Danfoss VLT AQUA Programming Manual

Also see for vlt aqua: Instructions Design guide Instruction manual Operating instructions Design guide

Contents

[180] HP This parameter determines the unit that is used for the setpointreference and feedback that the PID Controller will use for con-trolling the output frequency of the frequency converter.2.17.3. 20-2* Feedback & SetpointThis parameter group is used to determine how the frequency converter’s PID Controller will usethe three possible feedback signals to control the output frequency of the frequency converter.This group is also used to store the three internal setpoint references.20-20 Feedback FunctionOption: Function:[0] Sum[1] Difference[2] Average[3] * Minimum[4] Maximum[5] Multi setpoint min[6] Multi setpoint max This parameter determines how the three possible feedbackswill be used to control the output frequency of the frequencyconverter.NB!Any unused feedback must be set to “No function”in its Feedback Source parameter: 20-00, 20-03or 20-06.The feedback resulting from the function selected in par. 20-20will be used by the PID Controller to control the output fre-quency of the frequency converter. This feedback can also beshown on the frequency converter’s display, be used to controla frequency converter's analog output, and be transmitted overvarious serial communication protocols.The frequency converter can be configured to handle multi zoneapplications. Two different multi zone applications are suppor-ted:• Multi zone, single setpoint• Multi zone, multi setpointThe difference between the two is illustrated by the followingexamples:Example 1 – Multi zone, single setpointIn an office building, a VAV (variable air volume) water systemmust ensure a minimum pressure at selected VAV boxes. Dueto the varying pressure losses in each duct, the pressure at eachVAV box cannot be assumed to be the same. The minimumpressure required is the same for all VAV boxes. This controlmethod can be set up by settingFeedback Function, par. 20-20to option [3], Minimum, and entering the desired pressure inpar. 20-21. The PID Controller will increase the speed of the fanVLT ® AQUA Drive Programming Guide 2. Parameter DescriptionMG.20.O2.02 - VLT ® is a registered Danfoss trademark 1772