Danfoss VLT 2800 Design Manual page 102

Programming
Select [1] OK - same direction if the motor shaft is only able
to rotate in the same direction when cutting in. Select [1]
OK - same direction if [0] Clockwise only has been selected
in parameter 200 Output frequency range.
Select [2] OK - both directions if the motor is able to rotate
in both directions when cutting in.
Select [3] DC brake and start if the adjustable frequency
drive is to be able to brake the motor using the DC brake
4 4
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 adjustable
frequency drive is not able to catch a rotating motor
without selecting [3] DC brake and start.
Limitations:
•
Too low inertia leads 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
Value:
0 - 500%
Function:
This parameter is only active if in parameter 100 Configu-
ration 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 has 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 variations
MAX
are only small.
100
Design Guide
452
Value:
0 - 200%
Function:
This parameter is only active if [1] Speed control, closed
loop has been selected in parameter 100 Configuration.
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
M,N
is less during initial tuning.
455
Value:
Function:
Use this parameter to turn off warning 33 Out of frequency
range in the display in process control closed loop. This
parameter does not affect the extended status word.
Description of choice:
Select [1] Enable to enable the readout in the display if
warning 33 Out of frequency range occurs. Select [0] Disable
to disable the readout in the display if warning 33 out of
frequency range occurs.
100%
456
Value:
0-25 V if 200 V device
0-50 V if 400 V 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 Brake function 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
MIN
problems with overvoltage in the intermediate circuit.
Danfoss A/S © Rev. May/2014 All rights reserved.
Controller range
. If the controller range is reduced, the speed variations
Frequency range monitor
Disable
Enable
Brake Voltage Reduce
10%
.
M,N
[0]
[1]
0
0
MG27E402