Motor Generates Heat Abnormally; Motor Rotates In Opposite Direction; Speed Greatly Differs From The Setting; Acceleration/Deceleration Is Not Smooth - Mitsubishi Electric FR-A720-0.4K Instruction Manual

Check first when you have troubles

5.5.3 Motor generates heat abnormally

Is the fan for the motor is running? (Check for accumulated dust.)
Check that the load is not too heavy. Lighten the load.
Check that the inverter output voltages (U, V, W) balanced.
Check that the Pr. 0 Torque boost setting is correct.
Was the motor type set? Check the setting of Pr. 71 Applied motor.
When using any other manufacturer's motor, perform offline auto tuning. (Refer to page 181.)

5.5.4 Motor rotates in opposite direction

Check that the phase sequence of output terminals U, V and W is correct.
Check that the start signals (forward rotation, reverse rotation) are connected properly. (Refer to page 28)

5.5.5 Speed greatly differs from the setting

Check that the frequency setting signal is correct. (Measure the input signal level.)
Check that the Pr. 1, Pr. 2, Pr. 19, Calibration parameter C2 to C7 settings are correct
Check that the input signal lines are not affected by external noise.
(Use shielded cables)
Check that the load is not too heavy.
Check that the Pr. 31 to Pr. 36 (frequency jump) settings are correct.

5.5.6 Acceleration/deceleration is not smooth

Check that the acceleration and deceleration time settings are not too short.
Check that the load is not too heavy.
Check that the torque boost (Pr. 0, Pr. 46, Pr. 112) setting is not too large to activate the stall function (torque
limit).

5.5.7 Motor current is large

Check that the load is not too heavy.
Check that the Pr. 0 Torque boost setting is appropriate.
Check that the Pr. 3 Base frequency setting is appropriate.
Check that the Pr. 14 Load pattern selection setting is appropriate.
Check that the Pr. 19 Base frequency voltage setting is appropriate.

5.5.8 Speed does not increase

Check that the maximum frequency (Pr. 1) setting is correct. (If you want to run the motor at 120Hz or
more, set Pr. 18 High speed maximum frequency. (Refer to page 153.))
Check that the load is not too heavy.
(In agitators, etc., load may become heavier in winter.)
Check that the torque boost (Pr.0, Pr.46, Pr.112) setting is not too large to activate the stall function under V/F
control.
Check that the brake resistor is not connected to terminals P/+-P1 accidentally.
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