Danfoss VLT Programming Manual page 194

3 Parameter Description
21-18 Ext. 1 Feedback [Unit]
Range:
0.000 Ex- [-999999.999 - 999999.999 Ex-
tPID1Unit* tPID1Unit]
21-19 Ext. 1 Output [%]
Range:
3
0 %* [0 - 100 %]
3.19.4 21-2* Closed Loop 1 PID
Configure the Closed Loop 1 PID controller.
21-20 Ext. 1 Normal/Inverse Control
Option:
[0] * Normal
[1] Inverse
21-21 Ext. 1 Proportional Gain
Range:
0.01 N/A* [0.00 - 10.00 N/A]
If (Error x Gain) jumps with a value equal to what is set in par. 20-14
equal to what is set in par. 4-13/4-14, Motor Speed High Limit, but in practice of course limited by this setting.
The proportional band (error causing output to change from 0-100%) can be calculated by means of the formula:
( )
1
× (
Proportional Gain
NB!
Always set the desired for par. 20-14
21-22 Ext. 1 Integral Time
Range:
10000.00 [0.01 - 10000.00 s]
s*
21-23 Ext. 1 Differentation Time
Range:
0.00 s* [0.00 - 10.00 s]
194
Function:
Readout of the feedback value for the Closed Loop 1 Controller.
Function:
Readout of the output value for the Closed Loop 1 Controller.
Function:
Normal
Select
Select Inverse
Function:
Max Reference )
Maximum Reference/Feedb.
Function:
Over time, the integrator accumulates a contribution to the output from the PID controller as long
as there is a deviation between the Reference/Setpoint and feedback signals. The contribution is
proportional to the size of the deviation. This ensures that the deviation (error) approaches zero.
Quick response on any deviation is obtained when the integral time is set to a low value. Setting it
too low, however, may cause the control to become unstable.
The value set, is the time needed for the integrator to add the same contribution as the proportional
part for a certain deviation.
If the value is set to 10,000, the controller will act as a pure proportional controller with a P-band
based on the value set in par. 20-93
from the proportional controller will be 0.
Function:
The differentiator does not react to a constant error. It only provides a gain when the feedback
changes. The quicker the feedback changes, the stronger the gain from the differentiator.
MG.11.C9.02 - VLT
[0] if the output should be reduced when feedback is higher than the reference.
[1] if the output should be increased when feedback is higher than the reference.
Maximum Reference/Feedb. , the PID controller will try to change the output speed
before setting the values for the PID controller in par. group 20-9*.
PID Proportional Gain
® is a registered Danfoss trademark
®
VLT HVAC Drive Programming Guide
. When no deviation is present, the output