Trane TR200 Programming Manual page 222

CAUTION
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 adjustable fre-
quency drive 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.
CAUTION
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
Low Limit [RPM] or par.4-12
vidual 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.
CAUTION
In pump systems, ensure that the minimum speed in par.4-11
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.
TR200 Programming Guide
Motor Speed Low Limit [Hz]. Actions are common with No Flow Detection (indi-
Parameter Description
Motor Speed Low Limit [RPM]
Motor Speed
or par.4-12 Motor Speed
4-185