Mitsubishi Electric FR-A800 Series Instruction Manual page 787

Operation panel
indication
Name
Description
Check point
Corrective action
*2 Differs according to ratings. The rating can be changed using Pr.570 Multiple rating setting. (Refer to
148% for SLD rating, 170% for LD rating, 235% for ND rating (initial setting), and 280% for HD rating
Operation panel
indication
Name
Description
Check point
Corrective action
*3 Differs according to ratings. The rating can be changed using Pr.570 Multiple rating setting. (Refer to
148% for SLD rating, 170% for LD rating, 235% for ND rating (initial setting), and 280% for HD rating
786
6. PROTECTIVE FUNCTIONS
6.5 Causes and corrective actions
Downloaded from ManualsNet.com
E.OC2
Overcurrent trip during constant speed
When the inverter output current reaches or exceeds approximately 235%
speed operation, the protection circuit is activated and the inverter output is shut off.
• Check for sudden load change.
• Check for a short-circuit in the output circuit.
• Check if the stall prevention operation level is set too high. Check if the fast-response current limit operation is
disabled.
• Check that the power supply for RS-485 terminal is not shorted (under Vector control).
• 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.
• Check that the inverter capacity matches with the motor capacity. (PM sensorless vector control)
• Check if a start command is given to the inverter while the motor is coasting. (PM sensorless vector control)
• Keep the load stable.
• Check the wiring to make sure that output short circuit does not occur.
• Lower the stall prevention operation level. Activate the fast-response current limit operation. (Refer to
431.)
• Check RS-485 terminal connection (under Vector control).
• 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.
• Choose inverter and motor capacities that match. (PM sensorless vector control)
• Input a start command after the motor stops. Alternatively, use the automatic restart after instantaneous power
failure/flying start function. (Refer to
E.OC3
Overcurrent trip during deceleration or stop
When the inverter output current reaches or exceeds approximately 235%
deceleration (other than acceleration or constant speed), the protection circuit is activated and the inverter output
is shut off.
• Check for sudden speed reduction.
• Check for a short-circuit in the output 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 power supply for RS-485 terminal is not shorted (under Vector control).
• 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.
• Check that the inverter capacity matches with the motor capacity. (PM sensorless vector control)
• Check if a start command is given to the inverter while the motor is coasting. (PM sensorless vector 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
431.)
• Check RS-485 terminal connection (under Vector control).
• 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.
• Choose inverter and motor capacities that match. (PM sensorless vector control)
• Input a start command after the motor stops. Alternatively, use the automatic restart after instantaneous power
failure/flying start function. (Refer to
search engine
FR-LU08 indication OC During Cnst Spd
page 635.) (PM sensorless vector control)
FR-LU08 indication OC During Dec
page 635.) (PM sensorless vector control)
*2
of the rated current during constant-
page
page 343.)
*3
of the rated current during
page
page 343.)