Mitsubishi Electric FR-D720-0.2K-G, Instruction Manual

Page: 261 / 302

258
Causes and corrective actions
Operation panel
indication
E.OC3
FR-PU07 OC During Dec
Name
Overcurrent trip during deceleration or stop
Description
When the drive unit's output current reaches or exceeds approximately 200% of it's rated current or approximately
250% of the rated motor current during deceleration (other than acceleration and constant-speed state), the
protective circuit is activated and the drive unit trips.
Check point
 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 that the drive unit capacity matches with the motor capacity.
 Check if a start command is given to the drive unit while the motor is coasting.
Corrective action
 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 (refer to page 83).
 Choose drive unit and motor capacities that match.
 Input a start command after the motor stops.
Operation panel
indication
E.OV1 FR-PU07 OV During Acc
Name
Regenerative overvoltage trip during acceleration
Description
If regenerative energy causes the drive unit's internal main circuit DC voltage to reach or exceed the specified value,
the protective circuit is activated and the drive unit trips. The circuit may also be activated by a surge voltage
produced in the power supply system.
Check point
 Check for too slow acceleration. (e.g. during downward acceleration in vertical lift load)
 Check that the setting of Pr. 22 Stall prevention operation level is not too small.
Corrective action
 Decrease the acceleration time.
 Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) . (Refer to page 228.)
 Set the Pr. 22 Stall prevention operation level correctly.
Operation panel
indication
E.OV2 FR-PU07 Stedy Spd OV
Name
Regenerative overvoltage trip during constant speed
Description
If regenerative energy causes the drive unit's internal main circuit DC voltage to reach or exceed the specified value,
the protective circuit is activated to stop the drive unit output. The circuit may also be activated by a surge voltage
produced in the power supply system.
Check point
 Check for sudden load change.

Check that the setting of
Pr. 22 Stall prevention operation level
is not too small.
Corrective action
 Keep load stable.
 Use regeneration avoidance function
(Pr. 882, Pr. 883, Pr. 885, Pr. 886)
.
(Refer to page 228.)
 Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
 Set the
Pr. 22 Stall prevention operation level
correctly.
Operation panel
indication
E.OV3 FR-PU07 OV During Dec
Name
Regenerative overvoltage trip during deceleration or stop
Description
If regenerative energy causes the drive unit's internal main circuit DC voltage to reach or exceed the specified value,
the protective circuit is activated to stop the drive unit output. The circuit may also be activated by a surge voltage
produced in the power supply system.
Check point Check for sudden speed reduction.
Corrective action
 Increase the deceleration time. (Set the deceleration time which matches the moment of inertia of the load)
 Make the brake cycle longer.
 Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) . (Refer to page 228.)
 Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.