Principle Of Operation - Vega VEGAFLEX 86 Operating Instructions Manual

Application area
Functional principle -
level measurement
Functional principle - in-
terface measurement
VEGAFLEX 86 • Two-wire 4 ... 20 mA/HART
3.2

Principle of operation

The VEGAFLEX 86 is a level sensor with coax probe for continuous
level or interface measurement, suitable for applications in liquids
with high temperatures up to 450 °C (842 °F).
High frequency microwave pulses are guided along a steel cable or
a rod. Upon reaching the medium surface, the microwave pulses are
reflected. The running time is evaluated by the instrument and output
as level.
h
Fig. 2: Level measurement
1 Sensor reference plane (seal surface of the process fitting)
d Distance to the level
h Height - Level
High frequency microwave impulses are guided along a steel cable or
rod. Upon reaching the medium surface, a part of the microwave im-
pulses is reflected. The other part passes through the upper product
and is reflected by the interface. The running times to the two product
layers are processed by the instrument.
3 Product description
1
d
9