Mitsubishi Electric FR-F800, Instruction Manual

Page: 740 / 834

Causes and corrective actions Protective functions
6 - 20
Operation panel
indication
E.THM FR-LU08 Motor overload trip
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 5-291.)
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 5-175.)
Resetting the inverter initializes the internal cumulative heat value of the electronic thermal O/L relay function.
Operation panel
indication
E.FIN FR-LU08 Heatsink overheat
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 5-226.)
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-LU08 Instant Pwr failure
Name Instantaneous power failure (Standard 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 5-409, page 5-417.)
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 5-409, page 5-417.)