Danfoss VLT HVAC Drive FC 102 Programming Manual page 162

Parameter Descriptions
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. Programme the
actual configuration in parameter 1-00 Configuration Mode.
Configuration mode for
•
3 3
Integrated PI controller: Closed loop
•
External PI controller: Open loop
NOTICE
Carry out no-flow tuning before setting the PI controller parameters.
Table 3.23 No Flow Detection
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. By monitoring the power, it
is possible to detect no-flow conditions in systems with fluctuating suction pressure, or if the pump has 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
valve(s) 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
also automatically storing the data measured. The frequency converter must be set 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.
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VLT HVAC Drive FC 102
Head
1
2
Flow
MG11CE02