Mitsubishi Electric FR-F800 Instruction Manual page 543

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
542
PROTECTIVE FUNCTIONS
E.OC3
Overcurrent trip during deceleration or stop
When the inverter output current reaches or exceeds approximately 170% (LD rating) / 148% (SLD rating) of
the rated current during deceleration (other than acceleration or constant speed), the protection circuit is
activated and the inverter trips.
• 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 inverter capacity matches with the motor capacity. (PM motor control)
• Check if a start command is given to the inverter while the motor is coasting. (PM motor control)
• Set the deceleration time longer.
• Check the wiring to make sure that output short circuit does not occur.
• Check the mechanical brake operation.
• Lower the stall prevention operation level. Activate the fast-response current limit operation. (Refer to
248.)
• Choose inverter and motor capacities that match. (PM motor control)
• Input a start command after the motor stops. Alternatively, use the automatic restart after instantaneous
power failure/flying start function. (Refer to
E.OV1
Regenerative overvoltage trip during acceleration
If regenerative power causes the inverter's internal main circuit DC voltage to reach or exceed the specified
value, the protection 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 downward acceleration in vertical lift load)
• Check that the Pr.22 Stall prevention operation level is not set to the no load current or lower.
• Check if the stall prevention operation is frequently activated in an application with a large load inertia.
• Set the acceleration time shorter.
Use the regeneration avoidance function (Pr.882 to Pr.886). (Refer to
• Set a value larger than the no load current in Pr.22.
• Set Pr.154 Voltage reduction selection during stall prevention operation = "10, 11". (Refer to
248.)
E.OV2
Regenerative overvoltage trip during constant speed
If regenerative power causes the inverter's internal main circuit DC voltage to reach or exceed the specified
value, the protection 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 set to the no load current or lower.
• Check if the stall prevention operation is frequently activated in an application with a large load inertia.
• Check that acceleration/deceleration time is not too short.
• Keep the load stable.
• Use the regeneration avoidance function (Pr.882 to Pr.886). (Refer to
• 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.
• Set Pr.154 Voltage reduction selection during stall prevention operation = "10, 11". (Refer to
248.)
• Set the acceleration/deceleration time longer. (Under Advanced magnetic flux vector control, the output
torque can be increased. However, sudden acceleration may cause an overshoot in speed, resulting in an
occurrence of overvoltage.)
FR-PU07
page 420.) (PM motor control)
FR-PU07
page
FR-PU07
page
OC During Dec
page
OV During Acc
514.)
page
Stedy Spd OV
514.)
page