VEGA VEGACAP 27 - Relay (DPDT) - Manual (Page 8)

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3 Product description
VEGACAP 27 • - Relay (DPDT)
33758-EN-130916
3.2 Principle of operation
VEGACAP 27 is a point level sensor with fully insulated, capacitive
electrode with screen segment and active tip for level detection.
VEGACAP 27 is very rugged and maintenance-free and can be used
in all areas of industrial process technology.
Typical applications are overfill and dry run protection.
Setup of the instrument is very easy because an adjustment is not
necessary. This means that changing products with different dielectric
values, such as e.g. water and oil or conductive and non-conductive
products, do not influence the settings on the instrument and their
switching accuracy.
Fully insulated probes with screen segment like VEGACAP 27 are
preferably used in conductive, very adhesive liquids.
Due to the mechanical constructions of the screen segment and the
active tip, buildup on the probe can be compensated.
The capacitive measuring principle places no special requirements
on installation. Hence, many different applications can be equipped
with VEGACAP 27.
The instrument can also be used problem-free in corrosive products.
Probe, measured product and vessel wall form an electrical capacitor.
The capacitance is influenced by three main factors.
1
2
3
Fig. 2: Functional principle - Plate capacitor
1 Distance between the electrode surfaces
2 Size of the electrode surfaces
3 Type of dielectric between the electrodes
The probe and the vessel wall are the capacitor plates. The measured
product is the dielectric. Due to the higher dielectric constant of the
product compared to air, the capacitance increases as the probe is
gradually covered.
The capacitance change is converted by the electronics module into
a switching command.
VEGACAP 27 is a compact instrument, i.e. it can be operated without
external evaluation system. The integrated electronics evaluates the
level signal and outputs a switching signal. With this switching signal,
Area of application
Functional principle
Voltage supply