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 P
set
is not known. Par. 1-00,
Configuration mode
, must be set for Open Loop.
Example: Boost system.
When low power or low speed is detected the motor is stopped, but the reference signal (f
ref
) from the external controller is still monitored and because
of the low pressure created, the controller will increase the reference signal to gain pressure. When the reference signal has reached a set value f
wake
the motor restarts.
The speed is set manually by an external reference signal (Remote Reference). The settings (par. 22-3*) for tuning of the No Flow function must be set
to default.
2 Parameter Description
VLT
p
Automation VT Drive FC322
Programming Guide
218
MG.20.W1.22 - VLT
p
is a registered Danfoss trademark
2
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