74
423
PID Proportional Gain
(PID PROP. GAIN)
Value:
0.00 to 10.00
★
0.30
Function:
The proportional gain determines how fast the system responds to a
change in feedback.
Used in
Closed Loop
, parameter 100.
Description of choice:
Quick regulation is obtained by a high gain, but, if the gain is too high,
the process may become unstable. See Optimization of the Process
Regulator for information on proper adjustment.
424
PID Integral Time
(PID INTEGR.TIME)
Value:
0.01 to 9999.00 sec. (OFF)
★
OFF
Function:
The integrator adds the error signal over time and uses this to correct
the speed of the drive.
The integral time is the time needed by the integrator to have the same
effect as the proportional gain.
Used in
Closed Loop
parameter 100.
Description of choice:
Fast regulation is obtained by setting a short integration time. However,
if this time is too short, the process will overcorrect and become
unstable. See Optimization of the Process Regulator for information on
proper adjustment.
425
PID Differentiation Time
(PID DIFF. TIME)
Value:
0.00 (OFF) to 10.00 sec.
★
OFF
Function:
The differentiator responds to the rate of change of the error signal.
The quicker the error changes, the greater the response from the
differentiator.
Used in
Closed Loop
, parameter 100.
Description of choice:
Fast regulation can be obtained by means of a long differentiation time.
If this time is too long, the process may overshoot. The differentiator is
generally set of OFF in HVAC applications. See Optimization of the
Process Regulator for information on proper adjustment.
426
PID Differentiator Gain Limit
(PID DIFF. GAIN)
Value:
5.0 to 50.0
★
5.0
Function:
When the differentiator is used, fast changes in the error can sometimes
cause unstable operation. In these cases it may be useful to limit the
contribution of the differentiator.
Used in
Closed Loop,
parameter 100.
Description of choice:
A lower limit will improve stability, but will reduce the effect of the
differential.
427
PID Lowpass Filter Time
(PID FILTER TIME)
Value:
0.01 to 10.00
★
0.01
Function:
Noise on the feedback signal can be reduced by the lowpass filter.
Used in
Closed Loop
, parameter 100.
Description of choice:
Select the desired time constant (t).
The cut off frequency equals ½
π
t. For example, if a time constant of 0.1
s is programmed, the cut off frequency for the lowpass filter will be
1/[2
π
(.1)] = 1.6 Hz.
The PID controller will then
only respond to changes in
the feedback signal whose
frequency is less than 1.6
Hz.
✭
I
ndicates factory default setting. Numbers in brackets [ ] represent selection as displayed on the serial bus.
