Operating instructions

44
8 Application examples
VEGAMET 625 • Double channel HART
28970-EN-150129
switchingpoints.Withthismeasure,asteadyutilizationofthepumps
is achieved and the reliability increased.
All relays with activated pump control are not assigned to a certain
switchingpointbutareswitchedonorodependingontheaccu-
mulated operating time. The signal conditioning instrument selects
the relay with the shortest operating time when the switch-on point
is reached and the relay with the longest operating time when the
switch-opointisreached.
Withthispumpcontrol,therearetwodierentversions:
•
Pump control 1: The upper switching point determines the switch-
o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-opoint
Two pumps should empty the vessel when a certain level is reached.
At80%lling,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oagainat10%lling.
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aected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
Example
Setup