Function And System Design; Measuring Principle - Endress+Hauser Levelflex FMP55 Technical Information

Measuring principle

8

Function and system design

Basic principles
The Levelflex is a "downward-looking" measuring system that functions according to the ToF method
(ToF = Time of Flight). The distance from the reference point to the product surface is measured.
High-frequency pulses are injected to a probe and led along the probe. The pulses are reflected by
the product surface, received by the electronic evaluation unit and converted into level information.
This method is also known as TDR (Time Domain Reflectometry).
For interface applications this method is combined with a capacitive measurement.
R
D
L
D
I
UP
LN
L
L
L
I
 1 Parameters for level and interface measurement with the guided radar
R Reference point of measurement
E Empty calibration (= zero)
F Full calibration (= span)
LN Probe length
UP Thickness upper medium
DL Distance level complete
LL Level complete
DI Distance interface (distance flange / DC
LI Level interface (distance probe end / DC
DC1 Dielectric constant of the upper medium
DC2 Dielectric constant of the lower medium
100%
DK ( DC )
1 1
DK (DC )
2 2
0%
)
2
)
1
Levelflex FMP55
E
F
A0011177
Endress+Hauser