Technical information

8 – THEORY OF OPERATION
Acceleration Control
124
UTS Timer When the start mode is set to open-loop voltage ramp acceleration, the UTS Timer acts as an
acceleration kick. When the UTS timer expires, full voltage is applied to the motor. This feature can
be used to reduce motor surging that may occur near the end of an open loop voltage ramp start. If a
surge occurs near the end of the ramp, set the UTS timer to expire at this time and restart the motor.
If the surge still occurs, set the UTS time to a lower time until the surging subsides. If motor surging
continues to be a problem, it is recommended that one of the other standard MX closed-loop starting
profiles be used.
Figure 21 – Effect of UTS Timer on Voltage Ramp
Voltage
Time
Kick Time
Ramp
Time
Initial Voltage
Optional Kick
Current
Full Voltage
Start
command
UTS Time