Danfoss VLT, Руководство по программированию

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1) Systems where the integrated PI controller is used for controlling pressure or temperature e.g. boost systems with a pressure
feed back signal applied to the frequency converter from a pressure transducer.
1-00 Configuration Mode must be set for Closed
Loop and the PI Controller configured for desired reference and feed back signals.
Example: Boost system.
p (Pressure)
Time
Time
No/Low Flow
detected
P 22-45
P 22-44
Sleep mode
activated
Boost
activated
P
Boost
P
Set
P
Wake
f
Ref
f
out
(Frequency)
P
System
130BA257.10
t
1
p
System
= p
Wake
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
22-45 Setpoint Boost ).
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).
External PID
controller
FC
130BA256.11
P
P
System
P
Set
f
Out
f
Ref
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.
1-00 Configuration Mode must be set for Open Loop.
Example: Boost system.
Parameter Description
VLT
®
HVAC Drive Programming Guide
146 MG.11.CB.02 - VLT
®
is a registered Danfoss trademark
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