Danfoss VLT FC 100 Series Programming Manual page 154

Parameter Description
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 [0.01 - Over time, the integrator accumulates a
s 10000.00 contribution to the output from the PID
*
s] 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 20-93 PID Proportional Gain.
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 The differentiator does not react to a
*
s] 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.
®
VLT HVAC Drive Programming Guide
3.19.4 21-3* Closed-loop 2 Ref./Fb.
21-30 Ext. 2 Ref./Feedback Unit
Option:
[0]
[1]
[5]
[10]
[11]
[12]
[20]
[21]
[22]
[23]
[24]
[25]
[30]
[31]
[32]
[33]
[34]
[40]
[41]
[45]
[60]
[70]
[71]
[72]
[73]
[74]
[75]
[80]
[120] GPM
[121] gal / sec.
[122] gal/min
[123] gal / hr.
[124] CFM
[125] ft³/s
[126] ft³/min
[127] ft³/h
[130] lbs / sec.
[131] lbs / min.
[132] lbs / hr.
[140] ft/s
[141] ft/min
[145] ft
[160] °F
[170] psi
[171] lb/in²
[172] in. wtr. gage
MG11CD22 - VLT ® is a registered Danfoss trademark
Function:
See 21-10 Ext. 1 Ref./Feedback Unit for details
%
*
PPM
min
RPM
PULSE/s
liter / sec.
liter / min
liter / hr.
m³ / sec.
m³/min
m³ / hr.
kg / sec.
kg/min
kg / hr.
ton / min
ton / hr.
m / sec.
m/min
m
°C
mbar
bar
Pa
kPa
m WG
mm Hg
kW
3 3
3-127