Follow these steps if the slow first
cycle is chosen as the startup method:
- Select Slow first cycle in the Motor startup option [MTR_STARTUP] in "Control
Configuration – Motor Startup Stationary" tab in the GUI.
- Select align or slow first cycle current reference
[ALIGN_OR_SLOW_CURRENT_ILIMIT]. Lower current reference can lose synchronization
of motor. Higher current can lead to sustained oscillations for high inertia
motors, or sudden jerky motion for low inertia motors. It is recommended to
start with 50% of the rated current of the motor. In applications where the
startup torque is high, the motor might lose synchronization. In such
applications, increase the current reference. In applications where sustained
oscillations or sudden jerks are observed, decrease the current reference.
- Select align or slow first cycle current ramp rate [ALIGN_SLOW_RAMP_RATE].
Current reference is ramped to avoid reverse rotation of the motor. Lower
current ramp rate can lose synchronization of motor. A higher current ramp rate
can lead to sustained oscillations for high inertia motors, or sudden jerking
motion for low inertia motors. Start with setting the ramp time to 0.5 seconds
to ramp to rated current of the motor. In applications where the startup torque
is high, the motor can lose synchronization. In such applications, increase the
current ramp rate. In applications where sustained oscillations or sudden jerks
are observed, decrease the current ramp rate.
- Select the frequency of the first cycle [SLOW_FIRST_CYC_FREQ]. Lower frequency
can give a jerky motion at startup. Higher frequency might not be able to
synchronize the motor. Start with 20% of the maximum speed of the motor. In
applications where the startup torque is high, the motor can lose
synchronization. In such applications, decrease the frequency. In applications
where jerky motions are observed, increase the frequency.