VEGA VEGAMET 381 Betriebsanleitung Seite 28

Setup with the integrated indicating and adjustment unit
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
corresponding 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
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 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.
à
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 for level detection. First of all,
determine at which switching points the relays
should switch on and off again. Furthermore you
have to distinguish between the relay modes
overfill and dry run protection. You switch over by
exchanging the ON/OFF values of the relay.
Overflow protection: Relay is switched off
l
when the max. level is exceeded (safe
currentless condition), relay is switched on
again when the level falls below the min. level
(switch on point < switch off point)
28
Dry run protection: Relay is switched off
l
when the level falls below the min. level (safe
currentless condition), relay is switched on
again when the max. level is exceeded (switch
on point > switch off point)
à
To adjust the on and off switching points of
relay 1, set the function switch to position [1] or
[2], enter the switching points for ON or OFF
and save your settings. If necessary, proceed
in the same way with relay 2 (position [3] or
[4]).
1
o n
2
o f f
o n
3
o f f
Fig. 14: Relay modes
Filling height
1
Mode overfill protection
2
Mode dry run protection
3
Scaling
Scaling means converting the measured value into
a certain parameter and unit. The indication can
then show the volume in litres e.g., instead of the
percentage value. Indication values from -9999 to
+9999 are possible.
à
First of all, determine the max. indicating range
and the number of decimal places after the
decimal point -- max. four decimal places can
be displayed. Select position [ 5 ] of the
function switch, place the decimal point in the
required position and save your settings.
à
Now select position [6] or [7] on the function
switch, enter the requested values for 100 % or
0 % and save your settings.
off (on)
on (off)
t
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VEGAMET 381