Demands On The Control System Of A Rainwater Pump; Previous Solution; Rainwater Pump - Siemens LOGO! 24RC Manual

Applications
8.7.1 Demands on the Control System of a

Rainwater Pump

The system must be capable of supplying water at all
times. If necessary, the control system must switch over
to mains water if the rainwater runs out.
The system must not allow rainwater to enter the mains
supply when switching over to mains water.
The pump cannot be switched on if there is not enough
water in the rainwater butt (run-dry prevention system).

8.7.2 Previous Solution

Auxiliary circuit
L1
K3
S1
K2
K1
N
Pump
The pump and a solenoid valve are controlled by means of
a pressure switch and 3 float switches that are fitted in the
rainwater butt. The pump must be switched on when the
pressure in the cylinder falls below the minimum level.
Once the operating pressure has been reached, the pump
is switched off again following a short overrun period of a
few seconds. The overrun time prevents the water pump
continuously cutting in and out if water is drawn off for any
length of time.
182
S3
p<
S4 K3
K2 K3
Overrun time Run-dry
protection
S2
S3 K4
K4 Y1
Pure water
inlet
LOGO! Manual
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