Danfoss VLT HVAC Drive FC 102 Programming Manual page 168

Parameter Descriptions
the system (boost to be set in parameter 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 setpoint for pressure (P
ramps up again and pressure controlled for reaching the
3 3
set value (P ).
set
FC
f
Out
Illustration 3.53 Boost System
2) In systems where the pressure or temperature is
controlled by an external PI controller, the wake-up
conditions cannot be based on feedback from the
pressure/temperature transducer as the setpoint is not
known. In the example with a boost system, desired
No-flow detection (pumps only) Yes
Low speed detection
External signal
Pressure/temperature
(transmitter connected)
Output frequency
Table 3.24 Configuration Overview
NOTICE
Sleep mode does not active when local reference is
active (press the navigation keys to set speed manually).
See 3-13 Reference Site.
Does not work in Hand mode. Carry out Auto set-up in
open loop before setting input/output in closed loop.
166
VLT
), the motor
set
External PID
controller
f
P
Ref
Set
P
System
P
Internal PI controller
(parameter 1-00 Configuration Mode: Closed loop)
Sleep mode
Yes
Yes
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®
HVAC Drive FC 102
pressure P
set
Mode for [0] Open Loop.
Example: Boost system.
p
P
Set
f f
Ref Out
f
Wake
Illustration 3.54 Boost System
When low power or low speed is detected the motor is
stopped, but the reference signal (f
controller is still monitored. Because of the low pressure
created, the controller increases the reference signal to
gain pressure. When the reference signal has reached a set
value, f , the motor restarts.
wake
The speed is set manually by an external reference signal
(Remote Reference). Use default settings (parameter group
22-3* No-Flow Power Tuning) for tuning of the no-flow
function.
Wake up
Yes
No
is not known. Parameter 1-00 Configuration
(Pressure)
p
System
(Frequency)
f f
Ref / Out
f
Ref
t
f
1
Out
No/Low Flow Sleep mode
detected activated
P
Ref
) from the external
ref
External PI controller or manual control
(parameter 1-00 Configuration Mode: Open loop)
Sleep mode Wake up
Yes (except manual
setting of speed)
Yes
Yes
No
Yes
Time
Time
= P
Wake
MG11CE02