Mitsubishi Electric FR-A740-00023 Instruction Manual page 408

Causes and corrective actions
(4) Major fault
When the protective function is activated, the inverter output is shut off and an alarm is output.
Operation Panel
Indication
Name
Description
Check point
Corrective action
Operation Panel
Indication
Name
Description
Check point
Corrective action
Operation Panel
Indication
Name
Description
Check point
Corrective action
398
E.OC1
Overcurrent shut-off during acceleration
When the inverter output current reaches or exceeds approximately 220% of the rated current during
acceleration, the protective circuit is activated to stop the inverter output.
1. Check for sudden acceleration.
2. Check that the downward acceleration time is not long in vertical lift application.
3. Check for output short circuit.
4. Check that stall prevention operation is correct.
5. Check that the regeneration is not performed frequently. (Check that the output voltage becomes
larger than the V/F reference voltage at regeneration and overcurrent due to increase in motor
current occurs.)
6. Check that the power supply for RS-485 terminal is not shorted. (under vector control)
7. Check that the rotation direction is not switched from forward to reverse rotation (or from reverse to
forward) during torque control under real sensorless vector control.
1. Increase the acceleration time.
(Shorten the downward acceleration time in vertical lift application.)
2. When "E.OC1" is always lit at starting, disconnect the motor once and start the inverter.
If "E.OC1" is still lit, contact your sales representative.
3. Check the wiring to make sure that output short circuit does not occur.
4. Perform a correct stall prevention operation. (Refer to page 144.)
5. Set base voltage (rated voltage of the motor, etc.) in Pr. 19 Base frequency voltage. (Refer to page 153.)
6. Check RS-485 terminal connection. (under vector control)
7. Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to
forward) during torque control under real sensorless vector control.
E.OC2
Overcurrent shut-off during constant speed
When the inverter output current reaches or exceeds approximately 220% of the rated current during
constant speed operation, the protective circuit is activated to stop the inverter output.
1. Check for sudden load change.
2. Check for output short circuit.
3. Check that stall prevention operation is correct
4. Check that the power supply for RS-485 terminal is not shorted. (under vector control)
5. Check that the rotation direction is not switched from forward to reverse rotation (or from reverse to
forward) during torque control under real sensorless vector control.
1. Keep load stable.
2. Check the wiring to make sure that output short circuit does not occur.
3. Check that stall prevention operation setting is correct. (Refer to page 144.)
4. Check RS-485 terminal connection. (under vector control)
5. Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to
forward) during torque control under real sensorless vector control.
E.OC3
Overcurrent shut-off during deceleration or stop
When the inverter output current reaches or exceeds approximately 220% of the rated inverter current
during deceleration (other than acceleration or constant speed), the protective circuit is activated to
stop the inverter output.
1. Check for sudden speed reduction.
2. Check for output short circuit.
3. Check for too fast operation of the motor's mechanical brake.
4. Check that stall prevention operation setting is correct.
5. Check that the power supply for RS-485 terminal is not shorted. (under vector control)
6. Check that the rotation direction is not switched from forward to reverse rotation (or from reverse to
forward) during torque control under real sensorless vector control.
1. Increase the deceleration time.
2. Check the wiring to make sure that output short circuit does not occur.
3. Check the mechanical brake operation.
4. Check that stall prevention operation setting is correct.(Refer to page 144.)
5. Check RS-485 terminal connection. (under vector control)
6. Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to
forward) during torque control under real sensorless vector control.
FR-PU04
OC During Accs
FR-PU07
FR-PU04
Stedy Spd OC
FR-PU07
FR-PU04
OC During Dec
FR-PU07