Danfoss VLT 2800 Series Operating Instructions Manual page 52

200 Output frequency range a selection has been of
Clockwise only .
Select OK - both directions [2] if the motor is able to
rotate in both directions when cutting in.
Select DC brake and start [3] if the frequency converter
is to be able to brake the motor using the DC brake
first, followed by start. It is assumed that parameters
126-127/132 DC brake are enabled. In the case of
higher 'Windmilling' (rotating motor) effects, the fre-
quency converter is not able to 'catch' a rotating motor
without selecting DC brake and start .
Limitations:
- Too low inertia will lead to load acceleration,
which can be dangerous or prevent correct
catching of a rotating motor. Use the DC
brake instead.
If the load is driven, e.g. by 'Windmilling' (ro-
-
tating motor) effects, the unit may cut out
because of overvoltage.
- Flying start does not work at lower values
than 250 rpm.
451 Speed PID feedforward factor
(feedforward fact)
Value:
0 - 500 %
Function:
This parameter is only active if in parameter 100 Con-
figuration the selection made is Speed regulation,
closed loop. The FF function sends a larger or smaller
part of the reference signal outside the PID controller
in such a way that the PID controller only has an influ-
ence on part of the control signal. Any change to the
set point will thus have a direct effect on the motor
speed. The FF factor provides high dynamism when
changing the set point and less overswing.
Description of choice:
The required % value can be selected in the interval f
- f . Values over 100 % are used if the set point
MIN MAX
variations are only small.
= factory setting, () = display text, [] = value for use in communication via serial communication port
®
MG.27.A2.02 - VLT is a registered Danfoss trademark
VLT
452 Controller range
(pid contr. range)
Value:
0 - 200 %
Function:
This parameter is only active if in parameter 100 Con-
figuration the selection made is Speed regulation,
closed loop.
The controller range (bandwidth) limits the output from
the PID controller as a % of motor frequency f
Description of choice:
The required % value can be selected for motor fre-
quency f . If the controller range is reduced the
M,N
speed variations will be less during initial tuning.
455 Frequency range monitor
(MON. FREQ. RANGE)
Value:
Disable
Enable
Function:
This parameter is used if warning 33 Out of frequency
range must be turned off in the display in process con-
trol closed loop. This parameter does not affect the
100 %
extended status word.
Description of choice:
Select Enable [1] to enable the readout in the display
if warning 33 Out of frequency range occurs. Select
Disable [0] to disable the readout in the display if warn-
ing 33 ut of frequency range occurs.
456 Brake Voltage Reduce
(BRAKE VOL REDUCE)
Value:
0 - 25 V if 200V device
0 - 50 V if 400V device
Function:
The user sets the voltage by which the level for resistor
braking is reduced. It is only active when resistor in
parameter 400 is selected.
Description of choice:
The greater the reduction value, the faster the reaction
to a generator overload. Should only be used if there
®
2800 Series
10 %
.
M,N
[0]
[1]
0
0
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