User's Guide _______________________________________________________________________
14____________________________________________________________________ M210543EN-B
measurements. These three independent measurements together
provide sufficiently data for an accurate evaluation of prevailing
visibility and weather type.
Hardware Structure
PWD22 is a self-contained instrument that can be fastened to the side
of the mast and into a crossarm using the mounting clamps.
0308-002
Figure 1
PWD22 Present Weather Detector
The following numbers refer to Figure 1 above.
1
=
Transmitter
2
=
Controller/Receiver
3
=
PWR211 Vaisala RAINCAP
®
Rain Sensor
(PWR111 in PWD22M)
4
=
Pt100 temperature sensor in the tube
5
=
Mounting clamp
6
=
Hood heaters (optional)
7
=
Place for Vaisala Luminance Sensor PWL111 (optional)
Sensing Element in PWD22
PWT11 Transmitter
PWT11 Transmitter emits pulses of near infrared light. It is
permanently tilted 20
°
downwards. The optical power is stabilized by
a closed hardware loop. The unit also includes a receiver circuit for
lens contamination monitoring.