Mitsubishi FR-A800

Causes and corrective actions
654
PROTECTIVE FUNCTIONS
Operation panel
indication
E.THT FR-PU07 Inv. Overload
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 150% 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.
• 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).
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.
• 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 page 62.)
 Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
Operation panel
indication
E.THM FR-PU07 Motor Ovrload
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 page 438.)
• 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 page 348.)
 Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
Operation panel
indication
E.FIN FR-PU07 H/Sink O/Temp
Name
Heatsink overheat
Description
When the heatsink 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 heatsink 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 page 384.)
Check point
• Check for too high surrounding air temperature.
• Check for heatsink clogging.
• Check that the cooling fan is not stopped. (Check that FN is not displayed on the operation panel.)
Corrective action
• Set the surrounding air temperature to within the specifications.
• Clean the heatsink.
• Replace the cooling fan.
Operation panel
indication
E.IPF FR-PU07 Inst. Pwr. Loss
Name
Instantaneous power failure (Standard models and IP55 compatible models only)
Description
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 page 528, page
534.)
Check point
Find the cause of instantaneous power failure occurrence.
Corrective action
• 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 528, page 534.)
 10 ms for IP55 compatible models