Mitsubishi Electric FR-E720-008 Instruction Manual page 288

Causes and corrective actions
(4) Fault
When a fault occurs, the inverter trips and a fault signal is output.
Operation panel
E.OC1
indication
Name
Overcurrent trip during acceleration
When the inverter output current reaches or exceeds approximately 230% of the rated current during acceleration, the
Description
protective circuit is activated and the inverter trips.
Check for sudden acceleration.
Check that the downward acceleration time is not long for lifts.
Check for output short-circuit/ground fault.
Check that the Pr. 3 Base frequency setting is not 60Hz when the motor rated frequency is 50Hz.
Check point
Check if the stall prevention operation level is set too high.
Check if the fast-response current limit operation is disabled.
Check that regeneration is not performed frequently. (Check that the output voltage becomes larger than the V/F
reference value at regeneration and overcurrent occurs due to the high voltage.)
Increase the acceleration time. (Shorten the downward acceleration time for lifts.
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.
Check the wiring to make sure that output short circuit/ground fault does not occur.
Corrective action
Set 50Hz in Pr. 3 Base frequency. (Refer to page 97)
Lower the setting of stall prevention operation level.
Activate the fast-response current limit operation. (Refer to page 91)
Set base voltage (rated voltage of the motor, etc.) in Pr. 19 Base frequency voltage. (Refer to page 97)
Operation panel
E.OC2
indication
Name Overcurrent trip during constant speed
When the inverter output current reaches or exceeds approximately 230% of the rated current during constant speed
Description
operation, the protective circuit is activated and the inverter trips.
Check for sudden load change.
Check for output short-circuit/ground fault.
Check point
Check if the stall prevention operation level is set too high.
Check if the fast-response current limit operation is disabled.
Keep load stable.
Check the wiring to make sure that output short circuit/ground fault does not occur.
Corrective action
Lower the setting of stall prevention operation level.
Activate the fast-response current limit operation. (Refer to page 91)
Operation panel
E.OC3
indication
Name Overcurrent trip during deceleration or stop
When the inverter output current reaches or exceeds approximately 230% of the rated inverter current during
Description
deceleration (other than acceleration or constant speed), the protective circuit is activated and the inverter trips.
Check for sudden speed reduction.
Check for output short-circuit/ground fault.
Check point
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.
Increase the deceleration time.
Check the wiring to make sure that output short circuit/ground fault does not occur.
Corrective action
Check the mechanical brake operation.
Lower the setting of stall prevention operation level.
Activate the fast-response current limit operation. (Refer to page 91)
288
FR-PU04
OC During Acc
FR-PU07
FR-PU04
Stedy Spd OC
FR-PU07
FR-PU04
OC During Dec
FR-PU07