Grundfos Control MPC-Serie Installationsanleitung Seite 31

8.7.2 PI controller (4.1.1)
Fig. 37 PI controller
Description
The system includes a standard PI controller which ensures that
the pressure is stable and corresponds to the setpoint.
You can adjust the PI controller if a faster or slower reaction to
changes of consumption is required.
To obtain a faster reaction, increase Kp and reduce Ti.
To obtain a slower reaction, reduce Kp and increase Ti.
Setting range
• "Gain Kp": -30 to 30.Note: For inverse control, set Kp to a
negative value.
• "Integral time Ti": 0.1 to 3600 seconds.
Setting via the operating panel
• Settings
• Primary controller
• PI controller.
1. Set "Gain Kp" and "Integral time Ti".Note: Usually it is not
necessary to adjust Kp.
Factory setting
The setting of Kp and Ti depends on the system and application.
PI controller settings for pressure boosting
If the application has been set to pressure boosting in the startup
wizard, the following values of Kp and Ti are set automatically:
• Kp: 0.5
• Ti: 1 second.
PI controller settings for heating and cooling
If another application than pressure boosting has been selected
in the startup wizard, the values of Kp and Ti are set automatically
according to the table below. As the system does not know the
pipe length, the default parameters are set according to the table
to a pipe length (L1 or L2) of 5 metres.
System/application
Heating
system
L [m]
1
Q
0.5
t
L [m]
L [m]
L [m]
0.5
t
1)
Heating systems are systems in which an increase in pump
performance will result in a temperature rise at the sensor.
2)
Cooling systems are systems in which an increase in pump
performance will result in a temperature drop at the sensor.
L1: Distance [m] between pump and sensor.
L2: Distance [m] between heat exchanger and sensor.
ΔP:
Measurement of differential pressure.
Q: Measurement of flow rate.
t: Measurement of temperature.
Δ
t:
Measurement of differential temperature.
Kp
Ti
Cooling
[seconds]
1) 2)
system
0.5 1
L1 < 5 m: 1
0.5 L1 > 5 m: 3
L1 > 10 m: 5
0.5 1
-0.5 10 + 5L2
0.5 10 + 5L2
-0.5 30 + 5L2
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