Mitsubishi Electric 800 Series Instruction Manual page 578

Abbreviation E.OV2
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
• 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
257.)
• 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.)
Abbreviation E.OV3
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
• Set Pr.154 Voltage reduction selection during stall prevention operation = "10, 11". (Refer to
257.)
Abbreviation E.THT
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 110% 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.
*1 Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
Abbreviation E.THM
Name
Motor overload trip
Description The electronic thermal O/L relay function in the inverter detects motor overheat, which is caused by overload
or reduced cooling capability during low-speed operation. When the cumulative heat value reaches 85% of the
Pr.9 Electronic thermal O/L relay setting, pre-alarm (TH) is output. When the accumulated value reaches the
specified value, the protection circuit is activated to stop the inverter output.
Check point • Check the motor for the use under overload.
• Check that the setting of Pr.71 Applied motor for motor selection is correct. (Refer to
• Check that the stall prevention operation setting is correct.
Corrective action • Reduce the load.
• For a constant-torque motor, set the constant-torque motor in Pr.71.
• Set the stall prevention operation level accordingly. (Refer to
*2 Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
FR-LU08
FR-PU07
FR-LU08
FR-PU07
FR-LU08
FR-PU07
*1
FR-LU08
FR-PU07
*2
OV During Cnst Spd
Stedy Spd OV
page 559.)
OV During Dec
page 559.)
Inv. overload trip
Inv. Overload
Motor overload trip
Motor Ovrload
page 351.)
page 257.)
6. PROTECTIVE FUNCTIONS
6.4 Causes and corrective actions
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