Danfoss VLT HVAC Drive FC 102 Operating Instructions Manual

Also see for VLT HVAC Drive FC 102: Operating instructions Service guide Programming guide Installation guide Installation guide

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20-20 Feedback FunctionOption: Function:NOTICEAny unused feedbacks must be set to NoFunction in parameter 20-00 Feedback 1Source, parameter 20-03 Feedback 2Source, or parameter 20-06 Feedback 3Source.Only setpoint 1 is used. The sum of setpoint 1and any other references that are enabled (seeparameter group 3-1* References) are used as thePID Controller’s setpoint reference.[5] MultiSetpointMinSets up the PID Controller to calculate thedifference between feedback 1 and setpoint 1,feedback 2 and setpoint 2, and feedback 3 andsetpoint 3. It uses the feedback/setpoint pair inwhich the feedback is the farthest below itscorresponding setpoint reference. If all feedbacksignals are above their corresponding setpoints,the PID Controller uses the feedback/setpointpair with the least difference between the 2.NOTICEIf only 2 feedback signals are used, setthe non-used feedback to [0] No Functionin parameter 20-00 Feedback 1 Source,parameter 20-03 Feedback 2 Source, orparameter 20-06 Feedback 3 Source. Notethat each setpoint reference is the sum ofits respective parameter value(parameter 20-21 Setpoint 1,parameter 20-22 Setpoint 2 and20-23 Setpoint 3) and any other referencesthat are enabled (see parameter group3-1* References).[6] MultiSetpointMaxSets up the PID Controller to calculate thedifference between feedback 1 and setpoint 1,feedback 2 and setpoint 2, and feedback 3 andsetpoint 3. It uses the feedback/setpoint pair inwhich the feedback is farthest above itscorresponding setpoint reference. If all feedbacksignals are below their corresponding setpoints,the PID Controller uses the feedback/setpointpair with the least difference between the 2.20-20 Feedback FunctionOption: Function:NOTICEIf only 2 feedback signals are used, setthe non-used feedback to [0] No Functionin parameter 20-00 Feedback 1 Source,parameter 20-03 Feedback 2 Source, orparameter 20-06 Feedback 3 Source. Notethat each setpoint reference is the sum ofits respective parameter value(parameter 20-21 Setpoint 1,parameter 20-22 Setpoint 2 and20-23 Setpoint 3) and any other referencesthat are enabled (see parameter group3-1* References).NOTICEAny unused feedback must be set to [0] No function inits Feedback Source parameter:Parameter 20-00 Feedback 1 Source,parameter 20-03 Feedback 2 Source, orparameter 20-06 Feedback 3 Source.The PID controller uses the feedback resulting from thefunction selected in parameter 20-20 Feedback Function tocontrol the output frequency of the frequency converter.This feedback can also• be shown on the frequency converter’s display• be used to control a frequency converter's analogoutput• be transmitted over various serial communicationprotocolsThe frequency converter can be configured to handlemulti-zone applications. 2 different multi-zone applicationsare supported:• Multi-zone, single setpoint• Multi-zone, multi-setpointExamples 1 and 2 illustrate the difference between the 2:Example 1 – Multi-zone, single setpointIn an office building, a VAV (variable air volume) VLT®HVAC Drive system must ensure a minimum pressure atselected VAV boxes. Due to the varying pressure losses ineach duct, the pressure at each VAV box cannot beassumed to be the same. The minimum pressure requiredis the same for all VAV boxes. This control method can beset up by setting parameter 20-20 Feedback Function tooption [3], Minimum, and entering the desired pressure inparameter 20-21 Setpoint 1. If any feedback is below thesetpoint, the PID Controller increases the fan speed. If allHow to Programme Operating Instructions84 Danfoss A/S © Rev. 06/2014 All rights reserved. MG16B20266