Mitsubishi Electric FR-D720S SC EC Instruction Manual page 446

Causes and corrective actions
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
7 - 10
E.OC3
Overcurrent shut-off during deceleration or stop
When the inverter output current reaches or exceeds approximately 200% of the rated
inverter current during deceleration (other than acceleration or constant speed), the protec-
tive circuit is activated and the inverter trips.
Check for sudden speed reduction.
Check for output short circuit/ground fault.
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.
Check the mechanical brake operation.
Lower the setting of stall prevention operation level.
Activate the fast-response current limit operation. (Refer to section 6.2.4).
E.OV1
Regenerative overvoltage shut-off during acceleration
If regenerative energy causes the inverter's internal main circuit DC voltage to reach or
exceed the specified value, the protective circuit is activated and the inverter trips. The cir-
cuit may also be activated by a surge voltage produced in the power supply system.
Check for too slow acceleration (e.g. during downward acceleration in vertical lift load).
Check that the Pr. 22 "Stall prevention operation level" is not too low.
Decrease the acceleration time.
Check that regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) is used.
(Refer to section 6.19.4)
Set a correct value in Pr. 22 "Stall prevention operation level".
E.OV2
Regenerative overvoltage shut-off during constant speed
If regenerative energy causes the inverter's internal main circuit DC voltage to reach or
exceed the specified value, the protective circuit is activated to stop the inverter output. The
circuit may also be activated by a surge voltage produced in the power supply system.
Check for sudden load change.
Check that the Pr. 22 "Stall prevention operation level" is not too low.
Keep load stable.
Check that regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) is used.
(Refer to section 6.19.4)
Use the brake resistor, brake unit or power regeneration common converter (FR-CV)
as required.
Set a correct value in Pr. 22 "Stall prevention operation level".
FR-PU04
OC During Dec
FR-PU07
FR-PU04
OV During Acc
FR-PU07
FR-PU04
U>>N = konst
FR-PU07
Troubleshooting