1 product description, 1 function and configuration, 2 application features – VEGA VEGAWELL 71 User Manual
Page 3: 3 types and versions
VEGAWELL 71
3
Product description
1 Product description
1.1 Function and configuration
The pressure transmitter is used for continu-
ous level measurement of water or waste
water with low solid contents.
The hydrostatic pressure of the product
effects a capacitance change on the abso-
lutely dry ceramic diaphragm of the measur-
ing cell. The integral processing electronics
converts the capacitance changes on the
ceramic diaphragm into a pressure propor-
tional current of 4 … 20 mA um.
Principle: Plate capacitor
The dry, ceramic-capacitive CERTEC
®
-meas-
uring cell is manufactured of a new devel-
oped high resistance ceramic. A ceramic
diaphragm is fastened on to a ceramic basic
body by means of glass joint. Ceramic basic
body and diaphragm form the plates of a
capacitor.
The plate distance between the ceramic
body and the diaphragm is only 16 µm. The
diaphragm moves in this small range and
effects capacitance changes via the "variable
plate distance“ which are provided as meas-
uring signal.
Up to 150-times overload resistant
In case of overload, the 16 µm wide gap
between ceramic basic body and the dia-
phragm is completely overcome. The dia-
phragm fits flush to the ceramic basic body
which absorbs the overpressure forces. The
overload therefore does not cause any fur-
ther "bending“ of the diaphragm and the
overpressure forces are absorbed up to the
stated limits without problems.
1.2 Application features
• Diameter of the transmitter 32 mm
• Absolutely dry
• Up to 150-times overload resistant
• Extreme long term stability
• High resistance, rugged up to 2,2 mm
thick ceramic
• Integral overvoltage protection
• Optionally Ex-approved Zone 1
(II 2G EEx ia IIC T4)
1.3 Types and versions
VEGAWELL 71 consists of:
- Fix mounted special cable with breather
capillaries
- Pressure transmitter with 4 … 20 mA-out-
put signal and integral overvoltage protec-
tion
- Optional straining clamp or closing screw
A measuring system consists of:
- a pressure transmitter and a voltage sup-
ply (supply voltage 12 … 36 V DC) or
- a pressure transmitter and a VEGA-signal
conditioning instrument.