7
UK
-Media which are very inhomogeneous, separate from each other thus forming
separation layers (e�g� oil layer on water)�
► Check the function by an application test�
> In case of signal loss, the unit displays [E�033] and switches the outputs to a
defined state (→ 11.5).
• The unit is not suitable for applications where the probe is subjected to per-
manent and high mechanical stress (e�g� strongly moving viscous media or
strongly flowing media)�
• Use preferably in metal tanks� When installed in plastic tanks, deteriora-
tion caused by electromagnetic interference may occur (noise immunity to
EN61000-6-2). Remedy: → 6.4.2.
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 us-
ing 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 pulse
directly relates to the travelled distance (D) and the current level� The reference for
distance measurement is the lower edge of the process connection�
