VLT
®
4000 VT
■
Sleep mode
Sleep mode makes it possible to stop the motor when
it is running at low speed, similar to a no load situation.
If consumption in the system goes back up, the AFD
will start the motor and supply the power required.
NOTE
Energy can be saved with this function,
since the motor is only in operation when
the system needs it.
Sleep mode is not active if
Local reference
or
Jog
has been selected
The function is active in both
Open loop
and
Closed loop
.
In parameter 403
Sleep mode timer
, the Sleep mode
is activated. In parameter 403
Sleep mode timer
,
a timer is set that determines how long the output
frequency can be lower than the frequency set in
parameter 404
Sleep frequency
. When the timer
runs out, the AFD will ramp down the motor to stop
via parameter 207
Ramp-down time
. If the output
frequency rises above the frequency set in parameter
404
Sleep frequency
, the timer is reset.
While the AFD has stopped the motor in sleep mode, a
theoretical output frequency is calculated on the basis
of the reference signal. When the theoretical output
frequency rises above the frequency in parameter 405
Wake up frequency
, the AFD will restart the motor and
the output frequency will ramp up to the reference.
In systems with constant pressure regulation, it is
advantageous to provide extra pressure to the system
before the AFD stops the motor. This extends the
time during which the AFD has stopped the motor
and helps to avoid frequent starting and stopping of
the motor, e.g. in the case of system leaks.
If 25% more pressure is required before the AFD stops
the motor, parameter 406
Boost setpoint
is set to 125%.
Parameter 406
Boost setpoint
is only active
in
Closed loop
.
NOTE
In highly dynamic pumping processes, it
is recommended to switch off the
Flying
Start
function (parameter 402).
MG.40.A7.22 - VLT is a registered Danfoss trademark
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