7
• The unit is not suitable for media with a dielectric constant < 20 (e�g� oils, fats,
plastic granulates, bulk material)�
• If the unit is to be used in acids or alkalis, in hygienic areas or in electroplating
applications: first check the compatibility of the product materials
(→ 12
Technical data and scale drawing) with the media to be monitored�
• The unit is not suitable for applications where the probe is subjected to
permanent and high mechanical stress (e�g� strongly moving viscous media or
strongly flowing media)�
• Use preferably in metal tanks� When installed in plastic tanks, deterioration
caused by electromagnetic interference may occur (noise immunity to
EN61000-6-2)� Corrective measures:
→ 6.4.2
• When operating with a single probe and small tanks (probe lengths shorter
than 200 mm and less than 300 mm distance to the tank wall), interference
from the tank (resonances) may occur in rare cases�
Corrective measures:
(→ 6.1)
5 Function
5.1 Measuring principle
Fig. 5-1
Fig. 5-2
D
The unit operates to the principle of guided wave radar� It measures the level
using electromagnetic pulses in the nanosecond range�
The pulses are transmitted by the sensor head and guided along the rod
(fig� 5-1)� When they hit the medium to be detected they are reflected and guided
back to the sensor (fig� 5-2)� The time between transmitting and receiving the