Mitsubishi Electric 800 Series Instruction Manual (Function page 482

 Pre-excitation signal (LX signal)
• When the Pre-excitation/servo ON (LX) signal is turned ON while the motor stops under Real sensorless vector control or
Vector control, pre-excitation (zero speed control / servo lock) starts.
• To input the LX signal, set "23" in any of Pr.178 to Pr.189 (Input terminal function selection) to assign the function.
Zero speed control
Servo lock
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 may start the motor running at a low speed even
when the start signal (STF or STR) is not input. This product with the start command ON may also rotate the motor at a low
speed when the speed limit value is set to zero. Confirm that the motor running does not cause any safety problems before
performing pre-excitation.
• Note that during the pre-excitation operation, a voltage is applied to the motor even when the [RUN] LED on the operation
panel or the FWD/REV indicator on the parameter unit is OFF.
• When offline auto tuning (Pr.96 Auto tuning setting/status = "1 or 11") is performed during pre-excitation operation, pre-
excitation is disabled.
• When the LX signal is ON and the start signal is OFF at the automatic restart after instantaneous power failure, the motor does
not decelerates to stop from the detected motor speed, and pre-excitation (zero speed control / servo lock) is applied.
CAUTION
• Install a mechanical brake to make an emergency stop or to stay stopped for a long time.
• Wait until the machine stops completely, and fix the motor with a mechanical brake, then turn the LX signal (pre-
excitation) OFF.
Parameters referred to
Pr.13 Starting frequencypage 244,
Pr.71 Applied motorpage 380
Pr.80 Motor capacitypage 385
Pr.178 to Pr.189 (Input terminal function
When Pr. 850 = 1
(Hz)
Normal operation
Pr. 11
Operation time
LX signal
page 245
selection)page 368
17.6 DC injection brake, zero speed control, servo lock, and magnetic flux decay output shutoff
Pr. 10
Operation
frequency
Normal operation
ON
Time
17. (G) Control Parameters
11
12
13
14
15
16
17
18
19
20
481