Mitsubishi Electric 800 Series Instruction Manual page 639

Causes and corrective actions
Abbreviation
Name
Description
Check point
Corrective action

Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
Abbreviation
Name
Description
Check point
Corrective action

Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
Abbreviation
Name
Description
Check point
Corrective action
Abbreviation
Name
Description
Check point
Corrective action
638
PROTECTIVE FUNCTIONS
E.THT
Inverter overload trip

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 150% 60 s)
• 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.
• Check that the encoder wiring and the specifications (encoder power supply, resolution, differential/
complementary) are correct. Check also that the motor wiring (U, V, W) is correct (under vector control).
• 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.
• Check the wiring and specifications of the encoder and the motor. Perform the setting according to the
specifications of the encoder and the motor (under vector control). (Refer to
E.THM
Motor overload trip

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 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.
• 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
E.FIN
Heat sink overheat
When the heat sink overheats, the temperature sensor activates, and the inverter output is stopped.
The FIN signal can be output when the temperature becomes approximately 85% of the heat sink overheat
protection operation temperature.
For the terminal used for the FIN signal output, assign the function by setting "26 (positive logic) or 126
(negative logic)" from Pr.190 to Pr.196 (Output terminal function selection). (Refer to
• Check for too high surrounding air temperature.
• Check for heat sink clogging.
• Check that the cooling fan is not stopped. (Check that FN is not displayed on the operation panel.)
• Set the surrounding air temperature to within the specifications.
• Clean the heat sink.
• Replace the cooling fan.
E.IPF
Instantaneous power failure (Standard models only)
If a power failure occurs for longer than 15 ms (this also applies to inverter input shut-off), the instantaneous
power failure protective function is activated to trip the inverter in order to prevent the control circuit from
malfunctioning. If a power failure persists for 100 ms or longer, the fault warning output is not provided, and
the inverter restarts if the start signal is ON upon power restoration. (The inverter continues operating if an
instantaneous power failure is within 15 ms.) In some operating status (load magnitude, acceleration/
deceleration time setting, etc.), overcurrent or other protection may be activated upon power restoration.
When instantaneous power failure protection is activated, the IPF signal is output. (Refer to
Find the cause of instantaneous power failure occurrence.
• Remedy the instantaneous power failure.
• Prepare a backup power supply for instantaneous power failure.
• Set the function of automatic restart after instantaneous power failure (Pr. 57).
(Refer to page 515.)
FR-LU08
Inv. overload trip
FR-PU07
FR-LU08
Motor overload trip
FR-PU07
page 332.)
FR-LU08
H/Sink O/Temp
FR-PU07
FR-LU08
Inst. Pwr. Loss
FR-PU07
page 60.)
page 423.)
page 370.)
page 515.)