Main Menu - Extended Closed Loop - Group - Danfoss VLT AQUA Programming Manual

®
VLT AQUA Drive Programming Guide
20-94 PID Integral Time
Range:
20.00 s
20-95 PID Differentiation Time
Range:
0.0 s
20-96 PID Diff. Gain Limit
Range:
*
5.0

2.18. Main Menu - Extended Closed Loop - Group 21

2.18.1. 21-** Ext. Closed Loop
The FC102 offers 3 Extended Closed Loop PID controllers in addition to the PID Controller. These
can be configured independently to control either external actuators (valves, dampers etc.) or be
used together with the internal PID Controller to improve the dynamic responses to setpoint
changes or load disturbances.
The Extended Closed Loop PID controllers may be interconnected or connected to the PID Closed
Loop controller to form a dual loop configuration.
Function:
* [0.01 - 10000.00 = The integrator adds over time (integrates) the error between
Off s] the feedback and the setpoint reference. This is required to en-
sure that the error approaches zero. Quick frequency converter
speed adjustment is obtained when this value is small. However,
if too small of a value is used, the frequency converter's output
frequency may become unstable.
Function:
* [0.00 = Off - 10.00 s] The differentiator monitors the rate of change of the feedback.
If the feedback is changing quickly, it will adjust the output of
the PID Controller to reduce the rate of change of the feedback.
Quick PID Controller response is obtained when this value is
large. However, if too large of a value is used, the frequency
converter's output frequency may become unstable.
Differentiation time is useful in situations where extremely fast
frequency converter response and precise speed control are re-
quired. It can be difficult to adjust this for proper system control.
Differentiation time is not commonly used in water/ wastewater
applications. Therefore, it is generally best to leave this param-
eter at 0 or OFF.
Function:
[1.0 - 50.0] The differentiator of a PID Controller responds to the rate of
change of the feedback. As a result, an abrupt change in the
feedback can cause the differentiator to make a very large
change in the PID Controller's output. This parameter limits the
maximum effect that the PID Controller's differentiator can pro-
duce. A smaller value reduces the maximum effect of the PID
Controller's differentiator.
This parameter is only active when par. 20-95 is not set to OFF
(0 s).
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MG.20.O2.02 - VLT is a registered Danfoss trademark
2. Parameter Description
185
2