Mitsubishi Electric F700 Instruction Manual page 248

Causes and corrective actions
(4) Major fault
When the protective function is activated, the inverter output is shut off and an alarm is output.
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
240
E.OC1
Overcurrent shut-off during acceleration
When the inverter output current reaches or exceeds approximately 170% of the rated current during
acceleration, the protective circuit is activated to stop the inverter output.
1. Check for sudden acceleration.
2. Check that the downward acceleration time is not long in vertical lift application.
3. Check for output short circuit.
4. Check that the Pr. 3 Base frequency setting is not 60Hz when the motor rated frequency is 50Hz.
5. Check that stall prevention operation is correct.
6. Check that the regeneration is not performed frequently. (Check that the output voltage becomes
larger than the V/F reference voltage at regeneration and overcurrent due to increase in motor
current occurs.)
1. Increase the acceleration time.
(Shorten the downward acceleration time in vertical lift application.)
2. 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.
3. Check the wiring to make sure that output short circuit does not occur.
4. Set the Pr. 3 Base frequency to 50Hz. (Refer to page 80.)
5. Perform a correct stall prevention operation. (Refer to
6. Set base voltage (rated voltage of the motor, etc.) in Pr. 19 Base frequency voltage. (Refer to
80.)
E.OC2
Overcurrent shut-off during constant speed
When the inverter output current reaches or exceeds approximately 170% of the rated current during
constant speed operation, the protective circuit is activated to stop the inverter output.
1. Check for sudden load change.
2. Check for output short circuit.
3. Check that stall prevention operation is correct.
1. Keep load stable.
2. Check the wiring to avoid output short circuit.
3. Check that stall prevention operation setting is correct.
(Refer to page 73.)
E.OC3
Overcurrent shut-off during deceleration or stop
When the inverter output current reaches or exceeds approximately 170% of the rated inverter current
during deceleration (other than acceleration or constant speed), the protective circuit is activated to
stop the inverter output.
1. Check for sudden speed reduction.
2. Check for output short circuit.
3. Check for too fast operation of the motor's mechanical brake.
4. Check that stall prevention operation setting is correct.
1. Increase the deceleration time.
2. Check the wiring to avoid output short circuit.
3. Check the mechanical brake operation.
4. Check that stall prevention operation setting is correct.
(Refer to page 73.)
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 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 with lifting load)
· Decrease the acceleration time.
· Use regeneration avoidance function (Pr. 882 to Pr. 886).
(Refer to page 214.)
FR-PU04
OC During Accs
FR-PU07
page 73.)
FR-PU04
Stedy Spd OC
FR-PU07
FR-PU04
OC During Dec
FR-PU07
FR-PU04
OV During Acc
FR-PU07
page