supply voltage or by setting the heaterOn
parameter to 0.