VEGA VEGAMET 381 Ex - Manual (Page 26)

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6 Setup with the integrated display and adjustment unit
VEGAMET 381 Ex • 4 … 20 mA signal conditioning instrument
30418-01-131025
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
•
Indication of the firmware version
•
The output signal jumps briefly to the set
fault 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
•
1: Relay 1 switching point ON
•
2: Relay 1 switching point OFF
•
3: Relay 2 switching point ON
•
2: Relay 2 switching point OFF
•
5: Decimal point position of the scaling
•
6: Scaling for 100 %
•
7: Scaling for 0 %
•
8: Switch over current output 0/4 … 20 mA
•
9: Damping of the measured value (integra-
tion time)
•
A: Offset correction
•
B: Min. adjustment in percent through
change of the level
•
C: Max. adjustment in percent through
change of the level
•
D: Min. adjustment in mA without changing
the level
•
E: Max. adjustment in mA without changing
the level
•
F: No function
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 (unpres-
surised) condition. The complete measuring
range will be shifted by the deviating amount.
1. Make sure that the pressure transmitter
is completely unpressurised, uncovered
(unimmersed) and mounted in its final posi-
tion.
2. 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
corresponding to the levels 0 % and 100 %.
When using a pressure transmitter, an offset
correction should be carried out to reach maxi-
mum accuracy. Carry out this offset correction
before adjustment and with the sensor unco-
vered (unimmersed).
→
Now select the 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 cur-
rent 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.
→
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 inVEGA-
MET 381 Ex for level detection. First of all,
determine at which switching points the relays