Product Description; Function And Configuration; Plate Capacitor; Capacitance Change With Covered Electrode - Vega EL 11 Operating Instructions Manual

1 Product description

1.1 Function and configuration

Capacitive electrodes series EL detect levels of
virtually any medium unaffected whether
liquids, powders or pastes. This is also valid for
adhesive products.
The electrode measures also the level
capacitance and the ohmic resistance
(admittance processing). Hence also
problematic medium and solids with fluctuating
humidity contents can be detected.
By the use of screening tubes and screen
segments, inactive areas can be provided on
the probe where pollution, condensation or
permanent build-up do not influence the
measuring result.
Measuring principle
Electrode, medium and vessel wall form an
electrical capacitor.
The capacitance of the capacitor is mainly
influenced by three factors:
- distance of the electrode plates (a)
- size of the electrode plates (b)
- kind of dielectricum between the electrodes
(c)
c
Fig. 1.1 Plate capacitor (schematic
demonstration)
4
Electrode and vessel wall are the capacitor
plates. The medium is the dielectricum. Due to
the higher dielectric constant figure (DK-value)
of the medium against air, the capacitance of
the capacitor increases with raising covering of
the electrode.
Fig. 1.2 Capacitance change with covered
electrode
The capacitance change is processed by the
oscillator and converted into a level proportio-
nal measured value. The measured value is
provided analogue as standardized, floating
4 ... 20 mA-current signal, optionally also
digitally with the HART
protocol.
The sensor can be adjusted via the integral
oscillator. Optionally the adjustment with
HART
software is also possible.
With the continuous level measurement the
appropriate level is continuously detected and
converted into a level proportional signal which
b
is either directly displayed or further processed.
You require a capacitive electrode series EL
with oscillator CAP E32 Ex or CAP E32 H Ex.
The continuous measurement assumes a
constant dielectric constant figure ε
medium should have steady features.
®
-communication
® -handheld or PC with VVO-adjustment
Capacitive electrodes EL 4 ... 20 mA - compact
Product description
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