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at slow changes and a constant differentiator gain
where quick changes to the deviation occur.
Description of choice:
Select a differentiator gain limit as required.
444 Process PID lowpass filter time
(PROC FILTER TIME)
Value:
0.02 - 10.00
Function:
Noise in the feedback signal is dampened by a first
order lowpass filter to reduce the noise's impact on
the process regulation. This can be an advantage
e.g. if there is a lot of noise on the signal.
Description of choice:
Select the required time constant (t). If a time constant
(t) of 0.1 s is programmed, the cut-off frequency
for the lowpass filter will be 1/0.1 = 10 RAD/sec.,
corresponding to (10 / 2 x π) = 1.6 Hz. The process
regulator will thus only regulate a feedback signal
that varies by a frequency lower than 1.6 Hz. If the
feedback signal varies by a higher frequency than 1.6
Hz, it will be dampened by the lowpass filter.
445 Flying start
(FLYING START)
Value:
Off (DISABLE)
OK - same direction
(OK-SAME DIRECTION)
OK - both directions
(OK-BOTH DIRECTIONS)
DC brake and start
(DC-BRAKE BEF. START)
Function:
This function makes it possible to 'catch' a rotating
motor shaft, which is no longer controlled by the
variable frequency drive, e.g. because of an AC line
drop-out. The function is activated each time a start
command is enabled. For the variable frequency
drive to be able to 'catch' the rotating motor shaft,
the motor speed must be lower than the frequency
= factory setting. () = display text [] = value for use in communication via serial communication port
MG.90.F2.22 - VLT is a registered Danfoss trademark
Decentral Solutions
that corresponds to the frequency in parameter
202 Output frequency, high limit, f
Description of choice:
Select Disable [0] if this function is not required.
Select OK - same direction [1] if the motor shaft
is only able to rotate in the same direction when
cutting in. OK - same direction [1] should be
selected if in parameter 200 Output frequency range
a selection has been of Clockwise only .
0.02
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 variable
frequency drive 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'
(rotating 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
[0]
(FEEDFORWARD FACT)
[1]
Value:
0 - 500 %
[2]
Function:
[3]
This parameter is only active if in parameter 100
Configuration 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
influence 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.
.
MAX
100 %
147
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