Danfoss VLT AutomationDrive FC 300 Programming Manual page 49

Parameter Descriptions
1-76 Start Current
Range: Function:
1-76 Start Current. Set 1-74 Start Speed [RPM]. Set
1-72 Start Function to [3] Start speed cw or [4]
Horizontal operation, and set a start delay time
in 1-71 Start Delay.
This parameter can be used for hoist
applications (cone rotor).
3.3.9 1-8* Stop Adjustments
1-80 Function at Stop
Option: Function:
Select the frequency converter function after
a stop command or after the speed is
ramped down to the settings in 1-81 Min
Speed for Function at Stop [RPM].
[0] Coast Leaves motor in free mode. The motor is
disconnected from the frequency converter.
[1] DC hold Energizes motor with a DC holding current
(see 2-00 DC Hold Current).
[2] Motor check Checks if a motor has been connected.
[3] Pre- Builds up a magnetic field while the motor is
magnetizing stopped. This allows the motor to produce
torque quickly at subsequent start
commands (asynchronous motors only). This
Pre-magnetizing function does not help the
very first start command. Two different
solutions are available to pre-magnetize the
machine for the first start command:
1. Start the frequency converter
with a 0 RPM reference and wait 2
to 4 rotor time constants (see
below) before increasing the speed
reference.
2a. Set 1-71 Start Delay to the
desired pre-mag time (2 to 4 rotor
time constants - see below).
2b. Set 1-72 Start Function to either
[0] DC-hold or [1] DC-Brake.
Set the DC-hold or DC-brake
current magnitude (2-00 DC Hold
Current or 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
®
VLT AutomationDrive Programming Guide
1-80 Function at Stop
Option:
[4] DC Voltage
[5] Coast at low
[6] Motor check,
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:
[0] Precise
[1] Cnt stop
[2] Cnt stop
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MG33MG02 - VLT is a registered Danfoss trademark
Function:
When the motor is stopped, the 1-55 U/f
U0 Characteristic - U [0] parameter defines the
voltage at 0 Hz.
When the reference is below 1-81 Min Speed
reference for Function at Stop [RPM], the motor is
disconnected from the frequency converter.
alarm
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:
NOTE
This parameter cannot be adjusted while
the motor is running.
FC 302 only.
Only optimal when the operational speed - of e.g.
ramp the conveyor belt - is constant. This is an open
stop loop control. Achieves high repetitive precision at
the stopping point.
Counts the number of pulses, typically from an
with reset encoder and generates a stop signal after a pre-
programmed number of pulses - 1-84 Precise Stop
Counter Value - has been received at T29 or T33
[30].
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
w/o reset during ramp down to 0 rpm is deducted from
the counter value entered in 1-84 Precise Stop
Counter Value.
This reset function can for example be used to
compensate for the extra distance done during
ramping down and to reduce the impacts of
gradual wear of mechanical parts.
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