Mitsubishi FR-A800

Check first when you have a trouble
PROTECTIVE FUNCTIONS
667
6
6.6.4 Motor generates heat abnormally
6.6.5 Motor rotates in the opposite direction
6.6.6 Speed greatly differs from the setting
Check
points
Possible cause Countermeasure
Refer to
page
Motor
Motor fan is not working
(Dust is accumulated.)
Clean the motor fan.
Improve the environment.

Phase to phase insulation of the motor is
insufficient.
Check the insulation of the motor. 
Main
Circuit
The inverter output voltage (U, V, W) are
unbalanced.
Check the output voltage of the inverter.
Check the insulation of the motor.
683
Parameter
Setting
Pr.71 Applied motor setting is incorrect. Check the Pr.71 Applied motor setting. 438

Motor current is large. Refer to "6.6.11 Motor current is too large". 669
Check
points
Possible cause Countermeasure
Refer to
page
Main
Circuit
Phase sequence of output terminals U, V and
W is incorrect.
Connect phase sequence of the output cables
(terminal U, V, W) to the motor correctly.
38
Input
signal
The start signals (forward rotation, reverse
rotation) are connected improperly.
Check the wiring.
(STF: forward rotation, STR: reverse rotation)
45, 436
The polarity of the frequency command is
negative during the polarity reversible
operation set by Pr.73 Analog input
selection .
Check the polarity of the frequency command. 406
Input
signal
Parameter
Setting
Torque command is negative during torque
control under vector control.
Check the torque command value. 216
Check
points
Possible cause Countermeasure
Refer to
page
Input
signal
Frequency setting signal is incorrectly input. Measure the input signal level. 
The input signal lines are affected by external
EMI.
Take countermeasures against EMI, such as using shielded
wires for input signal lines.
84
Parameter
Setting
Pr.1 Maximum frequency, Pr.2 Minimum
frequency, Pr.18 High speed maximum
frequency, and calibration parameter C2 to
C7 settings are improper.
Check the settings of Pr.1, Pr.2, and Pr.18. 345
Check the calibration parameter C2 to C7 settings. 415
Pr.31 to Pr.36, Pr.552 (frequency jump)
settings are improper.
Narrow down the range of frequency jump. 346
Load
Stall prevention (torque limit) function is
activated due to a heavy load.
Reduce the load weight. 
Parameter
Setting
Set Pr.22 Stall prevention operation level (torque limit level)
higher according to the load. (If Pr.22 is set too high, an
overcurrent trip (E.OC[]) is likely to occur.)
185, 348
Motor
Check the capacities of the inverter and the motor. 