
18 CONTENTS
1.2.4 Precipitaion
Lambrecht 15152
User Information
In order to provide a detection of all kinds of precipitation the precipitation
instrumentation is enlarged by the Lambrecht 15152. At the beginning of a
precipitation event rain drops will cause a conductive connection between the
two sensing electrodes to trigger the relay contacts. By this means a relay is
cut through and the controlling event is done.
Figure 1.12: Lambrecht Precipitation Sensor 15152
The sensor surface is heated in two levels. The first level is switched on con-
stantly to prevent ice and dew formation. As soon as the sensing area is
moistured, the second heating level is switched on to make sure that the sur-
face drys up as soon as possible. After drying up, the second level is switched
off again.
Maintenance
According to the atmospheric pollution a layer of dirt can form on the sensors
surface. This dirt has an isolating effect and may lead to short-circuits. So the
sensor is not able to set off an accurate signal by falling rain. Therefore the
sensor surface has to be cleaned with a light cleaner on every maintenance visit.
NOTE: Take care not to damage the sensing electrodes by using the wrong
cleaner!
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