Vega VEGAMET 381 Ex Instrucción De Servicio página 25

adjustment of an integration time to smooth the
measured value or a modifcation of the current
output characteristics.
To clearly denote the measuring unit, the supplied
labels can be inserted in the cover. In case several
VEGAMET 381 Ex are used, each measurement
loop should be clearly labelled.
Switch-on phase
After being switched on, VEGAMET 381 Ex first of
all carries out a short self-check. The following
steps are carried out:
Internal check of the electronics
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Indication of the firmware version
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The output signal jumps briefly to the set fault
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value
Then the actual measured value is displayed and
the corresponding current is transmitted to the
current output.
Measured value indication
The measured value indication shows the digital
indication value and also an analogue bargraph.
Here, it is absolutely necessary that the function
switch is set to position [ 0] ("OPERATE").
Function switch
The following functions can be selected via the
rotary switch:
0: Measured value display and simulation
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1: Relay 1 switching point ON
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2: Relay 1 switching point OFF
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3: Relay 2 switching point ON
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4: Relay 2 switching point OFF
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5: Decimal point position of the scaling
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6: Scaling for 100 %
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7: Scaling for 0 %
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8: Switch over current output 0/4 ... 20 mA
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9: Damping of the measured value (integration
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time)
A: Offset correction
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B: Min. adjustment in percent by changing the
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level
C: Max. adjustment in percent by changing the
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level
D: Min. adjustment in mA without modifying the
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level
E: Max. adjustment in mA without modifying
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the level
F: No function
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VEGAMET 381 Ex
Setup with the integrated indicating and adjustment unit
Offset correction
When a pressure transmitter is used, an offset
correction should be carried out first. These
instruments are factory-set in a certain position. If
the pressure transmitter is now mounted in a
different position, its measuring range is shifted
slightly. The zero point is readjusted by carrying out
the offset correction in uncovered (unpressurised)
condition. The complete measuring range will be
shifted by the deviating amount.
à
Make sure that the pressure transmitter is
completely unpressurised, uncovered (unim-
mersed) and mounted in its final position.
à
Set the function switch to position [A ]. The
display indicates now the actual sensor current
in mA. Save the current status by pushing the
[+/- ] keys simultaneously.
Adjustment in mA without changing the level
For this adjustment procedure, two sensor current
values (4 ... 20 mA) must be entered correspond-
ing to the levels 0 % and 100 %.
When using a pressure transmitter, an offset
correction should be carried out to reach maximum
accuracy. Carry out this offset correction before
adjustment and with the sensor uncovered (unim-
mersed).
à
Select now position [D] or [E] on the function
switch, enter the current values in mA for min.
or max. adjustment and save your settings.
Adjustment in % by changing the level
During this adjustment procedure, the current level
is assigned to a certain percentage value. For this
reason, percentage values that correspond to the
actual filling levels must be entered for the min. and
max. adjustment. The ideal calibration is at 0 %
and 100 %. Because it is not always possible to
empty or fill a vessel completely, any value can of
course be entered. The greater the difference
between the two adjustment points, the more
precise the measurement. It does not matter which
value is entered first.
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Select position [B] or [C] on the function switch,
enter the percentage values for the min. and
max. adjustment and save your settings
Relay outputs
Two operating relays are integrated inVEGAMET
381 Ex for level detection. First of all, determine at
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