Danfoss VLT HVAC Drive 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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Cascade Controllerprepares forremoving pumpLead pump startsto ramp upTimeSpeedLead pump(controlled by freq. conv.)DestagingFixed speed pump(controlled by soft starter)P 25-41t 2130BC372.10Illustration 3.77 Destaging25-42 Staging ThresholdRange: Function:Sizerelated*[ 0 -100%]When adding a fixed speed pump, to preventan overshoot of pressure, the variable speedpump ramps down to a lower speed. Whenthe variable speed pump reaches the “StagingSpeed” the fixed speed pump is staged on.The staging threshold is used to calculate thespeed of the variable speed pump when the“cut-in point” of the fixed speed pump occurs.The calculation of the staging threshold is theratio of parameter 4-11 Motor Speed Low Limit[RPM] or parameter 4-12 Motor Speed Low Limit[Hz], to the parameter 4-13 Motor Speed HighLimit [RPM] or parameter 4-14 Motor SpeedHigh Limit [Hz], expressed in percent.Staging threshold must range fromSTAGE % = LOWHIGH × 100 %to 100%, where nLOW is motor speed low limitand nHIGH is Motor Speed High Limit.SecondsVariable speedpumpFixed speedpumpMotor speedhigh limitStaging speedMotor speedlow limit4 50130BA366.10Illustration 3.78 Staging Threshold25-43 Destaging ThresholdRange: Function:Sizerelated*[ 0 -100%]When removing a fixed speed pump toprevent an undershoot of pressure, thevariable speed pump ramps up to a higherspeed. When the variable speed pumpreaches the destaging speed, the fixed speedpump is destaged. The destaging threshold isused to calculate the speed of the variablespeed pump when the destaging of the fixedspeed pump occurs. The calculation of thedestaging threshold is the ratio ofparameter 4-11 Motor Speed Low Limit [RPM] orparameter 4-12 Motor Speed Low Limit [Hz], toparameter 4-13 Motor Speed High Limit [RPM]or parameter 4-14 Motor Speed High Limit [Hz],expressed in percent.Destaging threshold must range fromSTAGE % = LOWHIGH × 100 % to 100%, where nLOW ismotor speed low limit and nHIGH is motorspeed high limit.130BA367.103 50 1 SecondsVariable speedpumpFixed speedpumpMotor speedhigh limitDestagingspeedMotor speedlow limitIllustration 3.79 Destaging ThresholdParameter Descriptions Programming GuideMG11CE02 Danfoss A/S © 03/2015 All rights reserved. 1953 3