Danfoss VLT AutomationDrive FC 302 Programming Manual page 54

Parameter Descriptions
1-80 Function at Stop
Option:
3 3
[4] DC Voltage
U0
[5] Coast at low
reference
[6] Motor check,
alarm
1-81 Min Speed for Function at Stop [RPM]
Range:
Size related
*
1-82 Min Speed for Function at Stop [Hz]
Range:
Size related
*
1-83 Precise Stop Function
Option:
52
Function:
1. Start the frequency converter
with a 0 RPM reference and wait 2
to 4 rotor time constants before
increasing the speed reference.
1a. Set parameter 1-71 Start Delay
to the desired pre-mag. time (2 to
4 rotor time constants. See the
time constants description further
in this section).
1b. Set parameter 1-72 Start
Function to either [0] DC hold or
[1] DC Brake.
Set the DC hold or DC brake
current magnitude
(parameter 2-00 DC Hold Current or
parameter 2-01 DC Brake Current)
to be equal to I_pre-mag = Unom/
(1.73 x Xh)
Sample rotor time constants =
(Xh+X2)/(6.3*Freq_nom*Rr)
1 kW = 0.2 s
10 kW = 0.5 s
100 kW = 1.7 s
1000 kW = 2.5 s
When the motor is stopped, the
parameter 1-55 U/f Characteristic - U [0]
defines the voltage at 0 Hz.
When the reference is below 1-81 Min Speed
for Function at Stop [RPM], the motor is
disconnected from the frequency converter.
Function:
[0 - 600 RPM] Set the speed at which to activate
1-80 Function at Stop.
Function:
[ 0 - 20.0 Hz] Set the output frequency at which
to activate 1-80 Function at Stop.
Function:
NOTICE
This parameter cannot be adjusted while
the motor is running.
FC 302 only.
Danfoss A/S © Rev. 10/2014 All rights reserved.
®
VLT AutomationDrive FC 301/302
1-83 Precise Stop Function
Option:
[0] Precise
ramp
*
stop
[1] Cnt stop
with
reset
[2] Cnt stop
w/o
reset
[3] Speed
comp
stop
[4] Com cnt
stop
w/rst
[5] Comp
cnt stop
w/o r
The precise stop functions are advantageous in
applications where high precision is required.
If using a standard stop command, the accuracy is
determined by the internal task time. That is not the case
when using the precise stop function; it eliminates the task
time dependence and increases the accuracy substantially.
Function:
Only optimal when the operational speed, for
example the operational speed of a conveyor belt
is constant. This is an open loop control. Achieves
high repetitive precision at the stopping point.
Counts the number of pulses, typically from an
encoder, and generates a stop signal after a pre-
programmed number of pulses, defined in
parameter parameter 1-84 Precise Stop Counter
Value,has been received at terminal 29 or terminal
33.
This is a direct feedback with one-way closed loop
control.
The counter function is activated (starts timing) at
the edge of the start signal (when it changes
from stop to start). After each precise stop, the
number of pulses counted during ramp down to
0 RPM is reset.
Same as [1] but the number of pulses counted
during ramp down to 0 RPM is deducted from the
counter value entered in parameter 1-84 Precise
Stop Counter Value.
This reset function can be used to compensate for
the extra distance done during ramping down
and to reduce the impacts of gradual wear of
mechanical parts.
Stops at precisely the same point, regardless of
the present speed. The stop signal is delayed
internally when the present speed is lower than
the maximum speed (set in parameter 4-19 Max
Output Frequency).
The delay is calculated on the basis of the
reference speed of the frequency converter and
not on the basis of the actual speed. Make sure
that the frequency converter has ramped up
before activating the speed compensated stop.
Same as [3] but after each precise stop, the
number of pulses counted during ramp down to
0 RPM is reset.
Same as [3] but the number of pulses counted
during ramp down to 0 RPM is deducted from the
counter value entered in parameter 1-84 Precise
Stop Counter Value.
This reset function can be used to compensate for
the extra distance done during ramping down
and to reduce the impacts of gradual wear of
mechanical parts.
MG33MJ02