Danfoss VLT AQUA Operating Instructions Manual

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

NOTICE3-41 Ramp 1 Ramp Up Time and 3-42 Ramp 1 Ramp DownTime must be the same for the master drive and for allfollower drives in the system.4. Set the ramps fast enough to enable the PIDcontroller to maintain control of the system.4.1.3 Closed Loop ControlThe master drive is the primary controller for the system. Itmonitors the output pressure, adjusts the speed of thefrequency converters and decides when to add or removestages.To perform this function:1. setup the master drive closed loop mode with afeedback sensor connected to an analog input ofthe frequency converter.2. setup the PID controller of the master drive tomatch the needs of the installation.For further information on setting up the PID parameters,see the VLT® AQUA Drive Programming Guide. See also6.1 Master/Follower.4.1.4 Staging/De-staging of Variable SpeedPumpsStaging occurs when the speed of the frequency converterhas reached the value in 27-31 Stage On Speed [RPM](27-32 Stage On Speed [Hz]). At this speed the systempressure is still maintained but the pumps start to operateoutside of their peak efficiency points. Staging on anadditional pump will lower the speed of all running pumpsand provide a more energy efficient operation.In master-follower configurations and mixed pump config-urations the variable speed pumps are staged and de-staged based on the speed of the frequency converters.De-staging occurs when the speed of the frequencyconverters drops below the value in 27-33 Stage Off Speed[RPM] (27-34 Stage Off Speed [Hz]). At this speed the systempressure is still maintained but the pumps are beginningto operate below their peak efficiency points. De-staging apump will cause the speed of the frequency converters toincrease into a more energy efficient range.27-31 Stage On Speed [RPM] (27-32 Stage On Speed [Hz]) and27-33 Stage Off Speed [RPM] (27-34 Stage Off Speed [Hz]) areinstallation dependent. These parameters are indexedparameters with one set of entries for each pump stage.The stage on and de-stage off speed can be auto tunedduring automation or set manually. If Auto-tune is enabledthe system will start operation using default settings or thepre settings done by the user in 27-31 Stage On Speed[RPM] (27-32 Stage On Speed [Hz]) and 27-33 Stage OffSpeed [RPM] (27-34 Stage Off Speed [Hz]) before enablingthe auto-tune.The tuning ensures optimum energy efficiency of thesystem. See Illustration 4.2.P totABCt1 2130BB024.11Illustration 4.21 1 pump running2 2 pumps runningA Incorrect stage on speed adjustmentB Correct stage on speed adjustmentC Stage on speed pump 2Table 4.2During operation the system monitors the actual energyconsumption and optimises every time a stage or de-stagetakes place.Parameter Range Default27-30 Auto TuneStaging Speeds{[0] Disabled, [1]Enabled} [1] EnabledTable 4.34.1.5 Staging/De-staging of Fixed SpeedPumpsFixed speed pumps are staged based or de-staged basedon system pressure.To avoid rapid turning on and off of pumps, define anacceptable range of system pressure along with a periodof time the pressure is allowed to be outside of this bandbefore staging or de-staging occurs. Set the valuesthrough:Configuring the System VLT® AQUA Drive MCO 101/MCO 102MI38C402 - VLT® is a registered Danfoss trademark 174 4