Danfoss VLT FC 102 Programming Manual

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

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25-25 OBW TimeRange: Function:10 s* [0 - 300 s] Staging a fixed-speed pump createsa momentary pressure peak in thesystem, which might exceed theoverride bandwidth (OBW). It is notrecommended to destage a pumpin response to a staging pressurepeak. The OBW time can beprogrammed to prevent staginguntil the system pressure hasstabilized and normal controlestablished. Set the timer to a valuethat allows the system to stabilizeafter staging. The 10 s factorysetting is appropriate in mostapplications. In highly dynamicsystems, a shorter time may bewanted.SetpointSBW (27-70)OBW (27-71)SBW (27-70)OBW (27-71)Actual headOBW timer (27-25)130BA370.11Illustration 3.80 OBW Time25-26 Destage At No-FlowOption: Function:This parameter ensures that when ano-flow situation occurs, the fixed-speed pumps are destaged 1 by 1until the no-flow signal disappears.This requires that no-flow detectionis active. See parameter group 22-2*No-Flow Detection.If [0] Disabled is selected, thecascade controller does not changethe normal behavior of the system.[0] * Disabled[1] Enabled25-27 Stage FunctionOption: Function:If the stage function is set to [0]Disabled, parameter 25-28 StageFunction Time is not activated.[0] Disabled[1] * Enabled25-28 Stage Function TimeRange: Function:15 s* [0 - 300 s] The stage function time isprogrammed to avoid frequentstaging of the fixed-speed pumps.The stage function time starts if itis [1] Enabled byparameter 25-27 Stage Function, andwhen the variable-speed pumpruns at motor speed high limit,parameter 4-13 Motor Speed HighLimit [RPM] or parameter 4-14 MotorSpeed High Limit [Hz], with at least 1fixed-speed pump in the stopposition. When the programmedvalue of the timer expires, a fixed-speed pump is staged.25-29 Destage FunctionOption: Function:The destage function ensures thatthe lowest numbers of pumps arerunning to save energy and toavoid dead head water circulationin the variable-speed pump. If thedestage function is set to [0]Disabled, parameter 25-30 DestageFunction Time is not activated.[0] Disabled[1] * EnabledParameter Descriptions Programming GuideM0010001 Danfoss A/S © 10/2019 All rights reserved. 2393 3