Application Example - VEGA VEGAMET 381 Ex Betriebsanleitung

6 Setup with the integrated display and adjustment unit
6.3

Application example

•
An upright cylindrical (linear) tank has a
volume of 2700 l
•
The max. filling volume is 2650 l, the min.
filling volume 50 l
•
The level sensor in the vessel is a pressure
transmitter (passive), outputting a standar-
dised 4 ... 20 mA signal
•
For further processing, an additional
4 ... 20 mA output signal is required
•
The full and empty adjustment was carried
out directly in the sensor. The following
values are outputted:
– Max. volume (display max.) 20 mA =
2650 l
– Min. volume (display min.) 4 mA = 50 l
•
Relay 1 should switch on an emptying pump
at a level of 90 % and switch off the pump at
a level of 10 %
General procedure
1. Select the following functions with the rotary
switch.
2. Push one of the two [+/-] adjustment keys,
the digital indication flashes (if the rotary
switch is set to "OPERATE", the [+/-] keys
are inoperable)
3. Adjust the requested value with the [+/-]
keys. If you hold the key pushed, the digital
indication changes the value more quickly.
4. Save your settings by pushing the [+/-] keys
simultaneously
Current output
. Set the function switch to position [8]. Select
with the [+/-] keys the measured value
output 4 ... 20 mA or 0 ... 20 mA. For this
example, choose 4 - 20.
The displayed numbers have the following
meanings:
•
0 - 20 = 0 ... 20 mA
•
4 - 20 = 4 ... 20 mA
. Save the value by pushing [+/-] simultane-
ously
VEGAMET 381 Ex requires for scaling of the
indication, the adjustment of the filling quantities
for 0 % and 100 %. The vessel must neither be
filled nor emptied.
Scaled indication at 0 %
1. Set the function switch to position [7] (dis-
play min.)
30
2. Set the value to 50 via the [+/-] keys
3. Save the value by pushing both keys simul-
taneously
Scaled indication at 100 %
1. Set the function switch to position [6] (dis-
play max.)
2. Set the value to 2650 via the [+/-] keys
3. Save the value by pushing both keys simul-
taneously
Decimal point
Since the range of the example tank is between
50 l and 2650 l, you need all 4 decimal places
for the digital indication.
1. Set the function switch to position [5] (Deci-
mal Point)
2. By pushing the [+/-] keys, you move the
decimal point
3. Save the value by pushing both keys simul-
taneously
Relay
•
Set the function switch to position [ 1 ]
(relay 1 on). For the given example, select
the value 90.0 (90.0 %) with the [ +/- ] keys.
The internal relay 1 then switches on when
this value is reached. Save the value by
pushing the two keys simultaneously.
•
Set the function switch to position [ 2]
(relay 1 off). Select the value 10.0 (10.0 %)
with the [ +/-] keys. The internal relay 1 then
switches off when the value falls below this
value. The respective relay control lamp
lights when the relay is energized. If the
switching points are too close together
(< 0.1 %), the appropriate LED flashes. The
relay takes on the safe condition. In mode
"OPERATE " an error message is outputted
on the display.
•
If you want to control additional relays, pro-
ceed in the same way, as with relay 1. The
switch positions for setting the respective
relays are stated in the list of the function
switch under "Setup procedure".
Note:
If you want to change the mode (i.e. the
switching function of the relays), you
have to exchange the On and Off values.
VEGAMET 381 Ex • 4 ... 20 mA signal conditioning instrument