Danfoss VLT FC 100 Series Programming Manual page 179

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VLT HVAC Drive Programming Guide 3. Parameter Description
3
If no flow is detected, the frequency converter will increase the set point for pressure to ensure a slight over pressure in the system (boost to be set in
Setpoint Boost
par. 22-45, ).
The feedback from the pressure transducer is monitored and when this pressure has dropped with a set percentage below the normal set point for
pressure (Pset), the motor will ramp up again and pressure will be controlled for reaching the set value (Pset).
2) In systems where the pressure or temperature is controlled by an external PI controller, the wake up conditions can not be based on feedback from
the pressure/temperature transducer as the setpoint is not known. In the example with a boost system, desired pressure Pset is not known. Par. 1-00,
Configuration mode
, must be set for Open Loop.
Example: Boost system.
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