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22
12.6 Controller
The pumps have a factory default setting of gain (K
p
) and integral
time (T
i
).
However, if the factory setting is not the optimum setting, you can
change the gain and the integral time:
• Set the gain within the range from 0.1 to 20.
• Set the integral-action time within the range from 0.1 to 3600
seconds.
If you select 3600 seconds, the controller functions as a P
controller.
Furthermore, you can set the controller to inverse control.
This means that if you increase the setpoint, the speed is
reduced. In the case of inverse control, you must set the gain
within the range from -0.1 to -20.
Guidelines for setting of PI controller
The tables below show the recommended controller settings:
L1: distance in metres between pump and sensor.
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.
L2: distance in metres between heat exchanger and sensor.
L2: Distance [m] between heat exchanger and sensor.
General 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.
Factory setting
See section 29. Factory settings.
Constant differential
pressure
K
p
T
i
0.5 0.5
0.5
L1 < 5 m: 0.5
L1 > 5 m: 3
L1 > 10 m: 5
Constant temperature
K
p
T
i
Heating
system
1)
Cooling
system
2)
0.5 -0.5 10 + 5L2
0.5 -0.5 30 + 5L2
Constant differential
temperature
K
p
T
i
-0.5 10 + 5L2
Constant flow rate K
p
T
i
0.5 0.5
Constant pressure K
p
T
i
0.5 0.5
0.5 0.5
Constant level K
p
T
i
-20 0
20 0
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