Grundfos MAGNA3 25-80 Installation And Operating Instructions Manual page 41

8.7.4 "Controller settings"
Not available for MAGNA3 model A.
Navigation
"Home" > "Settings" > "Controller settings"
This menu offers the following options:
• Controller gain Kp
• Control. integr. action time Ti
• Temperature sensor offset (available for pumps with
production code from 1838).
Setting
1. Select "Controller settings" with
2. Choose either "Controller gain Kp", "Control. integr. action
time Ti" or "Temperature sensor offset" with
[OK].
3. Press [OK] to start the setting.
4. Select digit with and and adjust with
5. Press [OK] to save.
A change of the gain and integral-time values affects all control
modes. If you change the control mode to another control mode,
change the gain and integral-time values to the factory settings.
Factory settings for all other control modes:
The gain, K , is equal to 1.
p
The integral time, T , is equal to 8.
i
The table below shows the suggested controller settings:
If you use a built-in temperature sensor as one of the sensors,
you must install the pump as close as possible to the consumer.
System/
Heating
application
system
0.5
t
L2 [m]
3)
Δt
L2 [m]
L2 [m]
0.5
t
1)
In heating systems, an increase in pump performance results
in a rise in temperature at the sensor.
2)
In cooling systems, an increase in pump performance results
in a drop in temperature at the sensor.
3)
Built-in temperature sensor.
L1: Distance in metres between pump and consumer.
L2: Distance in metres between consumer and sensor.
or and press [OK].
or . Press
or .
K
p
T
Cooling
i
1) 2)
system
10 + 5
- 0.5
(L + L )
1 2
10 + 5
- 0.5
(L + L )
1 2
- 0.5 30 + 5L
2
Guidelines for setting of PI controller
For most applications, the factory setting of the controller
constants, gain and integral time, ensures optimum pump
operation. However, in some applications an adjustment of the
controller may be required.
You find the setpoint displayed in figs
Fig. 59 "Controller gain Kp"
Fig. 60 "Control. integr. action time Ti"
Proceed as follows:
1. Increase the gain until the motor becomes unstable. Instability
can be seen by observing if the measured value starts to
fluctuate. Furthermore, instability is audible as the motor
starts hunting up and down.
Some systems, such as temperature controls, are
slow-reacting, meaning that it may be several minutes before
the motor becomes unstable.
2. Set the gain to half the value of the value which made the
motor unstable.
3. Reduce the integral time until the motor becomes unstable.
4. Set the integral time to twice the value which made the motor
unstable.
Rules of thumb
If the controller is too slow-reacting, increase the gain.
If the controller is hunting or unstable, dampen the system by
reducing the gain or increasing the integral time.
Model A:
Use Grundfos GO to change the controller constants, gain and
integral time. You can only set positive values.
Models B, C and D:
Change the control settings by means of the display or Grundfos
GO. You can set both positive and negative values.
59 and 60.
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