Mitsubishi Electric 800 Series Instruction Manual page 605

(G) Control parameters
Pre-excitation signal (LX signal)
• When the Pre-excitation/servo ON (LX) signal is turned ON at the time of Real sensorless vector control or vector control,
pre-excitation (zero speed control, servo lock) will be ON while stopped.
• To input the LX signal, set "23" in any of Pr.178 to Pr.189 (Input terminal function selection) to assign the function.
NOTE
• Changing the terminal assignment using Pr.178 to Pr.189 (Input terminal function selection) may affect the other
functions. Set parameters after confirming the function of each terminal.
• Performing pre-excitation (LX signal and X13 signal) under torque control (Real sensorless vector control) may start the
motor running at a low speed even when the start command (STF or STR) is not input. The motor may run also at a low
speed when the speed limit value = 0 with a start command input. It must be confirmed that the motor running will not cause
any safety problem before performing pre-excitation.
• Note that during the pre-excitation operation, a voltage is applied to the motor even with the FWD/REV indicator OFF on the
operation panel.
• When offline auto tuning (Pr.96 Auto tuning setting/status = "1, 11, 101") is executed at the time of pre-excitation operation,
pre-excitation is disabled.
CAUTION
 Do not set Pr.11 to "0, 8888" and Pr.12 to "0" at the time of orientation operation. The motor may not
stop properly.
 Install a mechanical brake to make an emergency stop or to stay stopped for a long time.
After the machine comes to a full stop and the motor is fixed by the mechanical brake, turn OFF the
LX signal (pre-excitation).
Parameters referred to
Pr.13 Starting frequency page
Pr.71 Applied motor page 423
Pr.80 Motor capacity page 426
Pr.178 to Pr.182 (Input terminal function selection)
Pr.422 Position control gain, Pr.1298 Second position control gain
604
PARAMETERS
When Pr. 850 = 1
Output
frequency
(Hz)
Zero speed control
Servo lock
Normal operation
LX signal
283, page 284
page 415
Pr. 10
Operation
frequency
Normal operation
Pr. 11
Operation time
ON
page 236
Time