Mitsubishi Electric FR-F820-00046, Instruction Manual

Page: 832 / 940

Causes and corrective actions Protective functions
6 - 20
Operation panel
indication
E.OV2 FR-LU08 OV During Cnst Spd
Name Regenerative overvoltage trip during constant speed
Description
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 point
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.
Corrective action
Keep the load stable.
Use the regeneration avoidance function (Pr. 882 to Pr. 886). (Refer to page 5-560.)
Use the brake unit 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, 11".
(Refer to page 5-180.)
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.)
Operation panel
indication
E.OV3 FR-LU08 OV During Dec
Name Regenerative overvoltage trip during deceleration or stop
Description
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 point
Check for sudden speed reduction.
Check if the stall prevention operation is frequently activated in an application with a large
load inertia.
Corrective action
Set the deceleration time longer. (Set the deceleration time which matches the moment of
inertia of the load.)
Make the brake cycle longer.
Use the regeneration avoidance function (Pr. 882 to Pr. 886). (Refer to page 5-560.)
Use the brake unit or power regeneration common converter (FR-CV) as required.
Set Pr. 154 "Voltage reduction selection during stall prevention operation" = "10, 11".
(Refer to page 5-180.)
Operation panel
indication
E.THT FR-LU08 Inv. overload trip
Name
Inverter overload trip
Description
When the temperature of the output transistor element exceeds the protection level while a
current flows at the rated output current level or higher without causing an overcurrent trip
(E.OC
), the inverter output is stopped. (Permissible overload capacity 120% 60 s)
Check point
Check that acceleration/deceleration time is not too short.
Check that torque boost setting is not too large (small).
Check that load pattern selection setting is appropriate for the load pattern of the using
machine.
Check the motor for the use under overload.
Corrective action
Set the acceleration/deceleration time longer.
Adjust the torque boost setting.
Set the load pattern selection setting according to the load pattern of the using machine.
Reduce the load.
Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.