Mitsubishi Electric FR-A800, Instruction Manual

Page: 908 / 1042

Causes and corrective actions Protective functions
6 - 20
Operation panel
indication
E.OC3 FR-LU-08 OC During Dec
Name Overcurrent trip during deceleration or stop
Description
When the inverter output current reaches or exceeds approximately 235% of the rated current
during deceleration (other than acceleration or constant speed), the protection circuit is
activated and the inverter trips.
Check point
앫
Check for sudden speed reduction.
앫
Check for output short-circuit.
앫
Check for too fast operation of the motor's mechanical brake.
앫
Check if the stall prevention operation level is set too high. Check if the fast-response
current limit operation is disabled.
앫
Check that the power supply for RS-485 terminal is not shorted (under vector control).
앫
Check that the rotation direction is not switched from forward to reverse rotation (or from
reverse to forward) during torque control under Real sensorless vector control.
앫
Check that the inverter capacity matches with the motor capacity.
(PM sensorless vector control)
앫
Check if a start command is given to the inverter while the motor is coasting.
(PM sensorless vector control)
Corrective action
앫
Set the deceleration time longer.
앫
Check the wiring to make sure that output short circuit does not occur.
앫
Check the mechanical brake operation.
앫
Lower the stall prevention operation level. Activate the fast-response current limit
operation. (Refer to page 5-84.)
앫
Check RS-485 terminal connection (under vector control).
앫
Prevent the motor from switching the rotation direction from forward to reverse (or from
reverse to forward) during torque control under Real sensorless vector control.
앫
Choose inverter and motor capacities that match. (PM sensorless vector control)
앫
Input a start command after the motor stops. Alternatively, use the automatic restart after
instantaneous power failure/flying start function. (Refer to page 5-571.)
(PM sensorless vector control)
Differs according to ratings. The rating can be changed using Pr. 570 "Multiple rating setting". (Refer to page 5-201.)
148% for SLD rating,170% for LD rating, 235% for ND rating (initial setting), and 280% for HD rating
Operation panel
indication
E.OV1 FR-LU-08 OV During Acc
Name Regenerative overvoltage trip during acceleration
Description
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 point
앫
Check for too slow acceleration. (e.g. during downward acceleration in vertical lift load)
앫
Check that the Pr. 22 "Stall prevention operation level" is not set to the no load current or
lower.
앫
Check if the stall prevention operation is frequently activated in an application with a large
load inertia.
Corrective action
앫
Set the acceleration time shorter.
Use the regeneration avoidance function (Pr. 882 to Pr. 886). (Refer to page 5-685.)
앫
Set a value larger than the no load current in Pr. 22.
앫
Set Pr. 154 "Voltage reduction selection during stall prevention operation" = "10, 11".
(Refer to page 5-84.)