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:
• 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
The actual setpoint is the actual input signal as a percentage
multiplied by the minimum sensor value subtracted from the
setpoint, plus the minimum sensor value.
For instance, at a minimum sensor value of 0 psi (0 bar), a
setpoint of 29 psi (2 bar) and an external setpoint of 60 %, the
actual setpoint is:
0.6 x (29 - 0) + 0 = 17.4 psi (1.2 bar)
See fig. 44.
[bar]
Sensor max.
Setpoint
2 100
Actual setpoint
1.2
Sensor min.
0 0
0
0.5
0
0
0
4
-50
Fig. 44 Example of setpoint influence with sensor feedback
Example with constant curve with linear influence
The actual setpoint (in percentage) is the actual input signal as a
percentage multiplied by the user-set minimum speed subtracted
from the setpoint, plus the user-set minimum speed.
For instance, at a user-set minimum speed of 25 %, a setpoint of
85 %, and an external setpoint of 60 %, the actual setpoint is:
0.60 x (85 - 25) + 25 = 61 %
See fig. 45.
Speed [%]
100
Setpoint
85
Actual setpoint
61
User-set min.
25
speed
0
0
0.5
0
0
0
4
-50
Fig. 45 Example of setpoint influence with constant curve
and
Actual External
100 %
3.5 V
input setpoint
5 V
signal 10 V signal
20 mA
(60 %)
20 mA
204 C
Fixed maximum
speed
Actual External
100 %
3.5 V
setpoint
input
5 V
10 V
signal signal
20 mA
(60 %) 20 mA
204 C
13.7.1 "Setpoint influence" functions
You can select the following functions:
• "Not active"
When set to "Not active", the setpoint is not influenced by any
external function.
• "Linear function"
The setpoint is influenced linearly from 0 to 100 %. See fig. 46.
Setpoint influence [%]
100
0
0
0.5
0
0
0
4
-50
Fig. 46 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 increases
above 15 %, the operating mode is changed back to "Normal".
See fig. 47.
Setpoint influence [%]
100
0
0 20
0.5
0
0
0
4
-50
Normal
Stop
Fig. 47 "Linear with Stop"
• "Influence table".
The setpoint is influenced by a curve made out of 2 to 8 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. 48 Influence table (example with five points)
External input
100 %
3.5 V
5 V
10 V
20 mA
20 mA
204 C
External input
100 %
3.5 V
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
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