21-15 Ext. 1 Setpoint
Range:
Function:
0.000
ExtPID1Unit
*
[-999999.999 -
999999.999
ExtPID1Unit]
The setpoint reference is used
in extended 1 closed loop.
Ext.1 Setpoint is added to the
value from the Ext.1
Reference source selected in
.
21-17 Ext. 1 Reference [Unit]
Range:
Function:
0.000
ExtPID1Unit
*
[-999999.999 -
999999.999
ExtPID1Unit]
Readout of the
reference value for the
Closed Loop 1
Controller.
21-18 Ext. 1 Feedback [Unit]
Range:
Function:
0.000
ExtPID1Unit
*
[-999999.999 -
999999.999
ExtPID1Unit]
Readout of the
feedback value for the
Closed Loop 1
Controller.
21-19 Ext. 1 Output [%]
Range:
Function:
0 %
*
[0 - 100 %] Readout of the output value for the Closed
Loop 1 Controller.
3.19.3 21-2* Closed Loop 1 PID
21-20 Ext. 1 Normal/Inverse Control
Option:
Function:
[0] Normal Select
Normal
[0] if the output should be reduced
when feedback is higher than the reference.
[1] Inverse Select
Inverse
[1] if the output should be increased
when feedback is higher than the reference.
21-21 Ext. 1 Proportional Gain
Range:
Function:
0.01
*
[0.00 - 10.00 ]
If (Error x Gain) jumps with a value equal to what is set in
20-14 Maximum Reference/Feedb.
, the PID controller will try to
change the output speed 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
)
× (
Max Reference)
NOTE
Always set the desired for
20-14 Maximum Reference/Feedb.
before setting the values for the PID controller in parameter
group 20-9*.
21-22 Ext. 1 Integral Time
Range:
Function:
10000.00
s
*
[0.01 -
10000.00 s]
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
. When no
deviation is present, the output from the
proportional controller will be 0.
21-23 Ext. 1 Differentation Time
Range:
Function:
0.00 s
*
[0.00 - 10.00
s]
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.
21-24 Ext. 1 Dif. Gain Limit
Range:
Function:
5.0
*
[1.0 - 50.0 ] Set a limit for the differentiator gain (DG). The
DG will increase if there are fast changes. Limit
the DG to obtain a pure differentiator gain at
slow changes and a constant differentiator
gain where quick changes occur.
Parameter Description
VLT
®
HVAC Drive Programming Guide
136
MG.11.CB.02 - VLT
®
is a registered Danfoss trademark
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