Mitsubishi Electric FR-A800, Instruction Manual

Page: 850 / 1042

(G) Control parameters Parameters
5 - 670
Pre-excitation signal (LX signal)
●
When the Pre-excitation/servo ON (LX) signal is turned ON at the time of Real sensorless vector
control, vector control, or PM sensorless 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.
I001560E
Fig. 5-332: Selection of pre-excitation using an external signal
NOTES 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 com-
mand 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.
E
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 5-251, page 5-253
Pr. 71 Applied motor => page 5-434
Pr. 80 Motor capacity => page 5-67
Pr. 178 to Pr. 182 (input terminal function selection) => page 5-422
Pr. 422 Position control gain => page 5-181
Ou
tput freq
uenc
y
[H
z]
Time
LX signal
Pr. 11
"Operation
time"
Normal operation
Zero speed control
Normal operation
Pr. 10
"Operation
frequency"
ON
Servo lock