Mitsubishi Electric FR-A720-0.4K Instruction Manual page 151

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
Operation Panel
Indication
Name
Description
Check point
Corrective action
144
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.
· 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. Activate the fast-response current limit operation. (Refer to
Chapter 4 of the Instruction Manual (Applied).)
· 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.
E.OV1
Regenerative overvoltage trip 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 to stop the inverter output. The circuit may also be
activated by a surge voltage produced in the power supply system.
· Check for too slow acceleration. (e.g. during descending acceleration in vertical lift load)
· Check that the Pr. 22 Stall prevention operation level is not lower than the no load current.
· Decrease the acceleration time.
· Use regeneration avoidance function (Pr. 882 to Pr. 886). (Refer to Chapter 4 of
Manual (Applied).)
· Set a value larger than the no load current in Pr. 22 Stall prevention operation level.
E.OV2
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, 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 lower than the no load current.
· Keep load stable.
· Use regeneration avoidance function (Pr. 882 to Pr. 886). (Refer to Chapter 4 of
Manual (Applied).)
· Use the brake unit or power regeneration common converter (FR-CV) as required.
· Set a value larger than the no load current in Pr. 22 Stall prevention operation level.
E.OV3
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, 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 speed reduction.
· Increase the deceleration time. (Set the deceleration time which matches the moment of inertia of the load)
· Longer the brake cycle.
· Use regeneration avoidance function (Pr. 882 to Pr. 886). (Refer to Chapter 4 of
Manual (Applied).)
· Use the brake unit or power regeneration common converter (FR-CV) as required.
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
the Instruction
the Instruction
the Instruction