Endress+Hauser Prosonic S FMU90 - Operating Mode; Non-Alternating Pump Control; Alternating Pump Control

The "relays/controls" menu
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L00-FMU90xxx-19-00-00-yy-052
A: switch-on point; B: switch-off point; C: pump on; D: pump off
Operating mode
The Prosonic S can control several pumps simultaneously - depending on the number of relays (s.
feature 70 of the product structure). If two or more pumps are applied for one level channel, you
can choose between two different operating modes:
a. Non-alternating pump control
In this mode, each pump is switched according to the switching points allocated to it.
b. Alternating pump control
In this mode, the switching points are not allocated to the individual pumps. Instead, the relays
are switched in a way that ensures uniform usage of all pumps. This is achieved by the
following rules:
1. If the level rises above one of the switch-on points, that relay switches on, which at that
moment has been switched off the longest time. This is not necessarily the relay to which
the switch-on point belongs.
2. If the level drops below one of the switch-off points, that relay switches off, which at that
moment has been switched on the longest time. This is not necessarily the relay to which
the switch-off point belongs.
However, there are two restrictions to these rules:
3. Rising of the level above a switch-on point effects switching on of a relay only if the
corresponding switch-off point has been reached before.
4. Dropping of the level below a switch-off points effects switching-off of a relay only if the
corresponding switch-on point has been reached before.
!
Note!
If two pumps in the same range are to operate alternately, their switch-on and switch-off points
are identical. This switching response can be achieved by assigning switch points to the second
relay which can never be reached.
Example
In the switching range between 60% and 40%, two pumps should be operated alternately, i.e.
when pump 1 in running, pump 2 is switched off and vice versa. These relays are programmed
as follows:
– Relay 1: switch-on point: 60%; switch-off point: 40%
– Relay 2: switch-on point: e.g. 160%; switch-off point: e.g. 120%.
L
A
B
t
t
C
D