Mitsubishi Electric FR-F800 Series Instruction Manual page 602

Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
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E.OC3
Overcurrent trip during deceleration or stop
When the inverter output current reaches or exceeds approximately 170% (LD rating) / 148% (SLD rating) of the
rated current during 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 inverter capacity matches with the motor capacity. (PM motor control)
• Check if a start command is given to the inverter while the motor is coasting. (PM motor 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
290.)
• Choose inverter and motor capacities that match. (PM motor control)
• Input a start command after the motor stops. Alternatively, use the automatic restart after instantaneous power
failure/flying start function. (Refer to
E.OV1
Regenerative overvoltage trip during acceleration
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 to Pr.886). (Refer to
• Set a value larger than the no load current in Pr.22.
• Set Pr.154 Voltage reduction selection during stall prevention operation = "10 or 11". (Refer to
E.OV2
Regenerative overvoltage trip during constant speed
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 to Pr.886). (Refer to
• Use the brake unit, multifunction regeneration converter (FR-XC), or power regeneration common converter
(FR-CV) as required.
• Set a value larger than the no load current in Pr.22.
• Set Pr.154 Voltage reduction selection during stall prevention operation = "10 or 11". (Refer to
• Set the acceleration/deceleration time longer. (Under Advanced 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.)
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FR-LU08 indication OC During Dec
page 472.) (PM motor control)
FR-LU08 indication OV During Acc
FR-LU08 indication OV During Cnst Spd
page
page 572.)
page
page 572.)
page
6. PROTECTIVE FUNCTIONS
6.5 Causes and corrective actions
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290.)
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290.)
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