Minimum switch-off times
4.4.23.1 Overview of variable minimum switch-off times
A minimum switch-off time is defined for each power unit, which expires in the de-
fault setting before the modulation can be reactivated.
If the bit "Enable operation" in the controlword is set to 1 and the time has not yet
expired, the state in st12 is set to "12: Mod off pause active“.
If the minimum switch-off time of the device has expired, no new edge of "Enable
operation" is required, the drive changes automatically into state "Start operation
active".
This minimum switch-off time reduces the load for the drive and the application. A
motor which is still rotating or a rotor flux that has not yet been reduced can gener-
ate undefined torques when switching on again.
In other cases, the minimum switch-off time is unnecessary or interferes with the
application, e.g. when the drive has come to a defined standstill.
4.4.23.2 Configuration of the minimum switch-off time
Use of the variable modulation minimum-off time
customer modulation off time
Setting of the variable modulation minimum
switch-off time
Display whether minimum switch-off time is active
Parameter pn85 can be used to configure whether and when the user-defined in-
stead of the default minimum switch-off times from the power unit data shall be
used.
Additionally the user-defined time can be preset there.
SubIndex 1 can be used to define when the alternative minimum switch-off time
shall be used.
Use the time from pn85[2] if a restart shall occur after auto-retry.
Use of the time from pn85[2] only if the actual speed at the time of mod-
ulation deactivation is < 10% of the rated motor speed.
If the user-defined minimum switch-on time is active, it will not be
changed again until the next switch-on.
The time parameterized by the customer is always used as the mini-
mum switch-off time.
If this bit is set, the other settings have no function.
after error reset the time from pn85[2] is used, unless it is an error that
requires a protection time (OC, OL2, OP, OP2). Then the protection
time is the minimum time that is always observed. If pn85[2] is higher
than the protection time, pn85[2] is used.
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