Mitsubishi Electric FR-F820-00077 Instruction Manual page 831

Protective functions
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
FR-F800
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 page 5-180.)
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 page 5-423.)
(PM motor control)
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 page 5-560.)
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 page 5-180.)
Causes and corrective actions
FR-LU08 OC During Dec
FR-LU08 OV During Acc
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