Danfoss VLT HVAC Drive FC 100 Series, Руководство по конструкции

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2.8.6 Feedback Handling
Figure 2.25 Block Diagram of Feedback Signal Processing
Feedback handling can be configured to work with applications requiring advanced control, such as multiple setpoints and
multiple feedbacks. Three types of control are common.
Single Zone, Single Setpoint
Single Zone, Single Setpoint is a basic configuration. Setpoint 1 is added to any other reference (if any, see Reference
Handling) and the feedback signal is selected using
20-20 Feedback Function .
Multi-zone, Single Setpoint
Multi-zone, Single Setpoint uses two or three feedback sensors, but only one setpoint. The feedbacks can be added,
subtracted (only feedback 1 and 2) or averaged. In addition, the maximum or minimum value may be used. Setpoint 1 is
used exclusively in this configuration.
If Multi Setpoint Min [13] is selected, the setpoint/feedback pair with the largest difference controls the speed of the
adjustable frequency drive. Multi Setpoint Maximum [14] attempts to keep all zones at or below their respective setpoints,
while Multi Setpoint Min [13] attempts to keep all zones at or above their respective setpoints.
Example:
A two-zone two setpoint application Zone 1 setpoint is 15 bar and the feedback is 5.5 bar. Zone 2 setpoint is 4.4 bar and
the feedback is 4.6 bar. If
Multi Setpoint Max [14] is selected, Zone 1’s setpoint and feedback are sent to the PID controller,
since this has the smaller difference (feedback is higher than setpoint, resulting in a negative difference). If Multi Setpoint
Min [13] is selected, Zone 2’s setpoint and feedback is sent to the PID controller, since this has the larger difference
(feedback is lower than setpoint, resulting in a positive difference).
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