Danfoss VLT AQUA Drive FC 200 Programming Manual page 154

Parameter Description
Sleep mode can be activated either from the No-Flow
Detection/Minimum Speed Detection or via an external
signal applied to one of the digital inputs (must be
programmed via the parameters for configuration of the
3 3
digital inputs, parameter group 5-1*).
To make it possible to use, for example, an electro-
mechanical flow switch to detect a no flow condition and
activate Sleep mode, the action takes place at raising edge
of the external signal applied (otherwise, the adjustable
frequency drive would never come out of Sleep mode as
the signal would be steady connected).
If 25-26 Destage At No-Flow is set for Enabled, activating
Sleep mode will apply a command to the cascade
controller (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, Figure 3.48.
There are three different ways of using the Sleep mode
function:
Figure 3.51 Legend: FC=adjustable frequency drive; f
out; P =P system; P
S
1) Systems where the integrated PI controller is used for
controlling pressure or temperature, e.g., boost systems
with a pressure feedback signal applied to the adjustable
frequency drive from a pressure transducer. 1-00 Configu-
ration Mode must be set for Closed-loop and the PI
controller configured for desired reference and feedback
signals.
Example: Boost system.
3-128
®
VLT
=P setpoint
SL
MG20O622 - VLT
AQUA Drive Programming Guide
P
Boost
P 22-45
P
Set
P 22-44
P
Wake
Figure 3.52
If no-flow is detected, the adjustable frequency drive will
increase the setpoint for pressure to ensure a slight
overpressure 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 setpoint for pressure (Pset), the motor
will ramp up again and pressure will be controlled for
reaching the set value (Pset).
FC
=frequency
O
Figure 3.53
®
is a registered Danfoss trademark
p (Pressure)
P
System
f (Frequency)
f
out
Ref
t
No/Low Flow Sleep mode
1
detected activated
p
System
Boost
activated
External PID
controller
f
P
Ref
Set
P
System
f
Out
P
Time
Time
= p
Wake