20-93 PID Proportional Gain
Range: Function:
0.50* [0.00 - 10.00 ]
If (Error x Gain) jumps with a value equal to what is set in par. 20-14
Maximum Reference/Feedb.
the PID controller will try to change the output speed
equal to what is set in par. 4-13
Motor Speed High Limit [RPM]
/ par. 4-14
Motor Speed High Limit [Hz]
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 par. 20-14
Maximum Reference/Feedb.
before setting the values for the PID controller in par. group 20-9*.
20-94 PID Integral Time
Range: Function:
20.00 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 par. 20-93
PID Proportional Gain
. When no deviation is present, the output
from the proportional controller will be 0.
6.3.10 22-** Miscellaneous
This group contains parameters used for monitoring water/wastewater applications.
22-20 Low Power Auto Set-up
Start of auto set-up of power data for No-Flow Power tuning.
Option: Function:
[0] * OFF
[1] Enabled When set for
Enabled
, an auto set-up sequence is activated, automatically setting speed to approx.
50% and 85% of rated motor speed (par. 4-13
Motor Speed High Limit [RPM]
, par. 4-14
Motor
Speed High Limit [Hz]
). At those two speeds, the power consumption is automatically measured
and stored.
Before enabling Auto Set-up:
1. Close valve(s) in order to create a no-flow condition
2. The adjustable frequency drive must be set for open-loop (par. 1-00
Configuration Mode
).
Note that it is important also to set par. 1-03
Torque Characteristics
.
NOTE!
Auto set-up must be done when the system has reached normal operating temperature!
6 How to Program the Low Harmonic Drive
VLT AQUA Low Harmonic Drive Instruction
Manual
6-34
MG.20.T1.22 - VLT
®
is a registered Danfoss trademark
6
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