Mitsubishi Electric 800 Series Instruction Manual page 23

 Overcurrent trip during acceleration
Operation panel
indication
When the inverter output current reaches or exceeds approximately 230%
Description
acceleration, the protection circuit is activated and the inverter output is shut off.
• Check for sudden speed acceleration.
• Check if the downward acceleration time is too long in a lift application.
• Check for output short-circuit.
• Check that the Pr.3 Base frequency setting is not 60 Hz when the motor rated frequency is 50 Hz.
• Check if the stall prevention operation level is set too high. Check if the fast-response current limit operation is
disabled.
Check point • 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.)
• 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 acceleration time longer. (Shorten the downward acceleration time of the lift.)
• If "E.OC1" always appears at start, disconnect the motor once and restart the inverter. If "E.OC1" still appears,
contact your sales representative.
• Check the wiring to make sure that output short circuit does not occur.
• Set 50 Hz in Pr.3 Base frequency.
• Lower the stall prevention operation level. Activate the fast-response current limit operation.
Corrective action
• Set the base voltage (rated voltage of the motor, etc.) in Pr.19 Base frequency voltage.
• 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. (PM sensorless vector control)
Reference FR-E800 Instruction Manual (Function)
*1 Differs according to ratings. The rating can be changed using Pr.570 Multiple rating setting.
170% for LD rating, 230% for ND rating (initial setting) (FR-E820-0175(3.7K) or lower, FR-E840-0095(3.7K) or lower, FR-E860-0061(3.7K) or
lower), and 235% for ND rating (initial value) (FR-E820-0240(5.5K) or higher, FR-E840-0120(5.5K) or higher, FR-E860-0090(5.5K) or higher)
 Overcurrent trip during constant speed
Operation panel
indication
When the inverter output current reaches or exceeds approximately 230%
Description
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 point
• 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.
• Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to forward)
Corrective action
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. (PM sensorless vector control)
Reference FR-E800 Instruction Manual (Function)
*2 Differs according to ratings. The rating can be changed using Pr.570 Multiple rating setting.
170% for LD rating, 230% for ND rating (initial setting) (FR-E820-0175(3.7K) or lower, FR-E840-0095(3.7K) or lower, FR-E860-0061(3.7K) or
lower), and 235% for ND rating (initial value) (FR-E820-0240(5.5K) or higher, FR-E840-0120(5.5K) or higher, FR-E860-0090(5.5K) or higher)
E.OC1
E.OC2
*1
of the rated current during
*2
of the rated current during constant-
2. Protective Functions
2.5 Causes and corrective actions
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