Mitsubishi Electric FR-A800 Series Instruction Manual page 789

*4 Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
Operation panel
indication
Name
Description
Check point
Corrective action
*5 Resetting the inverter initializes the internal cumulative heat value of the electronic thermal relay function.
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
*6 10 ms for IP55 compatible models
788
6. PROTECTIVE FUNCTIONS
6.5 Causes and corrective actions
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E.THM
Motor overload trip (electronic thermal relay function)
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. When the inverter is used to drive a
dedicated motor, such as a multiple-pole motor, or several motors, the motor cannot be protected by the
electronic thermal O/L relay. Install an external thermal relay on the inverter output side.
• 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 is activated, 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 and IP55 compatible models only)
If a power failure occurs (or when power input to the inverter is shut off) for longer than 15 ms
instantaneous power failure protective function is activated to shut off the inverter output 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
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
635.)
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
635.)
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FR-LU08 indication Motor Ovrload
*5
page 431.)
FR-LU08 indication Heatsink overheat
page
FR-LU08 indication Instant Pwr failure
*6
.) In some operating status (load magnitude,
page 528.)
473.)
*6
, the
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page 628 and page