Vega VEGAMET 861 - Page 46

46
11 Applications and functions
VEGAMET 861 • 4 … 20 mA/HART
58866-EN-200401
Rel. 1: 60% On
Rel. 1..3: 10% Off
Rel. 2: 75% On
Rel. 3: 90% On
t(h)
Rel. 3
Rel. no.
Rel. 2
12 3123 12 31 2
Rel. 1
Fig. 20: Example of pump control 4
Pump control 2/4 with dry weather pump is used to protect e.g.
rainretentionbasinswithdierentsizedpumpsagainstoverlling.
Normally (in fair weather), a pump with low capacity (dry weather
pump)issucienttomaintainthelevelintheretentionbasinata
safelevel(Hi-Level).Ifheavyrainfallcausesanincreasedinow,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o.Thelargepumpthenremainsin
operationuntiltheswitch-opointisreached.Ifthelevelrisesagain,
thedryweatherpumpswitchesbackonrst.
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.
Fig. 21: Example of a pump control with option "Dry weather pump"
Note:
If the option "Dry weather pump" is activated, only the mode "Alternat-
ing pump operation" will be available, i.e. only one pump at a time is
in operation.
Option Dry weather pump