Mitsubishi FR-A721-11K Instruction Manual page 155

Causes and corrective actions
Operation Panel
Indication
Name
Description
Check point
Corrective action
Operation Panel
Indication
Name
Description
Check point
Corrective action
148
E.OC2
Overcurrent trip 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.
Check for sudden load change.
Check for output short circuit.
Check if the stall prevention operation level is set too high.
Check if the fast-response current limit operation is disabled.
Check that the power supply for RS-485 terminal is not shorted. (under vector control)
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.
Check if a start command is given to the inverter while the motor is coasting.
Keep load stable.
Check the wiring to make sure that output short circuit does not occur.
Lower the setting of stall prevention operation level. (Refer to Chapter 4 of
(Applied).)
Activate the fast-response current limit operation.
Check RS-485 terminal connection. (under vector control)
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.
Input a start command after the motor stops. Alternatively, set the automatic restart after
instantaneous power failure/flying start function. (Refer to Chapter 4 of
(Applied).)
E.OC3
Overcurrent trip 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.
Check for sudden speed reduction.
Check for output short circuit.
Check for too fast operation of the motor's mechanical brake.
Check if the stall prevention operation level is set too high.
Check if the fast-response current limit operation is disabled.
Check that the power supply for RS-485 terminal is not shorted. (under vector control)
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.
Check if a start command is given to the inverter while the motor is coasting.
Increase the deceleration time.
Check the wiring to make sure that output short circuit does not occur.
Check the mechanical brake operation.
Lower the setting of stall prevention operation level. (Refer to Chapter 4 of
(Applied).)
Activate the fast-response current limit operation.
Check RS-485 terminal connection. (under vector control)
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.
Input a start command after the motor stops. Alternatively, set the automatic restart after
instantaneous power failure/flying start function. (Refer to Chapter 4 of
(Applied))
FR-PU04
Stedy Spd OC
FR-PU07
FR-PU04
OC During Dec
FR-PU07
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