Figure 9 Recommended Location Of Pwd22. Alternative Ways To Mount The Sensor (A Or B) - Vaisala PWD22 User Manual

User's Guide _______________________________________________________________________
38____________________________________________________________________ M210543EN-B
Figure 9 Recommended Location of PWD22. Alternative
Ways to Mount the Sensor (A or B).
- The receiver and transmitter optics should not point towards
powerful light sources. It is recommended that the receiver
will point north in the northern hemisphere, and south in the
southern hemisphere. The receiver circuit may become
saturated in bright light, in which case the built-in diagnostics
will indicate a warning. Bright daylight will also increase the
noise level in the receiver.
- The transmitter and receiver should face away from any
obvious source of contamination such as spray from passing
vehicles. Dirty lenses will cause the sensor to report too high
visibility values. Excessive contamination is automatically
detected by the sensor.
- In the road environment the receiver should face away from
passing vehicles. The preferred orientation is along the road.
A receiver pointing towards driving direction of the closest
lane. The possible reflections from the passing cars might
generate false snow detections in the winter time.
3. Power supply and communication lines must be available.
- When siting PWD22, consideration must be given to the
available power supply and communication lines, as this
influences the amount of work and accessories needed, and
hence the actual cost of installation.
Although PWD22 is designed to withstand harsh weather conditions,
there are locations where the environment places further demands for
installation. For harsh wintry conditions, optional hood heaters are
available to prevent ice and snow accumulation.
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