Danfoss VLT AQUA High Power Operation Instructions Manual page 126

5 How to programme the frequency converter
20-81 PID Normal/Inverse Control
Option:
[0] * Normal
[1] Inverse
20-82 PID Start Speed [RPM]
Range:
0 RPM* [0 - par. 4-13 RPM]
5
20-93 PID Proportional Gain
Range:
0.50 N/A* [0.00 - 10.00 N/A]
If (Error x Gain) jumps with a value equal to what is set in par. 20-14
equal to what is set in par. 4-13
The proportional band (error causing output to change from 0-100%) can be calculated by means of the formula:
( )
1
× (
Proportional Gain
NB!
Always set the desired for par. 20-14
20-94 PID Integral Time
Range:
20.00 s* [0.01 - 10000.00 s]
5.2.10 22-** Miscellaneous
This group contains parameters used for monitoring water/ wastewater applications.
126
Function:
Normal [0] causes the frequency converter's output frequency to decrease when the feedback is
greater than the setpoint reference. This is common for pressure-controlled supply fan and pump
applications.
Inverse
[1] causes the frequency converter's output frequency to increase when the feedback is
greater than the setpoint reference.
Function:
When the frequency converter is first started, it initially ramps up to this output speed in Open Loop
Mode, following the active Ramp Up Time. When the output speed programmed here is reached,
the frequency converter will automatically switch to Closed Loop Mode and the PID Controller will
begin to function. This is useful in applications in which the driven load must first quickly accelerate
to a minimum speed when it is started.
Function:
The proportional gain indicates the number of times the error between the set point and the feed-
back signal is to be applied.
Motor Speed High Limit [RPM]
Max Reference )
Maximum Reference/Feedb.
Function:
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,
from the proportional controller will be 0.
MG.20.P3.02 - VLT
VLT AQUA High Power Operation Instructions
NB!
This parameter will only be visible if par. 0-02
Maximum Reference/Feedb.
the PID controller will try to change the output speed
Motor Speed High Limit [Hz]
/par. 4-14
before setting the values for the PID controller in par. group 20-9*.
Proportional Gain
®
is a registered Danfoss trademark
Motor Speed Unit is set to [0], RPM.
but in practice of course limited by this setting.
. When no deviation is present, the output