Danfoss VLT AQUA Drive FC 202 Programming Manual

Also see for VLT AQUA Drive FC 202: Service guide Installation guide Installation guide Operating guide Installation guide

Contents

NOTICECarry out no-flow tuning before setting the PI controllerparameters.FC130BA253.10PIllustration 3.64 No-flow Detection Scheme130BA254.10HeadFlow21Illustration 3.65 No-flow Detection GraphNo-flow detection is based on the measurement of speedand power. For a certain speed, the frequency convertercalculates the power at no flow.This coherence is based on the adjustment of 2 sets ofspeed and associated power at no flow. By monitoring thepower, it is possible to detect no-flow conditions insystems with fluctuating suction pressure, or if the pumphas a flat characteristic towards low speed.Base the 2 sets of data on measurement of power atapproximately 50% and 85% of maximum speed with thevalve closed. The data is programmed in parameter group22-3* No-flow Power Tuning. It is also possible to run aparameter 22-20 Low Power Auto Set-up, automaticallystepping through the commissioning process, and alsoautomatically storing the data measured. Set the frequencyconverter for open loop in parameter 1-00 ConfigurationMode, when carrying out the auto set-up (see parametergroup 22-3* No-flow Power Tuning).NOTICEWhen using the integrated PI controller, carry out no-flow tuning before setting the PI controller parameters.Low-speed detectionLow-speed detection gives a signal if the motor operateswith minimum speed as set in parameter 4-11 Motor SpeedLow Limit [RPM] or parameter 4-12 Motor Speed Low Limit[Hz]. Actions are common with no-flow detection(individual selection not possible).The use of low-speed detection is not limited to systemswith a no-flow situation. It can be used in any systemwhere operation at minimum speed allows for a stop ofthe motor until the load calls for a speed higher thanminimum speed. An example is systems with fans andcompressors.NOTICEIn pump systems, ensure that the minimum speed inparameter 4-11 Motor Speed Low Limit [RPM] orparameter 4-12 Motor Speed Low Limit [Hz] has been sethigh enough for detection as the pump can run with arather high speed even with valves closed.Dry-pump detectionNo-flow detection can also be used to detect if the pumphas run dry (low power consumption and high speed). Itcan be used with both the integrated PI controller and anexternal PI controller.The conditions for dry-pump signal are:• Power consumption below no-flow level.• Pump running at maximum speed or maximumreference open loop, whichever is lowest.The signal must be active for a set time(parameter 22-27 Dry Pump Delay) before the selectedaction takes place.Possible actions to select (parameter 22-26 Dry PumpFunction) are:• Warning.• Alarm.Enable the low-power detection in parameter 22-21 LowPower Detection. Perform the tuning using parameter group22-3*, No-Flow Power Tuning.Parameter Description VLT® AQUA Drive FC 202178 Danfoss A/S © 05/2018 All rights reserved. MG20OB0233