Danfoss VLT AQUA Design Manual

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

Contents

The Remote Reference is comprised of:• Preset references.• External references (analog inputs, pulse frequency inputs, digital potentiometer inputs and serial communication bus references).• The Preset relative reference.• Feedback controlled setpoint.Up to 8 preset references can be programmed in the drive. The active preset reference can be selected using digital inputs or the serial communicationsbus. The reference can also be supplied externally, most commonly from an analog input. This external source is selected by one of the 3 ReferenceSource parameters (par. 3-15, 3-16 and 3-17). Digipot is a digital potentiometer. This is also commonly called a Speed Up/Speed Down Control or aFloating Point Control. To set it up, one digital input is programmed to increase the reference while another digital input is programmed to decrease thereference. A third digital input can be used to reset the Digipot reference. All reference resources and the bus reference are added to produce the totalExternal Reference. The External Reference, the Preset Reference or the sum of the two can be selected to be the active reference. Finally, this referencecan by be scaled using the Preset Relative Reference (par. 3-14).The scaled reference is calculated as follows:Reference =X +X × (Y100 )Where X is the external reference, the preset reference or the sum of these and Y is the Preset Relative Reference (par. 3-14) in [%].NB!If Y, the Preset Relative Reference (par. 3-14) is set to 0%, the reference will not be affected by the scaling2.9.9. Feedback HandlingA block diagram of how the drive processes the feedback signal is shown below.Feedback handling can be configured to work with applications requiring advanced control, such as multiple setpoints and multiple feedbacks. Threetypes of control are common.Single Zone, Single SetpointSingle Zone Single Setpoint is a basic configuration. Setpoint 1 is added to any other reference (if any, see Reference Handling) and the feedback signalis selected using par. 20-20.VLT® AQUA Drive Design Guide 2. Introduction to VLT AQUA DriveMG.20.N3.02 - VLT® is a registered Danfoss trademark 292