External Setpoint Function - Grundfos Hydro Multi-E Series Installation And Operating Instructions Manual

13.7 External setpoint function

You can influence the setpoint with an external signal via
• one of the analog inputs
• one of the Pt100/1000 inputs if an advanced functional module
(FM 300) is fitted,
Before you can enable the function, you must set one
of the analog inputs or Pt100/1000 inputs to "External
setpoint function".
See sections 13.1 Analog inputs
13.2 Pt100/1000 inputs.
Example with constant pressure with linear influence
Actual setpoint: actual input signal x (setpoint - sensor min.) +
sensor min.
At a sensor min. of 0 bar, a setpoint of 2 bar and an external
setpoint of 60 %, the actual setpoint is 0.60 x (2 - 0) + 0 = 1.2 bar.
See fig. 50.
[bar]
Sensor
max.
Setpoint
2 100
Actual
1.2
setpoint
Sensor min.
0 0
0
0.5
0
0
0
4
-50
Fig. 50 Example of setpoint influence with sensor feedback
Example with constant curve with linear influence
Actual setpoint: actual input signal x (setpoint - user-set minimum
speed) + user-set minimum speed.
At a user-set minimum speed of 25 %, and a setpoint of 85 % and
an external setpoint of 60 %, the actual setpoint is 0.60 x (85 - 25)
+ 25 = 61 %. See fig. 51.
Speed [%]
100
Setpoint
85
Actual
61
setpoint
User-set min.
25
speed
0
Actual
0
0.5
0
0
signal
0
4
(60 %)
-50
Fig. 51 Example of setpoint influence with constant curve
and
Actual External
100 %
3.5 V
input setpoint
5 V
10 V
signal signal
20 mA
20 mA
(60 %)
204 C
Fixed maximum
speed
External
100 %
3.5 V
input setpoint
5 V
10 V
signal
20 mA
20 mA
204 C
13.7.1 "Setpoint influence" functions
You can select these functions:
• "Not active".
When set to "Not active", the setpoint is not influenced from
any external function.
• "Linear function".
The setpoint is influenced linearly from 0 to 100 %. See fig. 52.
Setpoint influence [%]
100
0
0
0.5
0
0
0
4
-50
Fig. 52 Linear function
• "Linear with Stop"
In the input signal range from 20 to 100 %, the setpoint is
influenced linearly.
If the input signal is below 10 %, the pump changes to
operating mode "Stop".
If the input signal is increased above 15 %, the operating
mode is changed back to "Normal". See fig. 53.
Setpoint influence [%]
100
0
0 20
0.5
0
0
0
4
-50
Normal
Stop
Fig. 53 Linear with Stop
• "Influence table".
The setpoint is influenced by a curve made out of two to eight
points. There is a straight line between the points and a
horizontal line before the first point and after the last point.
Setpoint influence [%]
100
0
0
0.5
0
0
0
4
-50
Fig. 54 Influence table (example with five points)
Factory setting
See section 29. Factory settings.
External
100 %
3.5 V
input
5 V
10 V
20 mA
20 mA
204 C
External
100 %
3.5 V
input
5 V
10 V
20 mA
20 mA
204 C
External
100 %
input
3.5 V
5 V
10 V
20 mA
20 mA
204 C
29