Mitsubishi Electric 800 Series Instruction Manual page 24

 Overcurrent trip during deceleration or stop
Operation panel
indication
Description
Check point
Corrective action
Reference
*3 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)
 Regenerative overvoltage trip during acceleration
Operation panel
indication
Description
Check point
Corrective action
Reference
 Regenerative overvoltage trip during constant speed
Operation panel
indication
Description
Check point
Corrective action
Reference
23
2. Protective Functions
2.5 Causes and corrective actions
E.OC3
When the inverter output current reaches or exceeds approximately 230%
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 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.
• 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)
FR-E800 Instruction Manual (Function)
E.OV1
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, Pr.883, Pr.885, and Pr.886).
• Set a value larger than the no load current in Pr.22.
• Set Pr.154 Voltage reduction selection during stall prevention operation = "11".
FR-E800 Instruction Manual (Function)
E.OV2
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 sudden load change.
• 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.
• Check that acceleration/deceleration time is not too short.
• Keep the load stable.
• Use the regeneration avoidance function (Pr.882, Pr.883, Pr.885, and Pr.886).
• Use the brake unit or multifunction regeneration converter (FR-XC) as required.
• Set a value larger than the no load current in Pr.22.
• Set Pr.154 Voltage reduction selection during stall prevention operation = "11".
• Set the acceleration/deceleration time longer. (Under magnetic flux vector control, the output torque can be
increased. However, sudden acceleration may cause an overshoot in speed, resulting in an occurrence of
overvoltage.)
FR-E800 Instruction Manual (Function)
*3
of the rated current during