FCM 300 Series
MG.03.B6.02 - VLT is a registered Danfoss trademark
62
Special functions
Description of choice:
Select a limit to differentiator gain as required.
444 Process PID lowpass filter time
(PROC. FILTER TIME)
Settings:
0.01 - 10.00 sec
[1 - 1000]
✭
0.01 sec
[1]
Function:
Oscillations on the feedback signal are dampened by
the lowpass filter in order to reduce their impact on
the process regulation. This can be an advantage e.g.
if there is a lot of noise on the signal.
Used together with
Process, closed loop
mode
(parameter 100).
Description of choice:
Select the desired time constant (
τ
). If a time constant
(
τ
) of 100 ms is programmed, the break 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, the Process regulator will not react.
✭
=
factory setting. ( ) = parameter window text. [ ] = value for use in communication via serial communication port
445 Flying start
(FLYING START)
Settings:
★
Disable (DISABLE)
[0]
OK - same direction (OK-SAME DIRECTION)
[1]
OK - both directions (OK-BOTH DIRECTIONS) [2]
DC-brake before start
(DC-BRAKE BEF. START)
[3]
Function:
This function makes it possible to ‘catch‘ a motor,
which is spinning freely because of a mains drop-
out.
Description of choice:
Select
Disable
if this function is not required.
OK - same direction:
Chosen if the motor can only
rotate in same direction on cut-in.
OK - both directions:
Chosen if the motor can rotate
in both directions on cut-in.
DC-brake - before start:
Selected if the motor is to be
stopped using DC brake before the motor is ramped
up to the desired speed. The DC brake time must be
set in parameter 126.
Limitations:
1. Too low inertia will cause acceleration of the load,
which may be dangerous or prevent succesful
Flying start
. Use DC brake instead.
2. If load is driven eg. by "windmilling", the unit
might trip due to overvoltage.
3. Below 250 rpm the
Flying start
will not function.
446 Switching pattern
(SWITCH PATTERN)
Settings:
60° AVM (60° AVM)
[0]
★
SFAVM (SFAVM)
[1]
Description of choice:
Normally it is not necessary for the customer to set
this parameter.
