Fantech VLT 2800 Series Instruction Manual page 75

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 .
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
(FEEDFORWARD FACT)
Value:
0 - 500 %
Function:
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.
= factory setting. () = display text [] = value for use in communication via serial communication port
74
.
MAX
100 %
VLT® 2800 Series
Description of choice:
The required % value can be selected in the interval
f - f . Values over 100 % are used if the
MIN MAX
set point variations are only small.
452 Controller range
(PID CONTR. RANGE)
Value:
0 - 200 %
Function:
This parameter is only active if in parameter
100 Configuration 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
frequency f . If the controller range is reduced the
M,N
speed variations will be less during initial tuning.
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 are
problems with overvoltage in the intermediate circuit.
MG.28.A8.22 - VLT is a registered Danfoss trademark
10 %
.
M,N
0
0