Danfoss VLT AQUA Drive FC 202 Operating Instructions Manual page 85

How to programme the freque...
20-21 Setpoint 1
Range:
0 [-999999.999 -
ProcessCtrlUnit 999999.999
*
ProcessCtrlUnit]
20-81 PID Normal/ Inverse Control
Option: Function:
[0] Normal The frequency converter's output frequency
*
decreases when the feedback is greater than the
setpoint reference. This is common for pressure-
controlled supply fan and pump applications.
[1] Inverse The frequency converter's output frequency
increases when the feedback is greater than the
setpoint reference.
20-82 PID Start Speed [RPM]
Range: Function:
Size [ 0 - When the frequency converter is first
related par. 4-13 started, it initially ramps-up to this output
*
RPM] speed in open loop mode, following the
active ramp up time. When the output
speed programmed is reached, the
frequency converter automatically switches
to closed loop mode and the PID
controller begins to function. This is useful
in applications that require quick
acceleration to a minimum speed at start-
up.
NOTICE
This parameter is only visible if
0-02 Motor Speed Unit is set to [0]
RPM.
20-93 PID Proportional Gain
Range: Function:
2 [0 - 10 ] The proportional gain indicates the number of
*
times the error between the set point and the
feedback signal is to be applied.
MG20Y202
Operating Instructions
Function:
Setpoint 1 is used in closed
loop mode to enter a
setpoint reference that is
used by the frequency
converter's PID controller.
See the description of
20-20 Feedback Function.
NOTICE
The setpoint reference
entered here is added
to any other references
that are enabled (see
parameter group 3-1*
References).
Danfoss A/S © Rev. 06/2014 All rights reserved.
If (Error x Gain) jumps with a value equal to what is set in
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]/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
× Max Reference
Proportional Gain
NOTICE
Always set the desired value for 20-14 Maximum
Reference/Feedb. before setting the values for the PID
controller in parameter group 20-9* PID Controller.
20-94 PID Integral Time
Range: Function:
8 s [0.01 - The integrator accumulates a contribution to the
*
10000 s] output from the PID controller as long as there
is a deviation between the reference/setpoint
and feedback signals. The contribution is propor-
tional 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 for a certain deviation.
If the value is set to 10,000, the controller acts as
a pure proportional 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.
6.2.7 22-0* Miscellaneous
This group contains parameters used for monitoring water/
wastewater applications.
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