Technical information

(if enabled) to start de-staging of lag pumps (fixed speed)
before stopping the lead pump (variable speed).
When entering Sleep Mode, the lower status line in the
Local Control Panel shows Sleep Mode.
See also signal flow chart in 3.20.1 22-2* No-Flow Detection.
There are three different ways of using the Sleep Mode
function:
130BA255.11
P
f
o
p
SL
FC
S
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.
130BA258.10
t
1
p
(Pressure)
Time
Time
No/Low Flow
detected
p
System
P
Set
Sleep mode
activated
P
Ref
= P
Wake
(Frequency)
f
Ref
f
Ref /
f
Out
f
Ref
f
Out
f
Wake
f
Out
Parameter Description
VLT
®
HVAC Drive Programming Guide
152 MG11CD02 - VLT
®
is a registered Danfoss trademark
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