Mitsubishi Electric FR-A800, Instruction Manual

Page: 906 / 1042

Causes and corrective actions Protective functions
6 - 18
6.5.4 Fault
When a protective function activates, the inverter trips and a fault signal is output.
Operation panel
indication
E.OC1 FR-LU-08 OC During Acc
Name Overcurrent trip during acceleration
Description
When the inverter output current reaches or exceeds approximately 235% of the rated current
during acceleration, the protection circuit is activated and the inverter trips.
Check point
앫
Check for sudden speed acceleration.
앫
Check if the downward acceleration time is too long in a lift application.
앫
Check for output short-circuit.
앫
Check that the Pr. 3 "Base frequency" setting is not 60 Hz when the motor rated frequency is
50 Hz.
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 regenerative driving is not performed frequently. (Check if the output
voltage becomes larger than the V/F reference voltage at regenerative driving and
overcurrent occurs due to increase in the motor current.)
앫
Check that the power supply for RS-485 terminal is not shorted (under vector control).
앫
Check that the encoder wiring and the specifications (encoder power supply, resolution,
differential/complementary) are correct. Check also that the motor wiring (U, V, W) is correct
(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 acceleration time longer. (Shorten the downward acceleration time of the lift.)
앫
If "E.OC1" always appears at start, disconnect the motor once and restart the inverter.
If "E.OC1" still appears, contact your sales representative.
앫
Check the wiring to make sure that output short circuit does not occur.
앫
Set 50 Hz in Pr. 3 "Base frequency". (Refer to page 5-654.)
앫
Lower the stall prevention operation level. Activate the fast-response current limit
operation. (Refer to page 5-84.)
앫
Set the base voltage (rated voltage of the motor, etc.) in Pr. 19 "Base frequency voltage".
(Refer to page 5-654.)
앫
Check RS-485 terminal connection (under vector control).
앫
Check the wiring and specifications of the encoder and the motor. Perform the setting
according to the specifications of the encoder and the motor (under vector control).
(Refer to page 2-61.)
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.) (IPM 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