Danfoss VLT HVAC Operating Instructions Manual

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Minimum [3] sets up the PID Controller tocompare Feedback 1, Feedback 2 and Feed-back 3 and use the lowest value as the feed-back.NB!Any unused feedbacks must beset toNo Function in par. 20-00,20-03, or 20-06. Only setpoint 1will be used. The sum of Set-point 1 and any other referencesthat are enabled (see par. group3-1*) will be used as the PIDController’s setpoint reference.Maximum [4] sets up the PID Controller tocompare Feedback 1, Feedback 2 and Feed-back 3 and use the highest value as the feed-back.NB!Any unused feedbacks must beset toNo Function in par. 20-00,20-03, or 20-06.Only Setpoint 1 will be used. The sum of Set-point 1 and any other references that areenabled (see par. group 3-1*) will be used asthe PID Controller’s setpoint reference.Multi-setpoint minimum [5] sets up the PIDController to calculate the difference betweenFeedback 1 and Setpoint 1, Feedback 2 andSetpoint 2, and Feedback 3 and Setpoint 3. Itwill use the feedback/setpoint pair in whichthe feedback is the farthest below its corre-sponding setpoint reference. If all feedbacksignals are above their corresponding set-points, the PID Controller will use the feed-back/setpoint pair in which the differencebetween the feedback and setpoint is theleast.NB!If only two feedback signals areused, the feedback that is not tobe used must be set toNo Func-tion in par. 20-00, 20-03 or20-06. Note that each setpointreference will be the sum of itsrespective parameter value(20-11, 20-12 and 20-13) andany other references that areenabled (see par. group 3-1*).Multi-setpoint maximum [6] sets up the PIDController to calculate the difference betweenFeedback 1 and Setpoint 1, Feedback 2 andSetpoint 2, and Feedback 3 and Setpoint 3. Itwill use the feedback/setpoint pair in whichthe feedback is farthest above its correspond-ing setpoint reference. If all feedback signalsare below their corresponding setpoints, thePID Controller will use the feedback/setpointpair in which the difference between the feed-back and the setpoint reference is the least.NB!If only two feedback signals areused, the feedback that is not tobe used must be set toNo Func-tion in par. 20-00, 20-03 or20-06. Note that each setpointreference will be the sum of itsrespective parameter value(20-21, 20-22 and 20-23) andany other references that areenabled (see par. group 3-1*).20-21 Setpoint 1Value:Ref MIN par.3-02 - Ref MAX par.3-03 UNIT (from par. 20-12) 0.000Function:Setpoint 1 is used in Closed Loop Mode to en-ter a setpoint reference that is used by thefrequency converter’s PID Controller. See thedescription ofFeedback Function, par. 20-20.NB!Setpoint reference entered hereis added to any other referencesthat are enabled (see par. group3-1*).20-22 Setpoint 2Value:Ref MIN - RefMAX UNIT (from par.20-12) 0.000Function:Setpoint 2 is used in Closed Loop Mode to en-ter a setpoint reference that may be used bythe frequency converter’s PID Controller. Seethe description ofFeedback Function, par.20-20.NB!The setpoint reference enteredhere is added to any other ref-6. How to programme the frequency converter VLT® HVAC Drive Operating Instructions80 MG.11.A4.02 - 09.10.06. VLT® is a registered Danfoss trademark6