Danfoss VLT FC 102 Programming Manual page 194

Parameter Descriptions
21-14 Ext. 1 Feedback Source
Option:
[104] Sensorless
Flow
[105] Sensorless
3 3
Pressure
[110] Air Pres. to
Flow
21-15 Ext. 1 Setpoint
Range:
0
ExtPID1Uni par. 21-12
t ExtPID1Unit]
*
21-17 Ext. 1 Reference [Unit]
Range:
0
ExtPID1Uni - 999999.999
t ExtPID1Unit]
*
21-18 Ext. 1 Feedback [Unit]
Range:
0
ExtPID1Uni - 999999.999
t ExtPID1Unit]
*
21-19 Ext. 1 Output [%]
Range:
0 %
*
3.19.3 21-2* Closed Loop 1 PID
21-20 Ext. 1 Normal/Inverse Control
Option:
[0] Normal
*
[1] Inverse
21-21 Ext. 1 Proportional Gain
Range:
0.01
*
192
Function:
Function:
[ par. 21-11 - 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 parameter 21-13 Ext. 1 Reference
Source.
Function:
[-999999.999 Readout of the reference value for
the closed-loop 1 controller.
Function:
[-999999.999 Readout of the feedback value for
the closed-loop 1 controller.
Function:
[0 - 100 %] Readout of the output value for the
closed-loop 1 controller.
Function:
Reduces the output when feedback
is higher than the reference.
Increase the output when feedback
is higher than the reference.
Function:
NOTICE
[0 - 10 ]
Always set
parameter 20-14 Maximum
Reference/Feedb. before setting
the values for the PID
controller in parameter group
20-9* PID Controller.
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®
VLT HVAC Drive FC 102
21-21 Ext. 1 Proportional Gain
Range:
If (error x gain) jumps with a value equal to what is set in
parameter 20-14 Maximum Reference/Feedb., the PID
controller tries to change the output speed equal to what
is set in parameter 4-13 Motor Speed High Limit [RPM]/
parameter 4-14 Motor Speed High Limit [Hz]. However, the
output speed is limited by this setting.
The proportional band (error causing output to change
from 0–100%) can be calculated with the formula
1
Proportional Gain
21-22 Ext. 1 Integral Time
Range:
10000 s
*
21-23 Ext. 1 Differentation Time
Range:
0 s
*
Function:
The proportional gain indicates the
number of times the error between
the setpoint and the feedback
signal is to be applied.
× Max Reference
Function:
[0.01 - 10000 Over time, the integrator
s] 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 0.
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 for
a certain deviation.
If the value is set to 10000, the
controller acts as a pure propor-
tional controller with a P-band
based on the value set in
parameter 20-93 PID Proportional
Gain. When no deviation is present,
the output from the proportional
controller is 0.
Function:
[0 - 10 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.
M0010001