Danfoss VLT DriveMotor FCP 106 Programming Manual page 107

Parameters
No-flow detection
This function is used for detecting a no-flow situation in pump systems where all valves can be closed. Can be used both
when controlled by the integrated PI controller in the frequency converter or an external PI controller. Program the actual
configuration in parameter 1-00 Configuration Mode.
Configuration mode for
•
Integrated PI controller: Closed loop.
•
External PI controller: Open loop.
NOTICE
Carry out no-flow tuning before setting the PI controller parameters.
FC
P
Table 4.13 No-flow Detection
No-flow detection is based on the measurement of speed and power. For a certain speed, the frequency converter calculates
the power at no-flow.
This coherence is based on the adjustment of 2 sets of speed and associated power at no-flow. Monitoring power enables
detection of no-flow conditions in systems with fluctuating suction pressure, or of the pump having a flat characteristic
towards low speed.
The 2 sets of data must be based on measurement of power at approximately 50% and 85% of maximum speed with the
valves closed. The data is programmed in parameter group 22-3* No-Flow Power Tuning. It is also possible to run a [0] Low
Power Auto Set Up (parameter 22-20 Low Power Auto Set-up) automatically stepping through the commissioning process and
storing the data measured. Set the frequency converter for [0] Open Loop in parameter 1-00 Configuration Mode, when
carrying out the auto set-up, see parameter group 22-3* No-Flow Power Tuning No-flow Power Tuning.
NOTICE
If to use the integrated PI controller, carry out no-flow tuning before setting the PI controller parameters.
Low-speed detection
Low-speed detection gives a signal if the motor operates with minimum speed as set in parameter 4-11 Motor Speed Low
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 systems with a no-flow situation. Low-speed detection can be used in any
system where operation at minimum speed allows a stop of the motor until the load calls for a speed higher than minimum
speed. This could, for example, be in systems with fans and compressors.
MG03N202
Programming Guide
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