Operating instructions

NOTE
Carry out No Flow tuning before setting the PI controller
parameters!
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 two 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 two sets of data must be based on measurement of power
at approx. 50% and 85% of maximum speed with the valve(s)
closed. The data are programmed in the parameter group
22-3*. It is also possible to run a Low Power Auto Set Up
(par. 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 Open Loop in par. 1-00 Configuration Mode, when
carrying out the Auto Set Up (See No Flow Tuning parameter
group 22-3*).
NOTE
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 is operating
with minimum speed as set in par. 4-11 Motor Speed Low Limit
[RPM] or par. 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, but can be used in any system where
operation at minimum speed allows for a stop of the motor
until the load calls for a speed higher than minimum speed,
e.g. systems with fans and compressors.
NOTE
In pump systems ensure that the minimum speed in
par. 4-11 Motor Speed Low Limit [RPM] or par. 4-12 Motor
Speed Low Limit [Hz] has been set high enough for
detection as the pump can run with a rather high speed
even with valves closed.
Dry pump detection:
No Flow Detection can also be used for detecting if the pump
has run dry (low power consumption-high speed). Can be
used with both the integrated PI controller and an external PI
controller.
The condition for Dry Pump signal:
- Power consumption below no flow level
and
- Pump running at maximum speed or maximum
reference open loop, whichever is lowest.
The signal must be active for a set time (par. 22-27 Dry Pump
Delay) before selected the action takes place.
Possible Actions to select (par. 22-26 Dry Pump Function):
- Warning
- Alarm
No Flow Detection must be enabled (par. 22-23 No-Flow
Function) and commissioned (parameter group 22-3*, No
Power Tuning).
Parameter Description
VLT
®
HVAC Drive Programming Guide
140 MG.11.CA.02 - VLT
®
is a registered Danfoss trademark
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