Mitsubishi Electric FR-D720 K Series Instruction Manual page 266

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 inverter rated current during
Description deceleration (other than acceleration or constant speed), the protective circuit is activated and the inverter output is
shut off.
 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 82.)
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 output is shut off. The circuit 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 point  Check that the setting of Pr. 22 Stall prevention operation level is not too small.
 Check if the stall prevention operation is frequently activated in an application with a large load inertia.
 Decrease the acceleration time.
 Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). (Refer to page 227.)
Corrective action
 Set the Pr.22 Stall prevention operation level correctly.
 Set Pr.154 Voltage reduction selection during stall prevention operation = "11".
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.
 Check for sudden load change.
Check point
 Check that the setting of Pr. 22 Stall prevention operation level is not too small.
 Check if the stall prevention operation is frequently activated in an application with a large load inertia.
 Keep load stable.
 Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). (Refer to page 227.)
Corrective action  Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
 Set the Pr.22 Stall prevention operation level correctly.
 Set Pr.154 Voltage reduction selection during stall prevention operation = "11".
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 for sudden speed reduction.
Check point
 Check if the stall prevention operation is frequently activated in an application with a large load inertia.
 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 227.)
 Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
 Set Pr.154 Voltage reduction selection during stall prevention operation = "11".
262
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