Danfoss VLT AutomationDrive FC 300 Programming Manual page 50

Parameter Descriptions
1-83 Precise Stop Function
Option:
[3] Speed
comp
stop
3 3
[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 you use 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.
The frequency converter tolerance is normally given by its
task time. However, by using its special precise stop
function the tolerance is independent of the task time
because the stop signal immediately interrupts the
execution of the frequency converter program. The precise
stop function gives a highly reproducible delay from the
stop signal is given until the ramping down starts. A test
must be done to find this delay as it is a sum of sensor,
PLC, frequency converter and mechanical parts.
To ensure optimum accuracy there should be at least 10
cycles during ramping down, see 3-42 Ramp 1 Ramp Down
Time, 3-52 Ramp 2 Ramp Down Time, 3-62 Ramp 3 Ramp
down Time and 3-72 Ramp 4 Ramp Down Time.
The Precise Stop Function is set up here and enabled from
DI T29 or T33.
1-84 Precise Stop Counter Value
Range:
100000 [0 -
*
999999999 ]
48
VLT
Function:
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 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. Please
therefore make sure that the frequency converter
has ramped up before you activate 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 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.
Function:
Enter the counter value to be used
in the integrated precise stop
function, 1-83 Precise Stop Function.
The maximum permissible frequency
at terminal 29 or 33 is 110 kHz.
MG33MG02 - VLT
®
AutomationDrive Programming Guide
1-84 Precise Stop Counter Value
Range:
1-85 Precise Stop Speed Compensation Delay
Range:
10 ms [0 - 100
*
ms]
3.3.10 1-9* Motor Temperature
1-90 Motor Thermal Protection
Option:
[0] No
protection
®
is a registered Danfoss trademark
Function:
NOTE
Not used for selection [0] and
[3] in 1-83 Precise Stop Function
Function:
Enter the delay time for sensors, PLCs, etc.
for use in 1-83 Precise Stop Function. In
speed compensated stop mode, the delay
time at different frequencies has a major
influence on the stop function.
NOTE
Not used for selection [0], [1] and [2] in
1-83 Precise Stop Function
Function:
Thermal motor protection can be
implemented using a range of techniques:
•
Via a PTC sensor in the motor
windings connected to one of the
analog or digital inputs
(1-93 Thermistor Source). See
3.3.11.1 PTC Thermistor Connection.
•
Via a KTY sensor in the motor
winding connected to an analog
input (1-96 KTY Thermistor Resource).
See 3.3.11.2 KTY Sensor Connection.
•
Via calculation (ETR = Electronic
Thermal Relay) of the thermal load,
based on the actual load and time.
The calculated thermal load is
compared with the rated motor
current I and the rated motor
M,N
frequency f . See 3.3.11.3 ETR and
M,N
3.3.11.4 ATEX ETR.
•
Via a mechanical thermal switch
(Klixon type). See 3.3.11.5 Klixon.
For the North American market: The ETR
functions provide class 20 motor overload
protection in accordance with NEC.
Continuously overloaded motor, when no
warning or trip of the frequency converter is
required.