VEGA WELL71 User Manual
Operating Instructions
VEGAWELL 71
Level and Pressure
p
Contents
Safety information ........................................................................ 2
Note Ex area ................................................................................ 2
1 Product description
1.1 Function and configuration .................................................. 3
1.2 Application features ............................................................. 3
1.3 Types and versions ............................................................. 3
2 Technical data
2.1 Data ....................................................................................... 4
2.2 Dimensions ........................................................................... 6
3 Mounting
3.1 Installation place ................................................................... 7
3.2 Mounting of the external connection housing .................... 7
3.3 Compensation of the atmospheric pressure ..................... 7
4 Electrical connection ................................................................ 8
Contents
5 Set-up .......................................................................................... 9
Safety information
Please read this manual carefully, and also take
note of country-specific installation standards
(e.g. the VDE regulations in Germany) as well
as all prevailing safety regulations and accident prevention rules.
For safety and warranty reasons, any internal
work on the instruments, apart from that involved in normal installation and electrical connection, must be carried out only by qualified
VEGA personnel.
2 VEGAWELL 71
Note Ex area
Please note the attached safety instructions
containing important information on installation
and operation in Ex areas.
These safety instructions are part of the
operating instructions and come with the Ex
approved instruments.
Product description
1 Product description
1.1 Function and configuration
The pressure transmitter is used for continuous level measurement of water or waste
water with low solid contents.
The hydrostatic pressure of the product
effects a capacitance change on the absolutely dry ceramic diaphragm of the measuring cell. The integral processing electronics
converts the capacitance changes on the
ceramic diaphragm into a pressure proportional current of 4 … 20 mA um.
Principle: Plate capacitor
The dry, ceramic-capacitive CERTEC®-measuring cell is manufactured of a new developed 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 measuring signal.
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-output signal and integral overvoltage protection
- Optional straining clamp or closing screw
A measuring system consists of:
- a pressure transmitter and a voltage supply (supply voltage 12 … 36 V DC) or
- a pressure transmitter and a VEGA-signal
conditioning instrument.
Up to 150-times overload resistant
In case of overload, the 16 µm wide gap
between ceramic basic body and the diaphragm is completely overcome. The diaphragm fits flush to the ceramic basic body
which absorbs the overpressure forces. The
overload therefore does not cause any further "bending“ of the diaphragm and the
overpressure forces are absorbed up to the
stated limits without problems.
VEGAWELL 71 3
2 Technical data
2.1 Data
Power supply
Supply voltage 12 … 36 V DC
Permissible load (dependent on the supply voltage)
Ω
900
600
300
12
18 24 30 36
Measuring ranges
Measuring range and overload in bar Measuring range Overload
0 … 0,1 15
0 … 0,2 20
0 … 0,4 30
0 … 1,0 35
0 … 2,5 50
0 … 5,0 65
0 … 10,0 90
0 … 20,0 130
Technical data
Supply voltage
in V
Output signal
4 … 20 mA-current signal; two-wire technology (supply and measuring signal via a twowire line)
Meas. accuracy (relating to the nominal measuring range)
Characteristics linear
Deviation in characteristics < 0,5 %
Long term stability of the zero signal 1)< 0,1 %/2 years
Hysteresis or repeatability < 0,02 %
Average temperature coefficient of the
zero signal
1)
Acc. to IEC 770
2)
In the compensated temperature range of 0°C … 80°C; reference temperature 20°C
4 VEGAWELL 71
2)
< 0,20 %/10 K
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