Vector control
5.17 Flying restart
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
271
After power ON, the "flying restart" function automatically connects a Motor Module to a
motor which may already be turning. This function can be activated during operation with or
without an encoder.
Unplanned movement of the motor when flying restart is activated
When the "flying restart" (p1200) is activated, the drive can still be accelerated by the
search current despite the fact that it is at standstill and the setpoint is "0"; this can result in
death, severe injury or material damage.
• Ensure that nobody is in the hazardous zone - and that the mechanical system can
freely move.
1. The "Flying restart" function should be activated via p1200 especially for loads which may
coast after power interruption.
This prevents sudden loads in the entire mechanics.
2. With an induction motor, the system waits for a demagnetization time to elapse before the
search is carried out. The demagnetization time can reduce the voltage at the motor
terminals. At the pulse enable, this avoids high equalizing currents due to a phase short-
circuit.
An internal demagnetization time is calculated. In addition, you can define a de-excitation
time via parameter p0347. The system waits for the longer of the two times to elapse.
– In operation without an encoder, a search is carried out initially for the current speed.
The search starts at the maximum speed plus 25%. A Voltage Sensing Module (VSM)
is required for permanent-magnet synchronous motors (for additional information, see
SINAMICS S120 Control Units Manual and SINAMICS S120/S150 List Manual in
parameter p1200).
– When operated with an encoder (actual speed value is sensed), the search phase is
eliminated.
3. For an induction or reluctance motor, immediately after the speed has been determined,
magnetization starts (p0346).
4. The current speed setpoint in the ramp-function generator is then set to the current actual
speed value.
The ramp-up to the final speed setpoint starts with this value.
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