37
10 Applications and functions
VEGAMET 841 • 4 … 20 mA
58864-EN-200401
•
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 elapsed 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.
For relay 1 and 2, the mode of operation "
Pump control 2
" is adjusted
with the option "
Sequenced operation
". The relay switching points are
configured 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. 16: Example of pump control 2
Pump control 2/4 with dry weather pump is used to protect e.g.
rain retention basins with different sized pumps against overfilling.
Normally (in fair weather), a pump with low capacity (dry weather
pump) is sufficient to maintain the level in the retention basin at a
safe level (Hi-Level). If heavy rainfall causes an increased inflow, the
fair weather pump can no longer maintain the level. In such cases, a
larger pump is switched on when the HiHi level is exceeded and the
dry weather pump is switched off. The large pump then remains in
operation until the switch-off point is reached. If the level rises again,
the dry weather pump switches back on first.
There is also the possibility of using multiple large pumps in alternat-
ing mode. The algorithm for the switching function is then determined
by the pump control mode.
Example
Option Dry weather pump
