Control Parameters - Lines 4-7, Circuit I - Danfoss ECL Comfort User Manual

26a
Control parameters -
lines 4-7, circuit I
4 Proportional band, Xp
Circuit Setting range
I 1 ... 250 K
Set the proportional band.
A higher value will result in a stable but slow
control of the flow temperature.
5 Integration time constant, Tn
Circuit Setting range
I 5 ... 999 sec.
Set a high integration time constant to obtain a
slow but stable reaction to deviations.
A small integration constant will make the
controller react fast but with less stability
6 Running time of the motorized control valve
Circuit Setting range
I 5 ... 250 sec.
Set the running time of the motorized control
valve according to the example. This is the time it
takes the controlled unit to move from fully closed
to fully open position.
How to calculate the running time of a motorized
control valve
The running time of the motorized control valve is calculated
using the following methods:
Seated valves
Running time = Valve stroke (mm) x actuator speed (sec. / mm)
Example: 5.0 mm x 15 sec. / mm = 75 sec.
Rotating valves
Running time = Turning degrees x actuator speed (sec. / degr.)
Example: 90 degrees x 2 = 180 sec.
The grey
side of the
ECL Card
Factory setting
80 K
Factory setting
140 sec.
Factory setting
140 sec.
7 Neutral zone, Nz
Circuit Setting range
I 0 ... 9 K
Set the neutral zone to a high value if you can
accept a high variation in flow temperature.
When the actual flow temperature is within the
neutral zone, the controller does not activate the
motorized valve.
The neutral zone is symmetrical around the desired flow
temperature value, i.e. half the value is above and half the value is
below this temperature.
Control parameters (lines 4-7) are overruled if thermo actuator is
chosen (OFF).
If you want to tune the PI regulation precisely, you can
use the following method:
• Set the integration time (line 5) to its max. value
(999 sec.).
• Decrease the value for the proportional band (line 4) until the
system starts hunting with a constant amplitude (it might be
necessary to force the system by setting an extreme value).
• Find the critical time period on the temperature recording or
use a stop watch.
Temp.
Critical time period
This time period will be characteristic for the system, and you can
evaluate the settings from this critical period.
Integration time = 0.85 x critical time period
Proportional band = 2.2 x proportional band value in the
critical time period.
If the regulation seems to be too slow, you can decrease the
proportional band value by 10%.
Make sure there is a consumption when you set the parameters.
26b
Factory setting
3 K
Time
The grey
side of the
ECL Card