Vaisala WXT520 Guia do Utilizador descarregar pdf (Página 43)

Chapter 4 _______________________________________________________________ Installation

VAISALA_______________________________________________________________________ 41

Aligning WXT520

To help the alignment, there is an arrow and the text "North" on the

bottom of the transmitter. WXT520 should be aligned in such a way that

this arrow points to the north.

Wind direction can be referred either to true north, which uses the

earth’s geographic meridians, or to the magnetic north, which is read

with a magnetic compass. The magnetic declination is the difference in

degrees between the true north and magnetic north. The source for the

magnetic declination should be current as the declination changes over

time.

0003-011

Figure 18 Sketch of Magnetic Declination

Compass Alignment

To align the WXT520, proceed as follows:

1. If WXT520 is already mounted, loosen the fixing screw on the

bottom of the transmitter so that you can rotate the device.

2. Use a compass to determine that the transducer heads of WXT520

are exactly in line with the compass and that the arrow on the

bottom of WXT520 points to the north.

3. Tighten the fixing screw on the bottom of the transmitter when the

bottom arrow is exactly aligned to north.

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Vaisala WXT520 Guia do Utilizador Página 43