With this pump control, there are two different versions:
l Pump control 1: The upper switching point determines the switch-
off point for the relay, whereas the lower switching point
determines the switch-on point
l Pump control 2: The upper switching point determines the switch-
on point for the relay, whereas the lower switching point
determines 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".
l Set mode "Pump control 2" for relay 1 and 2.
l Enter the switching points for the concerned 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
diagram. The previously described example is used as a basis.
Fig. 11: Example of a pump control 2
Switch on reaction of the pump control 2
After the signal conditioning instrument is switched on, the relays are
still in switched-off condition. Depending on the input signal and the
switch-on period of the individual relays, the following relay switching
conditions can occur after the start procedure:
l Input signal is higher than the upper switching point -> Relay with
the shortest switch on period is switched on
Example
Setup
38 VEGAMET 624 • 4 … 20 mA/HART signal conditioning instrument
8 Application examples
28969-EN-091116
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