NovaLynx Corporation________________________________________________________________________________
200-WS-04
Page 9
April 2021
10
FUNCTIONAL TESTS
The following checks can be done with an ohm-meter after the sensor has been dis-mounted from the
weather station mast or tower. These tests can help determine whether the sensor needs repair or
adjustment. Wind vane calibration involves checking the potentiometer output and verification of the
sensor alignment to north.
Set the ohm-meter to the 20k range (or greater range if needed). Connect the black meter lead to the
black sensor wire, and the red meter lead to the red sensor wire. The reading on the meter should be a
stable output of about 20,000 ohms (+/-20%). Rotate the vane once around while watching the meter
to ensure the reading does not change.
Connect the red meter lead to the white wire. Observe that the meter reading changes as you rotate
the vane. Check the "dead band" where the meter goes to "infinite" and verify that the counterweight
is pointing the same direction as the north indicator label on the base of the sensor. Now rotate the
vane slowly clockwise and observe that the resistance changes smoothly from near zero to the
maximum just before hitting the "dead band" again as you approach north.
If the "dead band" does not align with the North label then the position of the vane can be changed to
correct the alignment:
1.
Using a 1/16" Allen wrench, loosen the potentiometer set screw located on one side of the hub
(Figure 1).
2.
Lift upwards to remove the vane assembly from the sensor. Note that the potentiometer body is
bonded to the sensor body and should not move.
3.
Using an ohmmeter to monitor the potentiometer output, turn the potentiometer shaft until the
center of the gap is located. You may wish to make a mark on the shaft aligned to the North label.
4.
Aim the counterweight in the same direction as the north label and carefully lower the hub onto
the potentiometer shaft. Tighten the set screw.
Note:
There must be a small gap between the hub
and the base, to allow the vane to turn freely.
5.
Check your work by observing the meter as you swing the vane across North.
The potentiometer test will indicate whether the sensor is working correctly. If there is no signal or the
signal is not changing then either there is a problem in the cable or inside the sensor. Minor problems
with the cable can be repaired on-site, but if the potentiometer is bad the whole assembly must be
returned for repair.