Mitsubishi Electric FR-A740-00023 Instruction Manual page 207

(6) Pre-excitation signal (LX signal)
⋅ When the LX signal is turned on under real sensorless vector control or vector control, pre-excitation (zero speed
control or servo lock) is exercised during a stop.
⋅ For the terminal used for LX signal input, set "23" in any of Pr. 178 to Pr. 186 to assign the function.
Zero speed control
Servo lock
CAUTION
⋅ Changing the terminal assignment using Pr. 178 to Pr. 189 (input terminal function selection) may affect the other functions. Make
setting 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. Perform pre-excitation after making sure that there will be no problem in
safety if the motor runs.
⋅ Although FWD/REV of the operation panel is not lit during pre-excitation, note that voltage is applied to the motor.
⋅ Note that when offline auto tuning (Pr. 96 Auto tuning setting/status = "1 or 101") is performed during pre-excitation, offline auto
tuning is not executed but the motor starts.
Do not set Pr. 11 to "0, 8888" and Pr. 12 to "0" under orientation operation. Otherwise, the motor will not stop properly.
As stop holding torque is not produced, install a mechanical brake.
After the machine stops fully and the mechanical brake is applied, switch the LX signal (pre-excitation) off.
♦ Parameters referred to ♦
Pr. 13 Starting frequency Refer to page 169
Pr. 71 Applied motor Refer to page 179
Pr. 178 to Pr. 189 (Input terminal function selection)
Pr. 422 Position loop gain Refer to page 133
When Pr. 850 = 1
(Hz)
Normal operation Pr. 11
Operation time
LX signal
CAUTION
Refer to page 222
Motor brake and stop operation
Pr. 10
Operation
frequency
Normal operation
ON
Time
197
4