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Causes and corrective actions
Operation Panel
Indication
E.THT
FR-PU04
FR-PU07
Inv. Overload
Name
Inverter overload trip (electronic thermal relay function) *1
Description
If a current not less than 120% of the rated output current flows and overcurrent trip does not occur
(170% or less), the electronic thermal relay activates to stop the inverter output in order to protect the
output transistors. (Overload capacity 120% 60s inverse-time characteristic)
Check point
· Check that acceleration/deceleration time is not too short.
· Check that Pr. 0 Torque boost setting is not too large (small). (V/F control)
· Check that Pr. 14 Load pattern selection setting is appropriate for the load pattern of the using
machine. (V/F control)
· Check the motor for use under overload.
Corrective action
· Increase acceleration/deceleration time.
· Adjust the Pr. 0 Torque boost setting. (V/F control)
· Set the Pr. 14 Load pattern selection setting according to the load pattern of the using machine. (V/F
control)
· Reduce the load weight.
*1 Resetting the inverter initializes the internal thermal integrated data of the electronic thermal relay function.
Operation Panel
Indication
E.THM
FR-PU04
FR-PU07
Motor Ovrload
Name
Motor overload trip (electronic thermal relay function) *1
Description
The electronic thermal relay function in the inverter detects motor overheat due to overload or reduced
cooling capability during constant-speed operation and pre-alarm (TH display) is output when the
integrated value reaches 85% of the Pr. 9 Electronic thermal O/L relay setting and the protection circuit is
activated to stop the inverter output when the integrated value reaches the specified value. When
running a special motor such as a multi-pole motor or multiple motors, provide a thermal relay on the
inverter output side since such motor(s) cannot be protected by the electronic thermal relay function.
Check point
· Check the motor for use under overload.
· Check that the setting of Pr. 71 Applied motor for motor selection is correct. (V/F control, Simple
magnetic flux vector control)
(Refer to page 122.)
· Check that stall prevention operation setting is correct.
Corrective action
· Reduce the load weight.
· For a constant-torque motor, set the constant-torque motor in Pr. 71 Applied motor. (V/F control,
Simple magnetic flux vector control)
· Check that stall prevention operation setting is correct. (Refer to page 91.)
*1 Resetting the inverter initializes the internal thermal integrated data of the electronic thermal relay function.
Operation Panel
Indication
E.FIN
FR-PU04
FR-PU07
H/Sink O/Temp
Name
Heatsink overheat
Description
If the heatsink overheats, the temperature sensor is actuated to stop the inverter output.
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) in any of Pr. 190 to Pr. 196 (output terminal function selection). (Refer to page 140)
Check point
· Check for too high surrounding air temperature.
· Check for heatsink clogging.
· Check that the cooling fan is stopped. (Check that is 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-PU04
FR-PU07
Inst. Pwr. Loss
Name
Instantaneous power failure
Description
If a power failure occurs for longer than 15ms (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 longer than 100ms, the fault 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 15ms.) 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 162
)
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 162.)