Mitsubishi Electric FR-D720-008 Instruction Manual page 256

Causes and corrective actions
Operation panel
E.OC3
indication
Name Overcurrent trip during deceleration or stop
When the inverter output current reaches or exceeds approximately 200% of the rated inverter current during
Description
deceleration (other than acceleration or constant speed), the protective circuit is activated and the inverter trips.
1. Check for sudden speed reduction.
2. Check for output short-circuit/ground fault.
Check point
3. Check for too fast operation of the motor's mechanical brake.
4. Check that stall prevention operation is appropriate.
1. Increase the deceleration time.
2. Check the wiring to make sure that output short circuit/ground fault does not occur.
Corrective action
3. Check the mechanical brake operation.
4. Perform stall prevention operation appropriately. (Refer to page 77).
Operation panel
E.OV1
indication
Name
Regenerative overvoltage trip during acceleration
If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value,
Description
the protective circuit is activated and the inverter trips. The circuit may also be activated by a surge voltage produced
in the power supply system.
1. Check for too slow acceleration. (e.g. during downward acceleration in vertical lift load)
Check point
2. Check that the setting of Pr. 22 Stall prevention operation level is not too small.
1. Decrease the acceleration time.
Corrective action Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). (Refer to page 224).
2. Set the Pr.22 Stall prevention operation level correctly.
Operation panel
E.OV2
indication
Name
Regenerative overvoltage trip during constant speed
If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value,
Description
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.
1. Check for sudden load change.
Check point
2. Check that the setting of Pr. 22 Stall prevention operation level is not too small.
1. Keep load stable.
Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). (Refer to page 224).
Corrective action
Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
2. Set the Pr.22 Stall prevention operation level correctly.
Operation panel
E.OV3
indication
Name
Regenerative overvoltage trip during deceleration or stop
If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value,
Description
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 point Check for sudden speed reduction.
Increase the deceleration time. (Set the deceleration time which matches the moment of inertia of the load)
Make the brake cycle longer.
Corrective action
Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). (Refer to page 224).
Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
252
FR-PU04
OC During Dec
FR-PU07
FR-PU04
OV During Acc
FR-PU07
FR-PU04
Stedy Spd OV
FR-PU07
FR-PU04
OV During Dec
FR-PU07