Function:
When the adjustable frequency drive registers that the
output current has reached the current limit I
LIM
(pa-
rameter 221
Current limit
) and remains there for the
preset time, it is disconnected. Can be used to protect
the application, like the ETR will protect the motor if
selected.
Description of choice:
Select how long the adjustable frequency drive should
maintain the output current at the current limit I
LIM
be-
fore it disconnects. At OFF parameter 409
Trip delay
overcurrent, I
LIM
is not working, i.e. disconnection will
not take place.
411
Switching frequency
(Switch freq.)
Value:
3000 - 14000 Hz (VLT 2803 - 2875)
4500 Hz
3000 - 10000 Hz (VLT 2880 - 2882)
4500 Hz
Function:
The set value determines the switching frequency of
the inverter. If the switching frequency is changed, this
may help to minimise possible acoustic noise from the
motor.
NOTE
The output frequency of the adjustable
frequency drive can never assume a value
higher than 1/10 of the switching frequen-
cy.
Description of choice:
When the motor is running, the switching frequency is
adjusted in parameter 411
Switching frequency
until
the frequency has been obtained at which the motor is
as low-noise as possible.
NOTE
The switching frequency is reduced auto-
matically as a function of the load. See
Temperature-Dependent Switching Fre-
quency
under
Special Conditions
.
When
LC-filter connected
is selected in
parameter 412, the minimum switching
frequency is 4.5 kHz.
412
Variable switching frequency
(Var carrier freq.)
Value:
Without LC-filter (WITHOUT LC-FILTER)
[2]
LC-filter connected
(LC-filter connected)
[3]
Function:
The parameter must be set to
LC-filter connected
if an
LC-filter is connected between the adjustable frequen-
cy drive and the motor.
Description of choice:
The LC-filter connected
[3] must be used if an LC-filter
is connected between the adjustable frequency drive
and the motor, as otherwise the adjustable frequency
drive cannot protect the LC-filter.
NOTE
When the LC filter is selected the switch-
ing frequency is changed to 4.5 kHz.
413
Overmodulation function
(OVERMODULATION)
Value:
Off (off)
[0]
On (on)
[1]
Function:
This parameter allows connection of the overmodula-
tion function for the output voltage.
Description of choice:
Off
[0] means that there is no overmodulation of the
output voltage, which means that torque ripple on the
motor shaft is avoided. This can be a good feature, e.g.
on grinding machines.
On
[1] means that an output
voltage can be obtained which is greater than the
mains voltage (up to 5 %).
VLT
®
2800 Series
= factory setting, () = display text, [] = value for use in communication via serial communication port
70
MG.27.A2.22 - VLT
®
is a registered Danfoss trademark