VEGA VEGAMET 625 - Manual (Page 44)

44
8 Application examples
VEGAMET 625 • Double channel HART
28970-EN-130701
is reached and the relay with the longest operating time when the
switch-off point is reached.
With this pump control, there are two different versions:
•
Pump control 1: The upper switching point determines the switch-
off point for the relay, whereas the lower switching point deter-
mines the switch-on point
•
Pump control 2: The upper switching point determines the switch-
on point for the relay, whereas the lower switching point deter-
mines the switch-off point
Two pumps should empty the vessel when a certain level is reached.
At 80 % filling, the pump with the shortest running time should switch
on. If the level nevertheless increases, a second pump should switch
on at 90 %. Both pumps should switch off again at 10 % filling.
Select in the DTM navigation section the menu items "Meas. loop -
Outputs - Relay".
•
Set mode "Pump control 2" for relay 1 and 2.
•
Enter the switching points for the affected relays as follows:
– Relay 1 upper switching point = 80.0 %
– Relay 1 lower switching point = 10.0 %
– Relay 2 upper switching point = 90.0 %
– Relay 2 lower switching point = 10.0 %
The function of pump control 2 is shown in detail in the following dia-
gram. The previously described example is used as a basis.
Rel. 1: 80% On
On
Off
Off
On
Rel. 2: 90% On
Rel. 1, 2: 10% Off
10 30 20 20 15
t [h]
5
Rel. 1
Rel. 2
Fig. 14: Example of pump control 2
Switch on reaction of the pump control 2
When the signal conditioning instrument is switched on, the relays are
at first in a switched-off status. Depending on the input signal and the
switched-on period of the individual relays, the following relay switch-
ing conditions can occur after the start procedure:
•
Input signal is higher than the upper switching point -> Relay with
the shortest switch on period is switched on
Example
Setup