Danfoss VLT FC 102 Programming Manual page 476

Programming Guide | VLT® HVAC Drive FC 102
The proportional gain indicates the number of times the error between the setpoint and the feedback signal is to be applied. If (error
x gain) jumps with a value equal to what is set in parameter 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]/parameter 4-14 Motor Speed High Limit [Hz].
However, the output speed is limited by this setting.
Calculate the proportional band (error causing output to change from 0–100%) with this formula:
21-22 Ext. 1 Integral Time
Default value: 10000 s
Setup:
All setups
Data type: Uint32
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 0. 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 10000, 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.
21-23 Ext. 1 Differentiation Time
Default value: 0 s
Setup: All setups
Data type: Uint16
The differentiator does not react to a 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
Default value: 5
Setup:
All setups
Data type: Uint16
Set a limit for the differentiator gain (DG). The DG increases if there are fast changes. Limit the DG to obtain a pure differentiator gain
when changes are slow and a constant differentiator gain when quick changes occur.
21-26 Ext. 1 On Reference Bandwidth
Default value: 5%
Setup: All setups
Data type: Uint8
476 | © 2024.10
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Parameter Descriptions
0.01 - 10000=Off s
-2
True
Range, 0=Off - 10 s
-2
True
Range, 1 - 50
-1
True
Range, 0 - 200%
0
True
AU430028034214en-001901 / 130R0310